• A long learning curve exists for some areas of expertise and image resolution is dependent on the machine that is available. Ultrasound does not give information of structure behind a bone and also gas flled structures.

#### **Specifc Role of High-Resolution Ultrasonography (HRUSG) in the Maxillofacial Region**

HRUSG is a grossly underutilized modality in evaluating lesions of the maxillofacial region. This is due to the lack of awareness of its application. The tissues in the maxillofacial region are ideal for sonographic evaluation and hence is widely applied to help diagnose a number of clinical conditions. It can serve as the best possible initial parallel imaging investigation for all the superfcial soft-tissue structures of head and neck region.

It is noninvasive and does not involve use of radiation. There are no contraindications to the use of ultrasound, and it can even be performed as a bed side examination. No prior specifc preparation is required except for shaving of the beard, which might hamper the study. The study results are immediately available, and it is an excellent modality for evaluating various soft-tissue planes of the cheek. Evaluation of various anatomical spaces such as superfcial masticator space, parotid space, carotid space, superfcial neck spaces, visceral space, foor of the mouth, and all the infrahyoid neck spaces like the submandibular and sublingual spaces are possible using HRUSG, as are also pathologies like pre- and paravertebral abscesses, cellulitis, Ludwig's angina, and ranula [9].

High-resolution ultrasound is also capable of evaluating the nature of lymph nodes, assessing fuid and solid components and also assessing tissue vitality. Procedures like drainage of abscesses and biopsies can be conveniently performed under ultrasound guidance. Being a highly economical imaging modality, it is excellent for follow-up studies, excellent as a screening method, and at most times proves to be the conclusive examination [9].

#### **Drawbacks of Ultrasound Examination of the Maxillofacial Region**

Drawbacks include diffculty in assessing structures behind bony elements and structures containing gas. In case of huge masses, only partial information may be obtained, while shortnecked individuals and obese patients are diffcult to evaluate. Structures at the base of the skull cannot be evaluated as are structures medial to ramus. Another limitation is that ultrasound cannot provide information about structures behind bone or any gas-flled structure. Scanning using a hockey stick probe might help overcoming this limitation. Scans need to be performed by individuals having vast experience and expertise.

There needs to be an increase in awareness regarding the developments in the application of HRUSG in the maxillofacial region and a close interaction between the surgeon and the sonologist for creating an atmosphere of better understanding among them.

#### **8.9.3 Thermography**

Medical thermography is used for early preclinical diagnosis and treatment of homeostatic imbalances. It is noninvasive and safe since it does not use any radiation. It makes use of body heat to diagnose a wide range of health conditions. By using high-speed computers and thermal imaging cameras, body heat is processed and recorded in the computer as an image map that can be analyzed. The analysis is based on determining the presence of abnormal hot and cold areas that can relate to different conditions.

#### **Applications in the Maxillofacial Region**

A variety of conditions related to blood fow in the head and neck vessels can be assessed by thermal imaging. Easy visualization of facial blood vessels by thermography is possible because of its superfcial location. Common venues of thermographic use in the head and neck region include evaluation of pain related to differentiation of different types of headache, facial nerve injury following a blow to the face or an accident, and visualization of disorders of the temporomandibular joint.

### **8.10 Role of Chest Radiograph in the Practice of Maxillo Facial Surgery**

One of the most frequently requested investigations by an MFS is the Chest radiograph. Hence, interpretation of chest radiographic fndings is of prime importance in determining the patient's clinical status.

#### **8.10.1 Chest Radiographic Evaluation for Optimum Diagnostic Quality**

An ideal chest radiograph, in terms of quality, is one that fulflls the following criteria (Fig. 8.24)

	- *Purpose*—Avoiding problems related to improper positioning that can obscure certain lung regions like the hila and mediastinal lines, can prevent clarity of borders, or can result in distorted position of structures like the trachea, which can be misinterpreted as a paratracheal mass.
	- *Ideal radiograph*—The vertebral spinous processes are equidistant from the medial ends of the clavicle
	- *Purpose*—avoids superimposition of scapulae over the lung felds
	- *Ideal radiograph*—Medial border of the scapulae should be out of the lung feld
	- *Purpose*—inclusion of entire lung felds from apex to diaphragmatic domes
	- *Ideal radiograph*—must include the lower neck, both shoulders, lateral chest walls, and both diaphragms, including upper abdomen
	- *Purpose*—Proper patient and radiographic verifcation.
	- *Ideal radiograph*—must include the patient name, medical record number, date of acquisition, and the side marker (the most important of all)
	- *Purpose*—Clear visualization of the normal anatomy or presence of any pathology
	- *Ideal radiograph*
		- Posterior third of ribs faintly visible through heart shadow
		- Intervertebral spaces faintly visible through the heart shadow
		- Obtained in deep inspiratory effort as revealed by position of diaphragms

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 8.24** A Normal Chest Radiograph

### **8.10.2 Reading a Chest Radiograph: Interpretation Basics**

The aim of reading a chest radiograph is to scan the whole image in a methodical way such that no anatomical part included in the radiograph is missed. While interpreting the radiograph, it is necessary for the interpreter to actually feel the structural component of the anatomical part being evaluated.

If, for example, a rib is being evaluated it needs to be traced, consciously keeping in mind, its component parts, the two cortical margins seen as white lines representing compact bone and the less dense central component representing marrow with fne normal trabeculae. This is in addition to evaluation of its number and shape. This meticulous evaluation will prevent missing of rib lesions and interpretation of the lesion is easier with prior knowledge of possible pathologies that affect ribs.

Many ways of methodical scanning have been documented in literature. The WHO-recommended method involves chest radiographic evaluation by beginning at one corner of the flm, continuing to horizontally scan till the other corner, followed by sliding down and again continuing to scan toward the other edge, continuing till the whole of the radiograph has been scanned. As part of the examination, both sides of the chest must be compared.

It can be likened to the painting of a wall by a professional painter with a perfect fnishing touch. Once the initial primary scan is complete, specifc areas called the lawyer's zone or hidden areas of the lung need to be looked over a second time. These areas include both the hilar regions, both cardiophrenic regions, both apical and clavicular regions, and fnally also through the heart and diaphragms.

#### **8.10.3 Requesting a Chest Radiograph: Clinical indications**

#### **<IP_ADDRESS> Preoperative evaluation**

#### **<IP_ADDRESS> Intra- / Postoperative recovery room**

#### **8.10.4 "The Chest Radiograph. A Mysterious Treasure"…the More you Search, the More you Find!!**

#### **<IP_ADDRESS> Consolidation**

It is one of the most common terminologies used in Radiology. Clinicians and pathology textbooks, however, commonly use the term pneumonia. Any infection of the lung parenchyma is broadly referred to as pneumonia. Involvement of the alveolar components of the lung parenchyma by the infection is called parenchymal consolidation [10]. It is a disease process in which the air normally present within the small lung air sacs (alveoli) is replaced by liquids like pus, blood, or other fuids, or solids like tumor cells.

Radiologically, consolidation appears opaque [11]. Normally, the alveoli are flled with air and so the normal opaque pulmonary vasculature can be visualized against the dark background of air. However, as discussed earlier, the replacement of the air spaces by any form of fuid or solid material makes the normally visualized pulmonary vessels inapparent with the air containing bronchi being visualized against the opaque background, which is called the air bronchogram (Fig. 8.25a–c).

The consolidation process involving a single lobe and limited by a fssure is called as lobar pneumonia, while the involvement of the entire lung is known as whole-lung consolidation. At times, the process is not as uniform and is distributed in the form of patchy opacities with intervening nonopacifed alveoli, an appearance referred to as the air alveologram, which is seen in Bronchopneumonia.

#### **Pulmonary Edema**

Maxillofacial surgeons are often faced with the problem of patients going into a state of sudden breathlessness in the postoperative recovery room for which the MFS asks for a portable chest radiograph. One of the most common causes of sudden breathlessness in the postoperative recovery room is pulmonary edema. The common confusion for which MFS postgraduates seek the radiologist's opinion is whether the cause of breathlessness is bronchopneumonia or aspiration bronchopneumonia.

In case of acute cardiogenic pulmonary edema caused either due to left ventricular failure or fuid overload, the characteristic radiographic abnormality would reveal bilateral symmetrical areas of consolidation predominantly in the

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 8.25** (**a**) and (**b**) Consolidation: Homogeneous opacities with "Air-bronchogram" sign. (**c**) Schematic diagram showing group of alveoli flled with fuid replacing normal air

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 8.26** (**a**) Congestive cardiac failure with cardiomegaly and pulmonary edema. (**b**) Resolution of pulmonary edema after treatment

perihilar and lower lung zones [10] (Fig. 8.26a, b). Noncardiogenic pulmonary edema caused by different pathologies, including fuid overload, acute glomerulonephritis and adult respiratory distress syndrome among others, affects the permeability of the pulmonary capillary membrane (Fig. 8.27). The distribution can vary depending on the position of the patient. The opacities seen on the portable radiograph should not be confused with the appearance of pneumonia (Fig. 8.28).

Rare causes of unilateral pulmonary edema, including raised intracranial pressure and the administration of fuid through the central venous catheter inadvertently placed in the pulmonary artery, need to be kept in mind as well.

#### **Atelectasis**

Diminished air within the lung associated with reduced lung volume is termed atelectasis manifesting radiologically as pulmonary opacity accompanied by volume loss. The causes are varied, including resorption, relaxation, adhesive and cicatrization atelectasis. Of these, the form of atelectasis a maxillofacial surgeon commonly deals with is resorption atelectasis, where there is an obstruction in the communication between the alveoli and trachea. The obstruction may be at any level from the common air way to the segmental bronchus; however, common air way obstruction resulting in bilateral atelectasis is a rare occurrence [11]. Radiologically, the appearance is that of a homogeneous opacity without an air bronchogram sign, with loss of lung volume and displacement of structures toward the opacity.

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 8.27** Noncardiac pulmonary edema in a patient with renal failure

The maxillofacial surgeon commonly comes across similar radiographs in the postoperative recovery room. The commonest cause of this is the inadvertent placement of the endotracheal tube into one bronchus, causing occlusion of the other bronchus, and resulting in atelectasis as a

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 8.28** Aspiration Bronchopneumonia

consequence. Early detection and diagnosis with readjustment of the endotracheal tube is bound to be life saving, helping prevent long-term complications (Fig. 8.29a–c). Thick mucus plugs are other common occluding elements, seen in postoperative recovery rooms resulting in lobar or segmental opacities with loss of volume. Again, early detection and good respiratory physiotherapy are keys to improved lung compliance with a radiograph taken at a later date as follow-up.

#### **Relaxation Atelectasis**

Normally negative intrapleural pressure is caused by competing thoracic pressures. Lung elasticity and surface tension of the alveolar fuid create an inward tension, pulling the lung inward, which is countered by opposing forces from the pleural fuid and thoracic wall, the pleural cavity surface tension, and the parietal pleural attachment to the thoracic wall causing outward pull of the lungs. The outward pull is slightly higher than the inward pull with a negative intrapleural pressure of about -4 mm of Hg. When this intrapleural negative pressure is lost as occurs commonly in cases of pneumothorax or pleural effusion, the lung has a natural tendency to recoil, with the loss of lung volume being proportional to the amount of air or fuid collected in the pleural space [11].

#### **Pneumothorax**

The presence of air in the pleural space is called pneumothorax, the most common cause of which is trauma either accidental or iatrogenic. In the absence of such causes, it is called spontaneous pneumothorax. Radiological fndings of pneumothorax include increased peripheral translucency, absence of lung markings within this area of translucency, and the identifable visceral pleural margin of the collapsed lung (Figs. 8.30 and 8.31). The detection of a pneumothorax should prompt the search for an underlying cause like a fractured rib or a ruptured bulla or iatrogenic causes like a central venous catheter procedure. Associated lesions like pneumomediastinum and surgical emphysema should also be looked for.

A maxillofacial surgeon might have to read supine portable radiographs of patients presenting with clinical signs suggesting respiratory distress and the presence of pneumothorax might be missed. In such a scenario, the MFS should look for radiographic evidence of pneumothorax at sites adjacent to the diaphragmatic silhouettes on either side and the cardiophrenic and costophrenic angles and he should also be able to appreciate the appearance of an exceptionally sharp cardiac border [11]. The MFS needs to be aware that air trapped within the skin folds can mimic pneumothorax (Fig. 8.32).

Identifcation of an air fuid level would prompt the diagnosis of a hydropneumothorax. It is diffcult to characterize the nature of the fuid as being transudate, exudate, blood, or chylous. An MFS may be unable to diagnose a hydropneumothorax, on an AP supine portable radiograph as the fuid level will not be identifed. Here, the collapsed lung tends to foat on the fuid, which is dependent posteriorly giving a veil effect (Fig. 8.33).

#### **Pneumomediastinum**

It is the collection of air within the pleural boundaries of the mediastinum and can arise secondary to barotrauma from mechanical trauma, intrathoracic, or iatrogenic trauma and infection or can occur spontaneously. A radiographic diagnosis of pneumomediastinum requires depiction of normal anatomic structures being outlined by air as they leave the mediastinum. The mediastinal air can cause elevation of the thymus, collect anterior or posterior to the pericardium, surround the pulmonary artery or its branches, or can collect adjacent to the major aortic branches or major bronchi (Fig. 8.34).

Most cases of pneumomediastinum described in maxillofacial surgery literature are as a result of dissection of air down the fascial planes of the neck. Chest radiographic fndings need to be carefully examined to make the diagnosis of pneumomediastinum, which is crucial to the MFS in planning appropriate treatment of affected patients. On rare occasions, a signifcant amount of air in the mediastinum can cause vessel or tracheal obstruction and induce symptoms and signs of tamponade and decreased venous return.

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 8.29** (**a**) Whole lung collapse: Left hemithorax is homogenously opaque with loss of volume of left lung with displacement of mediastinum to left. Note: Abnormal placement of endotracheal tube blocking the (Lt.) Bronchus. (**b**) Schematic diagram showing loss of volume of alveoli as seen in collapse with absence of air. (**c**) Reversion of normal left lung aeration after repositioning of endotracheal tube

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 8.30** Left-sided pneumothorax

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**Fig. 8.32** Right-sided pseudopneumothorax due to air trapped in skin fold

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**Fig. 8.31** Right-sided tension pneumothorax

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 8.33** Right-sided hemopneumothorax with multiple rib fractures as seen in supine radiograph

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 8.35** (**a**) and (**b**). Surgical emphysema with

pneumothorax

**Fig. 8.34** Pneumomediastinum. Air around the pulmonary artery and heart.

#### **Surgical Emphysema**

Though subcutaneous emphysema or surgical emphysema actually means gas in the subcutaneous tissues, it also includes soft-tissue emphysema that dissects into the deeper soft tissues and musculature along fascial planes. The translucent air spreads over the chest wall and axilla into the root of the neck. Fascial planes clearly outline the pectoralis muscle and neurovascular bundles in neck (Fig. 8.35a, b). If trauma is the cause, the gas by itself may not need treatment, but its identifcation is of importance as it may be the only indication of the presence of other serious injuries requiring urgent management. Surgical emphysema can uncommonly occur as a serious complication of oral and maxillofacial surgical procedures. It may also occur following teeth extraction, endodontic treatment, or procedures like restorative dentistry, periodontal and temporomandibular joint surgery, or facial fracture repair.

#### **Pulmonary Nodules**

For all intents and purposes, a nodule seen in the lung (especially in the lower zones) should be considered as metastasis unless proven otherwise, by a maxillofacial surgeon.

©Association of Oral and Maxillofacial Surgeons of India

*Pulmonary nodules* can be characterized, based on some signature fndings. In the absence of these fndings, the nodule remains nonspecifc. Common causes of pulmonary nodules are granulomas, bronchogenic cysts, hydatid cysts, hamartomas, pulmonary hematoma following laceration, rheumatoid nodules, fungal granulomas, and pulmonary metastasis.

*Tuberculomas* usually range in size from 1 to 3 cm in diameter, have central calcifc lesions, and are surrounded by satellite scarred lesions. They are commonly seen in the upper zones, but they can occur anywhere in the lung (Fig. 8.36).

*Bronchogenic cysts* are well-defned nodules, around 3 to 4 cm in size, usually seen in the parahilar region, and are sometimes purely in the mediastinum (Fig. 8.37a–e).

*Hamartomas* are nodules that can occur anywhere in the lung having well-defned margins with central popcorn-like calcifcation (Fig. 8.38a, b).

*Hydatid cysts*, too, can occur anywhere in the lung. They have a stenciled outline and vary in size from 1 to 10 cms. The radiographic air crescentic sign is pathognomonic of a hydatid cyst, appearing like the arc of the moon caused by the separation of the endocyst from the exocyst. Continued separation of the endocyst from the exocyst results in an air fuid level typically called the 'water lily' appearance. Pulmonary hydatid cysts do not calcify.

Presence of a solitary nodule in the lower lung without any characteristic fndings makes pulmonary metastasis a strong possibility, which should be further evaluated with imaging and HPR. Multiple nodules of varying sizes in the lower zones are very much suggestive of pulmonary metastasis.(Fig. 8.39a, b).

#### **Role of Chest Radiograph in Cases Developing Sudden Onset of Breathlessness in Postoperative Period**

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 8.36** Pulmonary Nodule—Tuberculoma

A maxillofacial surgeon should be capable of identifying all of these causes of sudden onset of breathlessness in a postoperative patient in the event of the absence of availability of expert radiological opinion and act accordingly. They also need to be aware that patients on ventilators may develop ventilator-dependent complications.

#### **A glance into the future of imaging for Maxillofacial Surgeons**

	- This is a modifed MRI study that helps in
	- Prediction of whether the primary tumor is benign or malignant (possible in 80 to 90% cases).
	- Differentiation of reactive versus malignant adenopathy.

This modality is still in the preliminary stage and needs further study.

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 8.37** (**a**), (**b**), and (**c**). Preop chest radiographs of a patient with cleft lip presenting with dyspnea, more with changing position. (**d**) **and** (**e**) Mediastinal mass—Bronchogenic Cyst confrmed on CT

**Fig. 8.38** (**a**) Pulmonary Nodule-Hamartoma. (**b**) Confrmed on CT

©Association of Oral and Maxillofacial Surgeons of India

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 8.39** (**a**) and (**b**). Pulmonary metastasis

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 8.40** (**a**), (**b**), and (**c**). Foreign body, a coin in the cervical esophagus

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 8.41** Abnormal placement of endotracheal tube with collapse of left lobe

#### **8.11 Role of High Resolution Ultrasonography (HRUSG) as a Diagnostic Aid in the Practice of Maxillofacial Surgery**

#### **8.11.1 Preface**

Primarily the use of HRUSG in the maxillofacial region is directed toward investigation of the cheek and the structures adjacent to it. Despite the layers of the cheek and the adjacent structures having a classical sonographic appearance, literature available on HRUSG of the cheek is limited. Having proper understanding of the relevant anatomy is critical in discerning the wide range of diseases affecting this region. Evaluation of these lesions by ultrasound is possible only once the normal ultrasound anatomy at various levels is defned and a comparison of the suspicious lesion with the normal expected appearance is made. An original attempt toward this goal was made at our institute with comparison of normal cadaveric sections at corresponding levels taken by HRUSG.

High-resolution ultrasonography has broad applications in the maxillofacial region especially in the cheek, which include evaluations of the unilateral or bilateral swollen cheek painful or pain less, restricted mouth opening, painful chewing without obvious clinical fndings, and varied causes of facial swelling. Since early detection decisively infuences patient prognosis in case of malignancy, it is one of the prime concerns in a presenting patient. Further, differentiation of lesions as being of benign, malignant, infective, or infammatory etiology is important in deciding on a treatment plan. HRUSG should however be used to complement and not replace other imaging modalities as it does have its limitations.

Compared to other facial components, the cheek is predominantly composed of adipose tissue and is relatively small in size. Swelling of the cheek is easily visible and palpable in most patients presenting with cheek masses. Most lesions have nonspecifc characteristics on computed tomography (CT) and magnetic resonance imaging (MRI). In contrast, HRUSG is ideal for evaluation of cheek lesions, because of its capability to differentiate between tissues like skin, fat, muscle, gland, ducts, and vessels especially since bony and gaseous interfaces are absent. Further, the superfcial location of the cheek makes it easily accessible to ultrasound. Vestibule can be evaluated with fruit jelly technique obliterating the void space.

This short review attempts to aid the MFS in his understanding of HRUSG of the maxillofacial region, with special reference to the cheek.

#### **8.11.2 Gross Cheek Anatomy**

In simple terms, the cheek is the feshy portion of the face, below the eye, extending from the angle of the mouth to the ear. Anatomically, it pertains to the buccomasseteric region comprising the buccal space and its contents, masseteric and buccinator muscles, the buccal fat pad, and Stenson's duct.

The region is continuous anteriorly with the lips. Its external anterior demarcation is formed by the nasolabial fold and groove extending from the side of the nose to the angle of the mouth. The mucosa lining the inner aspect of the cheek adheres to the buccinator muscle, while the gingival mucosa covers the mandibular and maxillary alveolar processes. The gingivobuccal sulcus is the junction formed between the gingival and buccal mucosae. The vestibule is the region of the mouth between the teeth, lips, and cheek, which is bound superiorly and inferiorly by buccal mucosal refections onto the mandible and maxilla. Posteriorly the vestibule is continuous with the oral cavity proper (Fig. 8.42) [12, 13].

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 8.42** Anatomical layers of the cheek

#### **8.11.3 Floor of Mouth, Anatomy (Relevant to HRUSG)**

The part of the oral cavity located underneath the tongue is called the foor of the mouth and it can be involved by a myriad of pathological processes. Superfcial lesions involving the mucosal surface are easily visualized and may not need imaging. Disease involving the deeper structures of the foor needs to be evaluated by imaging, and HRUSG is many times the frst line of investigation because of its superior soft-tissue differentiation capability, thus allowing for clear depiction of contents of the foor [14].

Infammatory processes, malignancies, and vascular abnormalities can affect the foor contents, while certain conditions like ranula and obstruction of the submandibular gland are specifc to this location [14].

### **8.11.4 Defning the HRUSG Anatomy of Maxillofacial Region (Predominantly Cheek)**

#### **Normal Ultrasound Cheek**

Various cheek layers have varying sonographic echogenicity and echotexture, and hence ultrasound is an invaluable tool in the characterization and localization of cheek lesions.

Depending on tissue density, the sound wave transmission, absorption, or refection capability of each tissue varies. Tissues, having high water content like blood, appear black and are called anechoic because they conduct sound waves well. In contrast, tissues that are poor conductors refect most of the sound wave energy back to the transducer appearing bright and are termed hyperechoic, examples of which include bones, tendons, and fascial planes. Tissues like muscle refect less of the sound wave energy and have a hypoechoic appearance. In the cheek, the mucosal and submucosal layers appear hyperechoic, the mucosa more so. Muscle tissue appears hypoechoic, while fatty tissue appears echogenic (Fig. 8.43).

Compared to other imaging modalities, ultrasound has proven to be superior as regards identifcation of small lesions, detection of lesion plane, and lesion characterization (Fig. 8.44).

The cheek layers and neighboring structures that can be identifed by HRUSG are.

#### **Cheek**

**Fig. 8.43** Normal Cheek/ Buccal layers on ultrasound

#### **Neighboring Structures**

#### **8.11.5 Techniques of HRUSG of Cheek**

For ultrasound examination, the cheek is considered to be a rectangular area bordered as follows (Fig. 8.45).

Various techniques, including the resting (neutral) and Puffed (Blow out) cheek technique, the tongue touch technique, and fruit jelly technique, were experimented with, each having their own advantages and limitations [15].

©Association of Oral and Maxillofacial Surgeons of India

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 8.44** (**a**-**d**) Cheek anatomy—a comparison. Comparative cheek anatomy- (**a**) cadaveric specimen, (**b**) CT, (**c**) MRI, and (**d**) Ultrasound

©Association of Oral and Maxillofacial Surgeons of India

#### **Fig. 8.45** Area of Cheek ultrasound study

	- Patient is instructed to blow, and ultrasound is performed in puffed cheek status.
	- Images obtained in axial and coronal planes. Advantage: Improved visibility of cheek layers and accurate defnition of lesion size.

Limitation: Occurrence of mirror image artifact. Less sensitivity in evaluation of lesions of the vestibule (gingivobuccal sulcus).

	- Patient is instructed to feel the cheek lesion with the tongue.
	- Lesion is brought closer to the probe creating a better acoustic window.
	- Lesions of the superfcial buccal mucosa and tongue lesions on its anterior half and corresponding lateral borders can be evaluated better.

Advantage: Better visualization of lesion details. Limitation: Inaccessibility to tongue lesions along the posterior half and corresponding lateral borders.

### (c) *Fruit Jelly Technique*.

(Figs. 8.49a, b, and 8.50a–d)

#### Advantages:

Limitation: Inability to evaluate lesions involving far posterior aspect of Vestibule.

**Fig. 8.46** Cheek layers by "Puffed Cheek" Technique. (1) Mucosa. (2) Submucosa. (3) Buccinator. (4) Buccal fat. (5) Subcutaneous tissue. (6) Skin

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©Association of Oral and Maxillofacial Surgeons of India

**Fig. 8.47** (**a**, **b**) Cheek layers by "Puffed Cheek" Technique. m-mucosa, sm-submucosa, b-buccinator, bf-buccal fat

©Association of Oral and Maxillofacial Surgeons of India

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 8.49** (**a**) Axial panoramic (**b**) Coronal Cheek layers by "Fruit Jelly" Technique. (1) Jelly (2) Angle of mouth (3) Alveolar process (4) Masseter (5) Mandible (6) Parotid (7) Maxilla (8) Mandible (Asterisk)- Upper and lower gingivobuccal sulcus

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 8.50** (**a, b, c**, and **d**).Cheek layers by "Fruit jelly" Technique. Panoramic axial slices. Coronal slices showing superior and inferior vestibules along with layers of cheek/alveolar surfaces

### **8.11.6 Case Presentation**

#### **HRUSG Cheek: Scope of Use and Limitations**

Scope of practice of HRUSG cheek includes

#### **Limitations**

#### **Clinical Conditions that Can Be Evaluated**

#### **Notifable Lesions**

#### **1. Infammatory / Infective Pathology**

(a) *Cheek cellulitis with evolving abscess (Fig. 8.51a–d).*

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**Fig. 8.51** (**a, b, c,** and **d**).Cheek cellulitis with evolving abscess. Diffuse soft-tissue thickening, edema of deep subcutaneous fat plane, edematous buccinators and submucosal plane with mild echogenic tracking collection within the fascial planes

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 8.53** (**a**–**d**) Chronic osteomyelitis mandible. HRUSG showing hyperechoic lesion with hypoechoic halofungal granuloma

**Fig. 8.52** (**a, b** and **c**). Cheek abscess. Focal organized thick echogenic collection in the deep subcutaneous plane with minimal extension into buccinator muscle (45 year old male, with habit of chewing betel nut)

©Association of Oral and Maxillofacial Surgeons of India

#### **2. Benign Pathology.**

#### **3. Malignant Pathology.**

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#### **4. Vascular malformations**

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 8.55** (**a, b** and **c**) Oral submucosal fbrosis. Axial slice showing thickening of the submucosal layer in OSMF in comparison to the normal thickness of the submucosal layer

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 8.56** (**a**) and (**b**). Tiny calculus of about 1.2 mm revealed by HRUSG at Stenson's duct opening. (Pain while chewing food. No swelling)

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 8.57** (**a**) and (**b**). Intraoral Mucocele. Well-defned cystic lesion in the submucosal layer with internal minimal echogenic contents. Possible diagnosis of mucocele given, later confrmed by HPR. (35 year old female, presenting with right-sided cheek swelling and mild pain)

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 8.58** (**a, b, c,** and **d**). Cheek lymphangioma. Fluid-flled cystic lesion deep to submucosal layer with deep space extension adjacent to the masseter medial to mandibular ramus MRI coronal T2W imaging confrms hyperintense fuid along left side of cheek extending into infratemporal fossa (25 year old male, presenting with soft, painless swelling of left cheek)

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 8.59** (**a**) and (**b**). Epidermoid cyst of cheek. Well-defned complex cystic lesion in the subcutaneous plane with internal echogenic contents causing displacement of underlying cheek layers (28 year old male presenting with painless left cheek swelling)

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**Fig. 8.60** Intramasseteric Lipoma. Elongated intramuscular lesion isoechoic to the subcutaneous fat with internal echogenic strands representing intramasseteric lipoma. (30 year old female, presenting with painless swelling of cheek)

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**Fig. 8.61** (**a**) and (**b**). Stenson's duct calculus. Hyperechoic calculus in the Stenson's duct with nondilated duct proximal to the calculus (23 year old male, with history of intermittent pain on right side of the cheek)

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 8.63** Buccal mucosal malignancy with intact submucosa and buccinator. Growth predominantly involving the mucosa, distinct from submucosa (between asterisk) buccinator (star) appears normal. (55 year old male with irritating nonhealing ulcer left cheek)

©Association of Oral and Maxillofacial Surgeons of India

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 8.64** (**a, b,** and **c**). Early Carcinoma of the cheek better seen on HRUSG than by CT slice at the same level. Proved by Histopathology (52 year old male with squamous cell carcinoma of the buccal mucosa)

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 8.65** Buccal mucosal carcinoma

**Fig. 8.66** (**a**) Buccal mucosal carcinoma (Resting phase). (**b**) Buccal mucosal carcinoma (Fruit jelly technique). Patient was unable to perform the puffed cheek technique. Mass involving the mucosa, submucosa, buccinator, and fat

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 8.67** (**a, b** and **c**). Superior vestibular malignant mass. Coronal sections revealing predominantly hypoechoic, superior vestibular mass with irregular margins extending into cheek layers and causing underlying bony destruction. Comparison between (**a**) neutral cheek, (**b**) fruit jelly Technique and (**c**) CT

©Association of Oral and Maxillofacial Surgeons of India

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 8.68** (**a**) and (**b**). Tongue malignancy against cheek wall. Irregular lesion along the Right anterolateral margin of the tongue by "Tongue touch" technique. Few enlarged lymph nodes are also noted with loss of hilar anatomy representing metastatic lymph nodes. (40 year old male, with complaint of swelling over the tongue)

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 8.69** (**a, b, c,** and **d**) Buccal malignancy with mandibular infltration. Heterogeneous mass lesion along the buccal mucosa extending into lower buccogingival sulcus with infltration into submucosa and buccinator muscle. Focal cortical break is also noted in the mandibular bone with intraosseous infltration. (48 year old male tobacco chewer presenting with right cheek swelling)

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 8.70** (**a, b, c,** and **d**) Arteriovenous malformation (AVM) cheek. Focal soft-tissue thickening with internal hypoechoic areas. Doppler study shows multiple vascular channels with high velocity, low resistance fow suggestive of AVM. (40 year old female presenting with history of swelling and intermittent pain)

**Fig. 8.71** Cheek Hemangioma. Mixed echoic hemangioma with phlebolith. Absence of fow signals due to low-velocity fow

©Association of Oral and Maxillofacial Surgeons of India

#### **8.12 Conclusion**

It is extremely diffcult to limit radiology to a chapter and what has been written does not represent the whole of maxillofacial radiology. Only the relevant aspects and the bare minimum essentials of radiology for maxillofacial surgeons have been covered in this chapter. The entire range of radiology for maxillofacial surgeons, dealing with surgical problems pertinent to the maxillofacial region, would require more expansive and elaborate writing.

This chapter on radiology provides an outlook to the surgeon, who can proceed to applying radiology in his everyday surgical practice. In the event of encountering any lacunae in the book, the MFS must refer to the textbooks dedicated to maxillofacial radiology. Being a surgeon, the MFS should be aware of the use of the chest radiograph and its applications in his practice. The role of high-resolution ultrasonography has also been emphasized in this chapter. Dental radiology, both extra and intraoral, has not been included since all maxillofacial surgeons have extensive knowledge of the same in their surgical practice.

Since it is the MFS who is acquainted with the patient's clinical status, he must properly plan the imaging pathway for the patient. It is for this purpose that the MFS should be aware of the various imaging modalities as regards their nature, mode of image formation, their usefulness over other modalities, and their drawbacks. Radiation safety and cost effectiveness of a specifc imaging modality also need to be kept in mind. The imaging method selected should be one that provides the required information within the shortest time possible, be the safest option for the patient, and be the most economical, while at the same time providing maximum information.

The MFS can commence with simple basic imaging methods like plain radiography or USG and later proceed to higher imaging methods in case the basic methods were not enough to satisfy the surgeon's needs for patient management. A recent costlier imaging method does not necessarily mean it is the best. Many times, it is the simpler basic imaging methods that provide more crucial fndings that help in understanding complex disease processes.

**Acknowledgments** The authors would like to acknowledge & thank Dr Niranjan Kumar, M.Ch FRCS. ; Honorable Vice-Chancellor, Shri Dharmasthala Manjunatheshwara University for his valuable constructive suggestions and constant support towards this endeavour.

#### **References**

#### **Further Reading**

**Open Access** This chapter is licensed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons. org/licenses/by/4.0/), which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license and indicate if changes were made.

The images or other third party material in this chapter are included in the chapter's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the chapter's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder.

**Part V**

**Principles of Maxillofacial Surgery**

K. Bonanthaya et al. (eds.), *Oral and Maxillofacial Surgery for the Clinician*, https://doi.org/10.1007/978-981-15-1346-6\_9

## **Operating Room Protocols and Infection Control**

Rishi Kumar Bali

#### **9.1 Introduction**

A study comprising data from 56 countries in 2004 stated that the annual major surgery volume was estimated to be 187–281 million operations, accounting for approximately one operation annually for every 25 human beings alive [1]. In subsequent studies, data were obtained from a total of 194 Member States of the World Health Organization for the years 2005–2012. According to these studies, 312.9 million operations took place in 2012, showing an increase from the 2004 estimate of 226.4 million operations. 6.3% and 23.1% of operations were carried out in *very-low* and *low*-expenditure countries representing only 36.8% (2573 million people) and 34.2% (2393 million people) of the global population of 7001 million people, respectively [2]. The incidence of postoperative infections reported among the developed countries like UK and USA was approximately 5% and 5–6%, whereas in developing countries like India it is much higher, accounting for approximately 10–25%. [3, 4].

The main problem encountered in the practice of surgical safety is that existing safety practices are not adequate in some countries. Lack of resources is the main reason behind this, particularly in developing countries. Good infection prevention and control is essential to ensure the safety of the patient undergoing any surgical procedure in the operating theater. The surgical site infections (SSIs) constitute 20% of the total hospital-acquired infections [4]. These infections cause substantial patient mortality and morbidity and burden healthcare systems with massive costs. Since these infections are primarily acquired during the operative procedure when the wound is still open, stringent protocols need to be followed at this point to minimize their onset.

### R. K. Bali (\*)

## **9.2 Terminology**

To establish surgical protocols, it is important to understand the basic concepts of sterilization, asepsis, and infection control. In this respect, the following terminologies are very commonly used:

#### **Antibiotics**

These agents are a by-product of certain microorganisms, which either have the capacity to destroy or inhibit the growth of other microorganisms at low concentrations.

#### **Anti-Infective**

A substance (or drug) capable of killing microorganisms or inhibiting their growth, in particular, pathogenic microorganisms. This is a general term used to encompass those drugs that specifcally act on certain types of microorganisms, including antibacterial (antibiotics), antifungal, antiviral, and antiprotozoal agents.

#### **Antimicrobial Agent**

Any agent synthetically or naturally obtained that can destroy or attenuate the microorganisms.

#### **Antisepsis**

It is the process in which microbial agents on a living surface are either killed or their growth is arrested.

#### **Antiseptic**

These are the substances applied on the living tissues to reduce the possibility of infection, sepsis, and putrefaction by inhibiting the activity or growth of the microorganisms.

#### **Asepsis**

The state of being free from living pathogenic organisms.

#### **Aseptic**

Free of or using methods to keep free from microorganisms.

**9**

<sup>©</sup> The Association of Oral and Maxillofacial Surgeons of India 2021 173

Postgraduate Department of OMFS, DAV Dental college hospital, Yamunanagar, Haryana, India

174

It is defned as the processing and packaging of a sterile product into sterilized containers followed by proper sealing with a sterilized closure in a manner to control microbiological recontamination.

#### **Bactericide**

It is an antimicrobial agent that has the capacity to destroy both nonpathogenic and pathogenic organisms but may not destroy bacteria in spore form.

#### **Bacteriostatic**

It is an antimicrobial agent that inhibits the growth of microorganisms but is not capable of killing them.

#### **Bioburden**

The occurrence of viable microorganisms on a surface or object before the sterilization procedure.

#### **Biologic Indicator (BI)**

A standardized test preparation of bacterial spores used to demonstrate effective sterilizing conditions by providing a defned resistance to a specifc sterilization process.

#### **Chemical Indicator**

These are agents or devices used to monitor or confrm the attainment of one or more of the parameters required for a satisfactory sterilization process or used in a specifc test of the sterilization equipment.

#### **Chemisterilant**

It is an agent, chemical in nature with properties that kills all forms of microbial agents, including spores.

#### **Cleaning**

It is the process of removing all forms of foreign materials (from objects using detergents & water, soaps, and enzymes) by employing the mechanical action of washing or scrubbing the object.

#### **Contamination**

It is the process of entry of microbial agents into tissues or any aseptic environment.

#### **Crossinfection**

The spread of infection from one person, object or place to another.

#### **Decontamination**

The process by which a person or a surface is made free from all the agents that contaminate the surface and lead to the spread of infections. [5]

#### **Detergent**

It is a chemical agent with cleansing actions in dilute solutions, which, on combining with impurities and dirt, make them more soluble.

#### **Disease**

Disruption of the normal performance of the vital functions of a plant or animal by an infection.

#### **Disinfectant**

This is an agent, usually a chemical, applied on inanimate objects that destroys microorganism in the vegetative form but not the spores.

Chemical disinfectant agents are categorized into low level, intermediate, and high level (depending on the product claims and regulatory requirements in different parts of the world).

#### **Disinfection**

Antimicrobial process to remove, destroy, or deactivate microorganisms on surfaces or in liquids. Disinfection is often considered as a reduction of the numbers and types of viable microorganisms (or "bioburden") but may not be assumed to render the surface or liquid free from viable microbial contamination (in contrast to sterilization).

#### **Droplet Nuclei**

These are those particles of 1–10 μm that are implicated in the spread of airborne infections.

#### **Exogenous Infection**

The infecting microorganism comes from an external source.

#### **Fomites**

Any inanimate object that is capable of absorbing or transmitting infectious microorganisms from one person to the other.

#### **Fumigation**

The process of disinfecting or purifying an area or object with the fumes of certain chemical agents.

#### **Infection**

It is the process of invasion of the tissues by microorganisms and their multiplication in the body of the host to produce disease.

#### **Microorganisms or Microbe**

Microscopic organisms, which may exist in its single-celled form or in a colony of cells.

#### **Minimum Effective Concentration (MEC)**

The lowest concentration of a chemical or product, used in a specifed process that achieves a claimed activity.

#### **Minimum Recommended Concentration (MRC)**

The lowest concentration of a chemical or product specifed by the equipment manufacturer to be used in a process.

#### **Nosocomial**

This comes from two Greek words, i.e., "*nosus"* meaning "*disease*" and "*komeion"* meaning "*to take care of."* Also known as "hospital-acquired infections." These are the infections originating or taking place in a hospital.

#### **Operating Room (OR)**

The operating room or operating theater is a facility within a hospital where surgical procedures are carried out in an aseptic environment.

#### **Pathogen**

A pathogen is a tiny living organism, such as a bacterium or virus that is capable of producing disease in an individual.

#### **Resistance**

It is the natural ability of the agent to oppose the effects of any harmful agents.

#### **Soil**

Natural or artifcial contamination on a device or surface following its use or simulated use.

#### **Sterile Barrier System**

Packaging that prevents the ingress of microorganisms following a sterilization process, thereby preserving the sterile state.

#### **Sterilizer**

Equipment designed to achieve sterilization.

#### **Sterilizing Agent**

Physical or chemical agent (or combination of agents) that has suffcient microbicidal activity to achieve sterility under defned conditions.

**Septic**

Contaminated or infected.

#### **Spores**

These are the reproductive forms of some microorganisms that can survive harsh environmental factors and have the capability of developing into new viable microbes.

#### **Sterilization**

Sterilization is a process that destroys or removes all microbial life completely, including spores by means of certain chemical or physical processes.

#### **Sterile**

Free from living microorganisms.

#### **Sterilize**

Total destruction of all living forms.

#### **Vector**

It is an organism that does not cause disease itself but which spreads infection by conveying pathogens from one host to another.

#### **Virulence**

It is a pathogen's ability to infect, sustain, or spread infection in a living a host. Historical background of present day protocols is enumerated in Table 9.1.

#### **9.3 Surgical Site Infections**

Approximately 2–5% of all surgical patients tend to acquire surgical site infections (SSIs) [4]. In developed & highincome countries (HICs), SSIs are the second most common cause of healthcare-associated infections [6], whereas in Low- & Middle-Income Countries (LMICs) or underdeveloped & developing countries these infections are the most common ones. Thus, to reduce the risk of surgical site infections, a more systematic approach has to be adopted, based on proper knowledge regarding the status of the patient, type, & time of the operation, personnel involved and the health care facilities available during a surgical procedure. The main pathogenic source of surgical site infections is the endogenous fora (usually aerobic gram positive cocci) of the patient present in the skin, the mucous membranes, or the hollow viscera. The exogenous sources of infection include

**Table 9.1** Historical background leading to proper sterilization and disinfection protocols

members of the surgical team, environment of the operating theater and tools, materials & instruments brought to the sterile zones during the surgical procedure. Various strategies employed to prevent or control the occurrence of surgical site infections include reducing the contamination by microorganisms on the sterile surgical instruments as well as the body of the patient, prophylactic preoperative antibiotic coverage, carrying out the surgical procedure carefully, proper handling of the operating room.

#### **9.4 Surgical Safety**

Surgical safety is of utmost importance in order to prevent major and life-threatening complications leading to undue loss of life and patient morbidity. Thus, a list of ten essential objectives with a surgical safety checklist have been elucidated by the WHO to be followed by all the personnel present in the operating room to reduce the risk of such complications [7] (Tables 9.2 and 9.3).

#### **9.5 Environmental Control and Design**

#### **Operating Room (OR)**

The operating room or operating theater is a facility within a hospital where surgical procedures are carried out in an aseptic environment. Since the operating theater is a highly sterile, aseptic, and restricted area in a hospital setting, it is **Table 9.2** WHO: Ten essential objectives for safe surgery

mandatory for all the personnel concerned to have a proper understanding of the working of the operation theater abiding by certain laws, regulations, and professional guidelines. Integrated infection control in the operation theater is the key to decreasing morbidity and mortality among the patients undergoing surgery.

Following essentials must be present in an operating room:

#### **Table 9.3** WHO's Surgical Safety Checklist

1.2 to 1.5 m. Sliding doors are preferred than spring-loaded doors in order to minimize the generation of the air currents during the opening and closing of the doors. Windows made from glass are preferred, which are to be planned on one side only.

#### **Different Zones of Operation Theater Complex**

There are four different zones observed in any operating room complex described on the basis of type of cleanliness present, presence or absence of microorganisms, and the different procedures to be carried out in each zone (Fig. 9.1).

	- Changing room for all the concerned persons
	- Transferring passage for the materials, equipment, and the patient
	- Rooms for administrative staff
	- Storage & record maintenance
	- Pre- and postoperative
	- Intensive and Coronary Care Units
	- Storage rooms to keep the sterilized objects
	- Clean rooms
	- Storage room for equipment
	- Rooms designed for surveillance, maintenance, and frefghting
	- Exit areas in case of emergencies exists

#### **Fig. 9.1** Different zones of operation theater complex

©Association of Oral and Maxillofacial Surgeons of India

#### **Important Points**

#### **Maintenance in the Operation Theater**

– The machinery must be surveyed at least every week.

#### **9.6 Disinfection and Sterilization**

Sterilization is the ultimate procedure in controlling the undesired activities of microorganisms that are outside of the human body. Its purpose in the operating feld is to prevent the spread of infectious disease, and in surgery, it primarily relates to processing reusable instruments. Surgical instruments are an integral part of surgical feld and, being reusable, have greater chances of spreading the microorganisms if any of the reprocessing steps fails. Steps of reprocessing include cleaning, repackaging, disinfection or sterilization, and reusing. Cleaning, being the frst step in the cycle of reprocessing,

**Table 9.4** Spaulding Classifcation of Medical Devices And Level of Disinfection

is the major step in the removal of any organic matter present on the surface of the instruments. Any failure in the removal of the visible soil at the initial stage can create a discrepancy in the effcacy of the subsequent disinfection and sterilization procedures. Sterilization is more effective a process than disinfection. The process of disinfection is carried out with the use of various chemical agents. Chemical disinfecting agent necessarily does not kill all microorganisms or spores present on an inanimate object but instead reduces the number of microorganisms to a level that is not harmful to health. Depending on their potency against microbes, they are classifed as *High-*, *Intermediate-,* or *Low-level* disinfectants.

The type of the sterilization procedures to be carried out for an object depends upon the classifcation of the instruments based according to the Spaulding Classifcation of the medical devices, the type of material of which the object is made of, the microorganisms to be present on the object, and availability of the sterilization methods and equipment (Table 9.4).

**The Instrument Processing (Decontamination Steps)**  (Fig. 9.2)

**Fig. 9.2** Instrument processing steps

©Association of Oral and Maxillofacial Surgeons of India

Various methods of decontamination include.

Processing of the clinical or surgical items is a two step procedure.

	- Cleaning is the process of removing all the foreign particles present on the surface of the object, which is accomplished by means of two main steps, i.e., cleaning by friction to remove foreign particles and rinsing away by fuids to remove the debris so cleaned.
	- If the objects to be sterilized, remain soiled with foreign materials, the microorganisms will be trapped in the organic matter and may interfere with the proper sterilization or disinfection procedure. Therefore, thorough cleaning should always precede the sterilization process.
	- Cleaning may be manual or mechanical and is normally accomplished by the use of water, detergents, and mechanical agents. Detergent is essential to dissolve proteins and oil that can reside on instruments and equipment after use.

With the advancement in the sterilization equipment, most units are automated and there is very less handling of dirty equipment by the concerned staff. The equipment to be processed is placed in trays and is ready for washing.

It is an active method that is carried out by thoroughly brushing the item with the help of a toothbrush under water to prevent the release of aerosols. The brush should be thoroughly cleaned after use and should be dried. The cleaned items are then dried and made ready for the proper sterilization procedure to be carried out depending upon the material of which they are made and the use they perform.

Manual cleaning is necessary when:

There are times when cleaning alone cannot remove the debris present on the surface of the objects as the items become highly soiled with foreign materials. For this, it is sometimes necessary to soak instruments/objects prior to cleaning. A container having a deeper base is flled with detergent & water and all the instruments are kept in it for 3–5 min. The solution prepared is agitated by shaking it vigorously. The cleaned instruments are now removed from the container and placed over a tray for air drying.

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 9.3** Manual Cleaning

#### B. **Disinfection and Sterlization**

	- (a) Most commonly used for heat-labile instruments/ objects (e.g., endoscopes) where single use is not cost effective.
	- (b) Disinfectants used for this purpose are
		- Glutaraldehyde: 2% for 20 min.
		- Hydrogen peroxide: 6%–7.5% for 20–30 min.
		- Per acetic acid: 0.2–0.35% for 5 min.
		- Ortho-phthalaldehyde (OPA) for 5–12 min.
	- (c) Steps:
		- All items to be disinfected are cleaned and dried.
		- Fresh disinfectant solution should be made each day in a sterile container. If a previously prepared solution is to be used, an indicator strip is dipped in the solution to check for the effectiveness of the solution.
		- Open all hinged instruments and disassemble whichever possible.
		- Place all items in the solution completely submerged in the container.
		- The container is covered and the instruments are allowed to soak in for 20 min.
		- Remove the items using dry, high-level disinfected pickups.
		- Rinse thoroughly with boiled water.
		- Air-dry by placing on disinfected tray.
		- Items disinfected are covered in a disinfected container and used within a week.

#### *Sterilization*

Sterilization is a method by which an article, medium, or surface is made free from all microbial invasions, including spores. The main aim of sterilization of instruments is proper delivery of sterilized instruments at the operating feld, thereby maintaining a sterile environment and reducing the spread of infections from one person to another. Proper handling of the sterilized instruments is done by appropriate wrapping and storage of the instruments, thereby increasing the shelf life of the sterilized instruments. The instruments should be bagged or wrapped in a muslin cloth or clear pouches or paper before and after the procedure and the wrapping should be sealed with tape. No pin, staple, or any paper clips are to be applied on the wrapping as these may create small openings, which may allow entry of microorganisms, thereby hampering the process of sterilization. Sterilization is accomplished by:

	- This is the most simple and effcient means of sterilizing instruments. It is also commonly called steam sterilizing or autoclaving.
	- The steam autoclaves best suited for outpatient practice are usually made to operate in the following range.
		- Temperature 121 °C (250 °F) at a pressure of 15 pounds per square inch (psi) for 15 min.
		- Temperature 134 °C (270 °F) at a pressure of 30 psi for 3 min. This process termed "fash sterilization" has practical use in the operating room where fast sterilization of instruments may be necessary.
	- This combination of moisture and heat provides the bacteria-destroying power currently most effective against all forms of microorganisms.
	- Mainly used for items that are wrapped or porous.
	- Autoclaves are either classifed as horizontal or vertical (based on design) and gravity displacement or vacuum type (based on functioning).
	- Autoclaves can also be classifed as Type "N" and Type "B."
	- Type "N" autoclaves are the ones that do not remove air from the sterilization chamber with the help of a vacuum pump. These are used for solid loads.
	- Type "B" autoclaves remove air from the sterilization chamber with the help of a vacuum pump. Wrapped and hollow instruments, which can be sterilized and used later, are to be sterilized by this type of autoclave.
	- Importance of bagging the instruments for sterilization.
		- The main aim of bagging or wrapping the instruments prior to sterilization procedure decreases the chances of contamination of the items after the sterilization procedure is complete.
		- Two-layer wrapping of objects should be preferred and the materials used for this can be cotton fabric or muslin, paper, newspaper (Fig. 9.4).
	- Monitoring of sterilization.
	- Sterilization monitoring is a process by which adequate sterile environment and the effectiveness of the procedure is determined by assessing the biological, mechanical, and chemical parameters.
	- The most widely used and accepted parameter of assessing the sterilization procedures is the use of biological indicators (BIs) that directly inhibit the growth of highly resistant microorganisms, rather than merely testing the physical and chemical conditions necessary for sterilization. Since the spores present in a biological indicator are in a much higher number and are highly resistant by nature compared to the other and common microorgan-

**Fig. 9.4** Diagram depicting the way the instruments are wrapped for sterilization

©Association of Oral and Maxillofacial Surgeons of India

isms found on items used for the patient, an inactivated biological indicator indicates that the other microorganisms are killed depicting an effective sterilization procedure. A control BI, from the same lot as the test indicator and not processed through the sterilizer, should be incubated with the test BI; the control BI should yield positive results for bacterial growth.

being exposed to the sterilizing conditions. These chemical agents are called the chemical indicators and these include TST (Time-Steam-Temperature) Strip. This TST strip is to be placed in a big surgical wire basket and when exposed to a critical time, steam, and temperature it undergoes a change in color from yellow to dark blue indicating complete sterilization procedure. Another strip is to be used when double-layered packing of instruments in crepe paper is done to assess the parameters inside the sterilizer.

	- There must be a separate area for storing of the sterile instruments and single-use (disposable) products.
	- The storing of the bagged sterilizer objects can be depicted either by the date on which they are sterilized or the procedure for which it is to be used or an event causing it to become contaminated.
	- All the packed items must be carefully inspected before using to verify the integrity of the outer covering and the condition of the packing (dry/wet).
	- Once the packing is assessed and if any breach is seen in the packing, the wrapping should be replaced and the instruments again sent for the sterilization procedure.
	- All the sterilized instruments must be kept in covered drawers.
	- It is used for sterilization of heat-labile and moisture-sensitive items, supplies, and equipment.
	- The operating cycle ranges from 2–24 h and it is a relatively expensive process.
	- It can be used for glass, paper surfaces, clothing, plastics and metals, food stuffs, and dental equipment.
	- It is unsuitable for fumigating rooms because of its explosive property.
	- It may be used for sterilization of instruments with cutting surfaces.
	- No corrosion occurs with this method of sterilization.
	- Dry heat sterilization, which usually occurs consists of hot air oven has typical cycles of 1 h at 171 °C or 2 h at 160 °C.
	- Air is a poor conductor of heat and requires a long time for getting the instruments effectively sterilized.
	- This is also a choice for some limited circumstances.
	- Some instruments cannot be subjected to high temperatures and in a feld environment chemical sterilization may have to be used.
	- The disinfectant must remain in contact with the surface for appropriate time.
	- Disinfectants include Chlorine solutions, 2–3.2% glutaraldehyde, iodophors, and phenols.

#### **9.7 Operating Room Decorum**

#### 1. *Hand hygiene:*

Hand hygiene by operation theater persons is the most effcient way to reduce the risk of spread of infections.

	- Surgical hand wash or surgical hand rub should be carried out prior to the procedure in order to decrease the residing fora of the hand.
	- Steps:
		- All jewellery from wrists and hands must be removed.
		- The temperature of water is to be adjusted so that it is slightly warm. Hands and forearms are to be washed 5 cm above the level of the elbows to remove any particles of dirt.
		- Before performing the frst scrub of the day, a nail cleaner is used to clean the fngernails and the nail beds.
		- The nails should be cut short and no nail polish should be used.
		- Antimicrobial agent is to be applied on the hands and in circular motion; lathering should begin at the fnger tips of one hand and between the fngers, continuing from the fngertip to 5 cm above the elbow. The same process is to be repeated for other arm and hand.
		- The rubbing should be done for a period of 3–5 min.
		- Each arm is to be washed separtely at the level of elbow, starting at the fngertips.
		- One side of the sterile towel is used to dry the fngertips up to the elbow of one hand and the other side is used to dry the same on the other hand.

3. *Barrier techniques:*

Barrier techniques are useful where the chances of spread of infection are higher.

(a) Head Cover

Prior or during the procedure, all facial and head hair should be tied properly and covered by means of head covers. Ideally head covers should be disposable and made of soft, nonporous cloth like material. If one has long hair, the hair should be tied in a bun. In situations where tying a bun is not possible, use of helmets or hoods or headgears is of utmost signifcance.

	- Tuberculosis is one of the most common infectious diseases that can spread through airborne route,
	- The main aim of using a mask is the prevention of transmission of infectious agents from the member of the operating team to the patient's wounds and also protecting the operating team members from the splashes and sprays from the patient.
	- The masks, which are disposable in nature, are always preferred.
	- The mask should be made of synthetic fbers, must be fat with two or three pleats that expand to cover the area up to chin, and should have flters of polypropylene or polyester (Fig. 9.5).

These are the pair of garments to be worn over, or instead of regular clothing of the persons involved in the surgical procedures to protect the transmission of any infectious agent present on the regular clothing from the operating personnel to the patient or any other personnel. These should have a simple design, should be comfortable, should be easy to clean and wash, should be economical, easily replicable if damaged and should have minimal place for the contaminants to hide.

(d) Surgical gowns

These are a loose pair of clothing to be worn over the scrub suits or cover gowns at the time of the surgery to protect both the patient and the operating personnel from transfer of microorganisms, blood or body fuids, and another particulate matter.

Steps of wearing gown:

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 9.5** Surgical Mask

(e) Gloves

They help to protect the operator from infection by bacteria and viruses from patient's blood. Gloving is essential to protect both the surgeon and the patient from blood-borne viruses and to prevent wound from becoming contaminated with the surgeon's skin fora. The "open gloving" and "closed gloving" technique of donning the gloves should be employed for wearing gloves.

	- Handwashing must be performed under aseptic conditions.
	- Inspect the outer covering for the integrity. Open the frst nonsterile packaging by peeling it completely off the heat seal exposing the inner sterile wrapper, but without touching it.
	- The inner sterile packing is kept on a dry area, without touching the outer surface. Open the package and fold it toward the bottom so as to unfold the paper and keep it open.
	- By using index fnger and thumb of one hand, the folded edge of the glove is grasped.
	- In a single movement the other hand is slipped into the glove.
	- The second glove is picked by using the cuff of the other glove and sliding the fngers of the gloved hand into it.

©Association of Oral and Maxillofacial Surgeons of India

	- If the cuffs are not ftting, a tuck is taken in each gown.
	- The circulating person should open the outer covering of the glove and should fip them onto the sterile feld.
	- The inner packing containing the gloves is opened carefully and the glove is picked up by the folded cuff edge with the hand covered by the sleeve.
	- The glove is placed on the sleeve of the opposite gown, the palm facing downwards, with the fngers of the glove pointing toward the shoulder.
	- The gloves should be placed in such a manner that the rolled cuff edge of the gloves connects

the sleeve to the gown cuff. Bottom cuffed and rolled edge of the glove is grasped at the bottom with the index fnger and thumb.

Drapes are used during surgical procedure to protect the contacting of the unprepared surfaces/areas and maintaining the sterility of environmental, equipment, and the surrounding of the patients.

The different drapes available are:-

• Towel drapes, which are used for squaring off the operative site, wrapping syringes & small instruments, and

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 9.8** Putting on sterile gloves by closed gloving technique

drying of the hands. These must be more resistant to water and must be made of cotton compared to linen.

#### **9.8 Classifcation of Surgical Wounds**

A widely used classifcation of surgical wounds is based on an estimate of likelihood of bacterial contamination of the operative site. In 1964 [9], National Academy of Sciences/ National Research Council defned fve general classes of operations:

1. *Refned-Clean:* Elective operations not drained and primarily closed.

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 9.9** Different types of drapes

Currently, this classifcation has been condensed into four groups for general use, without a subdivision of the clean category and in the modifed form it is categorized into four categories [10]

	- Elective (not urgent or emergency).
	- Primary closed.
	- No acute infammation or transection of tracheobronchial, biliary, gastrointestinal, oropharyngeal tracts.
	- No technique breaks.
	- Emergency or urgent cases that are otherwise "clean."
	- Elective procedures.
	- Reoperation via "clean incision" within 7 days.
	- Blunt trauma, intact skin, and negative exploration.
	- Acute nonpurulent infammation.
	- Major technique break or major spill from hollow organs.
	- Entrance of genitourinary or biliary tracts in presence of infected urine or bile, respectively.
	- Penetrating trauma less than 4 h old.
	- Purulence or abscess.
	- Preoperative perforation of tracheobronchial, biliary, gastrointestinal, oropharyngeal tracts.
	- Penetrating trauma more than 4 h old.

### **9.9 Risk Factors Afecting the Rate of Postoperative Wound Infections**

*"Cut Well, Sew Well, Heal Well"* is an axiom favored by surgeons but is not always destined to be true. Altemeir and Culbertson (1965) [11] depicted that the risk of infection varies:

These factors interact in a complex way to fasten the development of infection. Since the days of Altemeier, clinical and epidemiologic studies have identifed the risk factors that affect the rate of postoperative surgical site infection. This can be best explained by the classical epidemiological triangular model, i.e., model of interaction between agent host and environment resulting in disease (Fig. 9.10).

The risk of postoperative wound infection also depends on the patient factors, pre and intraoperative factors (Table 9.5). Haley et al. (1985), in the Study of the Effcacy of Nosocomial Infection Control "(SENIC)," [13] identifed four independent and additive risk factors for postoperative wound infection. These factors are operation on the abdomen, operation lasting for more than 2 h, contaminated or dirty wounds (NRC CLASSIFICATION), and the presence of more than three discharge diagnoses.

• Hair removal should not be performed on routine basis to decrease the risk of surgical site infection. Razors should not be used to remove the hair as they increase the chances

©Association of Oral and Maxillofacial Surgeons of India

**Fig. 9.10** Classical Epidemiological triangle

of infections [14]. Electric clippers with disposable heads must be used only for removing hair few hours prior to the surgical procedure.

#### **9.9.1 Factors Infuencing the Development of Nosocomial Infections**

#### **<IP_ADDRESS> The Microbial Agent**

Hospital infections occur as a result of a variety of microorganisms. The microorganisms causing the disease may be divided into the following categories:

During the stay in a hospital, the patient comes in contact with various kinds of microbial agents (such as viruses, fungi, parasites, and bacteria), which are the main cause of the occurrence of infections in a patient. This exposure is not the only reason for the development of hospital-acquired infections. The other possible reasons are the host's natural defense mechanisms (healthy/compromised/immunosuppressed), conditions present in a hospital environment, microbiology of the microbial agents (characteristic features), infective material present on the microbial agent, resistance to the antimicrobial agents, and other factors. The hospital-based infections may be a result of the spread of infection from one person to the other or by the residential fora of the patient or from any contaminated sources or from sources of the external origin (e.g., airborne diseases).

Following are the factors that are the main sources of spread of hospital-based infections:

#### **<IP_ADDRESS> Susceptibility of the Patient**

Patient factors that lead to the occurrence of infection are age, host's immune response, presence of any disease, and interventions, which either help in diagnosing or treating any condition. Patients, either infant or older individuals, are at a higher risk of acquiring infections. Patients having a compromised immune system, undernourished, having some underlying chronic disease (AIDS, leukemia, malignant tumors, renal failure, diabetes mellitus, etc.), undergoing irradiation therapy, all at the highest risk of being infected by the hospital-based infections. Certain processes like catheterization, biopsy, intubations, etc. make the patient more vulnerable to these infections.

#### **<IP_ADDRESS> Resistance of the Bacteria**

Resistance of bacteria to antimicrobial agents is seen with the prolonged or prophylactic use of these agents. The microbial agents present normally in the human fora have both sensitive and resistant strains. Some antimicrobial agents have their action on sensitive strains by suppressing their activity, whereas the resistant strains are still active. These active resistant strains are the major cause of the development of resistance against the antimicrobial agents. Examples of resistant microbial agents are Multiresistant Klebsiella, strains of pneumococci, staphylococci, etc. In low-income or middle-income countries, this is the major problem faced due to unavailability and unaffordability of the better drugs.

#### **<IP_ADDRESS> Month of Operation**

The possible explanation for increased infection rates in summer is the relatively high environmental temperature leading to humid climate, resulting in excessive sweating. In addition, excessive sweating results in the displacement of bacteria lodged in skin appendages to the surface.

#### **<IP_ADDRESS> Use of Electric Cautery**

The use of electric cautery for cutting and coagulation during surgery causes more infammation; more necrosis and abscess than the conventional use of scalpel and thus it increases the susceptibility of tissue for infection. Soballe et al [15], in their experimental study, found that electric cautery lowers the contamination threshold for infection of laparotomies and concluded that electric coagulation current should be used only when the need for meticulous hemostasis outweighs the considerably increases risk of infection.

#### **Fig. 9.11** Sources of hospital-acquired infections

©Association of Oral and Maxillofacial Surgeons of India

#### **<IP_ADDRESS> Duration of Operation**

There is a direct correlation between the infection rate and time taken for the procedure. This may be the result of the more complicated operations being of longer duration, increased wound contamination from airborne bacteria, increased damage to the tissues due to large exposure of the wound, and increased manipulation; moreover, local resistance of tissue is reduced due to drying.

#### **<IP_ADDRESS> Spread of Infection**

The microbial agents are spread by different ways in a health care setup. The different ways with which the agents can spread are contacting, droplets, airborne route, via vehicle, and vector-borne (Fig. 9.11).

Sources of the infectious agents are either external, i.e., from one person to the other, or from the hospital's environment; or internal, i.e., within the patient himself.

• *Contacting* is the most frequent and important route of spread of infections. It is further of two types, i.e.

these particles. The main diseases to be spread via the airborne route are Tuberculosis, Infuenza, Common cold, etc.

• *Vehicle spread* is the spread of infectious microbial agents to the individuals by means of contaminated items such as food, water, medications, devices, and equipment.

*Vector*-borne transmission occurs when vectors such as mosquitoes, fies, rats, and other vermin transmit microorganisms.

#### **9.10 COVID 19 and Maxillofacial Surgery**

The occupational risk of acquiring viral diseases has been well known in Maxillofacial Surgery [16]. The WHO announced the Corona virus pandemic also known as COVID-19 as a public health emergency of international concern on January 30, 2020.

Coronaviruses are RNA viruses infecting many species of animals including humans, name coronavirus was derived from corona meaning crown like because of the morphology observed for these viruses in the electron microscope. This family of viruses includes Middle East Respiratory Syndrome (MERS-CoV), Severe Acute Respiratory Syndrome (SARS-CoV), and novel Coronavirus (n CoV).

Coronavirus is enveloped having round, spherical, or sometimes pleomorphic structure, with size ranging from 80 to 120 nm in diameter, containing a positive-strand RNA. The virus is made up of lipid bilayer envelop, membrane protein, and nucleocapsid, these structures also protect the virus when the virus is outside the host cell. The lipid bilayer forms the viral envelop which anchors the membrane protein, envelop protein, and the spike protein. The spike protein (S-protein) is responsible for the crown-like structure of the coronavirus as it forms the protrusions from the surface which bind to the host cells.

#### **9.10.1 Mode of Transmission of SARs-CoV 2**

Human to human transmission is due to respiratory droplet transmission and contact transmission. Spread occurs through coughing, sneezing, spitting, contacting the body fuids of the infected patient. The COVID-19 can remain infectious on inanimate surfaces from 2 h to 9 days, depending on the humidity, temperature, surface type, and viral load [17]. It has become an occupational threat to health care providers worldwide.

Some of the known routes of spread of infection to health care providers are:

Aerosols generating procedures (AGP) create widespread environmental contamination and therefore pose a greater risk of transmission of infection to healthcare workers. Oral and maxillofacial surgeons are particularly vulnerable to this transmissible disease by way of the droplet or aerosol transmission due to the area of work and the type of instrumentation [18].

The incubation period is long and unpredictable ranging from 0 to 27 days with a mean of 6.4 days. Recent studies have shown that asymptomatic patients and those within the incubation period are also potential spreaders of the disease [19].

#### **9.10.2 Symptoms**

Symptoms may range from mild symptoms to severe respiratory distress and some patients may be asymptomatic.

#### **9.10.3 Radiographic Findings**

#### **9.10.4 Testing and Laboratory Findings**

The real time polymerase chain reaction (RT-PCR) of respiratory secretions from bronchoalveolar lavage, endotracheal aspirate, and nasopharyngeal or oropharyngeal swab is the defnitive test.

Other laboratory fndings include lymphopenia, increased prothrombin time, and mildly raised CRP and ESR.

#### **9.10.5 General Preventive Measures**

COVID 19 has shifted the focus on teleconsulting which includes tele screening, telemedicine, and triage. Telemedicine should be practiced whenever possible to decrease the footfall.

Thorough history should be obtained from the patient regarding COVID 19 illness and elective procedures should be postponed and only emergent conditions should be taken up for surgery.

Patient should be called on the basis of appointments, time between two appointments should be suffcient enough to perform all necessary sanitization measures and ensure minimal patient to patient overlap. In the waiting area, posters should be displayed to encourage hand hygiene and the wearing of masks and the area should be well ventilated. A minimum of 2 m distance should be maintained between the individuals.

Extraoral radiographs should be preferred as an alternative to intraoral periapical radiographs.

In the operatory there should be minimum personnel present, Air Conditioners should be avoided, doors and windows are advised to be kept open. The operating room should be spacious with adjoining two rooms for donning and doffng of the PPE's. No touch sensor-based sanitizer dispenser should be installed at the entry and exit of OR [20].

All the surfaces of equipment like OR table, motor drills etc., should be covered with plastic sheets and sheets to be changed after every patient.

OT's should be equipped with HEPA flter (0.1 micron effciency) and high frequency of air changes (ideally 25 per hour) should be ensured to reduce the viral load [20].

High-volume suctions should be used with one-third of suction jars preflled with povidone-iodine solution.

The Povidone Iodine solution has been shown to have signifcant viricidal activity up to 3 h and it has been advised to coat the oral cavity and nasal passages of both the patient and the operating team before the surgery [21, 22].

Fogger machines with 0.5% sodium hypochlorite can be used for sterilization of dental chairs, tables, doors, doorknob, etc. [20]. One-minute contact of the chemical ensures viral kill.

#### **9.10.6 Personal Protective Equipment**

• Masks including three-ply surgical masks, N95, N99 (FFP3), and the Powered air-purifying respirators (PAPR's) provide viral fltration in the increasing order. It is important to mention that N95 masks were not found to be adequate to prevent transmission in Chinese surgeons and PAPR's had to be used to prevent transmission from COVID patients [23].

#### **9.10.7 Specifc Precautions to Be Taken During Surgery**

As the COVID-19 situation is a dynamic evolving one and there is no defnitive treatment available proper planning and implementation of infection control protocols are key to preventing transmission of the disease in the Maxillofacial settings.

#### **9.11 Control of Nosocomial Infections**

CDC elucidated certain guidelines to check the nosocomial infections in the Study on effcacy of nosocomial infection control (SENIC). These guidelines have decreased the emergence of hospital-acquired infections by a greater number. However, any breach in the infection control procedures can lead to spread of such infections.

Certain conditions leading to improper infection control and spread of such infections are:

#### **9.11.1 Prevention from Nosocomial Infections**

Following are the steps that can be taken by the staff in a hospital setup to prevent the spread of such infections:

#### **9.12 Conclusion**

Preventing and controlling infections is the key factor in improving care and ensuring safety of both the patient and the health care worker. Infection control addresses factors related to the spread of infections within the operation theater complex (whether patient-to-patient, from patients to staff and from staff to patient, or among staff), including prevention (via hand hygiene/hand washing, cleaning/disinfection/sterilization, vaccination, monitoring).

Integrated infection control in the operation theater has various aspects, ranging from its designing ,environmental cleaning , management of biomedical waste and adherence to theatre attire. Use of Personal Protective Equipment (PPE) including gloves, gowns, face masks ,respirators and full face visors are essential to minimize risks of occupational infections. Whether in developed or developing country, where resources are limited, thorough knowledge about the principles of infection control and a little ingenuity will suffce to solve the problem of hospital-acquired infections.

Surgical site infections are a result of microbial invasion in a sterile atmosphere. The main sources of microbial invasion in the operating theater include the atmosphere of the operating theater, the medical and the paramedical staff present at the time of the procedure, surgical instruments, and the patient at times also. Proper designing of operation theater, appropriate microbiological monitoring, proper sterilization, and strict adherence to barrier techniques form the basis to prevent infections in an operating environment.

#### **References**

dine gluconate, 4%, in surgical patients. JAMA Surg. 2015 Nov 1;150(11):1027–33.

#### **Additional Reading**

Surgical site infections: prevention and treatment. https://www.nice.org.uk/guidance/cg74

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## **Pharmacotherapy in Oral and Maxillofacial Surgery**

Latha P. Rao

The human fascination—and sometimes infatuation—with chemicals that alter biological function is ancient and results from long experience with, and dependence on, plants. Many plants produce harmful compounds for defense that animals have learned to avoid and humans to exploit [1]

#### **10.1 Introduction**

With phenomenal increase in the knowledge about mechanism of action of chemical compounds and rapid introduction of new drugs, pharmacology—the science of drugs—has become increasingly important to all health professionals. Practice of maxillofacial surgery utilizes drugs either as primary treatment modality or as a facilitator of surgical procedures. A detailed description of the pharmacodynamics & pharmacokinetics of these drugs is beyond the scope of this chapter. The readers are encouraged to refer to the standard textbooks of pharmacology for the same.

#### **10.2 Antimicrobial Agents**

Infections caused by microorganisms have threatened human life since time immemorial. Some of the organisms had the potential to spread from one infected person to another at an alarming rate causing worldwide pandemics and epidemics. With the discovery of the frst antibiotic, "the magic bullet"—Penicillin, patients could effectively be cured of many life- threatening infections [2].

Antimicrobial agents are of the few classes of drugs that effectively treat the etiology of conditions and not simply alleviate the symptoms of the diseases.

#### **10.2.1 Defnition**

The term antibiotic was frst used by Selman Waksman et al. to describe any substance produced by a microorganism that is antagonistic to the growth of other microorganisms in high dilution [3]. This defnition excluded substances like gastric juices and hydrogen peroxide that kill bacteria but are not produced by microorganisms. It also excluded synthetic antibacterial compounds like the sulfonamides. In current usage, however, the term "antibiotic" is applied to any medication that kills bacteria or inhibits their growth, regardless of whether that medication is produced by a microorganism or not.

#### **10.2.2 Classifcation**

The antibiotics have been classifed in many ways, based on their chemical nature, mechanism of action, type of organisms against which primarily active spectrum of activity, etc. (Table 10.1). The antibiotics exert their remarkably specifc action on the microorganisms, sparing the host, due to their selectivity for target components, which are either absent or not very important in humans. Among these targets are bacterial and fungal cell wall synthesizing enzymes, the bacterial ribosome, the enzymes required for nucleotide synthesis and DNA replication, etc.

#### **10.2.3 Oral Microfora**

The infectious diseases associated with the oral and maxillofacial region have unique microbiological features because of the abundance and variety of microorganisms in this region. The normal fora of the oral cavity consists of up to 1011 bacteria per gram of tissue, with anaerobic bacteria predominating [4]. Although the subtypes and proportions of organisms differ, the general pattern of the indigenous

K. Bonanthaya et al. (eds.), *Oral and Maxillofacial Surgery for the Clinician*, https://doi.org/10.1007/978-981-15-1346-6\_10

**10**

L. P. Rao (\*)

Department of craniomaxillofacial surgery, Aster Medcity, Kochi, Kerala, India

<sup>©</sup> The Association of Oral and Maxillofacial Surgeons of India 2021 195

L. P. Rao

microfora is similar in healthy individuals. However, systemic diseases and concurrent use of medications result in the presence of unusual organisms as part of the normal fora and an increase in diseases caused by normal organisms that usually are considered to have low pathogenicity. Usually, the microorganisms are held in check by the body's defense mechanisms. When these mechanisms are impaired, infection may result from an otherwise minor bacterial exposure.

The pathobiology of mixed odontogenic infection is relatively clear. The early cellulitis is the result of streptococci, the moderate-to-severe infection is caused by a combination of aerobic and anaerobic bacteria, and the well- circumscribed chronic abscess is caused primarily by anaerobic bacilli alone [5]. A complex mix of strict anaerobes and facultative anaerobes account for most of the odontogenic infections. Empirical antibiotic choices can be made in this situation where the microbiological pattern is well established (Table 10.2).

#### **10.2.4 Guidelines to the Therapeutic Use of Antibiotics**

Understanding that infections are ultimately dealt by the host's immune systems, and antibiotics play only an adjunctive role, is critical. Antibiotic therapy should be reserved for those with clearly established infection. Surgical treatment of the infection also should be initiated as early as possible.

Antibiotics help in preventing infections after a contamination has happened or they can abort a developing infection, if administered early. Antibiotics should not be used as a substitute for the needed surgical treatment.

In most clinical situations, it is easy to determine whether a patient has an infection—local and systemic fndings would point to the diagnosis. Diagnostic diffculty arises when a patient who has had a maxillofacial procedure performed, during the second or third day after surgery, develops swelling and pain. Similarly, elevated temperature and white blood cell count also may be found. Surgical insult and

**Table 10.2** Effcacy of commonly used antibiotics against head and neck pathogens and dosage

prolonged general anesthesia often result in these symptoms. Clinical judgment is important in making the diagnosis, and the clinician should weigh all information available before making the diagnosis of infection.

There are a few basic guidelines to be followed in the administration of antibiotics (Table 10.3).

#### **10.2.5 Consistency in Route of Administration**

In severe infection, parenteral antibiotics are needed to get adequate blood levels. But with an initial response within couple of days, one is always tempted to switch to oral administration. When this is done, the infection may recur because blood levels achieved with oral dose are suboptimal. Maintenance of peak blood levels of antibiotic, until eradication of bacteria, is important, which may take 5–6 days. After the ffth day of parenteral administration, the blood levels achievable with oral administration are usually suffcient.

#### **10.2.6 Cross-allerginicity between Penicillins & Cephalosporins**

A frequently asked question about penicillin allergic patients is whether the cephalosporins can be used safely. Overall the frequency of crossallergenicity between the two groups of drugs is low (7–18%) [10, 11]. Cross-allergenicity appears to be most common among penicillin, aminopenicillins, and early-generation cephalosporins, which share similar R-1 side chains; this is thought to increase the risk of cross-reactivity. Patients with a history of anaphylaxis to penicillins should not receive frst- or second-generation cephalosporins, while third- and fourth-generation cephalosporins should be administered with caution, preferably in a monitored setting.

#### **10.2.7 Patient Monitoring**

The patient should be monitored for the response to treatment and any deterrent should be identifed and rectifed. A second empirical choice should be avoided, if at all possible because the likelihood of success is substantially less. Repeat cultures may also be attempted.

In some cases, the patient may respond well to the empirical antibiotics, but the culture and sensitivity report would reveal that the organisms isolated are resistant to the antibiotics being used. The combined surgical and antibiotic treatment, along with natural host defenses, would have resulted in resolution of infection. The antibiotic may or may not have played an important role. The antibiotic that was clinically effective for the patient should be continued despite the contradictory data.

### **10.3 General Considerations in the Prophylactic Use of Antibiotics**

The original guidelines for timing and use of antibiotics to prevent infection postoperatively were established by Burke and Miles et al.'s experimental observations [12, 13]. They

#### **Table 10.3** Guidelines for the use of antibiotics

#### 1. *Empirical therapy*

noted that antibiotics must be given within 4 h after injection of bacteria into a surgical site to prevent the aggressive level of infection that occurs when no antibiotics are administered.

Antibiotic prophylaxis entails administering the antibiotic appropriate for the potential microbial contamination before the surgical insult, at a high enough dosage to establish an appropriate bacteriologic titer [14].

With judicious use of antibiotics, the infection rates are known to be lesser [16, 18].

#### **Table 10.4** Indications for antibiotic prophylaxis

	- (a) Physiological—old age, obesity, malnutrition
	- (b) Disturbances in circulation—massive transfusion, recent surgery
	- (c) Disease related—poorly controlled diabetes, cancer, leukemia, alcoholic cirrhosis, end-stage renal diseases
	- (d) Compromised immunity—multiple myeloma, total body irradiation, splenectomy
	- (e) Immunosuppressants—cytotoxic drugs, glucocorticoids, azathioprine, cyclosporine

#### **Table 10.5** Classifcation of surgical wounds

#### **Table 10.6** Need for postoperative antibiotics

One must be vigilant in identifying cases where antibiotics are required for the success of surgery, as antibiotic usage and overusage have considerable risks [6, 7, 20, 21]—gastrointestinal disturbances, toxicity reactions, antibiotic resistance and superinfections, anaphylaxis, pseudomembraneous colitis, etc.

#### **10.3.1 Prophylactic Uses of Antibiotics in Maxillofacial Surgery**

Infection, one of the most common postoperative complications, can be prevented by the timely use of appropriate antibiotic. In spite of many studies in literature, a defnitive conclusion cannot be made regarding the need for antibiotic prophylaxis in maxillofacial surgery and, if needed, the dose required. The antibiotic prescription pattern is still hugely based on personal preferences and shows wide regional variation, which many a time is inappropriate. The drugs would be initiated either at an incorrect time, or would be continued beyond the time required, and this has greatly contributed to the emergence of resistant bacteria [6].

Prophylactic use of antibiotics should be evidence based taking into consideration the effectiveness and the possible adverse outcomes of antibiotic therapy. Moreover, a thorough knowledge of the likely organisms involved in the infection is needed to prevent the prescription of unsuitable antibiotics. Antibiotics, if needed, should have a spectrum of activity that involves streptococci, anaerobic Grampositive cocci, and anaerobic Gram-negative rods, which are considered the most pathogenic for oral infections and should be bactericidal and the least toxic agents available amoxicillin being the most common choice of the clinicians [12, 18].

The need for antibiotic prophylaxis and the preferable drugs for wisdom teeth removal, orthognathic surgery, dental implants, maxillofacial trauma, and in special circumstances like patients with diabetes mellitus, patients—pre- and postorgan transplant, rheumatic heart disease—valve replacements, oncological surgery & reconstruction, cleft surgeries, etc. are mentioned in the following sessions.

#### **10.3.2 Antibiotic Prophylaxis in the Surgical Removal of Wisdom Teeth**

Though one of the most commonly performed minor oral surgical procedures, the reported infection rate with the removal of mandibular third molars is ≤10% [22]. However, the rate can be as high as 25% when the patient's immunity is compromised [20]. The infection rate associated with the corresponding procedure in maxilla is quite low, <1% [20, 22]. The higher rate of postoperative infection in relation to mandibular third molar has been attributed to the reduced vascularization and the gravity-induced pooling of bacterialrich saliva.

The prophylactic use of antibiotics in wisdom teeth removal had been an issue of many debates. There are studies for [20, 23] and against [24, 25] the practice of antibiotic prophylaxis in third molar removal. Considering the potentially contaminating oral environment in which the third molar removal is carried out, it is reasonable to favor antibiotic prophylaxis. Moreover, since the postoperative infection and alveolar osteitis, an infammatory response whose etiology could be traced to bacterial contamination and fbrinolysis of the socket blood clot, cause debilitating pain and severe functional impairment, it is only prudent to consider the use of prophylactic antibiotics.

Studies have shown that preoperative administration of antibiotics reduces the postoperative infection when administered 1-2 h prior to the procedure [26, 27]. Amoxicillin/ amoxicillin—clavulanic acid is the widely used antibiotic in the prophylaxis for the surgical removal of impacted teeth [28] and when given as a single dose preoperatively is found to reduce postoperative infection and alveolar osteitis [21]. But certain other studies have failed to show a considerable difference between amoxicillin, clindamycin, metronidazole, and placebo in terms of postoperative infection rates [25]. Studies have found topical tetracycline [29], chlorhexidine irrigation [30],& metronidazole dressings [31]into the mandibular third molar sockets, effective in reducing the postoperative infection & the incidence of dry socket. Review of literature does not give defnite indication to use of antibiotics as prophylaxis in healthy patients or asymptomatic impacted teeth and in case of the removal of maxillary wisdom teeth [22].

Studies have advocated the use of antibiotic prophylaxis in immunocompromised patients to prevent infection after surgical removal of impacted teeth [22].

Two recent meta-analyses [28, 32] summarize the antibiotic prophylaxis in wisdom teeth removal (Table 10.7).

#### **10.3.3 Antibiotic Prophylaxis in the Placement of Dental Implants**

Dental implants play a crucial role in the successful restoration of missing dentition. The success rate of dental implants is high, with only 0-10% of reported failure rates [33]. However, risk of failure is high during the frst year after implant placement [34]. The implant surfaces can become colonized by oral and perioral microorganisms during surgery (perioperative contamination) [35]. This can lead to pain, swelling, bone loss, and eventually failure of implants. The failure of the dental implants is multifactorial (Table 10.8).

**Table 10.7** Antibiotic prophylaxis in wisdom teeth removal—Key points

**Table 10.8** Factors affecting the survival of implants [33, 34]

Hence all these local, systemic, surgical, and procedural factors contributing to implant failure should be eliminated before considering infection as the reason for failure [33].

Because of the morbidity associated with infection of the implants, antimicrobial therapy is routinely used with the aim of prevention of surgical site infection. Though by defnition, dental implant placement is a clean-contaminated surgery with 3–11% chances of infection, the infection rate can be brought down to about 1% by proper patient selection, attention to surgical details, and by judicious use of antibiotics [18].

There are studies supporting antibiotic use to reduce implant failures [33, 34] and studies that fail to show any added benefts of antibiotics against implant failurte [36]. Few other studies have observed similar failure rates for the implants with a single preoperative dose and routine use of antibiotic for 7 days [37].

The currently advocated dose of antibiotic prophylaxis for implant surgery is 2–3 g of amoxicillin 2 h prior to multiple implant placement, especially along with bone graft [33]. If the patient is allergic to penicillin group, 600 mg clindamycin should be given 1 h before surgery. For sinus augmentation, 1.2 g of amoxicillin/clavulanic acid starting day before the surgery is the prophylaxis of choice [33]. Chlorhexidine gluconate mouth rinses have been known to reduce the number of pathogenic microorganisms, by lysing the bacterial cell membranes, and by virtue of its substantivity, can get retained in the oral soft tissues and get released slowly for up to 12 h [30, 33]. The key points in the antibiotic prophylaxis for dental implants are given in Table 10.9.

### **10.3.4 Antibiotic Prophylaxis in Orthognathic Surgery**

Orthognathic surgical procedures aim to correct the facial deformities and malocclusion, thereby improving the functional disorders of the stomatognathic system. It is an elective procedure, usually carried out in young healthy adults. It is considered as a clean-contaminated procedure with a reported infection rate of 3–11% [18, 39]. But certain studies have reported the rate of infection after orthognathic surgery to be as high as 6–33.4% [39]. The postoperative infection was found to be related to poor oral hygiene and the habit of smoking.

The surgical site infections (SSIs) that develop can be incisional SSIs and organ and space SSIs [40]. Both types of SSIs can occur after orthognathic surgery and may develop within the frst few weeks after surgery. The development of SSIs increased the total length of hospital stay and expenditure. Though the potential for postoperative infections after orthognathic surgery is known for a very long time, a consensus has not yet been achieved with regard to the drug that is useful, the dose, and the duration of administration.

The specifc orthognathic procedure that has been associated with higher infection rate was mandibular sagittal split osteotomy, especially where a transbuccal approach had been adopted for fxation [38]. Increased rate of infection associated with mandibular procedures has been attributed to the diminished vascularity of mandible in comparison with maxilla and pooling of food and saliva along the vestibular incision line in the mandible. Till the incision seals off, oral microfora can freely enter the deeper tissues from the pooled saliva. Though concomitant extractions, especially of partially erupted mandibular third molars had been implicated as a risk factor for the development of postoperative infec**Table 10.9** Antibiotic prophylaxis in dental implants—Key points

*Care to be taken* [35]: Through oral prophylaxis & measures to improve oral hygiene Stabilize oral focus of infection Procedure in a well-monitored asceptic environment disinfection, draping, hand scrubbing, sterile gowns & gloves, sterile instruments Prevent contamination of implants with contact with skin, infected oral mucosa, & sinus lining Bactericidal antibiotic with coverage against pathogenic oral microfora [12, 18, 33] Preoperative administration of antibiotics—1 h before the procedure, twice the therapeutic dose [18, 33]—Amoxicillin 2gm, / clindamycin 600 mg 1 h prior to surgery Chlorhexidine gluconate rinses—hugely effective in controlling the immediate local infection [30, 33]. 1 *Only Chlorhexidine 0.12% rinse twice daily in healthy individuals* [33]

	- (a) Multiple implants with minimal tissue refection,
	- (b) Immediate extraction & implant placement,
	- (c) Socket bone grafting.
	- (a) Multiple implants with extensive tissue refection,
	- (b) Multiple extractions & implant placement,
	- (c) Bone grafting—allografts,
	- (d) Long duration.
	- (a) In medically compromised patients,
	- (b) Extensive tissue refection,
	- (c) Full arch implants,
	- (d) Block bone grafting—autografts,
	- (e) Indirect sinus foor lift procedures,
	- (f) Active periodontal disease.

tion, studies were not able to support or refute this [38, 41] Longer surgeries involving multiple/segmental procedures also show a higher rate of infections [12, 18, 38].

Use of various antibiotics has been proposed—penicillin [42], ampicillin [43], amoxicillin with or without clavulanate [43], clindamycin [42], or a member of the cephalosporin group [19, 41]. Literature fails to report a signifcant difference in the infection rate when using a penicillin or nonpenicillin group of antibiotics or among the various types of penicillins [18, 19, 44]. Based on the bacteriological studies, penicillin, amoxicillin, or amoxicillin—clavulanic acid or cephalosporins is commonly recommended in the preoperative antibiotic prophylaxis for orthognathic surgery [19, 38, 41–44].

The preoperative single dose of antibiotic increases the level of the drug in circulation prior to incision. Whether short-term antibiotics (single dose or dose × 24 h) [ 42] or extended-term antibiotics (for more than 24 h) [ 41, 43] is benefcial in the prevention of postoperative infection after orthognathic surgery is still a debatable question [19, 38, 41, 44].

#### **10.3.5 Is Antibiotics Needed when Bone Plates and Screws Are Being Inserted?**

One question that keeps on surfacing is whether prophylactic antibiotics are needed in cases where bone plates and screws are used to hold the bony segments together. Any foreign body inserted into the body, be it a medical device or implant, may elicit a foreign body reaction. Moreover, the microorganisms can colonize on the implant surface in a bioflm, while they are being inserted, and as the physical presence of the implants may compromise the blood supply to the region, thereby reducing the delivery of body's immune cells to the region and resulting in infections at the host –implant interface by normal fora with low virulence [45, 46]. The oral bioflm and its toxins, adhered to the surface of titanium plates and screws used for stabilization of osteotomy segments, could be a source of local or regional infectious complications [19]. Hence, the use of antibiotic prophylaxis is justifed.

*Take-home points regarding antibiotic prophylaxis in orthognathic surgery are mentioned in* Table 10.10*.*

#### **10.3.6 Antibiotic Prophylaxis in Maxillofacial Trauma**

In today's world of fast-moving vehicles and expressways, hundreds of thousands of people get involved in road traffc accidents. Head and face are among commonly injured body parts. Both the soft and hard tissues of the face may be involved in the trauma. Firearms, contact sports, and interpersonal violence are other reasons for facial injuries. The management of these injuries should follow protocols and be done in a systematic manner. With advances in anesthetic and surgical techniques and availability of better implant materials with favorable metallurgy, open reduction and internal fxation (ORIF) has become the norm. The reestablishment of form, function, & cosmesis is of paramount importance. To arrive at this goal, the probable complications of ORIF need to be prevented or managed correctly. Of the various complications reported, none has generated more interest and controversy than the occurrence of postoperative infection. By adhering to the standard surgical protocols and strict aseptic techniques, the occurrence of postoperative **Table 10.10** Antibiotic prophylaxis in orthognathic surgery—Key points

	- (a) Longer surgery;
	- (b) Short-term antibiotic prophylaxis;
	- (c) Extraction of a third molar during surgery;
	- (d) Greater number of osteotomies performed;
	- (e) Older age;
	- (f) Smoking;
	- (g) Poor oral hygiene;
	- (h) Compromised immune system.

infection can be brought down considerably. But the presence of the microorganisms in the oral cavity and facial skin and possible contamination from environment necessitate the consideration of antibiotics in the maxillofacial trauma management.

Though prophylactic antibiotics were considered essential in the management of maxillofacial trauma for many years [18], the evidence for this preventive intervention was weak and confusing. Among facial fractures, mandibular fractures are most commonly studied, because of the compound nature of the fractures, except in the ramus—condyle unit, where the fractures usually do not communicate with the external environment. Fractures of the mandibular condyles or Lefort fractures of maxilla are rarely infected when compared with the fractures involving mandibular angle, body, or symphysis [49, 50].

The decision to use antibiotic prophylaxis depends on whether the fracture is an open or closed type and whether it is going to be managed with open or closed reduction. Open procedures were four times more commonly prone to postoperative infections according to a few studies [41, 51, 53, 54], whereas certain other studies reported no difference between the patients treated with closed reduction and maxillomandibular fxation and those who underwent open reduction and internal fxation [54]. The microbiology of the infected fractures was mixed and responded to betalactam antibiotics well.

**Table 10.11** Antibiotic prophylaxis in maxillofacial trauma—Key points

	- (a) Longer surgery;
	- (b) Older age;
	- (c) Smoking;
	- (d) Poor oral hygiene;
	- (e) Compromised immune system.

Studies have shown that single dose of preoperative antibiotic prophylaxis is suffcient to prevent wound infection [51, 54]. If the surgery extends beyond the half-life of the antibiotic, the antibiotic can be redosed [51]. The need for postoperative antibiotics in the maxillofacial trauma too has been extensively studied [16, 49, 53, 55, 56]. These studies reported no statistically signifcant difference in the development of SSIs between the patients who had received perioperative antibiotics and those who had received extended antibiotics in the postoperative period.

Longer antibiotic usage has been advocated in the immunocompromised patients [32, 52, 56]. The habit of tobacco smoking was found to have a deleterious effect on the healing of mandibular fractures by inducing hypovascularity and prolonged infammation [54]. The other major factors, which contribute to the occurrence of SSIs, are poor oral hygiene, extremes of age and malnutrition [22, 32].

*Important points mentioning the need for antibiotics in the management of maxillofacial trauma are given in* Table 10.11*.*

#### **10.3.7 Diabetes Mellitus & Antibiotic Prophylaxis in Maxillofacial Surgery**

Diabetes mellitus is a metabolic disorder resulting in elevated glucose levels, due to inadequate insulin secretion (type I) or reduced insulin secretion with an accompanying insulin resistance (type II). Diabetic patients pose a special challenge to the surgeon as the balance between the insulin they can secrete and the hyperglycemia induced by surgical stress-adaptive hormones catecholamines, cortisol, growth hormone, and glucagon is lost. Patients, who are nondiabetic, usually are able to handle this glucose overload effectively, whereas diabetic patients may have issues resulting in cardiovascular complications, infection, and reduced rates of wound healing. Moreover, the defective polymorphonuclear leukocytes function and macro- and microvascular dysfunction resulting in compromised local circulation increases the susceptibility to infections [57]. With the vast microbiological colonization of the oral cavity, it has always been assumed that maxillofacial surgical procedures carry a high risk of infection and prolonged or delayed wound healing. The guidelines as to the prophylactic use of antibiotics in diabetic patients had been vague as "….are more prone to infection necessitating routine antibiotic prophylaxis for all maxillofacial procedures" [58].

In many of the literature surveys, authors have noted that well-controlled diabetic patients are at no increased risk of postoperative infection than normal healthy patients and delayed wound healing is not a pressing concern due to the rich vascularity of the region [59, 60]. Antibiotic prophylaxis is warranted only in conditions where a normal patient also would beneft from it. Poorly controlled diabetic patients would require normalization of their hyperglycemic state prior to elective procedures. In emergency situations, antibiotic prophylaxis prior to the surgical incision is desirable and attempts should be made to control the glycemic level during the peri- and postoperative period [58–60].

#### **10.3.8 Antibiotic Prophylaxis in Head and Neck Oncology**

Head and neck oncology patients usually require a major surgical procedure +/− with radiation therapy. The surgical site tends to be large, the surgical time and postoperative immobilization period longer. The surgical management attempts at removal of the tumor, clearance of the neck nodes, and involves an additional surgical site from where fap is harvested for reconstruction—either microvascular faps or pedicled ones [61]. The large wound area exposed to local fora of the oral cavity and the skin is at risk of wound contamination and infection. Nosocomial infections are known to run a protracted course and pre-existing general comorbidities further increase the morbidity and, thus, the hospital expenses associated with these surgeries.

The reasons for increased infection rate are mainly the number of procedures carried out in the same operation (excision, neck dissection, tracheostomy, and distant fap harvest), the pooling of saliva due to diffculty in swallowing, leading to aspiration, and the inability in obtaining a watertight closure when the fap is inset in the recipient bed leading to salivary leak and contamination of neck wounds with saliva [62, 63].

**Table 10.12** Key points in oral oncology & antibiotic prophylaxis

The need for antibiotic prophylaxis is well established in the oncologic surgery, but the need for a long postoperative course of antibiotics is still debated upon. There are studies, which have shown benefts of prolonged antibiotics in preventing postoperative infections like pneumonia, urinary tract infections, sepsis, and SSIs in patients who had oral squamous cell carcinoma [64], and there are studies, which have shown no extra benefts of prolonged postoperative antibiotics [63, 64].

Escherichia spp. and Staphylococcus spp. are predominantly responsible for the infections and in 72% were sensitive to ampicillin & sulbactum [62].

*A few key points, which would be benefcial in making a decision, are given in* Table 10.12*.*

#### **10.3.9 Antibiotic Prophylaxis in Cleft Surgeries**

Orofacial clefting is one of the more common congenital anomalies and cleft lip & palate deformity is the most common among them. Management of cleft lip & palate deformity involves staged procedures and spans over 12–16 years. The management aims at correction of the deformity so that function and cosmesis are restored as much as possible and the psyche of the individual is minimally scarred. Postoperative infections can result in wound breakdown, poor speech & esthetics, and nasal regurgitation of food in cleft lip and palate patients.

Various authors had reported on obtaining swabs from nose and oral cavity to identify the possible pathogens and using antibiotics according to the culture reports before cleft lip and palate repair [65–67]. The pathogenic bacteria isolated from the swabs were Staphylococcus aureus and beta hemolytic streptococci [67]. But later studies demonstrated that there were not many differences between the group that underwent swab acquisition and corresponding antibiotics therapy and the group that didn't receive any antibiotics in terms of postoperative complications [68]. The rate of complications was found to be independent of the potential pathogens in the mouth [65].

*Factors, which have been implied as contributing factors to wound dehiscence, are given in* [66, 67] Table 10.13*.*

**Table 10.13** Factors contributing to wound dehiscence in cleft surgeries

In a recent prospective study, Azner et al. (2015) noted a statistically signifcant reduction in the incidence of palatal fstulas with 5 days of postoperative antibiotics [69]. But 80% of their control group, who had received no postoperative antibiotics, too healed without any complications. Both study and control groups had received a single dose of cefuroxime 30 mg / kg body weight, before incision. The use of one dose of antibiotics before incision has been advocated by other authors also and may be more effective in preventing complications related to wound infection than a prolonged course of postoperative antibiotics [68].

#### **10.3.10 Organ Transplant and Antibiotic Prophylaxis**

The concept of organ donation had always excited mankind. Twentieth century saw developments that made the dream of replacing a diseased organ with a healthy one a reality. Understanding the human immunology and the development of powerful immunosuppressant drugs laid the foundation for modern transplant medicine, making transplantation of kidney, liver, lungs, and heart a successful treatment option. As the transplant science advanced, so did the numbers and life span of transplant patients and their need for dental/maxillofacial surgical procedures. As these patients are on immunosuppressants, they are more prone to opportunistic infections and their sequel. Hence, care must be given to treat or remove the existing/potential sources of infection before the transplant procedures.

In a pretransplant patient, the need for maintaining oral hygiene should be stressed upon. The treating physician should be consulted with regard to the ftness to undergo the planned procedures and the safety of using any drugs if required. Drugs, which have a hepatic metabolism or renal clearance, should be used with caution in patients with compromised liver or kidney function. The selection of antibiotics is made after careful evaluation of the existing pathology and the chances of spread of infection with the planned dental treatment.

In the immediate post-transplant period—the frst 3 months post-surgery, the graft, and the patient are very vulnerable to any insult—graft anastomoses are susceptible to endarteriris due to bacterial colonization as they are not yet **Table 10.14** Key points—organ transplant and antibiotic prophylaxis

	- 1. Elimination of potential focus of infection,
	- 2. Oral hygiene,
	- 3. Liver / kidney friendly drugs.

Post-transplant patients:

	- 1. Only emergency procedures,

3 months postop—noninvasive elective procedures 6 months postop—invasive elective procedures under antibiotics Beta-lactam antibiotics - relatively safer to be used in renal and hepatic transplant patients [72]

No consensus on minimally invasive procedures in patients with meticulous oral hygiene [71]

fully epithelialized. Hence, only emergency procedures should be done. Any acute orofacial infection developing should be managed aggressively, surgical drainage, culture and sensitivity of the organism, and appropriate antibiotics would be required [70]. After 3 months, elective, noninvasive procedures can be carried out. Since the patients who have undergone organ transplantation are immunosuppressed and are at high risk of infection, prophylactic antibiotics need to considered for any invasive dental procedures, even after 6 months. Beta-lactam antibiotics are relatively safer to be used in renal and hepatic transplant patients [71]. But for those with meticulous oral hygiene, there is no consensus regarding the need for antibiotic prophylaxis for minimally invasive procedures [71]. The decision to use antibiotics should be done on a case-to-case basis.

*Important points to be kept in mind while contemplating antibiotic prophylaxis in organ transplant patients are given in* Table 10.14*.*

#### **10.4 Infective Endocarditis**

Bacterial endocarditis, a rare but life-threatening condition, was initially described by Lewis & Grant in 1923 [72]. They suggested that bacteria released into the blood stream after a dental procedure colonize on the heart valves or the endocardium. The bacteremia associated with infections of skin and soft tissues, genitourinary tract, and gastrointestinal tract are also known to result in infective endocarditis (IE). Bacteria can gain direct access to the bloodstream through the indwelling catheters. The American Heart Association (AHA) came up with the frst guidelines to reduce the risk of IE following invasive procedures in 1955 [73]. The AHA guidelines have been updated regularly since then and the latest one was released in 2007 [74]. The 2007 guidelines categorized cardiac conditions into having a low risk, moderate risk, and high risk of developing IE and advocated the use of antibiotic prophylaxis only in

**Table 10.15** High-risk cardiac conditions, which require antibiotic prophylaxis [75]

high-risk-category patients (Table 10.15) who were to undergo dental procedures that involved the manipulation of gingival tissues or the periapical region of teeth or incision of the oral mucosa.

The guidelines prescribed a single dose of antibiotic 30-60 minutes prior to the procedure—Amoxicillin 2 g PO, Cephazolin/Cephtriaxone 1gm IV/IM, or Clindamycin 600 mg PO/IM/IV, depending on whether the patient is unable to take oral preparations or is allergic to penicillin or not [74]. The reason for the revision of the antibiotic policy was predominantly the observation that IE is more likely to result from transient bacteremias caused by routine daily activities, like chewing food, and by regular oral hygiene care. The authors concluded that maintaining optimal oral hygiene is more important in reducing the risk of IE and the adverse effects of antibiotics exceeded the benefts of antibiotic prophylaxis. The British Society for Antimicrobial Chemotherapy (BSAC) also recommend antibiotic prophylaxis only in those who have a history of healed IE, prosthetic heart valves, and surgically constructed conduits [75]. The advice to the patient is to concentrate on achieving and maintaining meticulous oral hygiene as this has been found to reduce the risk of IE. Similar observations were made by the National Institute for Health and Care Excellence (NICE) [76] and the European Society of Cardiology (ESC) [77].