teeth are stimulated, and the direction that forces are applied to the individual teeth.

platelet aggregation or mediate an inflammatory response [41].

26 Temporomandibular Joint Pathology - Current Approaches and Understanding

tomic ties to the stomatognathic system:

**6.1. Pain: an alarm system for protection of the body**

pulp meter to the tooth surface can lead to a typical jaw jerk reflex.

afferent and efferent arms within the chain of spinal interneurons.

• Trigeminal ganglion

• Mesencephalic nucleus

for example, contain conscious and unconscious processes that allow for the acquisition of altered behavior in response to environmental stimuli [46]. After a very hot liquid is brought into the mouth, this warm sensation will be placed in the permanent memory to be remembered easily in later scenarios where the patient will drink a very hot liquid once again. However, if a new hot liquid experience is repeated a number of times over a long time frame, the patient's reflex response to hot liquid will slowly disappear. As a learned function repeats, it becomes a reflex state.

Myofascial Pain Dysfunction Syndrome: Etiology, Diagnosis, and Treatment

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29

A new complete denture adaptation process a patient must go through when receiving a different prosthesis than they are physically used to involves the development of a new denture chewing model. If the new prosthesis causes pain, the pain will be perceived as more prominent in the patients' psyche, compared to the known chewing pattern of the old denture that was saved in the patient's memory. The central nervous system (CNS) will develop a reflex protective mechanism against the pain, such that the protected pattern of chewing will take a

The electromyographic record of the same patient with the new denture shows that all four elevator muscles are in hyperactivity, exhibiting higher than the average values (**Figure 6**).

Chronic pain is a habitual pattern generated by the central nervous system (CNS) that must

Chronic pain is a nonphysiologic and extraordinary somatosensory process that can take place either in the peripheral or central nervous systems that is sustained beyond the normally expected time frame relative to the existence of a stimulus. This scenario, although somewhat explanatory, only provides for part of the story. Chronic pain is often clandestinely ambiguous and can be difficult to pinpoint its primary causative location. The perception of pain results from the summation and culmination of the nerve transduction process that arises from temporarily stimulated and affected peripheral nociceptors. Nociceptors may be specific for painful stimuli or they may be generally responsive to a wide range of mechanical, thermal, chemical, and/or electrical stimuli. Nociceptive responses are transmitted from peripheral sites into the CNS via myelinated (type A-delta) or unmyelinated (type C) nerve

Masticatory system myofascial pain constitutes one of the most important chronic problems that is encountered in clinical dental practice. Pain is a critical factor in evolving this chronic problem because pain increases muscle contraction, and more spasms from the excess contractions increase the level of pain. Elongation of the contraction time leads to the formation

Within the literature, dental occlusion appears to be a key causative agent for MPDS because all kinds of treatment suggestions for MPDS are targeted on changing the occlusion in some way. In a study by Laskin et al. [48], the authors remarked that although many aspects of the MPDS are either controversial or unexplored, most investigators and clinicians seem to agree

**7. The importance of breaking the pain cycle in treatment of MPDS;**

very different shape from a healthy average chewing pattern (**Figure 5**).

be broken before trying to treat myofascial pain dysfunction syndrome.

**the role of occlusal splints**

fibers [47].

of trigger points.

**Figure 5.** Irregular masticatory pattern of a patient with new denture while the CNS tries to develop a new chewing pattern to accommodate the new denture. Chewing patterns are not similar to each other and irregular.

**Figure 6.** Both the temporalis and masseter muscle electrical activity levels are higher than the physiological average resting values. This is not unexpected during the development of new prosthesis adaptation.

Pain perception is not simply determined by the intensity of nociceptive stimulation but also depends upon psychological factors such as the emotional and motivational state of the patient. The chronic pain threshold is divergent from the patient's level of fear and/or anxiety [45]. Memory and pain, though two richly diverse fields, have many underlying commonalities. Both, for example, contain conscious and unconscious processes that allow for the acquisition of altered behavior in response to environmental stimuli [46]. After a very hot liquid is brought into the mouth, this warm sensation will be placed in the permanent memory to be remembered easily in later scenarios where the patient will drink a very hot liquid once again. However, if a new hot liquid experience is repeated a number of times over a long time frame, the patient's reflex response to hot liquid will slowly disappear. As a learned function repeats, it becomes a reflex state.

A new complete denture adaptation process a patient must go through when receiving a different prosthesis than they are physically used to involves the development of a new denture chewing model. If the new prosthesis causes pain, the pain will be perceived as more prominent in the patients' psyche, compared to the known chewing pattern of the old denture that was saved in the patient's memory. The central nervous system (CNS) will develop a reflex protective mechanism against the pain, such that the protected pattern of chewing will take a very different shape from a healthy average chewing pattern (**Figure 5**).

The electromyographic record of the same patient with the new denture shows that all four elevator muscles are in hyperactivity, exhibiting higher than the average values (**Figure 6**).

## **7. The importance of breaking the pain cycle in treatment of MPDS; the role of occlusal splints**

Chronic pain is a habitual pattern generated by the central nervous system (CNS) that must be broken before trying to treat myofascial pain dysfunction syndrome.

Chronic pain is a nonphysiologic and extraordinary somatosensory process that can take place either in the peripheral or central nervous systems that is sustained beyond the normally expected time frame relative to the existence of a stimulus. This scenario, although somewhat explanatory, only provides for part of the story. Chronic pain is often clandestinely ambiguous and can be difficult to pinpoint its primary causative location. The perception of pain results from the summation and culmination of the nerve transduction process that arises from temporarily stimulated and affected peripheral nociceptors. Nociceptors may be specific for painful stimuli or they may be generally responsive to a wide range of mechanical, thermal, chemical, and/or electrical stimuli. Nociceptive responses are transmitted from peripheral sites into the CNS via myelinated (type A-delta) or unmyelinated (type C) nerve fibers [47].

Masticatory system myofascial pain constitutes one of the most important chronic problems that is encountered in clinical dental practice. Pain is a critical factor in evolving this chronic problem because pain increases muscle contraction, and more spasms from the excess contractions increase the level of pain. Elongation of the contraction time leads to the formation of trigger points.

Within the literature, dental occlusion appears to be a key causative agent for MPDS because all kinds of treatment suggestions for MPDS are targeted on changing the occlusion in some way. In a study by Laskin et al. [48], the authors remarked that although many aspects of the MPDS are either controversial or unexplored, most investigators and clinicians seem to agree

Pain perception is not simply determined by the intensity of nociceptive stimulation but also depends upon psychological factors such as the emotional and motivational state of the patient. The chronic pain threshold is divergent from the patient's level of fear and/or anxiety [45]. Memory and pain, though two richly diverse fields, have many underlying commonalities. Both,

**Figure 6.** Both the temporalis and masseter muscle electrical activity levels are higher than the physiological average

resting values. This is not unexpected during the development of new prosthesis adaptation.

**Figure 5.** Irregular masticatory pattern of a patient with new denture while the CNS tries to develop a new chewing

pattern to accommodate the new denture. Chewing patterns are not similar to each other and irregular.

28 Temporomandibular Joint Pathology - Current Approaches and Understanding

that the majority of patients with MPDS report relatively rapid improvement or symptom disappearances with splint therapy [48]. Splint therapy is a very effective occlusion determinant because when splint is placed between occluding teeth, the occlusion changes dramatically which can quickly break the pain generating pattern. However, all researchers agree that a splint therapy protocol must be provided by only skilled clinicians.

There are many types of splints in dentistry such as custom splints, prefabric splints, posterior splints, anterior jig, hard splints, soft splints, etc. Each splint is described in detail by its advocate. The following factors should be taken into account during splint construction [44, 49]:

The very simple principal rule that was widely believed, purported is that proper occlusal function resulted from the close relationship between condylar movements and the occlusal contact relationships. To utilize this thinking clinically, most articulator systems were

**Figure 7.** Splint therapy must be performed by a skilled clinician. Hard splints are very effective for changing the occlusal relationship between upper and lower jaws (maxillary splint; left pane). Hydrostatic soft splints (right pane) are helpful in creating muscular balance and physiologic harmonization. An etiologically based treatment for MPDS can be

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31

**1.** Some special equipment was built to detect condylar movements. The Lauritzen Hinge Axis Locator [54, 55] or Condylator Joint Tracer [56, 57] are examples of these types of condylar movement analysis tools. However, these devices are not easy to manage, often require repeated and difficult-to-make registrations, both intra- and extra-orally [58].

**2.** Completion of the condylar tracing procedure usually requests more than one visit.

**3.** Registration of centric relation location needs special devices and careful working.

**4.** Articulator-based diagnostic work is not repeatable and cannot be digitally stored. It is difficult to compare two different analyses on the same articulator, as one must be removed

**5.** Two different registrations may be quite different, spatially. This difference can arise from making registrations at different times of the day for both the operator and the patient, from impression material setting distortion, registration material setting distortion, and from differing degress of poured stone setting contraction. Because many variables come into play with the articulating of dental casts, precision levels of the differing analyses may

Therefore, occlusal analysis performed on articulators for occlusal adjustment can be difficult and time-consuming; and once completed, it is not necessarily reliably to be accurate for diag-

The development of the computerized occlusal analysis method (T-Scan 9, with the Novus Recording Handle, and the HD Recording Sensor, Tekscan, Inc. S. Boston, MA, USA) has been

designed with the following requirements:

instituted after 3–5 days of successful splint therapy.

to mount another set of casts.

nosis and treatment.

be quite inconsistent from one analysis to another.

Basically, splints are applied for a specific purpose [48, 50–52]. Therefore, it is very important to determine the type of splint, application period, and schedule, if applicable (**Figure 7**). Using a proper splint for a longer period of time may cause the patient to worsen in a variety of ways (worsening of MPDS symptoms; creating an open occlusion, intruding of teeth out of occlusal contact). Hence, splint treatment duration and its daily schedule are important to manage properly.

#### **7.1. Occlusal analysis and occlusal adjustments**

Removing of premature contacts with occlusal adjustment is one of the most important methods for breaking the neuromuscular cycle in myofascial pain dysfunction syndrome [53]. Changing the occlusal scheme and balancing of the occlusion are very effective methods for pinpointing and eliminating extraordinary neural firings. Hence, an occlusal analysis has always been an important diagnostic component of the treatment efforts to resolve MPDS symptoms. Several decades ago, dentists were performing occlusal analysis solely with mounted casts on semi-adjustable or fully adjustable dental articulators. There was no scientific method for performing intraoral occlusal analysis, and no real effective way to measure occlusal forces between all the contacting teeth.

Myofascial Pain Dysfunction Syndrome: Etiology, Diagnosis, and Treatment http://dx.doi.org/10.5772/intechopen.72529 31

that the majority of patients with MPDS report relatively rapid improvement or symptom disappearances with splint therapy [48]. Splint therapy is a very effective occlusion determinant because when splint is placed between occluding teeth, the occlusion changes dramatically which can quickly break the pain generating pattern. However, all researchers agree that a

There are many types of splints in dentistry such as custom splints, prefabric splints, posterior splints, anterior jig, hard splints, soft splints, etc. Each splint is described in detail by its advocate. The following factors should be taken into account during splint construction [44, 49]:

**3.** Splint therapy changes the tooth-to-tooth occlusal relationships, which then changes the

**4.** Prolonged hyperactivity of muscles can cause heightened synaptic transmission. Consequently, long contraction durations decrease action potential threshold levels and decrease

**5.** During the use of a splint, there must be careful follow-up; if complications occur from

**6.** If the splint is only used for a temporary occlusal correction, a 3–4 day use period should be sufficient. The best splints to be used for this purpose are either hydrostatic splints or hard splints because the surface of these designs does not allow teeth to engage and clash,

**7.** After acquiring muscle balance and improved physiologic muscle contraction reestablishment, splint therapy must be stopped and an etiological treatment must be initiated.

Basically, splints are applied for a specific purpose [48, 50–52]. Therefore, it is very important to determine the type of splint, application period, and schedule, if applicable (**Figure 7**). Using a proper splint for a longer period of time may cause the patient to worsen in a variety of ways (worsening of MPDS symptoms; creating an open occlusion, intruding of teeth out of occlusal contact). Hence, splint treatment duration and its daily schedule are important to

Removing of premature contacts with occlusal adjustment is one of the most important methods for breaking the neuromuscular cycle in myofascial pain dysfunction syndrome [53]. Changing the occlusal scheme and balancing of the occlusion are very effective methods for pinpointing and eliminating extraordinary neural firings. Hence, an occlusal analysis has always been an important diagnostic component of the treatment efforts to resolve MPDS symptoms. Several decades ago, dentists were performing occlusal analysis solely with mounted casts on semi-adjustable or fully adjustable dental articulators. There was no scientific method for performing intraoral occlusal analysis, and no real effective way to measure

which allows the masticatory muscles to freely exist in a harmonic balance.

splint therapy protocol must be provided by only skilled clinicians.

30 Temporomandibular Joint Pathology - Current Approaches and Understanding

**1.** The treatment protocol must be provided by skilled clinicians

neuromuscular activity accordingly

the patient's pain threshold.

manage properly.

**7.1. Occlusal analysis and occlusal adjustments**

occlusal forces between all the contacting teeth.

**2.** All masticatory activities can be changed by changing the occlusion

splint treatment, the therapy should be terminated immediately.

**Figure 7.** Splint therapy must be performed by a skilled clinician. Hard splints are very effective for changing the occlusal relationship between upper and lower jaws (maxillary splint; left pane). Hydrostatic soft splints (right pane) are helpful in creating muscular balance and physiologic harmonization. An etiologically based treatment for MPDS can be instituted after 3–5 days of successful splint therapy.

The very simple principal rule that was widely believed, purported is that proper occlusal function resulted from the close relationship between condylar movements and the occlusal contact relationships. To utilize this thinking clinically, most articulator systems were designed with the following requirements:

Therefore, occlusal analysis performed on articulators for occlusal adjustment can be difficult and time-consuming; and once completed, it is not necessarily reliably to be accurate for diagnosis and treatment.

The development of the computerized occlusal analysis method (T-Scan 9, with the Novus Recording Handle, and the HD Recording Sensor, Tekscan, Inc. S. Boston, MA, USA) has been removed from the making of occlusal analyses, the necessity of using inaccurate articulatorbased methods, which present the clinician with many challengers that complicate their clinical usefulness.

#### **7.2. Computer-based occlusal analyses and computer-guided occlusal adjustments**

Computer-based occlusal analyses have many clinical advantages over the articulator-based method:

As with every new method, the earliest T-Scan computer-based occlusal analyzing systems (T-Scan I, II, III; Tekscan Inc. S. Boston, MA, USA) were questioned as to their clinical reliability [59, 60]. However, the modern The T-Scan HD recording sensor (**Figure 8a**) has been shown to accurately measure 256 differing relative occlusal force levels [3–6, 55, 61] with 95% of force reproduction capability [4]. Other recent T-Scan studies show the T-Scan accurately records occlusal contact time sequencing [62, 63]. Today's T-Scan Novus System with the version 9 software is a highly advanced digital occlusal force and timing analyzer that can be used

chairside to treat a wide range of commonly encountered occlusal force problems. Moreover, additional research and clinical publications have illustrated how the T-Scan occlusal analysis

**Figure 9.** Premature contacts are contacts that rise to very high force well before the maximum intercuspal position (MIP) (pane 1) are visible with the T-Scan occlusal analysis system. Tooth #18 rises quickly to high occlusal force (tall pink column; left pane #1), as other closure contacts are low force (dark blue columns; left pane #1). Then later in the same T-Scan recording (pane 2), the #18 forceful contact lessens to low force while other occluding teeth increased in

Myofascial Pain Dysfunction Syndrome: Etiology, Diagnosis, and Treatment

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33

The correction of orthodontic and prosthodontic occlusal problems has become much easier for clinicians who use computerized occlusal analysis. Prior to the development of the T-Scan, dentists could only "look at" the occlusion, and now with T-Scan sensor interposed between occluding teeth during mandibular functional movements, dentists are able to see occlusal force changes over time as occlusal contacts on opposing teeth engage and interact frictionally (**Figure 9**). Note in **Figure 9** how during the early part of a patient self-closure into MIP, tooth #18 rises quickly to high occlusal force (tall pink column; left pane #1), as all the other closure tooth contacts maintain a low force state (dark blue columns; left pane#1). Then later in the same T-Scan recording, when more of the patient's teeth fully interdigitate closer to complete intercuspation, the #18 premature forceful contact lessens to a low force state, while other occluding teeth increased in force bilaterally (light green and yellow col-

method can be used in many dental medicine disciplines (**Figure 8a** and **b**) [64–67].

**7.3. Disclusion time reduction therapy with the immediate complete anterior**

Changing occlusal relationships between the upper and lower teeth breaks sharply the neuromuscular loop that causes acute muscle spasm. There are many studies that have shown the effect periodontal receptors have on functional and parafunctional occlusal excursions [34–38, 68]. An

umns: right pane #2).

force bilaterally (pane #2).

**guidance development coronoplasty**

**Figure 8.** (a) The T-Scan Novus Definition (HD) sensor records 256 levels of relative occlusal force in 0.003 s time frames to reveal an occlusal playback video that illustrates changing occlusal force levels across time. (b) The T-Scan Novus recording handle with the HD sensor in place, connected directly to a computer with a USB plug.

removed from the making of occlusal analyses, the necessity of using inaccurate articulatorbased methods, which present the clinician with many challengers that complicate their clini-

Computer-based occlusal analyses have many clinical advantages over the articulator-based

**1.** Digital occlusal analysis is usually completed in one session. It can be repeated at another

**2.** Digital occlusal analysis data can be stored and recalled easily, so that many analyses of a single patient can be compared with each other, over time, to observe changes in the oc-

**3.** The recording and data acquisition is quick to accomplish chairside, so that many occlusal analyses and corrective adjustments can be performed in same treatment session.

**4.** Adjustment results can be compared with the preoperative status of the occlusion to observe that occlusal force and timing improvements have been therapeutically obtained.

As with every new method, the earliest T-Scan computer-based occlusal analyzing systems (T-Scan I, II, III; Tekscan Inc. S. Boston, MA, USA) were questioned as to their clinical reliability [59, 60]. However, the modern The T-Scan HD recording sensor (**Figure 8a**) has been shown to accurately measure 256 differing relative occlusal force levels [3–6, 55, 61] with 95% of force reproduction capability [4]. Other recent T-Scan studies show the T-Scan accurately records occlusal contact time sequencing [62, 63]. Today's T-Scan Novus System with the version 9 software is a highly advanced digital occlusal force and timing analyzer that can be used

**Figure 8.** (a) The T-Scan Novus Definition (HD) sensor records 256 levels of relative occlusal force in 0.003 s time frames to reveal an occlusal playback video that illustrates changing occlusal force levels across time. (b) The T-Scan Novus

recording handle with the HD sensor in place, connected directly to a computer with a USB plug.

**5.** The cost of performing the occlusal analysis has decreased sharply.

**7.2. Computer-based occlusal analyses and computer-guided occlusal adjustments**

32 Temporomandibular Joint Pathology - Current Approaches and Understanding

cal usefulness.

session, if there is a need.

clusal status as the patient ages.

method:

**Figure 9.** Premature contacts are contacts that rise to very high force well before the maximum intercuspal position (MIP) (pane 1) are visible with the T-Scan occlusal analysis system. Tooth #18 rises quickly to high occlusal force (tall pink column; left pane #1), as other closure contacts are low force (dark blue columns; left pane #1). Then later in the same T-Scan recording (pane 2), the #18 forceful contact lessens to low force while other occluding teeth increased in force bilaterally (pane #2).

chairside to treat a wide range of commonly encountered occlusal force problems. Moreover, additional research and clinical publications have illustrated how the T-Scan occlusal analysis method can be used in many dental medicine disciplines (**Figure 8a** and **b**) [64–67].

The correction of orthodontic and prosthodontic occlusal problems has become much easier for clinicians who use computerized occlusal analysis. Prior to the development of the T-Scan, dentists could only "look at" the occlusion, and now with T-Scan sensor interposed between occluding teeth during mandibular functional movements, dentists are able to see occlusal force changes over time as occlusal contacts on opposing teeth engage and interact frictionally (**Figure 9**). Note in **Figure 9** how during the early part of a patient self-closure into MIP, tooth #18 rises quickly to high occlusal force (tall pink column; left pane #1), as all the other closure tooth contacts maintain a low force state (dark blue columns; left pane#1). Then later in the same T-Scan recording, when more of the patient's teeth fully interdigitate closer to complete intercuspation, the #18 premature forceful contact lessens to a low force state, while other occluding teeth increased in force bilaterally (light green and yellow columns: right pane #2).

#### **7.3. Disclusion time reduction therapy with the immediate complete anterior guidance development coronoplasty**

Changing occlusal relationships between the upper and lower teeth breaks sharply the neuromuscular loop that causes acute muscle spasm. There are many studies that have shown the effect periodontal receptors have on functional and parafunctional occlusal excursions [34–38, 68]. An occlusal movement is modeled within the central nervous system (CNS), but the main trigger of action potential firing is the excitation of peripheral neurons from the peripheral nervous system (PNS) [33]. Continuous peripheral neuronal firing causes ongoing muscle contractions that lead to muscle fatigue and ischemia from toxic lactic acid buildup, which all ultimately leads to muscle spasms that rise and repeatedly peak, unless the continuous neuronal firing stopped.

movement occlusal surface contact frictional durations. The main objective of ICAGD is to shorten the posterior disclusion time to ≤0.5 s per excursion because 0.41 was the first studied, physiologic mean disclusion time. ICAGD is always performed today with the T-Scan synchronized to the BioEMG III Electromyography system (T-Scan 9/BioEMG III, Tekscan Inc. S. Boston, MA, USA; Bioresearch Assoc., Milwaukee, WI, USA). The patient wears electromyography electrodes upon the masseter and temporalis muscles throughout the entire occlusal adjustment process to ensure that changes in muscle hyperactivity can be properly observed post treatment. Most importantly, ICAGD treats both the working and nonworking sides including all premolars involved in excursive contacts, thereby greatly reducing the PDL and pulpal mechanoreceptor CNS input from all fictionally engaged posterior occlusal surfaces. All these procedural differences are published in occlusal adjustment studies, ICAGD has been shown

Myofascial Pain Dysfunction Syndrome: Etiology, Diagnosis, and Treatment

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35

An example of disocclusion time reduction therapy performed with the immediate complete

A 30-year-old female airline flight attendant presented with a Class I anterior relationship post orthodontics that was completed in her teenage years. A number of posterior teeth demonstrated cuspal wear and appear slightly sanded away. All third molars were previously

For 1.5 years before consultation, the patient had experienced chronic bilateral masseter tension, with regular morning jaw soreness that worsened during stressful periods. The patient reported clenching during the day and bruxing to some degree during the nighttime. Most of her discomfort was in the masseter region bilaterally, with some temporal headache

**Figure 10.** Frontal view of an MPDS female patient showing a Class I anterior relationship with average vertical overlap

to be far more effective than Occlusal Equilibration in treating MPDS.

anterior guidance development coronoplasty is presented below.

**8. Disclusion time reduction case example**

**8.2. History and presentation of occlusal disease**

**8.1. Patient description**

extracted (**Figures 10** and **11a**, **b**).

and available canine guidance contacts bilaterally.

This neurologic mechanism is the main reason why adjusting the dental occlusion with T-Scan time-based occlusal surface modifications has been highly effective MPDS therapy [4–38, 59, 69–71]. Applying occlusal splints, local anesthetic injections, botox injections, and similar nonocclusal treatment methods are temporary and symptomatic. Orthodontic treatment, restorative dentistry that changes the occlusal relationship, and occlusal coronoplasty are treatments aimed at the neurologic etiologically and are permanent treatment methods.

It has long been advocated that to achieve a balanced occlusal relationship, the acute spasm must be eliminated before commencing definitive occlusal changes. Occlusal splints are the most common method for eliminating the acute symptoms of MPDS. However, since 1991, a new T-Scan-based "Disocclusion Time Reduction Therapy (DTR)" method has been developed by Dr. Robert B. Kerstein, for changing and breaking of the firing-reaction-spasm in the neuromuscular loop. The treatment itself requires no pretreatment splint therapy and has been shown in multiple studies performed over the past 26 years to rapidly lessen muscle activity levels and improve human chewing function in 7 days following initial treatment because the therapy works from within the CNS [69, 70, 72–74]. According to Dr. Kerstein, "Disocclusion Time Reduction Therapy" reduces the Disocclusion Time [15], which lessens the time posterior teeth frictionally engage during excursions, which thereby stops the neuronal action potentials from hyperfunctioning the masticatory muscles. To accomplish this, the Disocclusion time must be less than 0.4 s per excursion. However, this particular time of 0.4 s cannot be accurately calculated without using the T-Scan occlusal analysis system. Disocclusion time reduction therapy is one of the most important, etiologically directed treatment methods available because it drastically lessens the volume of PDL mechanoreceptor compressions thereby disrupting the neuronal trigger for occlusally induced MPDS symptoms. However, there are still many disagreements on the reliability of the "Disocclusion Time Reduction Therapy", despite it being repeatedly shown in multiple studies to affect positive physiologic changes within the stomatognathic system. As DTR is usually performed as a coronoplasty (known as immediate complete anterior guidance development (ICAGD)), [9] these disagreements about DTR's patient benefits are founded in that prior, unmeasured occlusal adjustment studies where no T-Scan measurements of the occlusion were involved in the rendered treatment have shown limited occlusal equilibration effectiveness in treating MPDS symptoms. Occlusal equilibration procedurally lacks precision and treats positionally eliminating the prematurity from CR-CO, while only adjusting nonworking side interferences [75–78]. Periodontal neuronal mechanoreceptors surround all teeth on all sides of the roots. By leaving the working side teeth untreated meant occlusal equilibration to CR did not alter the CNS input enough to obtain predictable therapeutic MPDS results.

ICAGD is very different occlusal adjustment procedure from occlusal equilibration [79], in that ICAGD is an excursively focused coronoplasty performed from the maximum intercuspal position (MIP) without mandibular manipulation to centric relation. ICAGD is a measurementdriven, computer-guided occlusal adjustment procedure that shortens prolonged excursive movement occlusal surface contact frictional durations. The main objective of ICAGD is to shorten the posterior disclusion time to ≤0.5 s per excursion because 0.41 was the first studied, physiologic mean disclusion time. ICAGD is always performed today with the T-Scan synchronized to the BioEMG III Electromyography system (T-Scan 9/BioEMG III, Tekscan Inc. S. Boston, MA, USA; Bioresearch Assoc., Milwaukee, WI, USA). The patient wears electromyography electrodes upon the masseter and temporalis muscles throughout the entire occlusal adjustment process to ensure that changes in muscle hyperactivity can be properly observed post treatment.

Most importantly, ICAGD treats both the working and nonworking sides including all premolars involved in excursive contacts, thereby greatly reducing the PDL and pulpal mechanoreceptor CNS input from all fictionally engaged posterior occlusal surfaces. All these procedural differences are published in occlusal adjustment studies, ICAGD has been shown to be far more effective than Occlusal Equilibration in treating MPDS.

## **8. Disclusion time reduction case example**

An example of disocclusion time reduction therapy performed with the immediate complete anterior guidance development coronoplasty is presented below.

#### **8.1. Patient description**

occlusal movement is modeled within the central nervous system (CNS), but the main trigger of action potential firing is the excitation of peripheral neurons from the peripheral nervous system (PNS) [33]. Continuous peripheral neuronal firing causes ongoing muscle contractions that lead to muscle fatigue and ischemia from toxic lactic acid buildup, which all ultimately leads to muscle spasms that rise and repeatedly peak, unless the continuous neuronal firing stopped.

34 Temporomandibular Joint Pathology - Current Approaches and Understanding

This neurologic mechanism is the main reason why adjusting the dental occlusion with T-Scan time-based occlusal surface modifications has been highly effective MPDS therapy [4–38, 59, 69–71]. Applying occlusal splints, local anesthetic injections, botox injections, and similar nonocclusal treatment methods are temporary and symptomatic. Orthodontic treatment, restorative dentistry that changes the occlusal relationship, and occlusal coronoplasty are treatments aimed at the neurologic etiologically and are permanent treatment methods. It has long been advocated that to achieve a balanced occlusal relationship, the acute spasm must be eliminated before commencing definitive occlusal changes. Occlusal splints are the most common method for eliminating the acute symptoms of MPDS. However, since 1991, a new T-Scan-based "Disocclusion Time Reduction Therapy (DTR)" method has been developed by Dr. Robert B. Kerstein, for changing and breaking of the firing-reaction-spasm in the neuromuscular loop. The treatment itself requires no pretreatment splint therapy and has been shown in multiple studies performed over the past 26 years to rapidly lessen muscle activity levels and improve human chewing function in 7 days following initial treatment because the therapy works from within the CNS [69, 70, 72–74]. According to Dr. Kerstein, "Disocclusion Time Reduction Therapy" reduces the Disocclusion Time [15], which lessens the time posterior teeth frictionally engage during excursions, which thereby stops the neuronal action potentials from hyperfunctioning the masticatory muscles. To accomplish this, the Disocclusion time must be less than 0.4 s per excursion. However, this particular time of 0.4 s cannot be accurately calculated without using the T-Scan occlusal analysis system. Disocclusion time reduction therapy is one of the most important, etiologically directed treatment methods available because it drastically lessens the volume of PDL mechanoreceptor compressions thereby disrupting the neuronal trigger for occlusally induced MPDS symptoms. However, there are still many disagreements on the reliability of the "Disocclusion Time Reduction Therapy", despite it being repeatedly shown in multiple studies to affect positive physiologic changes within the stomatognathic system. As DTR is usually performed as a coronoplasty (known as immediate complete anterior guidance development (ICAGD)), [9] these disagreements about DTR's patient benefits are founded in that prior, unmeasured occlusal adjustment studies where no T-Scan measurements of the occlusion were involved in the rendered treatment have shown limited occlusal equilibration effectiveness in treating MPDS symptoms. Occlusal equilibration procedurally lacks precision and treats positionally eliminating the prematurity from CR-CO, while only adjusting nonworking side interferences [75–78]. Periodontal neuronal mechanoreceptors surround all teeth on all sides of the roots. By leaving the working side teeth untreated meant occlusal equilibration to CR did not

alter the CNS input enough to obtain predictable therapeutic MPDS results.

ICAGD is very different occlusal adjustment procedure from occlusal equilibration [79], in that ICAGD is an excursively focused coronoplasty performed from the maximum intercuspal position (MIP) without mandibular manipulation to centric relation. ICAGD is a measurementdriven, computer-guided occlusal adjustment procedure that shortens prolonged excursive A 30-year-old female airline flight attendant presented with a Class I anterior relationship post orthodontics that was completed in her teenage years. A number of posterior teeth demonstrated cuspal wear and appear slightly sanded away. All third molars were previously extracted (**Figures 10** and **11a**, **b**).

#### **8.2. History and presentation of occlusal disease**

For 1.5 years before consultation, the patient had experienced chronic bilateral masseter tension, with regular morning jaw soreness that worsened during stressful periods. The patient reported clenching during the day and bruxing to some degree during the nighttime. Most of her discomfort was in the masseter region bilaterally, with some temporal headache

**Figure 10.** Frontal view of an MPDS female patient showing a Class I anterior relationship with average vertical overlap and available canine guidance contacts bilaterally.

**Figure 11.** (a) 1 mm into the right excursion as the canine teeth began to engage. Note the complete buccal posterior group function and excursive friction visible. (b) Early in the left lateral movement, opposing posterior teeth frictionally engage both buccally and lingually (unseen). The posterior group function visible is worsened by the nonvertical opposing tooth orientation.

**Figure 12.** (a) The preoperative right excursive T-Scan/BioEMG data showed (in the T-Scan left pane) prolonged disclusion time with mostly working and minimal balancing excursive frictional occlusal contacts present in the 2D and 3D ForceViews. Between C and D (in the EMG data right pane), there was very high muscle contractions visible in the two masseter MM-R MM-L and right temporalis muscles TA-R, as the patient moved laterally across their teeth toward the right canine. The nonworking (left temporalis TA-L) does not fire in the right excursion. The right disclusion time pretreatment was 3.58 s long, causing this high muscle firing and the MPDS symptoms the patient has been forced to live with since her bite changed after the upper premolar fillings were done. (b) The preoperative left excursive T-Scan/ BioEMG data showed (in the T-Scan left pane) prolonged disclusion time with only working side excursive frictional occlusal contacts present in the 2D and 3D ForceViews the total force (black) line "step downs," indicating sharp force drops as the patient's posterior teeth frequently stopped the mandible from moving freely laterally. Between C and D (in the EMG data right pane), there was very high muscle contractions left temporalis TA-L muscle with right temporalis TA-R spasm visible for the same duration the left temporalis hyperfunctions. The right and left masseters MM-R and MM-L both fired excursively well above rest. The left disclusion time pretreatment was 1.37 s long causing the visible high muscle firing and the MPDS symptoms the patient has been forced to live with since her bite changed after the upper premolar fillings were done.

component present, as well. Her symptoms came on after having two fillings placed in her two upper premolar teeth #s 14 and 15. Muscular pain ensued shortly after the fillings were done as they changed her occlusal contact comfort. Since then, further occlusal adjusting to

**Figure 13.** (a) The post-ICAGD right excursion showing slight space between the group function teeth that was not there before performing of the ICAGD coronoplasty. (b) The right excursion after ICAGD. The disclusion time equaled 0.45 s duration, which reduced the right temporalis and right and left masseter excursive hyperactivity dramatically compared to pretreatment. (c) Right excursive EMG improvements from pretreatment (left pane) to after ICAGD (right pane), where there is markedly lowered muscle activity levels post treatment at rest (before A), and in the excursion (to the right of C). With lessened excursive muscular hyperactivity, the muscle physiology can heal and MPDS symptoms can then abate.

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The patient reported wearing an appliance for 10 months nightly, but also reported symptom worsening with his attempted regular appliance use. She felt it made her clench more than if it was not worn. As such, she stopped wearing the appliance some months before consultation. Anti-inflammatory and pain medication gave her some marginal relief that would last

The following figures (**Figures 12**–**15**) detail the patients in preoperative occlusal and muscle physiology status, as well as her post-ICAGD disclusion time reduction changes. For brevity, only the right and left excursions were illustrated, and protrusive excursions were not described.

the teeth involved did not resolve her MPDS symptoms.

**8.3. Previous unsuccessful treatments**

only for a few hours.

Myofascial Pain Dysfunction Syndrome: Etiology, Diagnosis, and Treatment http://dx.doi.org/10.5772/intechopen.72529 37

**Figure 13.** (a) The post-ICAGD right excursion showing slight space between the group function teeth that was not there before performing of the ICAGD coronoplasty. (b) The right excursion after ICAGD. The disclusion time equaled 0.45 s duration, which reduced the right temporalis and right and left masseter excursive hyperactivity dramatically compared to pretreatment. (c) Right excursive EMG improvements from pretreatment (left pane) to after ICAGD (right pane), where there is markedly lowered muscle activity levels post treatment at rest (before A), and in the excursion (to the right of C). With lessened excursive muscular hyperactivity, the muscle physiology can heal and MPDS symptoms can then abate.

component present, as well. Her symptoms came on after having two fillings placed in her two upper premolar teeth #s 14 and 15. Muscular pain ensued shortly after the fillings were done as they changed her occlusal contact comfort. Since then, further occlusal adjusting to the teeth involved did not resolve her MPDS symptoms.

#### **8.3. Previous unsuccessful treatments**

**Figure 12.** (a) The preoperative right excursive T-Scan/BioEMG data showed (in the T-Scan left pane) prolonged disclusion time with mostly working and minimal balancing excursive frictional occlusal contacts present in the 2D and 3D ForceViews. Between C and D (in the EMG data right pane), there was very high muscle contractions visible in the two masseter MM-R MM-L and right temporalis muscles TA-R, as the patient moved laterally across their teeth toward the right canine. The nonworking (left temporalis TA-L) does not fire in the right excursion. The right disclusion time pretreatment was 3.58 s long, causing this high muscle firing and the MPDS symptoms the patient has been forced to live with since her bite changed after the upper premolar fillings were done. (b) The preoperative left excursive T-Scan/ BioEMG data showed (in the T-Scan left pane) prolonged disclusion time with only working side excursive frictional occlusal contacts present in the 2D and 3D ForceViews the total force (black) line "step downs," indicating sharp force drops as the patient's posterior teeth frequently stopped the mandible from moving freely laterally. Between C and D (in the EMG data right pane), there was very high muscle contractions left temporalis TA-L muscle with right temporalis TA-R spasm visible for the same duration the left temporalis hyperfunctions. The right and left masseters MM-R and MM-L both fired excursively well above rest. The left disclusion time pretreatment was 1.37 s long causing the visible high muscle firing and the MPDS symptoms the patient has been forced to live with since her bite changed after the upper

**Figure 11.** (a) 1 mm into the right excursion as the canine teeth began to engage. Note the complete buccal posterior group function and excursive friction visible. (b) Early in the left lateral movement, opposing posterior teeth frictionally engage both buccally and lingually (unseen). The posterior group function visible is worsened by the nonvertical

36 Temporomandibular Joint Pathology - Current Approaches and Understanding

premolar fillings were done.

opposing tooth orientation.

The patient reported wearing an appliance for 10 months nightly, but also reported symptom worsening with his attempted regular appliance use. She felt it made her clench more than if it was not worn. As such, she stopped wearing the appliance some months before consultation. Anti-inflammatory and pain medication gave her some marginal relief that would last only for a few hours.

The following figures (**Figures 12**–**15**) detail the patients in preoperative occlusal and muscle physiology status, as well as her post-ICAGD disclusion time reduction changes. For brevity, only the right and left excursions were illustrated, and protrusive excursions were not described.

**Figure 14.** (a) The post ICAGD left excursion showing slight space between the group function teeth that was not there before performing of the ICAGD coronoplasty. (b) The left excursion after ICAGD when the disclusion time equaled to 0.34 s. The excursive EMG improvements show markedly lowered muscle activity levels post-treatment at rest (before A), and in the excursion (to the right of C). (c) The left excursive EMG improvements from pretreatment (left pane) to after ICAGD (right pane), where there is markedly lowered muscle activity levels present at rest (before A), and in the excursion post-treatment (to the right of C). With lessened excursive muscular hyperactivity, the muscle physiology can heal and MPDS symptoms can then abate.

**9. Final thoughts**

are dramatically lessened (**Figures 13c** and **14c**).

This chapter describes in detail how the peripheral neural receptors that are located in and around the posterior teeth periodontal ligaments and in the dental pulp create ongoing masticatory muscle hyperactivity that can lead to the clinical appearance of myofascial pain dysfunction syndrome symptoms. MPDS commonly afflicts the masticatory musculature with chronic muscular pain, frequent temporal headaches, chewing pain and weakness, opening limitations, and frequent clenching and bruxing of teeth. Because unmeasured, published Occlusal Equilibration studies did not predictably treat the MPDS condition, conventional MPDS treatments have focused on lessening MPDS symptoms without treating the occlusion directly. The use of occlusal splints, physical therapy, and trigger point injections has been predominant. However, since the development of the T-Scan system in the 1980s, and the discovery of prolonged posterior disclusion time, a computer-guided alternative coronoplasty to occlusal equilibration, has evolved to treat MPDS (known as disclusion time reduction (DTR) with the ICAGD coronoplasty).

**Figure 15.** (a) Opposing occlusal surfaces with many pre-ICAGD articulating paper ink lines that describe that long disclusion time friction is present on all upper and lower posterior opposing occlusal surfaces (teeth #s 28–24 and #s 38–34). Note the very long red ink line visible on #37 distolingual occlusal incline. Its counterpart frictionally prolonged contact is the #27 distopalatol black ink line. (b) Post-ICAGD articulating paper markings showing 1–2 short disclusion time red and black pinpoint closure contacts per tooth, present on the opposing posterior occlusal surfaces (teeth #s 28–24 and #38–34). There are anterior guidance ink tracks visible across the occluding canine surfaces (#s 23 and 33). The small posterior closure contacts allow for the minimum posterior excursive contact, which are indicative of a disclusion time of <0.4 s. This small overall volume of tooth contact posteriorly is how the ICAGD coronoplasty controls the repetitive PDL mechanoreceptor neuronal action potential from heading into the CNS. Without the neural input, muscle contractions

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With the pretreatment T-Scan/BioEMG data showing prolonged disclusion times and very high levels of excursive muscular hyperactivity, the patient was a good candidate to undergo the ICAGD coronoplasty. She was a Class I MPDS patient with adequate bilateral canine contact present to be safely treated with ICAGD.

It is through the measurement of the occlusion and muscles together using the T-Scan 9/ BioEMG III synchronized occlusal measurement technologies so that these diagnostic and treatment improvements demonstrated within this case can become clinically predictable in managing MPDS patient. By quantifying occlusal function and muscle function together, the therapeutic effectiveness the ICAGD measured occlusal adjustment procedure has a dramatic effect on the central nervous system (CNS) that greatly reduces muscle activity levels and quickly lessens many common MPDS symptoms.

Myofascial Pain Dysfunction Syndrome: Etiology, Diagnosis, and Treatment http://dx.doi.org/10.5772/intechopen.72529 39

**Figure 15.** (a) Opposing occlusal surfaces with many pre-ICAGD articulating paper ink lines that describe that long disclusion time friction is present on all upper and lower posterior opposing occlusal surfaces (teeth #s 28–24 and #s 38–34). Note the very long red ink line visible on #37 distolingual occlusal incline. Its counterpart frictionally prolonged contact is the #27 distopalatol black ink line. (b) Post-ICAGD articulating paper markings showing 1–2 short disclusion time red and black pinpoint closure contacts per tooth, present on the opposing posterior occlusal surfaces (teeth #s 28–24 and #38–34). There are anterior guidance ink tracks visible across the occluding canine surfaces (#s 23 and 33). The small posterior closure contacts allow for the minimum posterior excursive contact, which are indicative of a disclusion time of <0.4 s. This small overall volume of tooth contact posteriorly is how the ICAGD coronoplasty controls the repetitive PDL mechanoreceptor neuronal action potential from heading into the CNS. Without the neural input, muscle contractions are dramatically lessened (**Figures 13c** and **14c**).

#### **9. Final thoughts**

With the pretreatment T-Scan/BioEMG data showing prolonged disclusion times and very high levels of excursive muscular hyperactivity, the patient was a good candidate to undergo the ICAGD coronoplasty. She was a Class I MPDS patient with adequate bilateral canine con-

**Figure 14.** (a) The post ICAGD left excursion showing slight space between the group function teeth that was not there before performing of the ICAGD coronoplasty. (b) The left excursion after ICAGD when the disclusion time equaled to 0.34 s. The excursive EMG improvements show markedly lowered muscle activity levels post-treatment at rest (before A), and in the excursion (to the right of C). (c) The left excursive EMG improvements from pretreatment (left pane) to after ICAGD (right pane), where there is markedly lowered muscle activity levels present at rest (before A), and in the excursion post-treatment (to the right of C). With lessened excursive muscular hyperactivity, the muscle physiology can heal and

It is through the measurement of the occlusion and muscles together using the T-Scan 9/ BioEMG III synchronized occlusal measurement technologies so that these diagnostic and treatment improvements demonstrated within this case can become clinically predictable in managing MPDS patient. By quantifying occlusal function and muscle function together, the therapeutic effectiveness the ICAGD measured occlusal adjustment procedure has a dramatic effect on the central nervous system (CNS) that greatly reduces muscle activity levels and

tact present to be safely treated with ICAGD.

38 Temporomandibular Joint Pathology - Current Approaches and Understanding

MPDS symptoms can then abate.

quickly lessens many common MPDS symptoms.

This chapter describes in detail how the peripheral neural receptors that are located in and around the posterior teeth periodontal ligaments and in the dental pulp create ongoing masticatory muscle hyperactivity that can lead to the clinical appearance of myofascial pain dysfunction syndrome symptoms. MPDS commonly afflicts the masticatory musculature with chronic muscular pain, frequent temporal headaches, chewing pain and weakness, opening limitations, and frequent clenching and bruxing of teeth. Because unmeasured, published Occlusal Equilibration studies did not predictably treat the MPDS condition, conventional MPDS treatments have focused on lessening MPDS symptoms without treating the occlusion directly. The use of occlusal splints, physical therapy, and trigger point injections has been predominant. However, since the development of the T-Scan system in the 1980s, and the discovery of prolonged posterior disclusion time, a computer-guided alternative coronoplasty to occlusal equilibration, has evolved to treat MPDS (known as disclusion time reduction (DTR) with the ICAGD coronoplasty).

DTR is an etiologically based treatment aimed at reducing prolonged occlusal surface friction, which drastically limits the tooth socket compressions and pulpal occlusal contact impacts that the posterior teeth sustain multiple times on a daily basis (and nightly, if there is parafunction). By cutting down the volume of socket compressions and impacts, the molar and premolar peripheral action potential response to the occlusal contacts is drastically lessened, which remove the stimulus that the occlusion inputs into the central nervous system (CNS) to fire muscles and create ischemia. This limiting neurophysiologic change allows the masticatory muscles to calm down and relax physiologically, because the ischemia reverses intramuscularly from within the CNS, requiring the patient to not wear an occlusal splint. In short order following the ICAGD coronoplasty, studies repeatedly show the MPDS symptoms, then abate, and lessen in severity and frequency.

[8] Svensson P. Pain mechanisms in myogenous temporomandibular disorders. Pain Forum. 1997;**6**(3):158-165. Available from: http://www.sciencedirect.com/science/article/

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[9] Kerstein RB. Disclusion time-reduction therapy with immediate complete anterior guidance development to treat chronic myofascial pain-dysfunction syndrome. Quintessence

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## **Author details**

#### Serdar Gözler

Address all correspondence to<EMAIL_ADDRESS>
TMD Clinic, Dentistry Faculty of Istanbul Aydin University, Istanbul, Turkey

## **References**

[8] Svensson P. Pain mechanisms in myogenous temporomandibular disorders. Pain Forum. 1997;**6**(3):158-165. Available from: http://www.sciencedirect.com/science/article/ pii/S1082317497700102

DTR is an etiologically based treatment aimed at reducing prolonged occlusal surface friction, which drastically limits the tooth socket compressions and pulpal occlusal contact impacts that the posterior teeth sustain multiple times on a daily basis (and nightly, if there is parafunction). By cutting down the volume of socket compressions and impacts, the molar and premolar peripheral action potential response to the occlusal contacts is drastically lessened, which remove the stimulus that the occlusion inputs into the central nervous system (CNS) to fire muscles and create ischemia. This limiting neurophysiologic change allows the masticatory muscles to calm down and relax physiologically, because the ischemia reverses intramuscularly from within the CNS, requiring the patient to not wear an occlusal splint. In short order following the ICAGD coronoplasty, studies repeatedly show the MPDS symptoms, then abate, and

lessen in severity and frequency.

Address all correspondence to<EMAIL_ADDRESS>
40 Temporomandibular Joint Pathology - Current Approaches and Understanding

TMD Clinic, Dentistry Faculty of Istanbul Aydin University, Istanbul, Turkey

Available from: http://cat.inist.fr/?aModele=afficheN&cpsidt=2551680

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**Chapter 3**

**Provisional chapter**

**Internal Derangements of the Temporomandibular**

Millions of individuals worldwide suffer from temporomandibular joint (TMJ) disorders and are characterized by pain and joint dysfunction. TMJ internal derangement (ID) is the most frequent type of temporomandibular disorders (TMDs). The ID of TMJ is defined as a joint dysfunction associated with an abnormal disc position. Identification and elimination of the causes of tissue breakdown of the TMJ that lead to ID are the key factors for successful treatment. The common causes for TMJ ID are trauma and parafunctional habits which lead to joint overload and degenerative changes in the articular structures, increased friction, and gradual disc displacement. Local and systemic inflammatory/degenerative arthropathies may also affect TMJ and cause ID. The aim of this chapter is to give comprehensive knowledge about the contemporary perspective of TMJ ID including diagnostic and therapeutic developments and innovations. Clinicians should establish the correct diagnosis and cause of the disease for appropriate management so that patients do not suffer from ineffective treatments. As an innovative development, TMJ replacements with alloplastic joint prosthesis and tissue-engineered structures hold promise for the future of management of TMJ ID.

**Keywords:** internal derangement, temporomandibular joint, TMJ, conservative

**Internal Derangements of the Temporomandibular**

DOI: 10.5772/intechopen.72585

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution,

© 2018 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

and reproduction in any medium, provided the original work is properly cited.

Millions of individuals worldwide suffer from temporomandibular joint (TMJ) disorders and are characterized by pain and joint dysfunction. TMJ internal derangement (ID) is the most frequent type of temporomandibular disorders (TMDs), including 41.1% of patients with TMD [1]. The ID of TMJ is defined as a joint dysfunction associated with an abnormal disc position [2]. Identification and elimination of the causes of tissue breakdown of the TMJ that lead to ID are the key factors for successful treatment. The common causes for TMJ ID are

**Joint: Diagnosis and Management**

**Joint: Diagnosis and Management**

Additional information is available at the end of the chapter

Additional information is available at the end of the chapter

Ufuk Tatli and Vladimir Machon

Ufuk Tatli and Vladimir Machon

http://dx.doi.org/10.5772/intechopen.72585

treatment, TMJ surgery

**1. Introduction**

**Abstract**

**Provisional chapter**

## **Internal Derangements of the Temporomandibular Joint: Diagnosis and Management Joint: Diagnosis and Management**

**Internal Derangements of the Temporomandibular**

DOI: 10.5772/intechopen.72585

Ufuk Tatli and Vladimir Machon Additional information is available at the end of the chapter

Ufuk Tatli and Vladimir Machon

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.72585

#### **Abstract**

Millions of individuals worldwide suffer from temporomandibular joint (TMJ) disorders and are characterized by pain and joint dysfunction. TMJ internal derangement (ID) is the most frequent type of temporomandibular disorders (TMDs). The ID of TMJ is defined as a joint dysfunction associated with an abnormal disc position. Identification and elimination of the causes of tissue breakdown of the TMJ that lead to ID are the key factors for successful treatment. The common causes for TMJ ID are trauma and parafunctional habits which lead to joint overload and degenerative changes in the articular structures, increased friction, and gradual disc displacement. Local and systemic inflammatory/degenerative arthropathies may also affect TMJ and cause ID. The aim of this chapter is to give comprehensive knowledge about the contemporary perspective of TMJ ID including diagnostic and therapeutic developments and innovations. Clinicians should establish the correct diagnosis and cause of the disease for appropriate management so that patients do not suffer from ineffective treatments. As an innovative development, TMJ replacements with alloplastic joint prosthesis and tissue-engineered structures hold promise for the future of management of TMJ ID.

**Keywords:** internal derangement, temporomandibular joint, TMJ, conservative treatment, TMJ surgery

## **1. Introduction**

Millions of individuals worldwide suffer from temporomandibular joint (TMJ) disorders and are characterized by pain and joint dysfunction. TMJ internal derangement (ID) is the most frequent type of temporomandibular disorders (TMDs), including 41.1% of patients with TMD [1]. The ID of TMJ is defined as a joint dysfunction associated with an abnormal disc position [2]. Identification and elimination of the causes of tissue breakdown of the TMJ that lead to ID are the key factors for successful treatment. The common causes for TMJ ID are

Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons

trauma and parafunctional habits which lead to degenerative changes in the articular structures, increased friction, and gradual disc displacement [2]. Systemic degenerative arthropathies may also affect TMJ and cause ID. Moreover, some kind of infections and tumors can cause the nonspecific symptoms and may mimic TMJ ID.

languages are available at http://www.rdc-tmdinternational.org). The current update of DC/ TMD was released in 2014 [5]. This diagnostic system has AXIS 1 for classification of the physical categories of the TMDs, and AXIS 2 for classification of psychosocial behavioral aspects of patients with TMDs. According to the last update of DC/TMD Axis 1, TMJ ID is defined in four stages: disc displacement with reduction (DDwR), disc displacement with reduction with intermittent locking, disc displacement without reduction (DDwoR) with limited mouth opening, and disc displacement without reduction without limited mouth opening. The weakness of these classification systems is that there is no causative information associated with the corresponding stages. However, understanding the true cause of damage to the joint structures is essential for proper treatment. Without useful categorization of cause and pathogen-

Internal Derangements of the Temporomandibular Joint: Diagnosis and Management

http://dx.doi.org/10.5772/intechopen.72585

49

In a physiologically normal joint, the disc is positioned between mandibular condyle and the posterior slope of articular eminence when the jaw is closed. When the jaw is opened, the disc slides into a position between condyle and top of the eminence. The attachments of the disc prevent its displacement during opening. The ID of TMJ can be divided into two subgroups basically: disc displacement with reduction and disc displacement without reduction (**Figure 1**). In the DDwR case, disc has slight deformation and forward displacement when the jaw is closed. The displaced disc reduces to normal position at maximal mouth opening (first click noise appears). When the jaw is intended to close, the disc displaces forward again (second click noise—reciprocal click—appears). The patient with DDwR has symptoms of TMJ pain with clicking, intermittent locking, and orofacial pain without limitation on mouth opening. The disc displacement and reduction can be observed in open- and closed-mouth MRI examination (**Figure 2**). In the DDwoR case, disc has moderate to severe deformation and forward displacement when the jaw is closed. During mouth opening, the disc cannot return to its normal position and is compressed between condyle and eminence so as the disorder progresses (**Figure 3**). The patient with DDwoR

**Figure 1.** The hand-sketch TMJ figure showing normal condyle-disc relationship, disc displacement with reduction, and

without reduction in closed- and open-mouth positions.

esis, treatments often fail because causative factors persist.

The natural course of TMJ ID without treatment was shown that some patients heal spontaneously and the length of time for symptoms to resolve is variable, but generally 1 year. This is thought to be associated with the adaptation capacity of the joint and the healing capacity of the individuals. However, it is not possible to predict the patients who are likely to have a return to asymptomatic condition. The older patients, the patients with longer time of disease onset, and those with magnetic resonance imaging (MRI) evidence of advanced TMD are at a higher risk for not improving spontaneously [3].

This chapter gives comprehensive knowledge about the contemporary perspective of TMJ ID including diagnostic and therapeutic developments and innovations with an emphasis on tissue engineering strategy for joint reconstruction.

## **2. Definition of the internal derangement of the temporomandibular joint**

The most popular definition of ID of TMJ can be explained as the joint dysfunction associated with an abnormal disc position and damage to the internal structures of the joint [2]. The signs and symptoms of ID are nonspecific and can be caused by multiple etiologic factors.

For the diagnosis and management of TMJ ID, updated guidelines and classification systems such as Wilkes staging [4] and Diagnostic Criteria for TMDs (DC/TMD) [5] are available. The Wilkes staging system for ID of TMJ is frequently used by oral and maxillofacial surgeons to provide a guide for treatment based on the severity of the joint damage (**Table 1**). The DC/ TMD classification system underwent extensive testing (in terms of sensitivity and specificity) and validated for different languages (the validated translations of DC/TMD into different

**Table 1.** Wilkes classification for internal derangement of temporomandibular joint [4].

languages are available at http://www.rdc-tmdinternational.org). The current update of DC/ TMD was released in 2014 [5]. This diagnostic system has AXIS 1 for classification of the physical categories of the TMDs, and AXIS 2 for classification of psychosocial behavioral aspects of patients with TMDs. According to the last update of DC/TMD Axis 1, TMJ ID is defined in four stages: disc displacement with reduction (DDwR), disc displacement with reduction with intermittent locking, disc displacement without reduction (DDwoR) with limited mouth opening, and disc displacement without reduction without limited mouth opening. The weakness of these classification systems is that there is no causative information associated with the corresponding stages. However, understanding the true cause of damage to the joint structures is essential for proper treatment. Without useful categorization of cause and pathogenesis, treatments often fail because causative factors persist.

In a physiologically normal joint, the disc is positioned between mandibular condyle and the posterior slope of articular eminence when the jaw is closed. When the jaw is opened, the disc slides into a position between condyle and top of the eminence. The attachments of the disc prevent its displacement during opening. The ID of TMJ can be divided into two subgroups basically: disc displacement with reduction and disc displacement without reduction (**Figure 1**). In the DDwR case, disc has slight deformation and forward displacement when the jaw is closed. The displaced disc reduces to normal position at maximal mouth opening (first click noise appears). When the jaw is intended to close, the disc displaces forward again (second click noise—reciprocal click—appears). The patient with DDwR has symptoms of TMJ pain with clicking, intermittent locking, and orofacial pain without limitation on mouth opening. The disc displacement and reduction can be observed in open- and closed-mouth MRI examination (**Figure 2**). In the DDwoR case, disc has moderate to severe deformation and forward displacement when the jaw is closed. During mouth opening, the disc cannot return to its normal position and is compressed between condyle and eminence so as the disorder progresses (**Figure 3**). The patient with DDwoR

**Stage Clinical findings Radiological findings**

intermittent locking, related headache

chronic restriction of motion, crepitus

**Table 1.** Wilkes classification for internal derangement of temporomandibular joint [4].

IV (Intermediate/late) Chronic pain, restriction of motion Severe disc displacement (without reduction),

trauma and parafunctional habits which lead to degenerative changes in the articular structures, increased friction, and gradual disc displacement [2]. Systemic degenerative arthropathies may also affect TMJ and cause ID. Moreover, some kind of infections and tumors can

The natural course of TMJ ID without treatment was shown that some patients heal spontaneously and the length of time for symptoms to resolve is variable, but generally 1 year. This is thought to be associated with the adaptation capacity of the joint and the healing capacity of the individuals. However, it is not possible to predict the patients who are likely to have a return to asymptomatic condition. The older patients, the patients with longer time of disease onset, and those with magnetic resonance imaging (MRI) evidence of advanced TMD are at a

This chapter gives comprehensive knowledge about the contemporary perspective of TMJ ID including diagnostic and therapeutic developments and innovations with an emphasis on

The most popular definition of ID of TMJ can be explained as the joint dysfunction associated with an abnormal disc position and damage to the internal structures of the joint [2]. The signs

For the diagnosis and management of TMJ ID, updated guidelines and classification systems such as Wilkes staging [4] and Diagnostic Criteria for TMDs (DC/TMD) [5] are available. The Wilkes staging system for ID of TMJ is frequently used by oral and maxillofacial surgeons to provide a guide for treatment based on the severity of the joint damage (**Table 1**). The DC/ TMD classification system underwent extensive testing (in terms of sensitivity and specificity) and validated for different languages (the validated translations of DC/TMD into different

**2. Definition of the internal derangement of the temporomandibular**

and symptoms of ID are nonspecific and can be caused by multiple etiologic factors.

cause the nonspecific symptoms and may mimic TMJ ID.

48 Temporomandibular Joint Pathology - Current Approaches and Understanding

higher risk for not improving spontaneously [3].

tissue engineering strategy for joint reconstruction.

**joint**

restriction of motion, closed locks

Slight disc displacement with early reduction,

Moderate disc displacement with late reduction,

Disc displacement without reduction, deformity of

Severe deformity of disc, degenerative changes

Gross deformity and/or perforation of disc, degenerative arthritic changes, osteophyte deformity subcortical cyst formation

normal disc morphology

disc, no hard tissue changes

mild disc deformity

I (Early) Painless clicking, no limitation of motion

II (Early/intermediate) Occasional painful clicking,

III (Intermediate) Frequent pain, joint tenderness,

V (Late) Variable and episodic joint pain,

**Figure 1.** The hand-sketch TMJ figure showing normal condyle-disc relationship, disc displacement with reduction, and without reduction in closed- and open-mouth positions.

flattening of articular surfaces, less pronounced articular eminence, osteophyte formation, subchondral cyst, and resorption of the condyle) occur [5, 6]. Several inflammatory mediators (such as tumor necrosis factor-α, interleukin 1-β, prostaglandin E2, etc.) play crucial roles in the pathogenesis of ID [7, 8]. The more detailed explanations about the inflammatory media-

Internal Derangements of the Temporomandibular Joint: Diagnosis and Management

http://dx.doi.org/10.5772/intechopen.72585

51

The challenge for clinicians is to diagnose the accurate condition that causes the ID. Once identified, the basis for the treatment is to relieve the patient's symptoms and to improve healing while simultaneously removing the causal factors. The following causal factors or diseases may lead to ID and should be addressed carefully: the excessive loading of the joint,

Joint overload is the most common cause of ID. The joint overload (often caused by stressmediated parafunction, acute or chronic trauma, unstable occlusion, and increased joint friction) deteriorates cartilage metabolism. This pathologic process causes the fibrillation of cartilage and ultimately leads to biomechanical failure impairing the sliding of the articular surfaces. Clinically, joint noise (clicking) is detected in this stage. The individuals who have persistent parafunction continue to overload articular structures beyond their adaptive capacity leading to pain, synovitis, intra-articular adhesions, osteoarthritis, and disc perforation [2]. Thus, the key principles in the management of ID caused by joint overloading are the reduction of joint loading and inflammation, maximizing joint mobility, and relieving pain. If the patients with ID have the signs of joint overload and if all other causal factors are ruled out, these patients should be managed by an intense 2–3 week regimen of conservative therapies as described below. If the symptoms begin to resolve, then conservative treatment should be continued. However, if the symptoms persist, minimally invasive surgical interventions should be considered. The advanced stages of ID leading to fibrosis, disc deformation or perforation, and TMJ ankylosis require arthrotomy.

A number of systemic and rheumatoid disorders play a role of causal factor and can contribute to inflammatory/degenerative arthropathy and ID. Since systemic disorders affect the structure and function of articular tissues, TMJ of the patients with systemic arthropathy may fail under normal joint loads. Thus, clinicians should be aware of this issue when considering patient management. The examples of systemic disorders, which can cause ID, include rheumatoid arthritis, psoriatic arthritis, juvenile idiopathic arthritis, pseudogout, ankylosing spondylitis, polymyalgia rheumatica, chondrocalcinosis, Ehler-Danlos syndrome, Lyme disease, lupus erythematosus, and other connective tissue disorders [2, 9, 10]. For these patients, management of systemic disorders is essential for the treatment of TMJ ID and requires coordination between a maxillofacial surgeon and a rheumatologist. Conservative therapies and arthrocentesis or arthroscopy can relieve symptoms. Moreover, arthroscopic biopsy led to the diagnosis.

This term describes an articular disorder that is atypical and not caused by joint overloading or systemic disease. A localized atypical arthropathy usually affects one joint only. The clinical

tor background of the ID were discussed in another chapter of this book.

and systemic and localized arthropathies may cause ID of TMJ [2].

**3.1. Excessive loading**

**3.2. Systemic arthropathy**

**3.3. Localized arthropathy**

**Figure 2.** T1-weighted MRI of a TMJ showing anterior disc displacement with reduction; (a) closed-mouth position (anterior displacement of the disc) and (b) open-mouth position (reduction of the disc). White arrow shows articular disc.

**Figure 3.** T1-weighted MRI of a TMJ showing anterior disc displacement without reduction in an open-mouth position. Note that the disc is still in a displaced position. White arrow shows articular disc.

has symptoms of increased TMJ and orofacial pain with restricted mandibular motion. The click noise disappears, however; in advanced cases, crepitation noise appears as a result of degenerative changes. In unilateral case, the patient shows restricted controlateral jaw movement while ipsilateral movement is normal. In advanced stages of DDwoR, increased degenerative changes including disc perforation and abrasion of the underlying bone occur.

## **3. Pathogenesis of internal derangement of temporomandibular joint**

The displaced disc can degenerate, become misshaped, perforated, or even torn. If the patient cannot achieve proper treatment, ID gets progressively worse with time, inflammation accompanied, and osteoarthritic changes (abrasion of articular cartilage and underlying bone, flattening of articular surfaces, less pronounced articular eminence, osteophyte formation, subchondral cyst, and resorption of the condyle) occur [5, 6]. Several inflammatory mediators (such as tumor necrosis factor-α, interleukin 1-β, prostaglandin E2, etc.) play crucial roles in the pathogenesis of ID [7, 8]. The more detailed explanations about the inflammatory mediator background of the ID were discussed in another chapter of this book.

The challenge for clinicians is to diagnose the accurate condition that causes the ID. Once identified, the basis for the treatment is to relieve the patient's symptoms and to improve healing while simultaneously removing the causal factors. The following causal factors or diseases may lead to ID and should be addressed carefully: the excessive loading of the joint, and systemic and localized arthropathies may cause ID of TMJ [2].

#### **3.1. Excessive loading**

Joint overload is the most common cause of ID. The joint overload (often caused by stressmediated parafunction, acute or chronic trauma, unstable occlusion, and increased joint friction) deteriorates cartilage metabolism. This pathologic process causes the fibrillation of cartilage and ultimately leads to biomechanical failure impairing the sliding of the articular surfaces. Clinically, joint noise (clicking) is detected in this stage. The individuals who have persistent parafunction continue to overload articular structures beyond their adaptive capacity leading to pain, synovitis, intra-articular adhesions, osteoarthritis, and disc perforation [2]. Thus, the key principles in the management of ID caused by joint overloading are the reduction of joint loading and inflammation, maximizing joint mobility, and relieving pain. If the patients with ID have the signs of joint overload and if all other causal factors are ruled out, these patients should be managed by an intense 2–3 week regimen of conservative therapies as described below. If the symptoms begin to resolve, then conservative treatment should be continued. However, if the symptoms persist, minimally invasive surgical interventions should be considered. The advanced stages of ID leading to fibrosis, disc deformation or perforation, and TMJ ankylosis require arthrotomy.

#### **3.2. Systemic arthropathy**

has symptoms of increased TMJ and orofacial pain with restricted mandibular motion. The click noise disappears, however; in advanced cases, crepitation noise appears as a result of degenerative changes. In unilateral case, the patient shows restricted controlateral jaw movement while ipsilateral movement is normal. In advanced stages of DDwoR, increased degenerative changes

**Figure 3.** T1-weighted MRI of a TMJ showing anterior disc displacement without reduction in an open-mouth position.

**Figure 2.** T1-weighted MRI of a TMJ showing anterior disc displacement with reduction; (a) closed-mouth position (anterior displacement of the disc) and (b) open-mouth position (reduction of the disc). White arrow shows articular disc.

**3. Pathogenesis of internal derangement of temporomandibular joint**

The displaced disc can degenerate, become misshaped, perforated, or even torn. If the patient cannot achieve proper treatment, ID gets progressively worse with time, inflammation accompanied, and osteoarthritic changes (abrasion of articular cartilage and underlying bone,

including disc perforation and abrasion of the underlying bone occur.

Note that the disc is still in a displaced position. White arrow shows articular disc.

50 Temporomandibular Joint Pathology - Current Approaches and Understanding

A number of systemic and rheumatoid disorders play a role of causal factor and can contribute to inflammatory/degenerative arthropathy and ID. Since systemic disorders affect the structure and function of articular tissues, TMJ of the patients with systemic arthropathy may fail under normal joint loads. Thus, clinicians should be aware of this issue when considering patient management. The examples of systemic disorders, which can cause ID, include rheumatoid arthritis, psoriatic arthritis, juvenile idiopathic arthritis, pseudogout, ankylosing spondylitis, polymyalgia rheumatica, chondrocalcinosis, Ehler-Danlos syndrome, Lyme disease, lupus erythematosus, and other connective tissue disorders [2, 9, 10]. For these patients, management of systemic disorders is essential for the treatment of TMJ ID and requires coordination between a maxillofacial surgeon and a rheumatologist. Conservative therapies and arthrocentesis or arthroscopy can relieve symptoms. Moreover, arthroscopic biopsy led to the diagnosis.

#### **3.3. Localized arthropathy**

This term describes an articular disorder that is atypical and not caused by joint overloading or systemic disease. A localized atypical arthropathy usually affects one joint only. The clinical signs and symptoms are nonspecific and include joint pain, noise, limited function, and changes in the occlusion. The imaging techniques and arthroscopic biopsy show unusual findings (multiple loose calcifications or synovial effusions) and confirm the diagnosis. The localized arthropathy of TMJ can be summarized as follows: osteochondroma, synovial chondromatosis, crystal deposition disease, and synovial cyst. The localized arthropathies may cause or mimic TMJ ID. The secondary inflammatory component from neighboring regions (otitis, tonsillitis, and maxillary sinusitis) can affect TMJ and cause ID [2, 11]. The correct diagnosis is crucial in these kinds of disorders and treatment usually includes arthroscopy or arthrotomy.

changes, degenerative involvements, and joint effusion [12]. Recently, the potential use of MRI-CBCT image fusion technique was introduced in order to improve the reliability and accuracy of assessment of disc positions [13]. Contemporarily, real-time MRI imaging of TMJ allows comprehensive data about the dynamics of all articular structures during jaw movement and offers more reliable diagnosis for ID of TMJ [14]. MRI is contraindicated in claustro-

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This technique is used to detect metabolic activity and inflammation on the joint structures. The single photon emission computed tomography (SPECT) can be used for conventional

This method is used to assess masticatory and cervical muscles' activities when bruxism or

The ultrasonography (USG) is used as an alternative imaging technique for the diagnosis of TMD. On USG images, condyle and glenoid fossa are hyperechoic (high reflection of sound waves) and appear white, bone marrow is hypoechoic (low reflection of sound waves) and appears black, connective tissues (joint capsule and retrodiscal tissue) and muscles (lateral pterygoid and masseter muscles) are isoechoic (intermediate reflection) and appear heterogeneously gray, and the disc appears as a thin area of hyperechogenity surrounded by a hypoechoic halo [17]. Diagnostic accuracy of USG was reported to be 54–100% for disc displacement, 72–95% for joint effusion, and 56–93% for osteoarthrosis [17]. The USG can be used to assess the thickness of the masticatory muscles in order to evaluate their causal effects for TMD [18]. Moreover, USG can also be used as an image guide for injection into the superior and lower joint space [19, 20].

If the clinician suspects systemic involvement (such as rheumatoid arthritis or juvenile idiopathic arthritis), appropriate tests including human leukocyte antigen-B27, anti-nuclear fac-

Some kinds of extra-articular disorders may mimic clinical signs and symptoms of TMJ ID and should be considered as differential diagnosis. These pathologic entities can be summarized as headache, neuralgia, migraine, atypical orofacial pain, ear disorders, coronoid process hyperplasia, trismus following inferior alveolar nerve anesthesia or muscle trauma, deepspace infections of maxillofacial region, radiation fibrosis, myositis ossificans, and metastasis

evaluation of osteoarthritis of TMJ (which is the further stage of ID) [15].

muscle-mediated joint overload is suspected as a causal factor for TMD [16].

phobic patients and those with pacemakers.

*4.2.5. Electromyography*

*4.2.6. Ultrasonography*

*4.2.7. Other methods*

**4.3. Differential diagnosis**

of other regions' cancer [2, 5].

tors, and rheumatoid factors should be ordered [10].

*4.2.4. Single photon emission computed tomography*

## **4. Diagnosis of internal derangement of temporomandibular joint**

#### **4.1. History and physical examination**

Complete medical history, clinical, and radiological examinations are essential for correct diagnosis. The most frequent signs and symptoms related to ID are pain on TMJ region, decrease in mouth opening (the normal values of maximum inter-incisal mouth opening are between 35 and 50 mm) and laterotrusive movements (the normal values of the ipsi- and contra-lateral movements of the joint are between 5 and 10 mm), TMJ noise (clicking and crepitation), intermittent lock of the joint, deflexion or deviation of the mandible during mouth opening [5]. The tenderness of the masticatory muscles may accompany.

#### **4.2. Imaging methods**

Imaging of TMJ is necessary to establish the proper diagnosis, to select the appropriate treatment, and to assess the treatment results. For imaging purposes, the following contemporary techniques are frequently used.

#### *4.2.1. Panoramic radiography or arthrography*

Orthopantomography (OPG) and/or arthrography are used to assess hard tissues of TMJ including condyle, glenoid fossa, and articular eminence. For detailed examination, computed tomography (CT)/cone-beam computed tomography (CBCT) is preferred.

#### *4.2.2.  A stereolithographic model of a patient's TMJ skeleton can be prefabricated using three-dimensional (3D) technology for reconstructive purposes.

#### *4.2.3. Magnetic resonance imaging*

MRI is the standard imaging technique for visualization of TMJ. It is used to assess retrodiscal tissue, disc position and morphology, displacement and reduction of the disc, bone marrow changes, degenerative involvements, and joint effusion [12]. Recently, the potential use of MRI-CBCT image fusion technique was introduced in order to improve the reliability and accuracy of assessment of disc positions [13]. Contemporarily, real-time MRI imaging of TMJ allows comprehensive data about the dynamics of all articular structures during jaw movement and offers more reliable diagnosis for ID of TMJ [14]. MRI is contraindicated in claustrophobic patients and those with pacemakers.

#### *4.2.4. Single photon emission computed tomography*

This technique is used to detect metabolic activity and inflammation on the joint structures. The single photon emission computed tomography (SPECT) can be used for conventional evaluation of osteoarthritis of TMJ (which is the further stage of ID) [15].

#### *4.2.5. Electromyography*

signs and symptoms are nonspecific and include joint pain, noise, limited function, and changes in the occlusion. The imaging techniques and arthroscopic biopsy show unusual findings (multiple loose calcifications or synovial effusions) and confirm the diagnosis. The localized arthropathy of TMJ can be summarized as follows: osteochondroma, synovial chondromatosis, crystal deposition disease, and synovial cyst. The localized arthropathies may cause or mimic TMJ ID. The secondary inflammatory component from neighboring regions (otitis, tonsillitis, and maxillary sinusitis) can affect TMJ and cause ID [2, 11]. The correct diagnosis is crucial in

these kinds of disorders and treatment usually includes arthroscopy or arthrotomy.

52 Temporomandibular Joint Pathology - Current Approaches and Understanding

**4. Diagnosis of internal derangement of temporomandibular joint**

opening [5]. The tenderness of the masticatory muscles may accompany.

Complete medical history, clinical, and radiological examinations are essential for correct diagnosis. The most frequent signs and symptoms related to ID are pain on TMJ region, decrease in mouth opening (the normal values of maximum inter-incisal mouth opening are between 35 and 50 mm) and laterotrusive movements (the normal values of the ipsi- and contra-lateral movements of the joint are between 5 and 10 mm), TMJ noise (clicking and crepitation), intermittent lock of the joint, deflexion or deviation of the mandible during mouth

Imaging of TMJ is necessary to establish the proper diagnosis, to select the appropriate treatment, and to assess the treatment results. For imaging purposes, the following contemporary

Orthopantomography (OPG) and/or arthrography are used to assess hard tissues of TMJ including condyle, glenoid fossa, and articular eminence.  A stereolithographic model of a patient's TMJ skeleton can be prefabricated using three-dimensional (3D) technology for

MRI is the standard imaging technique for visualization of TMJ. It is used to assess retrodiscal tissue, disc position and morphology, displacement and reduction of the disc, bone marrow

puted tomography (CT)/cone-beam computed tomography (CBCT) is preferred.

*4.2.2. Computed tomography or cone-beam computed tomography*

**4.1. History and physical examination**

**4.2. Imaging methods**

techniques are frequently used.

reconstructive purposes.

*4.2.3. Magnetic resonance imaging*

*4.2.1. Panoramic radiography or arthrography*

This method is used to assess masticatory and cervical muscles' activities when bruxism or muscle-mediated joint overload is suspected as a causal factor for TMD [16].

#### *4.2.6. Ultrasonography*

The ultrasonography (USG) is used as an alternative imaging technique for the diagnosis of TMD. On USG images, condyle and glenoid fossa are hyperechoic (high reflection of sound waves) and appear white, bone marrow is hypoechoic (low reflection of sound waves) and appears black, connective tissues (joint capsule and retrodiscal tissue) and muscles (lateral pterygoid and masseter muscles) are isoechoic (intermediate reflection) and appear heterogeneously gray, and the disc appears as a thin area of hyperechogenity surrounded by a hypoechoic halo [17]. Diagnostic accuracy of USG was reported to be 54–100% for disc displacement, 72–95% for joint effusion, and 56–93% for osteoarthrosis [17]. The USG can be used to assess the thickness of the masticatory muscles in order to evaluate their causal effects for TMD [18]. Moreover, USG can also be used as an image guide for injection into the superior and lower joint space [19, 20].

#### *4.2.7. Other methods*

If the clinician suspects systemic involvement (such as rheumatoid arthritis or juvenile idiopathic arthritis), appropriate tests including human leukocyte antigen-B27, anti-nuclear factors, and rheumatoid factors should be ordered [10].

#### **4.3. Differential diagnosis**

Some kinds of extra-articular disorders may mimic clinical signs and symptoms of TMJ ID and should be considered as differential diagnosis. These pathologic entities can be summarized as headache, neuralgia, migraine, atypical orofacial pain, ear disorders, coronoid process hyperplasia, trismus following inferior alveolar nerve anesthesia or muscle trauma, deepspace infections of maxillofacial region, radiation fibrosis, myositis ossificans, and metastasis of other regions' cancer [2, 5].

## **5. The treatment methods of internal derangements of temporomandibular joint**

The most frequently used diagnostic classification system in order to decide proper management for ID of TMJ is Wilkes classification (**Table 1**) [4]. Wilkes defined five stages with clinical and radiographic features of ID and offered different treatment methods according to the stages of the disorder [4]. The treatment methods of TMJ ID can be basically divided into two subgroups: conservative and surgical. According to Wilkes classification [4], early stages of ID can be managed with conservative or minimally invasive methods; however, advanced stages (IV or V) might require open joint surgery. The principle of treatment consists of removal of the factors which can cause ID, reduction of symptoms, and also promote the healing of the articular structures. The disc displacement does not always cause mechanical obstruction. In the literature, MRI studies [21, 22] showed a high percentage of disc displacement in asymptomatic patients (about 32–38%) and thus it is controversial whether repositioning the disc into normal position should be a treatment goal or not.

**b. Anti-spasmodic and muscle relaxants:** They are used to reduce muscle spasm accompanying a number of painful conditions (in addition to reducing the skeletal muscle tone, it

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**c. Chondroprotective drugs:** These drugs are capable of restoration of the metabolic balance in articular cartilage cells; their anti-inflammatory and analgesic effects are also described [8]. In our previous study [8], we concluded that glucosamine-chondroitin combination, which are structural molecules of joint cartilage and necessary for proteoglycan and glycosaminoglycan synthesis, significantly increases the mouth opening and decreases the inflammatory cytokine levels of synovial fluid in ID of TMJ. Moreover, this chondropro-

**d. Antidepressant drugs:** High prevalence of stress, depression, and anxiety is associated with TMD. Antidepressant medications are used to solve stress-related causal factors of TMD. These drugs have adjunct effects in improving sleep quality and reducing stressrelated parafunctional habits including bruxism and clenching [23]. Low doses of antide-

**e. Antibiotics:** These drugs are only indicated in the event of accompanying infectious dis-

This is one of the basic therapeutic methods. The indications include discopathy and the hypermobility of the joint. The position of the dislocated disc can be improved by physiotherapy in discopathy cases. In hypermobility cases, the physiotherapy supports the strengthening of the ligaments of the articular capsule, thus reducing the excessive movement in the joint. Physiotherapy techniques are also used to improve the mobility in the masticatory and cervical spine muscles [6]. During physiotherapy, following cautions should be applied: the exercises should be performed at short time intervals (three to five times in a row) and multiple times in a day, which is better than exercising once a day for a longer time period (which can lead to the overload of the joint and occurrence and/or progression of the pain). Moreover, the exercise should always be done to the pain limit—avoid trying to overcome the pain by the movement. Aside from the reduction of joint loading, it is crucial to perform passive-motion exercises for a minimum of 2 months after surgical interventions [2]. The basis of the physiotherapy consists in **a. Isometric exercises:** Exercises against palm resistance during which the active muscle groups are strengthened, strengthening the muscles and ligaments of the articular capsule.

**b. Post-isometric relaxation exercises:** Relaxation of muscle groups for the treatment of the

**c. Repositioning exercises:** These exercises are indicated for the alignment of the dislocated disc and mobilization of the joint (restoration of the jaw motion, indicated for the luxation of the jaw—the *Hippocrates maneuver* as well as for the acute dislocation of the disc).

**d. Massages of the chewing muscles:** These exercises are used to improve muscle blood flow, thus enhancing functions of the muscles and reducing their pain; they contribute to

tective combination provides efficient pain relief as well as narcotic analgesics.

is also effective to reduce emotional stress).

pressant drugs have also analgesic effects.

increased muscle tone due to the emotional stress.

eases of the joint (septic arthritis).

*5.1.3. Physiotherapy*

The conservative and surgical treatments should never be considered separately. The two therapeutic options should always be taken into account. The lack of control of causal factors such as joint overload usually causes failure of the treatment.

#### **5.1. Conservative methods**

The conservative treatment is a fundamental therapeutic element. Mostly, it is also the firstline therapeutic step (except for the ankylosis, tumor diseases and cysts. For the corresponding diseases, the primary treatment method is the open surgery). The basis of the conservative therapy is the reduction of the joint loading and pain and also improvement of healing. If the causal factor of ID is diagnosed as excessive joint loading, most of these patients can be successfully managed with conservative methods. The conservative therapy includes a number of different treatment methods:

#### *5.1.1. Patient education*

The most important aspect of conservative treatment is to inform and educate the patients about the natural course, etiology, and pathogenesis of the ID. The diet modification, improved sleeping, and awareness of mandibular parafunction should be established by patient education. Patient education is the first and essential part of the management and makes the patients important partners for their care. The education of patients is crucial for control of all causal factors (especially excessive loading) leading to ID.

#### *5.1.2. Drug treatment*

This therapy includes several groups of drugs:

**a. Analgesic drugs:** They are used to reduce pain (most often non-steroidal anti-inflammatory— NSAI—drugs). NSAI drugs are also used to reduce inflammation.

#### *5.1.3. Physiotherapy*

**5. The treatment methods of internal derangements of**

54 Temporomandibular Joint Pathology - Current Approaches and Understanding

into normal position should be a treatment goal or not.

such as joint overload usually causes failure of the treatment.

causal factors (especially excessive loading) leading to ID.

This therapy includes several groups of drugs:

The most frequently used diagnostic classification system in order to decide proper management for ID of TMJ is Wilkes classification (**Table 1**) [4]. Wilkes defined five stages with clinical and radiographic features of ID and offered different treatment methods according to the stages of the disorder [4]. The treatment methods of TMJ ID can be basically divided into two subgroups: conservative and surgical. According to Wilkes classification [4], early stages of ID can be managed with conservative or minimally invasive methods; however, advanced stages (IV or V) might require open joint surgery. The principle of treatment consists of removal of the factors which can cause ID, reduction of symptoms, and also promote the healing of the articular structures. The disc displacement does not always cause mechanical obstruction. In the literature, MRI studies [21, 22] showed a high percentage of disc displacement in asymptomatic patients (about 32–38%) and thus it is controversial whether repositioning the disc

The conservative and surgical treatments should never be considered separately. The two therapeutic options should always be taken into account. The lack of control of causal factors

The conservative treatment is a fundamental therapeutic element. Mostly, it is also the firstline therapeutic step (except for the ankylosis, tumor diseases and cysts. For the corresponding diseases, the primary treatment method is the open surgery). The basis of the conservative therapy is the reduction of the joint loading and pain and also improvement of healing. If the causal factor of ID is diagnosed as excessive joint loading, most of these patients can be successfully managed with conservative methods. The conservative therapy includes a number

The most important aspect of conservative treatment is to inform and educate the patients about the natural course, etiology, and pathogenesis of the ID. The diet modification, improved sleeping, and awareness of mandibular parafunction should be established by patient education. Patient education is the first and essential part of the management and makes the patients important partners for their care. The education of patients is crucial for control of all

**a. Analgesic drugs:** They are used to reduce pain (most often non-steroidal anti-inflammatory—

NSAI—drugs). NSAI drugs are also used to reduce inflammation.

**temporomandibular joint**

**5.1. Conservative methods**

of different treatment methods:

*5.1.1. Patient education*

*5.1.2. Drug treatment*

This is one of the basic therapeutic methods. The indications include discopathy and the hypermobility of the joint. The position of the dislocated disc can be improved by physiotherapy in discopathy cases. In hypermobility cases, the physiotherapy supports the strengthening of the ligaments of the articular capsule, thus reducing the excessive movement in the joint. Physiotherapy techniques are also used to improve the mobility in the masticatory and cervical spine muscles [6]. During physiotherapy, following cautions should be applied: the exercises should be performed at short time intervals (three to five times in a row) and multiple times in a day, which is better than exercising once a day for a longer time period (which can lead to the overload of the joint and occurrence and/or progression of the pain). Moreover, the exercise should always be done to the pain limit—avoid trying to overcome the pain by the movement. Aside from the reduction of joint loading, it is crucial to perform passive-motion exercises for a minimum of 2 months after surgical interventions [2]. The basis of the physiotherapy consists in

the movement coordination and to the stretching of spastic muscle fibers. These exercises are also used for rehabilitation of the opening, the most often used method in the postoperative care. It is divided into the passive one (when patients open their mouths using some aids or fingers) and the active ones (when the mouth opening is accompanied with the actual activities of the muscles).

#### *5.1.4. Thermotherapy*

Thermal stimuli—cold or heat—can be used in the treatment of ID. Cold causes reduction in passing of nerve impulses on nerve endings, thus reducing perception of pain. Furthermore, it causes local vasoconstriction and it acts as an anti-inflammatory agent. Cold is indicated mainly for bacterial inflammations. The use of cold may include compresses or the application of cooling sprays. The application of heat effects pain receptors in muscles and synovium, thus reducing the pain accompanying aseptic inflammations (such as arthritis and osteoarthritis). Heat is most often used in the form of hot compresses.

> The indications for the occlusal splint include the discopathy as well as inflammatory and degenerative changes. The splint is also used for patients with para-functional activities (night guard). In our previous clinical study [26], we observed that stabilization splint therapy provided significant improvements in pain relief, joint mobility (mouth opening and laterotrusive movements), disability, and psychological status of the patients with DDwoR after 6 months of treatment. However, the success rate of splint therapy was shown to be 60% for DDwoR. Splint therapy can be used alone or in combination with arthrocentesis. Our recent study showed that simultaneous splint application following arthrocentesis (success rate was 95%) has no significant additional effect on arthrocentesis alone (success rate was 92.5) for the treatment of

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**Figure 4.** Clinical view of occlusal splint therapy used for conservative treatment of ID of TMJ.

It is used to restrict the jaw motion, thus soothing inflammatory affections of the joint, leading to the reduction of pain. The inter-maxillary fixation (IMF) is most often used in the form of inter-maxillary screws and elastic bands. The indications for the IMF include, in particular, septic arthritis. Another application consists in a conservative treatment of articular eminence fractures, and it is further used for non-cooperating patients with recurrent luxations of the TMJ.

The surgical treatment is provided in the event when the conservative treatment does not have any effects (the painful symptoms as well as joint dysfunctions still persist) for a period of 3–6 months. The risk of surgical intervention is the injury to the surrounding anatomic structures (in particular the facial nerve). The surgical treatments for ID consist in the following:

This is the mini-invasive surgical method in order to perform the lavage of the superior joint space [27]. The intervention is performed directly into the joint structures; however, the operation input is limited to the injection needle only (**Figure 5**). It can be performed under local

DDwoR [26].

*5.1.7. Inter-maxillary fixation*

**5.2. Surgical methods**

*5.2.1. Arthrocentesis*

#### *5.1.5. Bio-stimulating laser therapy*

Low-level laser therapy (LLLT) supports reparation processes; it acts as the analgesic and anti-inflammatory agent (it stimulates mitochondria, supporting the production of aminisine triphosphate, increasing the blood flow in tissues, and increasing the lymphatic drainage). Moreover, the laser application stimulates blood microcirculation and reduces muscle contraction [24]. The bio-stimulation laser is indicated especially for aseptic arthritis and degenerative changes. The advantages of LLLT for the management of ID are that it provides aseptic, noninvasive, painless, non-pharmaceutical therapy without postoperative discomfort [24]. However, long-term effectiveness of LLLT for the management of TMD is limited [25].

#### *5.1.6. Occlusal splint*

This is a removable appliance of plastic material (most often resin) with a thickness of 1.5–3 mm. The splint can be made on the superior or inferior dental arch, while the splint on the inferior dental arch is preferred as it is better hidden and patients consider it better (**Figure 4**). The splints can be partial (covering only a part of the dental arch) or total (covering the dental arch completely). The treatment effect consists in the reduction in intra-articular pressure (thus reducing overload and pain), balancing of the occlusion, relaxation of the muscle spasm, and creation of the environment for easier alignment of the dislocated disc. It should be kept in mind that continuous and/or long-term use of an appliance may develop a malocclusion and must be avoided. An occlusal splint must meet several conditions: