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#### **Chapter 4**

## The Use of Fluoride for Enamel Caries Management in Infants

*Ana Cláudia Rodrigues Chibinski, Anna Bárbara Maluf, Larissa Yumi Ito, Letícia Maira Wambier, Mayara Vitorino Gevert and Vitória Monteiro*

#### **Abstract**

The presence of one or more decayed surfaces (cavitated or non-cavitated), lost or restored (due to caries) in any primary tooth in a child under 6 years old is considered Early Childhood Caries (ECC). Therefore, as soon as an initial enamel caries lesion is detected in a primary tooth, adequate measures must be adopted to halt the progression of this lesion into a cavity. To achieve this objective, fluoridated products are the most common resource, being available worldwide. Considering the age group, the use of fluoridated toothpaste and fluoride varnishes are indicated as simple and effective preventive and therapeutic methods. This chapter will discuss the advantages of these methods based on contemporary scientific evidence, as well as their expected clinical results when properly indicated and used.

**Keywords:** fluorides, toothpastes, fluoride varnishes, infants, dental caries

#### **1. Introduction**

It is expected that more than 530 million children around the world have untreated caries lesions, with the largest number of these lesions concentrated at the age of 5 years old [1]. These lesions are the clinical sign of Early Childhood Caries (ECC), defined as "the presence of one or more decayed surfaces (cavitated or noncavitated), lost or restored (due to caries) in any primary tooth in a child under 6 years old" [2]. Specifically, in America, data from a systematic review showed a 48% prevalence (CI 95% 42–54) of ECC [3].

Therefore, any clinical evidence of disease activity in babies may be classified as ECC, since a white spot can evolve to cavitation. So, different strategies must be adopted, which include effective procedures for controlling lesions in their different stages of development. Ideally, this disease management should occur before cavitation, preventing the need for restorative treatment and maintaining the integrity of the dental structure.

Considering current knowledge about cariology, the treatment can be done through non-invasive procedures and carious lesions can be controlled before cavitation (primary prevention) [2]. These procedures offer the patient a "friendly"

treatment for the child and tooth that prevents further loss of tooth structure, associating home care performed by parents/caregivers with in-office professional care. The aim is to adapt hygiene and diet to control the dysbiosis responsible for dental demineralization, associated with non-invasive methods to remineralize active lesions.

The prevention and treatment of caries disease involve the use of fluoride, which is a substance that interferes in demineralization-remineralization dynamics (DES-RE process). Therefore, fluoride is considered "a therapeutic agent that acts by controlling the beginning and development of caries lesions from the pre-cavitated stage of lesions formation" [4]. After topic application, the fluoride may be present in 5 different sites in the mouth: (1) biofilm and saliva; (2) incorporated into hydroxyapatite crystals into fluorapatite-like crystals; (3) enamel fluid; (4) adsorbed into hydroxyapatite surface, and (5) in the form of calcium fluoride (CaF2) [5]. Furthermore, its action is based on the constant presence of fluoride in the mouth, acting to reduce the demineralization and favoring the remineralization of the tooth. Therefore, the benefit is achieved by local and not systemic action [5], which is why oral fluoride supplementation is not recommended.

The fluor may be administered collectively to the population (fluoridation of public water supply, fluoridated salt, fluoridated milk), individually for selfapplication (fluoridated toothpaste, fluoridated solutions for mouthwashes), and exclusively for professional use (gels, foams, varnishes, slow-release devices, and fluoride-releasing restorative materials).

The use of fluoride agents in children and adolescents was analyzed by different systematic reviews, and it was concluded that toothpastes [6], fluoride mouthwashes [7], fluoride gel applications [8] and fluoride varnishes [9] are effective in reducing the incidence of caries.

Notwithstanding, not all forms of fluoride administration may be used in babies, safely, for prevention and caries treatment. Despite the patient's risk, fluoridated water and fluoridated toothpaste should be a constant in the baby's daily life. However, additional methods should only be indicated by a professional if an imbalanced condition is present in the baby's oral cavity. Fluoride gels, foams, and mouthwashes are not indicated for use in babies due to the possibility of inadvertent ingestion of the product.

Therefore, in this chapter, the discussion is focused on fluoride toothpaste, the main individual method, and fluoride varnishes, the main professional method, for the use of fluoride in infants.

#### **2. Fluoride toothpaste**

The understanding that caries is a biofilm-dependent disease can justify that toothbrushing is an essential process to control dental caries, using the association of systematic disorganization of the biofilm (toothbrushing) with daily topical application of the fluoride present in the toothpaste.

Strong evidence supports the use of fluoride toothpaste for caries prevention [10] with a minimum concentration of 1.000 ppm of Fluor [6]. This protocol was recommended in the Bangkok Declaration to reduce the prevalence of ECC [2].

In addition to the fluoride concentration in the toothpaste, other factors can also influence the use of toothbrushing in the prevention of caries. The best results are obtained with at least two brushings a day [2], and the toothbrushing before bedtime is the most important one because there is a reduction in salivary flow during sleep. It is also advisable not to rinse with water after brushing, as it may reduce the amount of fluoride in the oral cavity.

#### **2.1 Fluoride toothpastes and acute toxicity**

The probably toxic fluoride dose is 5.0 mg F/kg of body weight. Therefore, a 2-year-old child weighing approximately 12 kg would only be at risk of acute toxicity if he/she ingests 60 g of fluoride toothpaste with a concentration of 1.000 ppm F, which is more than the whole amount in a tube of toothpaste commonly sold (50 mg) [11]. So, although it is a possibility, it is a quite remote one. Conversely, chronic toxicity (fluorosis) occurs more frequently and it is what will be discussed below.

#### **2.2 Fluoride toothpastes and fluorosis**

Children under 5 years old have not yet developed the expectoration reflex and they swallow most of the fluoride in the toothpaste used during toothbrushing. For this reason, for a long time, fluoridated toothpaste and fluoridated water were considered responsible for the prevalence of fluorosis, and the recommendation was to use fluoride-free toothpaste for babies [12].

Currently, the importance of fluoride toothpaste in daily oral hygiene procedures is known, but the dose used in each brushing must be controlled (**Table 1**), since the amount of toothpaste swallowed is inversely proportional to the child's age and directly proportional to the distribution of toothpaste in the toothbrush [14].

The use of fluoridated dentifrices in babies is based on the concept that the benefit in controlling dental caries is obtained with a minimum risk for the development of fluorosis. There is a "window of susceptibility" for the occurrence of dental fluorosis,

#### **Table 1.**

*Use of fluoride dentifrices with 1.100 ppm in the first years of life and the risk of dental fluorosis.*

which is the period that coincides with enamel formation. For most permanent teeth, this occurs in the first 6 to 8 years of a child's life, with the exception of permanent incisors, when it corresponds to the first 3 years of a baby's life [15]. Therefore, since the birth of the first deciduous tooth, when brushing with fluoridated dentifrices is implemented, until approximately 8 years old, constant supervision is important to minimize swallowing while maintaining effective exposure to fluoride. Using the correct amount of toothpaste on the toothbrush, even if it is ingested (which is common in babies), the daily limit of systemic fluoride needed to develop fluorosis is not reached (**Table 1**).

Association with additional sources of fluoride like fluoridated water, may result in levels capable of causing fluorosis. However, it has been observed in most of the studied populations that if fluorosis develops, it is very mild, with little importance for the esthetics and quality of life of patients [16].

An important advice during this step is to guide parents/caregivers about the correct amount of toothpaste in each brushing according to the baby's age group. Often, the description used by the dentist may not be correctly interpreted by parents/caregivers, as demonstrated in a recent study [17]. These parents/caregivers tend to use larger amounts of toothpaste as the baby grows. Also, they tend to use significant variations from the ideal portion, which may interfere with the preventive effect of the dentifrice or have a greater influence on the development of fluorosis. Such observations show the importance of adequate guidance for parents/caregivers, preferably demonstrating the ideal amount with a toothbrush and toothpaste.

#### **3. Fluoride varnishes**

In this topic, the use of fluoride varnishes for the prevention of carious lesions and the treatment of initial lesions in enamel is discussed. This is not the first choice of dental material for the treatment of dentin lesions, but it may be considered a good treatment option for enamel lesions, mostly white spot lesions.

According to the American Dental Association (ADA), in addition to silver diamine fluoride (SDF) [18], fluoride varnishes are the only products for professional topical application recommended for use in patients younger than 6 years old [19].

The main advantages of fluoride varnishes are the prolonged contact time with the dental tissue, which favors the absorption of the ion and the formation of calcium fluoride (CaF2) reservoirs, and the possibility of using reduced amounts of the product, minimizing the possibility of ingestion and making it safer for use in babies.

The traditional formulation consists of a natural resin matrix (colophony) with a high concentration of sodium fluoride (22.600 ppm, 2.26% F- ions, or 5% NaF).

The natural resin base forms a film on the tooth surface and, once NaF is exposed to the oral cavity, it dissolves and solubilizes, forming CaF2 reservoirs. The reaction continues for periods up to 24 hours, which is favored by the contact of the varnish with the tooth, because it is time/contact-dependent. Therefore, it is recommended that patients treated with fluoride varnishes remain without brushing their teeth for different periods [20], which can vary from 45 minutes after application to 24 hours. This procedure not only increases the amount of CaF2 formed, but also favors remineralization over time [20].

#### **3.1 Effectiveness of fluoride varnish for prevention and treatment of caries disease in babies**

Varnishes can be applied to a specific carious lesion, where they will have a therapeutic/remineralizing effect, or to the entire dentition for a preventive effect.

Analyzing randomized clinical trials that studied the preventive effect of fluoride varnishes applied twice a year, it was observed that, in babies aged 18 to 47 months old, the preventable fraction was 31%, namely, there is 31% more chance that babies who received varnish treatment will not develop caries lesions when compared to those who did not receive the treatment [21]. On the other hand, with the same frequency of application, treatment with varnish in patients aged 2 to 5 years old had a preventive effect similar to supervised toothbrushing [22]. Systematic reviews on this topic are also available. The first one shows that the estimated preventable fraction in patients who received the application of fluoride varnish is 37% (95% CI 25–51%) when compared to placebo or no treatment and, therefore, there is a protective effect in deciduous teeth [9]. The second, considering the same comparison, found a protective effect of varnish on the tooth surface, but with questionable clinical relevance, concluding that the preventive effect of fluoride varnish is uncertain [23]. What is common in both reviews is that primary studies (those studies from which data are extracted) are at high-risk of bias or uncertain bias. Still, the preventive use of fluoride varnishes in babies is recommended by the American Dental Association (ADA) [19, 24] and by the International Association of Pediatric Dentistry [25].

There is consensus in the literature regarding the ability of varnish to remineralize enamel lesions. Among non-restorative treatments, varnish is effective [24, 26], with better results than fluoride gel [27]. In the remineralization of initial carious lesions of deciduous teeth, fluoride varnish with 5% NaF reached the level of 65.9% (95% CI 41.2–90.7%) of inactivated lesions [28]. The remineralizing capacity of varnish was also confirmed when only studies with patients with ECC (early childhood caries) were considered [29].

The vast majority of studies are performed with Duraphat (Colgate-Palmolive), which was the first fluoride varnish manufactured in the 1960s and is considered the gold standard when it comes to research. However, variations have been observed in the formulas of fluoride varnishes, with the addition of active ingredients such as tricalcium phosphate (TCP), calcium and phosphate, calcium sodium phosphosilicate (CSPS), amorphous calcium phosphate (ACP), casein phosphopeptide and amorphous calcium phosphate (CPP-ACP), xylitol, among others [30], aiming to increase the formation of CaF2 on the tooth surface and potentialize remineralization in the body of the lesion [31], in a synergistic effect with fluorine. Varnishes with 5% NaF and CPP-ACP [32] and with TCP have already demonstrated, in randomized clinical trials, greater remineralizing potential than varnish exclusively based on 5% NaF in children with ECC.

#### **3.2 Application protocol and periodicity**

The application of fluoride varnish is indicated for babies with high-risk or caries activity; for low-risk patients who live in regions with fluoridated water, there is no need for professional fluoride application, for these patients, only brushing with fluoridated dentifrice is recommended.

The fluoride varnish application protocol has variations according to the manufacturer's instructions. Some products require humidity for application on tooth surface

#### **Table 2.**

*Commercially available fluoride varnishes, percentage of fluoride, other active components, and protocol of use according to manufacturers.*

and others recommend drying the teeth; there are different guidelines regarding the time to restrict toothbrushing and ingestion of hard food after application. Therefore, it is essential to read the instructions before using a specific product. The application characteristics of each varnish, according to the manufacturer's recommendations, is described in **Table 2**.

As for periodicity, it is believed that the preventive effect of fluoride varnish is achieved with 2 to 4 annual applications [9]. The American Dental Association (ADA) recommends the application of varnish every 3–6 months [19, 24], and the International Association of Pediatric Dentistry (IAPD) every 3 months, in patients with high-risk of caries [25].

When fluoride varnish is used for remineralization of initial enamel lesions, there is no standard protocol in the literature. There are reports of two applications (initial consultation and after 4 months), four consecutive weekly applications, applications every 3 months, and even daily applications [27]. More frequent applications can be advantageous, accelerating the inactivation of the carious lesions. Recently, an in vitro study confirmed this hypothesis: the use of fluoride varnish with CPP-ACP applied at 4-week intervals was more effective in remineralizing white spots than applications every 12 or 6 weeks [33]. This effect was observed in permanent teeth, but it can be extrapolated to primary teeth. Therefore, the protocol depends on the individual analysis of the patient, the clinical characteristics of the lesion, and the response obtained during the treatment.

#### **3.3 Toxicity of fluoride varnishes**

Even considering the high concentration of fluoride present in varnishes, the possibility of acute toxicity after ingestion of small amounts of the product is practically non-existent. The bioavailability of fluorides was studied after the application of fluoride varnishes in 5-year-old patients, concluding that, despite a transient increase in the amount of fluoride in the urine, the levels returned to normal after 48 hours and the product is safe for use in children [34]. Plasma levels are also far below from the toxic dosage [35].

The probably toxic level of fluoride corresponds to 5 mg of fluoride per kg of body weight. The approximate amount of fluoride in 1 g of fluoride varnish is 22 mg. Approximately 0.5 g of fluoride varnish is used in one application. In order to be toxic, it would be necessary that the baby ingests 4.5 g of varnish at once. Knowing that in a tube of Duraphat (Colgate-Palmolive), the varnish most used in the world, there is 10 mg of the product, the child would have to ingest half of its content at once, which will hardly happen.

The possible adverse effects of using fluoride varnish were evaluated based on 3 different clinical trials carried out with patients with ECC and whose treatment protocol included periodic applications of fluoride varnish. A total of 2.424 children aged between 0 and 5 years old were included. On average, each child received 4 treatments with fluoride varnish. No systemic alterations (nausea, vomiting, etc.) or the need for medical consultation, which could be considered as an adverse effect to the application of fluoride varnish, were reported by parents/guardians within 10 days after treatment. At the end of 3 years of follow-up, no adverse effects were related to the application of fluoride varnish [36].

#### **4. Conclusion**

Toothbrushing with fluoridated dentifrice is the main resource to prevent and treat white spot lesions in babies. In patients who are at high-risk of caries and during the active phase of the disease, the association with fluoride varnishes is indicated to accelerate the inactivation process of the lesions. Irrespective of the fluoride treatment selected, when correctly indicated and performed, home-based or professionally applied fluoride treatments are safe for babies and effective in controlling enamel carious lesions.

#### **Conflict of interest**

"The authors declare no conflict of interest".

*The Use of Fluoride for Enamel Caries Management in Infants DOI: http://dx.doi.org/10.5772/intechopen.113204*

### **Author details**

Ana Cláudia Rodrigues Chibinski\*, Anna Bárbara Maluf, Larissa Yumi Ito, Letícia Maira Wambier, Mayara Vitorino Gevert and Vitória Monteiro State University of Ponta Grossa, Paraná, Brazil

\*Address all correspondence to<EMAIL_ADDRESS><EMAIL_ADDRESS>
© 2023 The Author(s). Licensee IntechOpen. 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.

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#### **Chapter 5**

## Current Concepts on Caries Removal

*Urvashi Bhimjibhai Sodvadia*

#### **Abstract**

This chapter offers a comprehensive introduction of dental caries management, with a central emphasis on selective caries removal as a cornerstone of minimally invasive dentistry. Rooted in evidence-based dentistry and a grasp of carious dentin progression, the shift from conventional dental paradigms is explored. Various challenges and debates surrounding selective caries removal techniques are discussed, encompassing non-selective, selective, and stepwise methods. Histological and clinical identification methods for carious dentin are explored till the date, including color, hardness, and texture variations. It is important to pay attention to the connection between tactile examinations and the International Caries Detection and Assessment System (ICDAS) index. The relationship between clinical staging and histological aspects of carious dentin is established. Diverse techniques like hand excavation, polymer-based burs, chemomechanical agents, air abrasion, lasers, and tungsten carbide burs are evaluated, highlighting benefits, limitations, and comparisons. The chapter underscores selective caries removal's role in minimally invasive dentistry, focusing on tissue preservation and its impact on pulp vitality, restoration durability, and patient well-being. This comprehensive presentation covers clinical, histological, and technological facets of caries management in a minimally invasive context.

**Keywords:** contemporary methods, dental caries, demineralized dentin, remineralized dentin, selective caries removal

#### **1. Introduction**

Dental caries is the most common dental disease caused by an imbalance between healthy microorganisms and cariogenic species. This ecological shift is developed and maintained by frequent consumption of fermentable dietary carbohydrates. This imbalance might disrupt the demineralization and compensation cycles, resulting in net mineral loss of the tooth structure, which leads to dental cavities [1].

Dental caries cannot be completely cured by only eliminating the causative microorganisms. Instead, it can also be treated by behavioral management. It includes reduction in consumption of fermentable dietary carbohydrates and frequent disruption of bacterial biofilm from the tooth surface. Bacterial penetration cannot be prevented if such management is not being practiced by the patients which can result in irreversible inflammatory damage to the pulp [2].

Contemporary dental practice is based on evidence-based dentistry, a clear understanding of carious dentin progress, and an awareness of potential of remineralizable dentin. Therefore, a shift from G. V. Black's concept of 'extension for prevention' to minimally invasive dentistry is being employed in the clinical practice [3]. Despite the development of adhesive dentistry and spreading awareness of environmental alarms over mercury levels, the acceptance towards minimally invasive techniques for caries removal is debatable. Therefore, Selective Caries Removal in Permanent Teeth (SCRiPT) Trial is being conducted to remove the barrier of confusion on this subject [4].

This chapter emphasizes the importance of selective caries removal approach, highlighting its advantages in preserving tooth structure, pulp vitality, and longevity. Different methods of caries removal, including non-selective, selective, and stepwise techniques, are discussed, with selective removal offering favorable outcomes. Histological analysis assists in distinguishing remineralizable and healthy dentin layers that provide guidance for an accurate excavation. The use of various caries removal techniques like polymer-based burs, chemomechanical agents, air abrasion, lasers, and tungsten carbide burs are explored.

#### **2. Concepts of caries removal**

According to a consensus assessment published by Schwendicke et al. numerous approaches of caries eradication have been explained in the literature and can be classified into three types [5]:

Although selective caries removal in a single visit presents more favorable outcome than step-wise selective caries removal approach, this has been remained as a controversy among the dental practitioners [6]. This can be due to inability to compare the long-term outcome between two techniques. One explanation for the preference for one-step selective caries removal is the avoidance of iatrogenic damage to the tooth structure while re-entering the cavity in order to replace the tooth with a permanent restoration, which would have been unavoidable with stepwise caries removal [7].

The primary goal of removing carious lesion is to preserve the pulp vitality in order to increase the tooth longevity in the mouth [8].

#### *Current Concepts on Caries Removal DOI: http://dx.doi.org/10.5772/intechopen.113122*

Recent recommendation on caries removal by consensus statement by Schwendicke et al. [9]:

#### **3. What makes selective caries removal the cornerstone of minimally invasive dentistry?**

Minimally invasive dentistry focuses on preservation of soft and hard dental tissue when managing carious lesions. This technique not only encompasses removal of carious lesion to firm dentin, but it also includes conservative approach including behavioral modification. This approach comprises of diet modification, disruption of biofilm by chemical or mechanical ways, and cutting of the nutrient supply of cariogenic biofilm by sealing it hermitically [10]. When this principle is applied to the operative dentistry, it can be inferred that selective caries excavation followed by placement of a restoration with hermetic peripheral seal will preserve the dental tissue even without having complete eradication of bacteria from carious dentin.

Traditional non-selective caries removal technique can result in dentin-pulp complex damage, compromised mechanical integrity of tooth structure, and in some cases, it can also lead to irreversible damage primary odontoblasts. Conversely, contemporary selective caries removal can preserve the remineralizable dentinal structure and primary odontoblast that will help in forming tertiary or reactionary dentin [10]. By dropping the burden of cariogenic bacteria, it reduces the number of bacteria approaching pulpal tissue via dentinal tubules. By and large, it boosts the tooth life and decreases management cost and burden associated with teeth overtime [9].

It should be noted that even though the adhesion of composite resin to remineralizable dentin is weaker, it is clinically nonsignificant and cannot hamper the overall outcome of tooth restoration. This can be explained by formation of hermetic seal of resin-based adhesive to peripheral sound enamel or dentin in aptly prepared cavity [11].

The primary challenge with the selective caries removal procedure is the ability to distinguish carious dentin clinically. Sometimes, it becomes difficult to decide the extent of removal, which may impact overall long-term outcome of the restoration.

#### **4. How can we clinically distinguish between different stages of dental caries?**

Carious dentin can be identified clinically based on the color, hardness, texture and results of caries detecting dyes. Following part describes the different techniques of caries identification, and their clinical comparison based on the literature.

Among all the techniques, visual and tactile examination are the most commonly employed techniques. The primary dentinal carious lesion can be categorized into

four different types when it is examined under natural daylight or standard dental light. These four colors are yellow, light brown, dark brown, and black. Whereas, Hellyer et al. categorized hardness of dentinal carious lesion as hard, medium (leathery), and soft [12].

The hardness of non-carious dentin ranges between 51 and 65 KHN. It drops down to 6.7 KHN in presence of active lesion, whereas hardness of arrested lesion reduces to 39.2 KHN. In other words, hardness of remineralizable and healthy dentin is 30.7 and 60 KHN, respectively [13].

Clinically, the texture or hardness can be evaluated using a new Ash No. 6 prob. The hard lesions are similar to the intact dentin. When moderate pressure is employed, a fresh Ash No. 6 probe can easily penetrate medium or leathery lesions and encounters resistance during withdrawal. Although soft lesions demonstrate smooth penetration of a fresh Ash No. 6 prob. with no resistance upon its withdrawal [14, 15].

The active and inactive carious lesions show different characteristics in terms of color and texture. **Table 1** and **Figure 1** show the difference in signs of staging of carious lesions [16]. The visual and tactile examinations show high specificity but due to subjective nature of tests, they show less reproducibility, and low sensitivity [17].

#### **Table 1.**

*Outlines clinically identifiable aspects of active and inactive lesions at various stages of cavity lesion progression.*

#### **Figure 1.**

*Three distinct case situations that demonstrate active and inactive lesions depending on certain characteristics. The images on the left and center show active lesions, whereas the image on the right shows a tooth with both types of lesions.*

#### *Current Concepts on Caries Removal DOI: http://dx.doi.org/10.5772/intechopen.113122*

According to the recent systemically reviewed evidences, when we compare the visual and tactile examination, the later produces results with more reliability and specificity. Therefore, it is desirable to opt for the tactile examination over the visual inspection when performing routine inspections to identify caries. It could be stated that texture variations warrant a higher index score. This evidence is in accordance to the current recommended dental caries scoring index, the International and Caries Detection Assessment System (ICDAS) [18].

#### **5. How is the clinical categorization of stages connected to the histological characteristics of dentinal caries?**

In the literature, correlation between different color, hardness, and texture of the carious dentin to histological staging of the carious process has been described. The clinical changes of the carious lesion can be resulted from the acidic attack of the cariogenic microorganisms. This acidic dissolution can change the color, texture, and the moisture element of dentinal tissue. Based on the color and texture of the dentinal tissue, the histological staging can be discriminated [19].

To identify the clinical carious examination technique with high sensitivity and specificity, it is advisable to compare the available methods in relation to the microbial activities in form of CFU. This will enable us to identify an accurate consistent method to evaluate caries quantitatively and qualitatively [18].

There are a few research that investigated the relationship between bacterial CFU and the color or hardness of carious dentin in the literature. Orhan et al. found no significant difference in bacteria CFU and color of carious dentin, although harder lesions had considerably fewer bacteria CFU than softer dentin [20]. Comparable outcomes were noted in the Lynch et al. investigation. They discovered that soft and leathery lesions, regardless of color, had greater CFU. There was no association between the color of the lesion and the overall number of bacterial species [21].

#### **6. Which portion of the dentinal caries needs to be eliminated during the selective caries removal?**

The precise point at which caries excavation ends clinically is ambiguous and remains subjective. As a particular dentist may be influenced by their own personal experiences, diagnostic tests such as surface hardness, dentin color, or caries detector dyes, are not completely reliable. As a result, a histological analysis is the optimal tool for evaluating carious changes in the dentin and obtaining consistent results to evaluate excavation procedures.

It has been observed that the carious dentin can be divided into distinctive layers using histological staining such as outer dentin containing non-remineralizable necrotic collagen matrix and cariogenic bacteria, and inner layer composed of non-altered collagen fibers. The bacterial count is negligible in the inner layer, and the possibility of remineralization is higher [22].

Mallory-Azan staining allow to differentiate histological staging of carious dentin. Blue staining is identified as un-denatured collagen containing dentin; while altered collagen matrix will catch red staining. Thus, clinically it enables accurate identification of remineralizable or healthy dentin and demineralized dentin, respectively [23].

As previously mentioned in the chapter, hardness is a better \_\_\_\_ to evaluate the severity of carious lesion and plays an important role in determining treatment modalities as well. For instance, softer lesion needs the immediate intrusive clinical modality (e.g., debridement and restoration) as it harbors more cariogenic microorganisms as compare to the harder lesions which does not contain any cariogenic microorganisms. Therefore, harder shallow lesion does not demand any clinical interventions [14].

Selective carious removal to firm dentin is advisable for moderately deep active areas. This procedure allows leathery dentin to left behind at the center of cavity towards pulpal area, whereas caries should be removed until firm hard dentin is reached towards the peripheral dentin and marginal walls of the cavity. Clinical terminology refers to leathery dentine as having a small "tackiness" and not deforming when an object is placed against it. Hard dentine requires pushing pressure to engage, and a scratchy sound known as "cri dentinaire" can be heard [3].

#### **7. What is the recommended method for removing dental caries?**

The traditional approach of treating dental caries entails removing the remineralizable tooth tissue and replacing it with a restorative substance. Using a dental air rotor drill is currently the most popular way to remove cavities. Despite its extensive use, potential side effects include dentinal sensitivity, intense noises while using, thermal stimulation of the pulpal tissue, bone-conducted vibration, and pressure inside the tooth itself. Whereas hand excavation allows the operator to have tactile sensation while removing carious tissue. Rotary instruments greatly limit tactile feedback during selective excavation and increase the possibility of iatrogenic removal of extra tooth structure at this critical region [24]. Other techniques investigated include air abrasion, chemical agents, polymer burs, and lasers for the eradication of caries.

#### **7.1 Tungsten carbide bur**

Utilizing burs on a high-speed handpiece to reach the carious area and a low-speed handpiece to eliminate carious dentine are the most common approaches for removing caries and preparing cavities. Steel bur excavation and traditional rotary practices result in over-preparation by removing greatest amount of sound tissue possible while potentially overextending the cavity and destroying healthy tissue. Additionally, it generates pressure and heat on the pulp, vibration, noise, causes pain stimulus, and requires the need for local anesthetic. This approach leaves aversion and pain anxiety in many individuals, particularly children [25].

Studies have been conducted to compare the traditional approach with other techniques. Divya et al. investigated the time required to remove the caries and found that the traditional burs (151 sec) remove caries faster as compared to Polymer bur (344.80 sec), Papacarie (359.60 sec), and Carisolv (461.60 sec). The number of bacterial colonies after caries excavation differed considerably among the four agents utilized, with Polymer bur samples containing the highest and Stainless Steel Bur representing only 10% of the specimens [26]. Whereas Somani et al. found no significant difference in the presence of microorganisms following caries eradication between traditional burs and smart burs [27].

#### **7.2 Polymer based bur**

The fundamental objective behind developing a polymer-based bur was to create a device with a hardness of 40–50 KHN, which falls between the hardness of healthy and cariously infected dentin. As a result, they selectively remove demineralized dentin and whenever the cutting edges come into touch with either healthy or remineralizable dentin, they become blunted. **Table 2** described characteristics and specifications of available the polymer based burs and traditional carbide bur.

There was no significant difference in the outcome was observed by Usha and Ranjani when different types of polymer bur were compared [28]. Furthermore, Lohmann in et al. concluded that PolyBur P1 was only able to remove carious dentin from 33.9% of the carious teeth specimen. Additionally, the remaining denatured collagen layer was significantly thicker (more than 1 mm) than in the conventional carbide bur group [13].

#### **7.3 Chemomechanical caries removal agents (CMCR)**

Since 1975, this modality has been utilized to soften diseased dentin before carefully removing it with hand devices. Because it only affects demineralized dentin, the goal of conserving damaged dentin can be achieved [29]. They are classified into two types: sodium hypochlorite (NaOCl)-based agents (e.g. GK-101, GK-101e, Carisolv) and enzyme-based agents (Papacarie, Biosolv, Carie-Care, Brix3000).

By subsequently destroying the irreparably weakened collagen fibers in demineralized dentin, CMCR chemicals enable removal while preserving the remaining intact impacted dentin [30]. Chlorination, which entails hydrolysis of linkages between tropocollagen components and/or breaking of polypeptide chains in the triple helix, is the key technique used to do this [31]. However, little is yet known about the chemistry of amino acid chlorination and its effects. In contrast to enzyme-based CMCR agents, which rely on an additional mechanism, NaOCl-based CMCR products use the chlorination process as their main mode of action [32].

The fundamental mode of action in enzyme-based CMCR agents is papain, which is considered an effective chemical debriding agent with antibacterial and anti-inflammatory properties. It is a cysteine protease developed from the fruits and latex of green papaya (Carica papaya. The papain is believed to work by promoting the decomposition of partially deteriorated collagen strands and assisting in the deconstruction and removal of fibrin mantle created by carious process and causing no harm to unaffected collagen filaments. As a result, the demineralized dentin softens, making it possible to remove it with no anesthesia and using non-cutting instruments. An absence of −1-antitrypsin in demineralized dentin rationalizes such unique relationship [33].

A risk to dental practitioners' wellbeing exists during the COVID-19 pandemic because many dental treatments generate aerosols that could be associated with the transmission of serious respiratory illnesses. Consequently, dental and health professionals cautioned against overusing aerosol-generating therapies during the outbreak. Given the aforementioned suggestions, utilizing CMCR products that need little to no aerosol-generating techniques instead of surgery in caries prevention may be more proficient for people of all ages, especially those who suffer from anxiety or have special needs [34].

The CMCR approach is becoming more commonly recognized and comfortable for patients, as it reduces pain, anxiety, and the need for a local anesthetic. Hosein

#### **Table 2.**

*Describes the available polymer-based burs and conventional carbide burs along with their properties and specifications.*

and Hasan reported the procedural time for CMCR as 12.97 min in 27 cases, whereas convention steel bur took 7.4 min for caries removal [35]. The CMCR approach could be taken into account as a possible replacement therapy modality in the field of dental care in the future, despite its extended length and greater expense.

#### **7.4 Air abrasion**

Air abrasion, utilized as a method for removing caries, involves the non-rotary abrading of a surface by directing a stream of high-speed abrasive particles produced from compressed air. Its mechanism involves cutting at the tip and shapes shallow, saucer-like cavities with vague boundaries. In contrast to rotary drilling, air abrasion's use of extremely small particles in contact with the tooth prevents the generation of vibrational forces, resulting in enhanced comfort and reduced stress on the tooth structure. This is especially beneficial in the dentine area near the pulp, where delicate caries elimination using the slow-speed handpiece is often uncomfortable due to the resulting vibrations. In this context, employing air abrasion with a slow cutting action becomes a practical choice. The forceful expulsion of particles through the air stream also reduces the effort required by the operator [36].

Aluminum oxide abrasives are commonly used for air abrasion in dentistry, but concerns exist regarding their potential to damage healthy tooth structure and controversial safety issues [37]. An alternative option is bioactive glass (Sylc), initially designed for bone replacement. Sylc, a bioactive glass abrasive, is available for tooth polishing and has shown potential for selective cutting. However, its cutting time is significantly longer than alumina, making it less practical [38].

#### *Current Concepts on Caries Removal DOI: http://dx.doi.org/10.5772/intechopen.113122*

Neither alumina nor Sylc contains fluoride, despite evidence of fluoride-assisted remineralization in dentine.

Farooq et al. have explored fluoride-incorporated bioactive glass, discovering that reducing sodium content increases its hardness, which could be advantageous for creating bioactive glass air abrasives. Additionally, they demonstrated apatite formation in bioactive glass in Tris buffer solution, with potential implications for its abrasiveness compared to alumina in dentine air abrasion [39]. Tan et al. invented a new customized fluoridated bioactive glass particles (Na0SR) and compared its efficacy against standard aluminum oxide particles. It was concluded that Na0SR can be considered a viable abrasive alternative for alumina in air abrasion cutting because it performs similarly and has the added benefit of potentially facilitating remineralization and hydroxyfluorapatite production [40].

#### **7.5 Lasers**

The initial dental lasers (ruby, Nd:YAG, holmium-doped Ho:YAG, CO2 lasers) led to elevated pulp temperature, microcracks, and carbonization. In the mid-1990s, the safety and effectiveness of erbium-doped Er:YAG laser were explored. Proper settings and water cooling minimized thermal damage [41]. Effective caries removal requires a laser wavelength that interacts significantly with mineral, water, or both, unless ultrashort pulses cause plasma-mediated ablation.

Er:YAG and erbium: yttrium-scandium-gallium-garnet Er:YSGG lasers (λ = 2.940 μm and λ = 2.790 μm) are highly absorbed by water and Er:YSGG is also absorbed by hydroxyl ions in tooth mineral, heating and exploding tissue from the surface. For effective caries removal, the laser pulse duration should approximately match the tissue's "thermal relaxation time," avoiding excessively short or long pulse durations that result in excessive or unnecessary energy distribution within the tissue [42]. The Food and Drug Administration (FDA) granted approval for its use in these applications in May 1997. This laser functions in a pulsed manner and incorporates a water spray in its handpiece to prevent tissue dryness and the accumulation of heat. This ensures efficient absorption of energy without causing tissue carbonization or significant heat production [43].

Montedori et al. conducted a systematic review and found no studies reported presence of residual caries after using laser to remove primary caries [44]. In a study conducted by Lui et al.; patients reported limited incidence of pain in Er:YAG laser group than drill group [45].

The carbon dioxide laser lasers can function within the wavelength range of 9000 to 11,000 nm. The most prevalent variant, working at 10,600 nm, is commonly utilized for dental procedures. This laser enables surgical operations without bleeding and minimizes discomfort following soft tissue dental surgeries. Investigations demonstrated that a 9300 nm carbon dioxide laser can prompt both chemical and structural alterations in hard dental tissues [46]. Moreover, it was observed that this laser efficiently eradicates enamel and dentine. Due to its capacity to prevent enamel cavities and eliminate caries lesions, the 9300 nm carbon dioxide laser is gaining increased attention in the field of dentistry for managing dental caries [47].

For laser treatment, the increase in pulp chamber temperature should not be greater than 5.5°C. Otherwise, severe heat buildup could harm the dentine-pulp complex by disrupting odontoblasts, destroying them, or possibly causing pulp necrosis. According to a series of studies, the thermal effect of 9300 nm carbon dioxide laser

irradiation on pulp is minimal because the laser is absorbed extremely close to the surface of the hard tissues and shortly converted into heat [48]. Assa et al. also reported that the usage of water aerosol spray with laser would significantly decreases the heat accumulation.

Exposure of enamel to a 9300 nm carbon dioxide laser leads to decomposition of its constituents. This process can cause enamel to melt and fuse due to the temporary elevation in temperature, which exceeds a certain threshold. The laser modifies the enamel's microstructure and surface appearance after it cools down. Additionally, the laser induces chemical transformations in dental hard tissues, including a reduction in carbonate levels. This change transforms carbonated apatite crystals into purer forms, rendering enamel less susceptible to acid erosion. Moreover, the calcium and phosphorus content in both enamel and dentine increases following laser treatment. The dentine subjected to irradiation displays three distinct intrinsic phosphate bands under Fourier transform infrared microscopy, indicating heightened crystallinity. A study highlights that the 9300 nm carbon dioxide laser raises the calcium-phosphorus ratio in healthy enamel and dentine, thus reducing their solubility. Furthermore, the results imply that the laser treatment eliminates organic components from decayed enamel and dentine [49].

#### **8. What factors contribute to a favorable prognosis for the selective caries removal method?**

A growing database of studies has also demonstrated that the selective caries excavation technique is prognostically effective. This procedure avoids injuring the dentine-pulp complex and removing a significant quantity of tooth tissue, preserving the pulp's vitality and improving the tooth's long-term prognosis.

In the management of deep carious lesions, it's essential to thoroughly assess the final restoration to prevent potential failures in the tooth-restorative complex. Dentists should carefully inspect the restoration for surface irregularities and proper marginal integrity to avoid creating areas where plaque can accumulate. Leaving some carious tissue under a restoration after selective excavation could lead to legal issues. Patients need to be informed about the rationale behind this approach and the need for regular check-ups to ensure the tooth's pulp health over time Nevertheless, for long-term stability, cuspal coverage would be necessary to counteract the impact of repeated stress on the restoration for some cases.

#### **9. Conclusion**

In conclusion, dental caries, a prevalent condition resulting from an imbalance in oral microorganisms triggered by fermentable carbohydrates, causes mineral loss in tooth structures. Traditional treatment approaches, involving complete bacterial eradication, have shifted towards minimally invasive strategies. Selective caries removal, a pivotal aspect of minimally invasive dentistry, preserves remineralizable dentin, vital odontoblasts, and supports the formation of reactionary dentin. Techniques like polymer-based burs, chemomechanical agents, air abrasion, and lasers offer less discomfort, reduced bacterial count, and more conservative excavation. Clinical staging, utilizing color, hardness, and texture evaluations, assists in precise diagnosis and treatment planning. While challenges persist,

*Current Concepts on Caries Removal DOI: http://dx.doi.org/10.5772/intechopen.113122*

evidence supports the effectiveness of selective caries removal, enhancing tooth longevity and patient comfort.

#### **Conflict of interest**

The authors declare no conflict of interest.

#### **Author details**

Urvashi Bhimjibhai Sodvadia Nova Southeastern University, Clearwater, Florida, United States

\*Address all correspondence to<EMAIL_ADDRESS>
© 2023 The Author(s). Licensee IntechOpen. 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.

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[43] Marcelino GD, Lopes JH, Faraoni JJ, Dias PC. The use of Er: YAG laser for dental caries removal. Stomatology Edu Journal. 2021;**8**(3):173-183. DOI: 10.25241/stomaeduj.2021.8(3).art.3

[44] Montedori A, Abraha I, Orso M, D'Errico PG, Pagano S, Lombardo G. Lasers for caries removal in deciduous and permanent teeth. Cochrane Database of Systematic Reviews. 2016;**9**:CD010229. DOI: 10.1002/14651858.CD010229.pub2

[45] Liu JF, Lai YL, Shu WY, Lee SY. Acceptance and efficiency of Er: YAG laser for cavity preparation in children. Photomedicine and Laser Therapy. 2006;**24**(4):489. DOI: 10.1089/ pho.2006.24.489

[46] Fried D, Zuerlein MJ, Le CQ, Featherstone JD. Thermal and chemical modification of dentin by 9-11-μm CO2 laser pulses of 5-100-μs duration. Lasers in Surgery and Medicine. 2002;**31**(4): 275-282. DOI: 10.1002/lsm.10100

[47] Rechmann P, Rechmann BM, Groves WH Jr, Le CQ, Rapozo-Hilo ML, Kinsel R, et al. Caries inhibition with a CO2 9.3 μm laser: An in vitro study. Lasers in Surgery and Medicine. 2016;**48**(5):546- 554. DOI: 10.1002/lsm.22497

[48] Assa S, Meyer S, Fried D. Ablation of dental hard tissues with a microsecond

pulsed carbon dioxide laser operating at 9.3-μm with an integrated scanner. In: Lasers in Dentistry XIV. Vol. 6843. Issue 684308. 2008. pp. 47-53

[49] Takahashi K, Kimura Y, Matsumoto K. Morphological and atomic analytical changes after CO2 laser irradiation emitted at 9.3 μm on human dental hard tissues. Journal of Clinical Laser Medicine & Surgery. 1998;**16**(3):167-173. DOI: 10.1089/ clm.1998.16.167

#### **Chapter 6**

## Perspective Chapter: Cost-Effectiveness of Caries Preventive Programs

*Thomas Davidson*

#### **Abstract**

This chapter presents the methodology of health economic evaluations within the field of oral health and more specifically discusses the need for cost-effectiveness analyses of various caries preventive programs. It also deals with prioritized questions of limited resources and effective implementation of caries preventive technologies. As the societal cost of caries preventive interventions may not equal the direct cost of the intervention, the cost-effectiveness results depend also on the perspective and time-horizon of the analysis, and several such key issues are presented. The chapter also presents some basics about simulation modeling techniques and how to deal with uncertainty in health economic evaluations. An example of a cost-effectiveness analysis of a caries preventive program and aspects to consider is furthermore provided, to guide in the economic evaluation. Some evidences of the cost-effectiveness of various caries preventive programs are presented. However, there are some methodological weaknesses in many of the studies, and more research is needed to determine the value of such programs.

**Keywords:** economic evaluation, cost effectiveness, quality of life, QALY, willingness to pay

#### **1. Introduction**

Oral diseases have a significant impact on the global economy, resulting in a burden of over US\$700 billion, which includes both direct and indirect costs [1]. This amounts to almost 5% of the global health expenditure. Dental caries is responsible for 15% of this burden, but the actual percentage may be higher due to its association with other oral diseases [2]. Consequently, dental caries presents substantial economic challenges for individuals and healthcare systems alike.

At the same time, dental caries can result in significant health losses, from physical pain and tooth loss to psychological and financial burdens. Hence, there are many reasons to prevent dental caries.

Reducing the incidence of dental caries may be achieved through various programs. However, implementation of these programs requires investment of resources, both private and public. As resources are limited, it is essential to allocate them

judiciously. Prioritizing the allocation of resources based on criteria such as effectiveness, ethics, and cost-effectiveness is important.

Comprehensive health economic evaluations play a crucial role in prioritizing healthcare services. Although a significant portion of oral health services is privately paid, there is still a need for guidance in the cost-effective use of resources. Many countries subsidize dentistry to some extent, and it is important that public resources are used efficiently. Moreover, public dental health programs may require health economic evaluations as they involve societal investments.

Health economic evaluations provide decision-makers with valuable information to allocate resources efficiently, develop guidelines, and fund research. They can also identify potential disparities in access to preventive care and oral health outcomes across different population groups. Decision-makers can use this information to direct certain programs to vulnerable groups to improve overall oral health equity.

This chapter presents health economic evaluations, different types of analyses, and some methodological issues such as the perspective and time horizon of the analysis. It briefly explains how to calculate the costs and outcomes of a program, how cost-effectiveness should be understood and interpreted, and the need for simulation studies and uncertainty analyses. A fictive example about the cost-effectiveness of a fluoride varnishing program in school is also presented. Finally, some general findings about the cost-effectiveness of caries preventive programs are discussed.

#### **2. Health economic evaluations**

#### **2.1 Type of analyses**

When it comes to health economic evaluations, there are various types of analyses. The main difference between them is how the outcomes are handled. In general, all analyses aim to determine the opportunity cost of a particular healthcare program in relation to its additional effects. Opportunity cost refers to the benefits that resources could have yielded if spent in the most optimal way. To determine the opportunity cost of a program, it should be compared with the best alternative [3].

Commonly used health economic analyses are:

A cost analysis is a type of evaluation that focuses only on measuring the costs of a program and is not intended to be used for comparing different programs. It does not require a comparator since its purpose is only to determine the cost of a particular program.

A cost-minimization analysis, on the other hand, can be used for prioritizing between different programs. This type of analysis assumes that the consequences of the compared programs are identical. Therefore, it studies the costs of at least two programs and recommends the one with the lowest cost. Ideally, there should be evidence supporting the assumption of equal outcomes to use this analysis; otherwise, it may lead to unintentional rationing.

A cost-effectiveness analysis is used when the outcomes are expected to differ. The outcome measure in such an analysis could be any measure that is relevant to the treatment analyzed, such as life-years gained, the number of infections, prevented decayed, missing, or filled teeth (DMFT), and so on.

A cost-utility analysis is similar to a cost-effectiveness analysis, but it relates outcomes to some kind of values that represent utility or quality of life (QoL), most often quality-adjusted life-years (QALYs).

Another type of analysis is the cost-benefit analysis, which uses monetary terms for both the costs and the outcomes. This is often measured by studying the willingness to pay. If the outcomes are valued higher than the costs in such an analysis, this means that the treatment has a positive net benefit and, hence, that it should be implemented. Such monetary outcomes may be especially relevant in dental care, as people are generally used to paying most of the costs themselves, in contrast to other healthcare fields where much of the cost is often covered by society or insurance companies.

The analyses presented above can be complemented by a budget impact analysis [4], which evaluates how the introduction of a new program affects one or several budgets and what other consequences are expected for the main actors. All types of health economic analyses may be suitable for economic evaluation of caries preventive programs. Which one to use depends on what question the evaluation strives to answer.

#### **2.2 Perspective and time horizon of the evaluation**

A health economic analysis can be performed from different perspectives. The healthcare and societal perspectives are the most used perspectives. The healthcare perspective covers all costs and effects that occur within the healthcare system such as clinic costs, material used, overhead costs, and so on. On the other hand, the societal perspective includes all costs and effects on society, regardless of who they impact. This perspective also considers indirect costs such as productivity loss and the need for informal care. Other perspectives may include the third-party payer, the clinic's, or the patient's perspective. Although there is no international agreement on what perspective to use [5], the health care and societal perspectives are the two most common in various national guidelines. Generally, the perspective used depends on the analysis's aim to provide information.

Most methodological guidelines in health economic evaluations agree that the analysis of costs and effects should have a time horizon that is long enough to reflect all significant differences in costs or outcomes related to the assessed program. This means that evaluations in, for example, prosthetics should include all future costs and effects related to the treatment, which may be a lifetime. The same applies to caries preventive programs, as this may affect the future incidence of new caries. However, the time horizon of the analysis should also be based on the level of data that exists and the uncertainty around that data. For instance, a decision-maker who considers a caries preventive program at school may not find a lifetime horizon to be relevant or trustworthy. Instead, a time horizon of, for example, 5 years could be more relevant.

It is essential to discount costs and effects that occur in the future annually to reflect their values at the time of the analysis. Although the discount rates may vary between guidelines, a rate of 3% per year is commonly used.

#### **2.3 Costs**

A program's cost goes beyond its price tag. The costs incurred are determined by the resources utilized and should be evaluated based on what those resources could have been used for elsewhere (the opportunity cost). It is best if all resources used are quantified and presented in natural units before being valued, to ensure transparency and transferability to other settings.

There are various ways to classify costs, but they are usually categorized as direct and indirect costs, or initial treatment and maintenance costs. Direct costs refer to resources such as dental personnel, all supplies and material used, dental clinic, administrative, and patient costs. Indirect costs are productivity losses linked to a treatment or health condition. Maintenance costs include all treatment costs that are not part of the initial treatment.

To accurately reflect the direct costs, the number of minutes the dental team spends on patients should be measured and valued. If a societal perspective is sought, all the time used by patients (and significant others, if applicable) should also be included. If the program requires multiple visits to the dental clinic, all time spent needs to be added up. The value of patients' time may be difficult to estimate, but it should reflect their opportunity cost. If the time used by patients would have otherwise been spent on paid production, the cost of having a person employed should be used (using the human capital method). If time off is used, the opportunity cost of this time off should be used, sometimes valued at 30% of paid production.

#### **2.4 Outcomes**

There are three different types of outcome measures that can be used to evaluate programs: clinical outcomes (including intermediate outcomes), measures of quality of life (QoL), and monetary outcomes. The choice of which measure to use depends on the purpose of the analysis.

Health economic evaluations allow for any kind of outcome measure to be used, but it is important that the chosen measure is relevant to the program being evaluated. For example, when evaluating a caries preventive program, the outcome measure should reflect the aims of the program. This might include factors such as the amount of caries, dmft/DMFT, pain, esthetics, or QoL.

The most commonly used outcome measure in healthcare programs is quality adjusted life year (QALY). This measure combines the value of a health state with the time spent in that state, providing scores on a scale with common anchor points. However, if QALY is to be used in caries preventive programs, it is important to consider whether it can capture oral health-related quality of life (OHRQoL) aspects [6].

It is necessary to choose outcome measures carefully, as they are used to inform decision-makers about the cost-effectiveness of proposed programs. If the chosen measure is not relevant to the decision-maker, then the analysis will not be useful. Therefore, it is important to consider the purpose of the analysis and who the decision-maker is when choosing an outcome measure.

#### **3. Cost-effectiveness**

If the evaluation's focus is on determining the cost-effectiveness of a program, then a cost-effectiveness analysis or cost-utility analysis is generally required. In this type of analysis, an incremental cost-effectiveness ratio (ICER) is calculated by dividing the difference in costs between at least two alternative programs with the difference in effects between the programs.

For instance, if program A costs \$100 per participant and causes 1 DMFT and program B costs \$50 per participant and causes 1.5 DMFT, this means that program A costs an additional \$50 and prevents 0.5 DMFT compared to program B. The ICER would then show that it costs an additional \$100 per DMFT prevented. Whether this is cost-effective or not depends on the willingness to pay to prevent DMFT. However, no such willingness-to-pay value exists, which makes it difficult to state if program A is cost-effective.

In the case where the outcome measure instead is QALY, the same program A may yield 0.80 QALY and program B 0.79 QALY, resulting in an increase of 0.01 QALY. The ICER of program A compared with program B would then be \$5000 per QALY gained (as shown in Eq. (1) below). Since QALY has been used in many studies and previous decisions, we know that the willingness to pay per QALY gained use to be much higher than \$5000. Therefore, program A can be considered cost-effective compared with program B.

Eq. (1). Calculation of the incremental cost-effectiveness ratio (ICER) of program a compared with program B is as shown below:

$$ICER = \frac{CostA - CostsB}{EffectsA - EffectsB} = \frac{\\$100 - \\$50}{0.80 \, QALY - 0.79 \, QALY} = \frac{\\$5000}{QALY} \tag{1}$$

A cost-effectiveness analysis can be represented on a cost-effectiveness plane, as shown in **Figure 1** below. The ICER can be located in any of the four quadrants, A, B, C, or D. Only in quadrant A or D, it is straightforward to determine whether the program being evaluated is cost-effective, as it leads to either increased costs and lower effects or decreased costs and higher effects. However, in quadrant B or C, it depends

#### **Figure 1.**

*The cost effectiveness plane. = ICER of program a compared with program B.*

on how much one is willing to pay for improved effects. The maximum willingness to pay for an additional effect can be shown on an acceptance curve, and all estimates below this curve are considered cost-effective. The star in the figure represents the potential ICER of program A compared with program B in Eq. (1) above, indicating that program A is deemed cost-effective.

#### **4. Simulation and uncertainty**

The main purpose of health economic analyses is to assist decision-makers in prioritizing between different programs or treatments. It is crucial to provide relevant and reliable information for this purpose, which often requires the use of simulation models and uncertainty analyses. In this part, we will briefly introduce these concepts.

#### **4.1 Simulation models**

Simulation involves creating models that replicate real-world scenarios to assess the potential impact of different programs on costs and outcomes. These models can be used to estimate the long-term costs and effects of a program and to synthesize available data from different sources [7]. Simulation models can also be used to generalize results from one context to another and to go from intermediate outcomes to other outcomes. There are three main types of simulation models used in health economic evaluations: decision trees, Markov models, and discrete event simulation.

Decision trees are the simplest type of model and are useful when the timeframe is short and when the process is not complex. For instance, a decision tree may be relevant in a caries preventive program to model how many people received caries with different programs. However, it is not suitable if you want to follow the caried tooth for a long time.

A Markov model is built around different states, in which a patient can stay or transfer to another state with certain probabilities. Such a model can be useful for dental caries as it may have a state of a sound tooth, another state with enamel caries, another one with dental caries, and so on. The model can run for many cycles, and the tooth (or the patient) may move between these states, causing costs or effects continuously, which can be summed up.

Finally, discrete event simulation is generally more advanced and requires data on a patient level. It allows the study of systems or processes whose state changes discretely over time.

#### **4.2 Uncertainty**

Uncertainty is a common challenge in health economic evaluations due to factors such as variations in patient outcomes, differences in care settings, and uncertainty in cost estimates. To ensure the reliability and application of evaluation results, it is important to address and quantify uncertainty. Sensitivity analysis is a fundamental tool for assessing the impact of uncertain parameters on the results of economic evaluations.

Sensitivity analysis involves varying key inputs and assumptions, such as treatment costs, disease prevalence, and treatment effectiveness, to identify the variables that have the greatest impact on outcomes. This process allows researchers to understand the strength of the results and make better-informed decisions.

#### *Perspective Chapter: Cost-Effectiveness of Caries Preventive Programs DOI: http://dx.doi.org/10.5772/intechopen.113817*

There are different types of uncertainty that need to be dealt with differently. Parameter uncertainty relates to the fact that the true value is unknown, and this can be tested with statistical tests. Methodological uncertainty relates to all the methodological choices that must be made in an economic evaluation, and the significance of this can be tested by varying those choices. Structural uncertainty relates to how the decision is labeled, the comparator chosen, and the simulation model created. This type of uncertainty is often the most difficult to test.

Another type of sensitivity analysis is called bootstrapping, which is a statistical resampling technique used to estimate the uncertainty around cost and outcomes. It involves drawing multiple random samples with replacement from the original data to generate a distribution of cost and effectiveness estimates. This method provides confidence intervals around the point estimates, which help to understand the level of certainty in evaluation results.

Probabilistic sensitivity analysis goes further than traditional sensitivity analysis by including probability distributions for uncertain parameters. Instead of using single point estimates, a probabilistic sensitivity analysis assigns probability distributions to these parameters and performs thousands of simulation runs to generate a range of possible outcomes with associated probabilities.

In summary, simulation techniques and uncertainty analysis are important components of health economic evaluations. By using sophisticated simulation techniques and carefully addressing uncertainty, researchers can increase the credibility and utility of their findings. This can guide decision-makers in making evidence-based decisions that improve oral health outcomes and optimize resource allocation in dental care systems.

#### **5. An example: fluoride varnishing program in school**

Here follows an example of an economic evaluation of a caries preventive program and some aspects to consider. In this example, we evaluate a fictitious caries preventive program from a health economic perspective. A decision-maker is considering starting a fluoride varnishing program in schools for 12-year-old children. The main reason for this is that dental health is uneven, and high-risk children are difficult to reach. A program within schools has a high chance of capturing these hard-to-reach children. The comparator is no such program (treatment as usual).

We have chosen a cost-effectiveness analysis with the number of DMFT as the outcome measure. We have chosen a societal perspective and a time horizon of 5 years to capture the wide effects over a long time. The direct cost of each application has been found to be relatively low as a whole class can be treated within a short time. The cost includes the varnish used, the time used by dental personnel, and the costs for the person to get to the school. The cost of the involved children's time is set to zero as only a few minutes of school time are used.

Assuming the program would cost \$50 per involved child and the varnish would lead to fewer DMFT compared to treatment as usual for children with moderate or high risk of caries, we need to study the relation between increased costs and improved outcomes to examine the cost-effectiveness. For children with low risk, the program only reduces DMFT by 0.1 compared to treatment as usual. For children with moderate or high risk, the number of DMFT is reduced by 0.4 and 1.0, respectively; see **Table 1**. This reduction in DMFT furthermore leads to reduced costs; that is why the cost difference in **Table 1** is lower than the cost of the program. However, the

#### **Table 1.**

*Presentation of the incremental cost-effectiveness ratio of the example.*

difference in cost is above zero for all risk groups, which means that the program will not lead to savings.

From **Table 1** we can see that the most favorable ICER is achieved for the group with a high risk of caries, but we could not state whether this is cost-effective or not as we do not know the willingness to pay per DMFT prevented.

If all the ICER of the risk groups from the example are plotted in the cost effectiveness plane, we might more easily see the difference between the groups; see **Figure 2**. If the maximum willingness-to-pay per DMFT prevented would be \$30, the program would only be cost-effective if directed toward the high caries risk group. If the maximum willingness-to-pay per DMFT prevented instead would be \$100, the program would be considered cost-effective also if directed toward those with a moderate risk. The program is probably not cost-effective if directed toward those with a low risk of caries. However, a school-based program would probably include all these groups, perhaps showing an average in risks close to the moderate risk group.

#### **Figure 2.**

*Illustration of the cost-effectiveness of the example in a cost-effectiveness plane. = ICER of program a compared with treatment as usual for three different risk groups.*

#### **6. Evidence of cost-effectiveness of caries preventive programs**

There's plenty of evidence to suggest that caries preventive programs are costeffective, as shown by various studies and health economic evaluations over the years; for example [8, 9]. However, there are some methodological weaknesses in many of the studies, and more research is needed to determine the value of such programs [10].

Most of the studies have focused on children with a high risk of caries, with fluoride varnish being the most common intervention. While these interventions have been successful and cost-effective, they are not directly applicable to the general population where caries incidence may be lower [8].

There are a few interventions that have been found to be effective and costefficient for the general population, such as risk-based interventions [11], frequency of dental check-ups [12], and taxes on sugar [13]. However, there is a lack of studies using QALY as the outcome measured, which makes it challenging for decisionmakers to prioritize caries preventive interventions.

Water fluoridation is probably the most efficient program, which has been found to save costs and reduce caries [14]. However, many countries or regions have made this program illegal for different reasons.

Additionally, it is important to note that the cost-effectiveness of caries preventive programs can vary depending on several factors, including the target population, the specific intervention, the dental care setting, and regional healthcare costs. Therefore, conducting local or regional health economic evaluations is necessary to tailor preventive programs to the specific context and population. Overall, more research is needed to determine the cost-effectiveness of caries preventive programs and to improve their quality.

#### **7. Discussion and conclusions**

The efficient use of scarce resources is crucial in dentistry, which is why health economic evaluations are necessary. In this chapter, we have discussed various methods to achieve this objective. Health economic evaluations can also help prevent socioeconomic inequalities in dental health and support research in preventive dental care. We have also discussed the different types of health economic evaluations and identified cost-effectiveness analysis, including cost-utility analysis, as the most used ones. However, before selecting a particular methodology, it is crucial to define the decision problem clearly. This involves identifying the patients, intervention, comparator, and outcomes (PICO), as well as determining the perspective of the analysis and the cost-effectiveness threshold.

To ensure that the analysis covers all the critical aspects, it is recommended to use checklists [3]. Nevertheless, these checklists should be used in the context of their influence on the decision-making process, rather than the number of boxes ticked. Some items in the checklist may not be relevant to the decision problem, while other important aspects may be overlooked. For instance, the analysis's relevance to the decision problem, the inclusion of the best comparator, and the selection of the most relevant outcome measure are critical considerations.

It is essential to assess values that are important to patients when conducting health economic evaluations. The social function of esthetics, such as "kissing," may be more important to patients than the appearance of their teeth. Similarly, patients may view the chewing function as "meal joy" rather than merely a dental function [15].

To provide relevant health economic evaluations in dentistry, well-developed simulation models are also necessary. These models should analyze programs over an appropriate time horizon, combine sources from different areas, and explore total uncertainty. Additionally, health economic evaluations in dentistry would benefit from estimating QALY values for various dental health states.

In conclusion, assessing the cost-effectiveness of caries preventive programs is crucial in evidence-based decision-making in oral health. These evaluations provide valuable insights into the financial feasibility, value for money, and the long-term impact of preventive interventions. By understanding the cost-effectiveness of different programs, policymakers and dental professionals can develop sustainable, efficient, and equitable strategies to combat dental caries effectively and promote better oral health outcomes for populations.

#### **Conflict of interest**

The author declares no conflict of interest.

#### **Author details**

Thomas Davidson Linköping University, Linköping, Sweden

\*Address all correspondence to<EMAIL_ADDRESS>
© 2023 The Author(s). Licensee IntechOpen. 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.

*Perspective Chapter: Cost-Effectiveness of Caries Preventive Programs DOI: http://dx.doi.org/10.5772/intechopen.113817*

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[8] Davidson T, Blomma C, Bagesund M, Krevers B, Vall M, Warnberg Gerdin E, et al. Cost-effectiveness of caries preventive interventions - a systematic review. Acta Odontologica Scandinavica. 2020;**79**(4):1-12

[9] Eow J, Duane B, Solaiman A, Hussain U, Lemasney N, Ang R, et al. What evidence do economic evaluations in dental care provide? A scoping review. Community Dental Health. 2019;**36**(2):118-125

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### *Edited by Ana Cláudia Rodrigues Chibinski*

This book is the result of collaborative efforts from esteemed professors and researchers worldwide, who understand that dentistry is a dynamic field and that research on dental caries is constantly evolving. *Dental Caries Perspectives - A Collection of Thoughtful Essays* is a collection of varied insights that will enrich readers' understanding of dental caries and inspire further exploration and discussion within the field. It addresses the importance of meticulous diagnosis of caries, highlighting new methods and technologies available to clinicians, as well as the significance of adopting minimally invasive dentistry approaches, such as selective caries removal and remineralization of incipient lesions, to enhance treatment quality and preserve dental tissue. *Dental Caries Perspectives - A Collection of Thoughtful Essays* is a valuable resource for clinicians, researchers, and students, fostering critical thinking and encouraging readers to continuously seek out new knowledge and innovative solutions.

### *Sergio Alexandre Gehrke, Dentistry Series Editor*

Published in London, UK © 2024 IntechOpen © Gile68 / iStock

Dental Caries Perspectives - A Collection of Thoughtful Essays

IntechOpen Series

Dentistry, Volume 16

Dental Caries Perspectives

A Collection of Thoughtful Essays

*Edited by Ana Cláudia Rodrigues Chibinski*