Introductory Chapter: Contemporary Concepts in Cariology

1. Introduction

Untreated tooth decay remains one of the most prevalent diseases around the world. Data from 1990 to 2019 showed that there were 3.09 billion of new cases of untreated dental caries in permanent teeth (48.00% increase) and 1.15 billion in deciduous teeth (11.74% increase) [1]. This accounts for approximately 44% of the world’s population.

Tooth decay is defined as a non-infectious, biofilm/sugar-dependent disease with multifactorial etiology and clinically manifests as lesions resulting from a process of mineral loss in the dental structure. Through a process of dysbiosis or imbalance, the microorganisms present in the oral environment become pathological, thus being responsible for the development of tooth decay. For many years, it was believed that Streptococcus mutans were largely responsible for this, but studies proved that this group represents only a small fraction of the bacterial community present in the biofilm responsible for disease process. Therefore, dental caries cannot be considered an infectious and contagious disease, since the ecological plaque hypothesis showed that tooth decay is not caused by a specific type of microorganism, but rather by the result of a change in the microbiota of the biofilm to more cariogenic species.

The oral microbiome has a symbiotic relationship with the host, and the presence of available sucrose in the mouth is a decisive factor to initiate the caries process. The American Academy of Pediatric Dentistry (AAPD) already cited that high frequency of sugar intake is one of the main risk factors for tooth decay, in addition to other variables such as low saliva flow, visible plaque on the tooth surface, use of dental appliances, health problems, sociodemographic factors, access to health care, among others.

Another factor that increases the risk of disease development and progression is the presence of alterations in dental structure, such as enamel defects, which hinder oral hygiene and biofilm control by the patient. Socio-economic-behavioral factors should also be considered as risk factors for tooth decay, as they can interfere with the course of the disease. Inadequate housing conditions, low income, low education, and habits that do not take into account the necessary oral health care also pose greater risks for the onset and development of the disease [2].

The risk factors and protective factors should be analyzed in each individual in a way that favors the assessment, prevention, and individualized intervention for each patient.

2. How a carious lesion is formed?

In a very simplistic way, a carious lesion begins with a mineral loss in the hard dental tissues due to the imbalance in the demineralization and remineralization processes that physiologically occur in the mouth. Bacteria present in dental biofilm metabolize fermentable carbohydrates ingested by the individual and consequently produce organic acids (mainly lactic acid), leading to microbial adaptation that results in the selection of acidogenic microorganisms. With the predominance of these microorganisms, the oral pH decreases, and the oral environment becomes acidic. Therefore, an imbalance in the ion exchange between the tooth and saliva is settled [3].

For enamel, the lesion occurs when the pH reaches the critical level, which is below 5.5 in the absence of fluoride and 4.5 in the presence of fluoride. In this situation, there will be a breakdown of hydroxyapatite crystals, and the biofilm/enamel interface will become supersaturated with ions compared to saliva, leading to a loss of minerals to the environment, a process known as demineralization.

If the cariogenic biofilm is disorganized by toothbrushing, for instance, and there is no more available sucrose in the oral cavity, the acid production will cease and the pH will return to neutrality. The buffering action of saliva helps in this process. As a consequence, the biofilm/enamel interface, which was previously hyper-saturated due to mineral loss, will now become undersaturated compared to saliva and will receive back calcium, phosphate, and hydroxyl ions, a process known as remineralization.

The process of demineralization and remineralization (DE-RE) mentioned above occurs daily in a subclinical manner in the oral cavity of all individuals. However, in cases of imbalance, such as lack of oral hygiene and high frequency of sugar consumption, this process remains much longer in the loss phase than in the mineral gain phase. If this movement is not interrupted, the acids will increase the porosity of the enamel, and there will be a widening between the spaces of hydroxyapatite crystals, resulting initially in a rough and opaque enamel surface, clinically seen as a white spot lesion. In cases where this process persists for a longer period, there will be a breakdown of the superficial layer of the lesion, resulting in a cavity.

3. Diagnosis

Timely and accurate diagnosis, as in all diseases, favors the definition of an effective treatment plan and improves the prognosis. Dental caries diagnosis involves the evaluation of signs and symptoms presented by the patient, but mainly the modifying factors involved in the onset and progression of tooth decay. Currently, the focus should no longer be solely on treating carious lesions or cavities, but rather on treating tooth decay as a whole disease.

The first step in diagnosis should be conducting an anamnesis to collect and assess the etiological or protective factors related to the disease. After completing the entire anamnesis, a clinical examination is necessary, during which all dental surfaces are evaluated for the detection and characterization of carious lesions.

It is important to note that there is no single method capable of assessing the onset of the disease. Therefore, we use various strategies to gather information and categorize the patient into a group that best corresponds to his/her current situation regarding the risk of developing the disease or its progression. This assessment is important for the development of a specific treatment plan or preventive strategy for that patient.

The diagnosis process may be divided into three main aspects: assessment of the risk of caries, detection of lesions, and diagnosis of caries activity.

Due to the fact that tooth decay is biofilm-sugar dependent, these are risk factors that must be evaluated in all patients, including the quality and frequency of oral hygiene, correct use of fluoride toothpaste, amount and frequency of sugar intake, dietary habits, presence of biofilm on the tooth surface, socioeconomic factors, among others [2]. A very important risk factor is that past experience of decay in children over 5 years old is undeniably the greatest risk factor for the disease [4].

The detection of carious lesions is based on a visual-tactile examination, that is, the combination of visual inspection aided by probing the dental surfaces. Other technological devices may also be included in this phase of the clinical exam, but visual-tactile examination is still the most widely used technique around the world. It is an easy, affordable, and quick method that allows the assessment of the caries lesions as well as their activity, without causing discomfort to the patient.

The dental examination should be accomplished on dental surfaces that are dry, clean, well-lit, and free from biofilm; therefore, it requires dental prophylaxis before the exam. The use of systems for detecting caries lesions, like the International Caries Detection and Assessment System (ICDAS), is advisable to standardize the examinations.

After detecting the presence of carious lesions, it is fundamental to determine their activity, that is, determining if the disease is progressing or has been inactivated. Active enamel lesions present as opaque, rough, and porous white spots. Inactive lesions already have a smooth, shiny, and polished clinical appearance. The dark color of caries lesions may be an indicative factor of inactive lesions, but it cannot be used as the sole method and evaluation factor.

The assessment of carious risk and the activity of the disease will guide the choice of different therapeutic approaches for each patient.

4. Treatment/control

The principles of Minimally Invasive Dentistry (MID) must be adopted in this phase of the treatment. Noninvasive and microinvasive techniques are the main choice to treat and control dental caries. Remineralizing strategies are fundamental during the first phases of the treatment. Patients must have sessions to educate and motivate them in order to obtain and keep good oral health, encouraging self-care capacity through access to information, skill development, and motivation. Restorative treatment should be performed aiming to favor biofilm control first, being function and esthetics as secondary objectives. Also, a restorative technique must preserve as much healthy and remineralizable tissue as possible and achieve a perfect seal while maintaining pulp and restoration integrity. Follow-up consultations must be scheduled according to the patient’s needs [5]; in these consultations, all the criteria cited above must be considered again. The patient’s condition will be re-evaluated and the strategies to control the disease will be reviewed, allowing for adjustments at the appropriate time.

Treatment and control of dental caries go beyond the removal of carious tissue and sealing of lesions; it is necessary to understand the etiological factors surrounding the patient to take a step forward toward solving this public health problem that affects the whole world to a greater or lesser extent.

5. Conclusion

The evolution of scientific knowledge in cariology has allowed for a paradigm shift regarding the management of dental caries. Purely surgical dental approaches focused on the elimination of cavities have been replaced by the Minimally Invasive Dentistry (MID) approach, which prioritizes prevention, remineralization, patient’s education, and individualized treatment plans.

MID techniques focus on the preservation of healthy tooth structure while addressing carious lesions, aligning with the concept of early intervention to halt disease progression. By emphasizing risk assessment and individualized treatment plans, dentists can proactively manage caries risk factors. Embracing MID principles not only minimizes unnecessary tissue removal and preserves natural dentition but also promotes patient-centered care, emphasizing prevention and early intervention to mitigate the burden of dental caries effectively.