**2. Evaluation of the performance of caries detection methods**

The performance of caries detection methods should be assessed considering two important parameters: reproducibility and validity. A reproducible method is the one that presents similar results and shows an agreement between two exams performed in different

Traditional and Novel Caries Detection Methods 109

fissures, guided by prisms direction and striae of Retzius. Histologically, the lesion forms in three dimensions and assumes the shape of a cone, with its base toward the enamel-dentin junction. Acids lead to the demineralization underneath the enamel surface and there is an enlargement in intercrystalline spaces, increasing its permeability. Over time, the surface porosity has increased and leads to a considerable increase of the lesion body (a subsurface lesion starts to form). Occlusal enamel breakdown is the result of further demineralization,

The lesions on smooth surfaces result from an accumulation of biofilm along the gingival margins. Characteristically, those lesions follow the form of the gingival contour and can progress to form a cavity in enamel, and subsequently, that can extend through the dentin (Nyvad et al., 1999). In section, the smooth-surface lesion is conical as a result of systematic variations in dissolution along the enamel prisms. The conically shaped lesion represents a range of increasing stages of lesion progression, beginning with dissolution at the

On the approximal surfaces, the biofilm accumulation occurs in the region below the contact point between the contact face and the gingival margin. The lesion may extend to the buccal and lingual directions, following the gengival contour (Nyvad et al., 1999). Histologically, the initial lesion in the approximal surface has a triangular shape with its base toward the outer surface and the apex facing the enamel-dentin junction. As mentioned earlier, this is because the acid diffusion from the bacterial metabolism is determined by the distribution of

Caries lesion on approximal surfaces in primary teeth presents a rapid rate of progression due to the morphologic characteristics of these teeth, making its detection difficult. Primary teeth have thinner enamel and dentin, lower mineralization rate, large dentinal tubules and larger contact proximal areas, which allow greater biofilm accumulation, and consequently, leading

The detection of carious lesions has been primarily a visual process, based principally on clinical-tactile inspection and radiographic examination. Caries detection methods should be capable of detecting lesions at an early stage, when progression can be arrested or reserved, avoiding premature tooth treatment by restorations. However, none of the conventional methods fulfill this requirement and are highly subjective. The development of some alternative non-invasive detection methods, such as laser fluorescence devices (DIAGNOdent and DIAGNOdent pen), quantitative light-induced fluorescence (QLF), fluorescence camera (VistaProof), LED technology (Midwest Caries I.D.), fiber-optic transillumination (FOTI), digital imaging fiber-optic transillumination (DIFOTI) and electrical caries monitor (ECM), can offer objectives assessments, where traditional methods

Visual changes of the dental structure resulting from the demineralization process can be visually observed during caries development, such as an increase in opacity and roughness

ultrastructural level at the edge of the lesion (Bjørndal & Thylstrup, 1995).

the biofilm and follows the direction of the enamel prisms (Nyvad et al., 2008).

to initiation and progression of dental caries (Mortimer, 1970; Pitts & Rimmer, 1992).

thus leading to cavity formation (Nyvad et al., 2008).

**4. Caries detection methods** 

**4.1 Visual-tactile examination** 

of the enamel.

could be supplemented by quantitative measurements.

moments or by different examiners using the same sample. Reproducibility can be assessed by Cohen's Kappa test or Intraclass Correlation Coefficient (ICC).

Validity is the ability of a method of assessing what it is suppose to assess. It is calculated by the proportion of correct results taking into account the gold standard, which is the true and definitive diagnosis reference. Using these results, the validity of a method can be obtained by calculating values of specificity and sensitivity. Specificity is the proportion of cases classified by a method as negative (disease absent) considering the total of cases that did not developed the disease. Sensitivity, however, is the proportion of cases classified as positive (disease present) considering the total of cases that really developed the disease. The total percentage of correctly assessed cases considering the presence and the absence of disease is represented by the accuracy. Table 1 summarizes how sensitivity (Sn) and specificity (Sp) values can be calculated:


Table 1. The generic 2 x 2 table used to calculate sensitivity (Sn) and specificity (Sp) values.

Concerning methods' validity and calculation of sensitivity and specificity values it is necessary to establish limits to define what "disease" and "healthy" mean considering the gold standard. These limits can also be called "cut-off points", which are combined according to the criteria used for the gold standard classification. For example, caries lesions can be classified in: (0) caries free, (1) caries extending up to halfway through the enamel, (2) caries extending into the inner half of enamel, (3) caries in dentin and (4) deep dentin caries. Therefore, cut-off points can be defined as follow:

D1: all caries lesions are considered disease (1, 2, 3 and 4);

D2: only caries lesions from the inner half of enamel are considered disease (2, 3 and 4); D3,D4: only dentin caries lesions are considered disease (3 and 4).

#### **3. Clinical and histological aspects of caries lesions on occlusal, approximal and smooth surfaces**

The occlusal surface is characterized by the pit and fissure systems, a favorable biofilm stagnation area where the bacterial accumulations receive the best protection against functional/mechanical wear (mastication, attrition, abrasion from brushing, flossing or toothpicks). Those aspects contribute to the high prevalence of caries on occlusal surfaces both in the primary and permanent dentition (Kidd & Fejerskov, 2004).

The complex anatomy of the occlusal surfaces requires professional special attention and deep understanding of how lesions develop on this surface. It is known that the deepest part of the fissure usually harbors non-vital bacteria or calculus (Ekstrand & Bjørndal, 1997). An enamel caries lesion begins along the pits and fissures through acids diffusion from bacterial metabolism in the biofilm. This diffusion occurs through the side walls of the pits and

moments or by different examiners using the same sample. Reproducibility can be assessed

Validity is the ability of a method of assessing what it is suppose to assess. It is calculated by the proportion of correct results taking into account the gold standard, which is the true and definitive diagnosis reference. Using these results, the validity of a method can be obtained by calculating values of specificity and sensitivity. Specificity is the proportion of cases classified by a method as negative (disease absent) considering the total of cases that did not developed the disease. Sensitivity, however, is the proportion of cases classified as positive (disease present) considering the total of cases that really developed the disease. The total percentage of correctly assessed cases considering the presence and the absence of disease is represented by the accuracy. Table 1 summarizes how sensitivity (Sn) and specificity (Sp) values can be calculated:

Disease present (+) Disease absent (-) Positive Test (+) A B Total positive

Negative Test (-) C D Total negative

Table 1. The generic 2 x 2 table used to calculate sensitivity (Sn) and specificity (Sp) values.

D2: only caries lesions from the inner half of enamel are considered disease (2, 3 and 4);

**3. Clinical and histological aspects of caries lesions on occlusal, approximal** 

The occlusal surface is characterized by the pit and fissure systems, a favorable biofilm stagnation area where the bacterial accumulations receive the best protection against functional/mechanical wear (mastication, attrition, abrasion from brushing, flossing or toothpicks). Those aspects contribute to the high prevalence of caries on occlusal surfaces

The complex anatomy of the occlusal surfaces requires professional special attention and deep understanding of how lesions develop on this surface. It is known that the deepest part of the fissure usually harbors non-vital bacteria or calculus (Ekstrand & Bjørndal, 1997). An enamel caries lesion begins along the pits and fissures through acids diffusion from bacterial metabolism in the biofilm. This diffusion occurs through the side walls of the pits and

Concerning methods' validity and calculation of sensitivity and specificity values it is necessary to establish limits to define what "disease" and "healthy" mean considering the gold standard. These limits can also be called "cut-off points", which are combined according to the criteria used for the gold standard classification. For example, caries lesions can be classified in: (0) caries free, (1) caries extending up to halfway through the enamel, (2) caries extending into the inner half of enamel, (3) caries in dentin and (4) deep dentin caries.

Sn%: A/(A + C) Sp%: D/(B + D) Total number (A

tests (A + B)

tests (C + D)

+ B + C + D)

by Cohen's Kappa test or Intraclass Correlation Coefficient (ICC).

Therefore, cut-off points can be defined as follow:

**and smooth surfaces** 

D1: all caries lesions are considered disease (1, 2, 3 and 4);

D3,D4: only dentin caries lesions are considered disease (3 and 4).

both in the primary and permanent dentition (Kidd & Fejerskov, 2004).

fissures, guided by prisms direction and striae of Retzius. Histologically, the lesion forms in three dimensions and assumes the shape of a cone, with its base toward the enamel-dentin junction. Acids lead to the demineralization underneath the enamel surface and there is an enlargement in intercrystalline spaces, increasing its permeability. Over time, the surface porosity has increased and leads to a considerable increase of the lesion body (a subsurface lesion starts to form). Occlusal enamel breakdown is the result of further demineralization, thus leading to cavity formation (Nyvad et al., 2008).

The lesions on smooth surfaces result from an accumulation of biofilm along the gingival margins. Characteristically, those lesions follow the form of the gingival contour and can progress to form a cavity in enamel, and subsequently, that can extend through the dentin (Nyvad et al., 1999). In section, the smooth-surface lesion is conical as a result of systematic variations in dissolution along the enamel prisms. The conically shaped lesion represents a range of increasing stages of lesion progression, beginning with dissolution at the ultrastructural level at the edge of the lesion (Bjørndal & Thylstrup, 1995).

On the approximal surfaces, the biofilm accumulation occurs in the region below the contact point between the contact face and the gingival margin. The lesion may extend to the buccal and lingual directions, following the gengival contour (Nyvad et al., 1999). Histologically, the initial lesion in the approximal surface has a triangular shape with its base toward the outer surface and the apex facing the enamel-dentin junction. As mentioned earlier, this is because the acid diffusion from the bacterial metabolism is determined by the distribution of the biofilm and follows the direction of the enamel prisms (Nyvad et al., 2008).

Caries lesion on approximal surfaces in primary teeth presents a rapid rate of progression due to the morphologic characteristics of these teeth, making its detection difficult. Primary teeth have thinner enamel and dentin, lower mineralization rate, large dentinal tubules and larger contact proximal areas, which allow greater biofilm accumulation, and consequently, leading to initiation and progression of dental caries (Mortimer, 1970; Pitts & Rimmer, 1992).
