Posterior_Direct_Restorations Salvatore_compressed

FIG 3-30 Ten-year-old child with cavitated lesion of the primary maxillary left first molar. Bitewing examination is justified because this condition places the child at high risk of caries.

Low sensitivity (50%).21

Ionizing radiation source.

Operator-dependent.

Does not distinguish cavitated lesions from noncavitated lesions (demineralization).

Does not distinguish active lesions from inactive lesions.

Lesion depth on the radiograph does not necessarily correspond to actual lesion depth.

Examination sensitivity decreases with decreasing caries risk (risk of false positives in patients without caries-related disease).

Sensitivity is not high at the occlusal level, where physical examination conducted in accordance with ICDAS II is the method of choice. Healthy buccal and palatal tissue at the lesion site can completely mask radiographic evidence of damaged tissue (Figs 3-31 and 3-32).24

FIG 3-31 (a to d) Diagram illustrating the rule of three thirds, ie, if the buccolingual lesion width is at least equal to one-third of total width, it will probably be visible on the radiograph. If the lesion width is less, it will be more difficult to see.

FIG 3-32 (a) Right bitewing radiograph. Due to the presence of devitalized teeth, additional radiographic examination of the maxillary first premolar and mandibular first molar was needed on the same day. (b) Periapical radiograph of the mandibular right first molar, where caries lesions on the mesial aspect of the mandibular right second molar and distal aspect of the left second premolar are more evident despite the radiographic superimposition. This can be explained by the rule of thirds: the different x-ray beam angle has changed the proportions between healthy and demineralized tissue.

On a radiograph, superficial areas of demineralization in a semicircular pattern can look like deeper lesions (Fig 3-33).

FIG 3-33 Diagram illustrating potential for a radiograph leading to overestimation of the extent of a lesion. In this case, what appears to be a lesion involving the dentin on the radiograph (a and b) is actually a circumferentially extensive but superficially demineralized WS (c)

Radiographic classifications

For many years, radiographic involvement of interproximal dental tissues was studied using the Lutz and Marthaler (L&M) classification, which dates back to 1966. This classification involves four dimensional stages, D1 to D4, based on radiographic lesion size, where D1 and D2 concern the involvement of the outer half (D1) and inner half (D2) of the enamel, while D3 and D4 concern the involvement of the outer half (D3) and the inner half (D4) of the dentin (Fig 3-34).