Abstract
This study was aimed to evaluate the diagnostic accuracy of cone beam computed tomography (CBCT) in detecting noncavitated approximal caries at different exposure parameters and to assess the impact of artifacts generated by amalgam restorations in an in vitro study. Seventy-eight approximal surfaces of extracted teeth were prepared with intentionally created noncavitated approximal caries of different depths; then, thirteen teeth with class 2 amalgam restorations were replaced with one tooth with normal surfaces in each block. CBCT volumes for all teeth were acquired using a Planmeca Promax 3D Mid imaging unit before and after placement of amalgam teeth, with different exposure parameters at low and high definition, both applying and omitting the Metal Artifact Reduction algorithm. The lesions were classified into four groups with regard to lesion extension. All teeth underwent histological analysis as gold standard. The histological examination showed that the distribution of lesions was as follows: 39.8% sound, enamel lesions of less and more than half the enamel thickness each 17.8%, and 24.6% dentin lesions. The detection sensitivity was found to be 0.972%, and specificity was found to be 0.937% for the detection of noncavitated approximal initial enamel and dentin caries. The highest diagnostic accuracy was found when using operating parameters of 90 kVp, 8 mA, and high resolution (75 μm) with nonamalgam teeth; all modes showed statistically significant higher AUCs than mode 2 (80 kVp, 7 mA, and 75 μm). However, for teeth with amalgam restorations, the highest accuracy was obtained at low resolution (200 μm) with the other parameters kept the same. It could be concluded that increasing the peak voltage and current improves diagnostic accuracy for the detection of noncavitated approximal caries. Moreover, diagnostic accuracy was found to be higher upon using high spatial resolution when diagnosing caries without adjacent amalgam restorations. There is a statistically significant difference with and without amalgam with respect to all modes.
Highlights
The early signs of approximal caries can be detected visually as discoloration or coarseness at the site, as well as radiographically
Of the 73 surfaces studied, 30 surfaces (41.1%) were sound, 13 surfaces (17.8%) had lesions involving less than half of the enamel thickness, 13 surfaces (17.8%) had lesions involving more than half of the enamel, and 17 surfaces (23.3%) had carious lesions extending into the dentin
The highest sensitivity, specificity, and area under the curve (AUC) were achieved with imaging Mode 1 (90 kVp, 8 mA, and 75 μm, i.e., high resolution), while the lowest was achieved with imaging Mode 2 (80 kVp, 7 mA, and 75 μm, i.e., high resolution)
Summary
The early signs of approximal caries can be detected visually as discoloration or coarseness at the site, as well as radiographically. Discoloration and approximal surface coarseness may indicate caries, detection of carious lesions by direct observation is difficult, if not impossible. Radiography is very important for the detection of approximal caries, being 88% more efficient than direct observation [1, 2]. Detection of noncavitated enamel lesions is of high significance, because caries progression can be ceased at this stage, and dental tissue can be preserved with minimally invasive approaches and without the need for restorative treatment [3, 4]. The challenges of clinical detection of approximal caries prior to cavitation and the ability to distinguish between the presence or absence of a carious lesion (i.e., sensitivity and specificity), become important when imaging methods are used.
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