Accuracy of an equation for estimating age from mandibular third molar development in a Thai population

PURPOSE: This study assessed the accuracy of age estimates produced by a regression equation derived from lower third molar development in a Thai population. MATERIALS AND METHODS: The first part of this study relied on measurements taken from panoramic radiographs of 614 Thai patients aged from 9 to 20. The stage of lower left and right third molar development was observed in each radiograph and a modified Gat score was assigned. Linear regression on this data produced the following equation: Y=9.309+1.673 mG+0.303S (Y=age; mG=modified Gat score; S=sex). In the second part of this study, the predictive accuracy of this equation was evaluated using data from a second set of panoramic radiographs (539 Thai subjects, 9 to 24 years old). Each subject's age was estimated using the above equation and compared against age calculated from a provided date of birth. Estimated and known age data were analyzed using the Pearson correlation coefficient and descriptive statistics. RESULTS: Ages estimated from lower left and lower right third molar development stage were significantly correlated with the known ages (r=0.818, 0.808, respectively, P≤0.01). 50% of age estimates in the second part of the study fell within a range of error of ±1 year, while 75% fell within a range of error of ±2 years. The study found that the equation tends to estimate age accurately when individuals are 9 to 20 years of age. CONCLUSION: The equation can be used for age estimation for Thai populations when the individuals are 9 to 20 years of age.

Diagnostic performance of cone-beam computed tomography on detection of mechanically-created artificial secondary caries

PURPOSE: The aim of this study was to compare the diagnostic accuracy of cone-beam computed tomography (CBCT) images and bitewing images in detection of secondary caries. MATERIALS AND METHODS: One hundred and twenty proximal slots of Class II cavities were randomly prepared on human premolar and molar teeth, and restored with amalgam (n=60) and composite resin (n=60). Then, artificial secondary caries lesions were randomly created using round steel No. 4 bur. The teeth were radiographed with a conventional bitewing technique and two CBCT systems; Pax-500ECT and Promax 3D. All images were evaluated by five observers. The area under the receiver operating characteristic (ROC) curve (Az) was used to evaluate the diagnostic accuracy. Significant difference was tested using the Friedman test (p value<0.05). RESULTS: The mean Az values for bitewing, Pax-500ECT, and Promax 3D imaging systems were 0.882, 0.995, and 0.978, respectively. Significant differences were found between the two CBCT systems and film (p=0.007). For CBCT systems, the axial plane showed the greatest Az value. CONCLUSION: Based on the design of this study, CBCT images were better than bitewing radiographs in detection of secondary caries.

Evaluation of the depth of non-cavitated carious lesions by radiographs

Aims: To evaluate and compare the depths of white and brown spot, non-cavitated, carious lesions by radiographs.Methods: Thirty white spot and 25 brown spot, non-cavitated carious lesions from proximal surfaces of extracted premolar and molar teeth were selected. The bucco-lingual dimension (size) of all lesions was measured using a vernier caliper. The teeth were radiographed. Three observers scored the lesions’ depths from the radiographs.  The lesions’ depths in ground sections were used as the gold standard. The depths of the white and brown spot lesions were compared. The relationship between the depth and the sizes of both types of lesion were evaluated. The depths measured on the radiographs were compared to those of the gold standard. Results: The white lesions were significantly deeper than the brown lesions. Radiographically, most of the brown lesions (72%) showed no radiolucency. Of the white lesions, 50% had lesion depths limited to enamel and 36.7% showed no radiolucency.  The remainder had lesions reaching at least to the DEJ. However, the ground sections showed that 60% of the white lesions reached at least to the DEJ. There was a significant correlation between the radiographic depth and the lesions’ sizes in only the white lesions. Compared to the gold standard, the radiographic measurement underestimated the lesions’ depths, equally for both white and brown spot lesions.Conclusions: For both radiographic and ground section examinations, white spot lesions were deeper than brown spot lesions. Therefore, they should be given more attention in disease prevention and treatment. Radiographs should be used as one of the aids for treatment planning of non-cavitated, carious, especially white, lesions. Key Words: non-cavitated carious lesion, depth, radiograph