Image analysis of the eruptive positions of third molars and adjacent second molars as indicators of age evaluation in Thai patients

PURPOSE: This study was performed to determine the relationship between the stage of tooth eruption (both vertical and mesio-angular) and chronological age. MATERIALS AND METHODS: Indirect digital panoramic radiographs were used to measure the distances from the dentinoenamel junction (DEJ) of the second molars to the occlusal plane of the second molar teeth and of the adjacent third molars in 264 Thai males and 437 Thai females using ImageJ software. The ratio of those distances was calculated by patient age, and the correlation coefficient of the ratio of the third molar length to the second molar length was calculated. RESULTS: The correlation between the height of the vertically erupted upper third molar teeth and age was at the intermediate level. The age range of > or =15 to <16 years was noted to be the range in which the correlation between the chronological age determined from the eruptional height and actual chronological age was statistically significant. The mean age of the female subjects, in which the position of the right upper third molar teeth was at or above the DEJ of the adjacent second molar but below one half of its coronal height was 19.9+/-2.6 years. That for the left side was 20.2+/-2.7 years. The mean ages of the male subjects were 20.1+/-3.3 years and 19.8+/-2.7 years for the right and left sides, respectively. CONCLUSION: It might be possible to predict chronological age from the eruption height of the wisdom teeth.

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