An improved method to analyse tooth and restoration contour using image analysis: Application in the maxillary anterior teeth in Chinese population

Abstract

Objectives The aim of this study was to develop a method to analyse tooth and restoration contour, and apply it to investigate the differences in coronal contour of maxillary anterior teeth in Chinese population. Methods One hundred and sixteen Chinese volunteers participated in this study. An upper cast was fabricated with self-cure acrylic resin for each participant. The images of serial slices obtained from the resin teeth were analysed to produce a data set ( x, y) representing the coronal contour. The data were used to find appropriate equations to describe the shape of the contours. The values of the equation parameter and the reliability of the technique were analysed using SPSS statistical software. Results A high level of repeatability was found suggesting that the method is reliable. In this study the facial and lingual contour were best represented by two equations: y = a + bx 0.5 and ln( y) = a + bx 2, respectively. The b values generated from this analysis provided a measure of tooth contour. In this group of Chinese population, the facial surfaces had a straighter coronal contour in male and the surfaces became gradually straighter from the canine to the central incisor with the greatest convexity being found in the mesial third of each tooth. On the lingual surfaces the greatest concavity was found in the middle third of each tooth, this being greatest in the canine. Conclusions This method was suitable for analysis of tooth contour, revealing statistically significant differences in contour between genders, tooth types and parts of tooth in a dentally healthy adult Chinese population. The method should also be suitable for analysis of contour in restored teeth.