Mathematic method to calculate the central incisor form using face records and vice versa

Selection of anterior teeth depends mainly on Leon William theory that hypothesizes the presence of harmony between the face and inverted central incisor forms. If this theory is approved mathematically then the central incisor form and width could be predicted and calculated with acceptable precision in clinical practice. The purpose of this study was to predict the tooth form and mesiodistal width from the facial measurements. 145 young volunteers from different ethnic groups (Malays, Chinese, and Middle easterners) were selected according to well-defined criteria. Frontal standardized digital photos were taken for each person face and left central incisor. Then, the face and central incisor image length and widths (at different levels) were measured using digital image analyzer. The results revealed the presence of high metric dependence between the face and the left central incisor widths. A linear regression analysis was used to formulate a general equation to predict the central incisor width and form outline from the face measurement successfully. On the other hand, the face form can be predicted from the central incisor records Keywords— Linear regression analysis, Tooth form prediction, Central incisor form prediction.