Overjet, overbite and dental midline shift as predictors of tooth size discrepancy in a Bangladeshi population and a graphical overview of global tooth size ratios

Abstract

Objectives. This study aimed to measure and compare tooth size ratios in a Bangladeshi population across the following groups: those with normal occlusion, crowding or spacing; those with normal, increased or decreased overjet; those with normal, increased or decreased overbite; those with or without dental mid-line discrepancy; and those with or without lip competence. It also presents a graphical overview of the anterior and overall ratios from the study and using available global data. Materials and methods. This study was performed on dental casts of 260 Bangladeshi individuals, comprising 114 males and 146 females (age range, 18–24 years, mean age = 20). The Bolton anterior ratio and overall ratio were determined for the following groups: those with normal occlusion, crowding or spacing; those with normal, increased or decreased overjet; those with normal, increased or decreased overbite; those with or without dental mid-line discrepancy; and those with or without lip competence. Results. There were statistically significant differences in the anterior tooth size ratios between those with or without dental mid-line discrepancy, with a mean value of 78.83% and 80.05%, respectively. Statistically significant differences were also found in overall tooth size ratios between those with normal, increased or decreased overjet and also between those with normal, increased or decreased overbite. Graphical presentations of anterior and overall ratios from the present study and using global data showed variations between populations. Conclusion. In the Bangladeshi population, increased tooth size ratios in subjects with dental mid-line discrepancy (anterior ratio) and also in those with decreased overjet or decreased overbite (overall ratio) may be predictors of tooth size discrepancies. The graphical overview also suggests that different international ethnic groups display unique Bolton ratios.