1 DDS, MS Assistant professor& director of postgraduate program Department of Orthodontics, School of I Detistry Mashhad university of Medical Sciences




Aim: An appropriate occlusal relationship, when there is a significant tooth size discrepancy between the lower and upper dental arches, is impossible. In this way, it is necessary to assess the Bolton's anterior and overall ratios. But it seems too difficult to Measure 24 teeth for each patient routinely. in this research our aim was to find an appropriate substitute for the Bolton ratio.
Material and Methods: One hundred pairs of dental casts were selected and the mesiodistal width of each tooth was measured by a sharpened gauge. Then correlation between lateral ratio (mesiodestal width of lower lateral incisors/ upper lateral incisors) and Bolton's anterior ratio (AR) and overall ratio (OR) was evaluated by paired T test and regression models.
Results: Mean overall ratio was 91:3 %, anterior ratio 79.0% and lateral ratio 88.4%correspondingly. No significant difference was found between males and females. A well correlation was found between LR and AR (r=0.70) and OR.
Conclusion: Strong correlation between LR and AR and OR was established. Mean value of 88.4% for LR was correspondent to normal Bolton ratios. (IJO 2006; 1: 53 - 57)