Abstract:
Executive Summary
Background: Tooth-size discrepancy refers to unbalance between the mesiodistal widths of the
maxillary and mandibular individual teeth or groups of teeth. For normal occlusion to occur, the
maxillary and mandibular teeth must be proportional in size. Bolton’s ratios are a useful
diagnostic tool used in clinical orthodontics to achieve ideal occlusion of the dentition for
diagnosis and treatment planning.
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Objective: To assess the Bolton’s anterior and overall tooth size discrepancy among different
malocclusion groups in of Jimma medical center dental outpatients with 20 to 25 age groups
Methods: Hospital-based cross sectional study was conducted in Jimma University medical
Center, Dental OPD, in Jimma medical center dental outpatients. A total of 105 patients were
recruited among 20 to 25 age groups. Inter arch tooth size discrepancy was assessed using patient
study models and mesiodistal tooth width was measured with digital vernier calliper.One-way
ANOVA was used to assess the Bolton ratio difference between the groups as function of
Angle’s malocclusion and gender. The one sample t-test was used to compare the differences
between the groups of the present study and Bolton’s original sample.
Results: The differences in tooth size ratio of the study groups were not significant statistically,
when the groups were compared on the basis of gender.A significant anterior tooth size
discrepancy was observed in in the three classes. Statistically significant differences were
exclusively observed between the study groups and Bolton’s original sample for the anterior
ratio. The frequency of the clinically significant tooth size ratio discrepancy was lower for the
overall ratio (35.2%) compared to the anterior ratio (58%).
Conclusions: Bolton’s analysis shows the clinically significant anterior tooth size discrepancy
was more prevalent than that of the overall ratio. In both anterior and overall tooth size
discrepancy the incidence of mandibular excess is greater than maxillary excess. In both
anterior and overall TSD, class III malocclusion had highest incidence.
