No abstract

BackgroundBolton’s two main ratios describing the proportional size of upper and lower teeth, could contribute to estimating the excess or deficiency of tooth size necessary to obtain an ideal occlusion. However, the mean Bolton values are not the same among different societies. Determining the prevalence of tooth size deviations from population-specific Bolton indices might help local orthodontists to have a more concise treatment plan.ObjectiveThe study aimed to define the prevalence of clinically significant tooth size discrepancies (TSD) in an Iranian population and to evaluate the influence of lateral incisors’ size on this discrepancy.MethodsThis cross-sectional study was conducted on study casts of orthodontic patients attending Imam Reza Dental Clinic from September 2008 to December 2016. The sample comprised of 150 randomly selected pre-treatment study casts (64 males and 86 females from 17 to 28). The mesiodistal diameter of all permanent teeth from the first molar on the right to the first molar on the left was measured using 2 similar digital calipers, and Bolton analysis was calculated. Subjective visual estimation of Bolton discrepancy was also performed. SPSS v18.0, Wilcoxon signed ranks test, Pearson correlation and Receiver Operating Characteristic (ROC) curve analysis were used for statistical analysis. A p<0.05 was considered statistically significant.ResultsIn the sample group, 34.7% had anterior Bolton index (ABI) and 20.7% had total Bolton index (TBI) greater than 2 Standard Deviations (2SDs) of Bolton’s means, and about half of them required correction of the ABI considering the actual size of discrepancies (mm). The sensitivity of estimating clinically significant tooth size discrepancy more than 2SDs of Bolton’s ABI and the visual judgment was 96.0% and a cut-off point of −0.12mm was obtained.ConclusionBolton’s analysis should be routinely performed in all orthodontic patients, and visual estimation of TSD would be suggested as a screening method in the first visit prior to measurements and set-ups.

No abstract

Objective: To compare palatal height index, arch width, and arch length characteristics in Iranian patients presenting with palatal and buccal canine impaction with a matched control group. Materials and methods: The case-control study examined 53 patients with canine impaction. The subjects were divided into two groups determined by buccal or palatal impaction which were compared with 53 control subjects presenting without impaction. Subjects in the experimental groups were matched with individuals in the control group according to age, gender, crowding and type of malocclusion. Palatal height and arch length were measured with a Korkhaus three-dimensional divider. Arch width was determined in the anterior and posterior portions of the maxillary arch with a digital caliper. Data were compared with paired t-tests. Results: The buccal canine impaction group exhibited mean differences in arch length between the case and control groups of 0.8 mm (SD 1.63, p = 0.041). The differences between the case and control groups in intermolar width, interpremolar width, intercanine width, palatal depth, and palatal height index were not statistically significant. The palatal impaction group showed no statistically significant differences between the case and control group in any of the dependent variables (p ≤ 0.05). In a re-test examination of arch dimensions, Bland-Altman plots showed no differences between the first and second measurements. Conclusions: Arch length in the buccal canine group was the only statistically significant variable. The difference was small and was considered not clinically significant.

The chin position after maxillary superior repositioning can be predicted according to the amount of maxillary vertical changes. The vertical change of the chin is more predictable than the horizontal change.