Abstract
This study aimed to assess and compare the overall and anterior ratios of tooth size discrepancies in all Angle malocclusion groups. The following null hypothesis (H0) was tested: no difference between tooth size discrepancies (overall and anterior) would be observed among Angle malocclusion groups. The sample comprised of 711 pre-orthodontic treatment study casts of Brazilian patients with a mean age of 17.42 years selected from private practices in Brazil. The casts were divided into 3 groups according to the type of malocclusion: Class I (n = 321), Class II (n = 324), and Class III patients (n = 66). The measurement of the greatest mesiodistal width of the teeth was performed using a centesimal precision digital caliper directly on the study casts, from the distal surface of the left first molar to the distal surface of the right first molar. The overall and anterior ratios between the maxillary and mandibular teeth were evaluated using Bolton's method. The following statistical tests were applied: chi-square, independent t-test, and one-way ANOVA. Results showed that all Angle malocclusions groups exhibited a ratio compatible with those recommended by Bolton. With respect to the overall and anterior ratios among the malocclusion groups, no statistically significant differences were found. The null hypothesis was accepted because the results showed no differences in the overall and anterior ratios of tooth size discrepancies among different Angle malocclusion groups.
Highlights
Several authors have expressed concerns regarding the association between the mesiodistal size of maxillary and mandibular teeth and its influence on the relationship between dental arches.[1,2] Bolton[3,4] developed a method to calculate the ratio between the mesiodistal width of maxillary and mandibular teeth and stated that a correct and harmonious occlusion is possible only with adequate proportionality of tooth sizes.Identifying the presence of tooth size discrepancies between the maxillary and mandibular arches is an important component of correct orthodontic diagnosis and treatment
The overall and anterior ratios of all malocclusion groups were compared with the ratios recommended by Bolton: 91.3 ± 1.91 and 77.2 ± 1.65 for overall and anterior ratio, respectively.[4]
The independent t-test was used to compare the overall and anterior ratios of the malocclusion groups with the ratios recommended by Bolton
Summary
Identifying the presence of tooth size discrepancies between the maxillary and mandibular arches is an important component of correct orthodontic diagnosis and treatment. 10,11,12,13 Wedrychowska-Szulc et al.[14] compared tooth size ratios in 600 study casts of patients with different malocclusion groups (Class I, Class II division 1, Class II division 2, and Class III) and found statistically significant differences in the overall ratio among all groups and in the mean ratio in the anterior region between Class I and Class III groups. Araujo and Souki[10] assessed the association between tooth size discrepancy in the anterior region and Class I, II, and III Angle malocclusions in 300 Brazilian patients. The mean tooth size discrepancies in the anterior region were significantly higher in patients with Class III malocclusion than in those with Class I and Class II malocclusions
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