New prediction equations for the estimation of maxillary mandibular canine and premolar widths from mandibular incisors and mandibular first permanent molar widths: A digital model study / 대한치과교정학회지

OBJECTIVE: The primary aim of the study was to generate new prediction equations for the estimation of maxillary and mandibular canine and premolar widths based on mandibular incisors and first permanent molar widths. METHODS: A total of 2,340 calculations (768 based on the sum of mandibular incisor and first permanent molar widths, and 1,572 based on the maxillary and mandibular canine and premolar widths) were performed, and a digital stereomicroscope was used to derive the the digital models and measurements. Mesiodistal widths of maxillary and mandibular teeth were measured via scanned digital models. RESULTS: There was a strong positive correlation between the estimation of maxillary (r = 0.85994, r2 = 0.7395) and mandibular (r = 0.8708, r2 = 0.7582) canine and premolar widths. The intraclass correlation coefficients were statistically significant, and the coefficients were in the strong correlation range, with an average of 0.9. Linear regression analysis was used to establish prediction equations. Prediction equations were developed to estimate maxillary arches based on Y = 15.746 + 0.602 × sum of mandibular incisors and mandibular first permanent molar widths (sum of mandibular incisors [SMI] + molars), Y = 18.224 + 0.540 × (SMI + molars), and Y = 16.186 + 0.586 × (SMI + molars) for both genders, and to estimate mandibular arches the parameters used were Y = 16.391 + 0.564 × (SMI + molars), Y = 14.444 + 0.609 × (SMI + molars), and Y = 19.915 + 0.481 × (SMI + molars). CONCLUSIONS: These formulas will be helpful for orthodontic diagnosis and clinical treatment planning during the mixed dentition stage.

Study on mesiodistal teeth size and the relationship between upper and lower teeth dimension of normal occlusion from Han Chinese in Xi'an / 实用口腔医学杂志

Objective:To study the mesiodistal teeth size and the relationship between upper and lower teeth dimension of normal occlusion from Han Chinese in Xi'an. Methods: 52 males and 55 females with normal occlusion were selected. The mesiodistal width of each tooth was measured using a vernier gauge caliper. Statistical analysis was performed. Results: For the 107 cases with normal occlusion, the mean and standard deviation of the teeth size were calculated. There were significant differences between males and females in maxillary incisors, canines, first molar and mandibular canines, premolars. The normal range was obtained for the anterior and overall tooth size ratio(anterior ratio:78.32?3.01 overall ratio:91.10?2.27); and the regression equation that was used to quantify the tooth size discrepancies was expressed according to the significant correlation between the upper and lower tooth (r anterior=0.754, rtotal=0.851). Conclusion: There is a relationship between upper and lower teeth dimension. Sex difference should be considered when tooth size was used in clinic.