Three-Dimensional Digital Analysis of Tooth Size and Arch Width Relationships in Different Malocclusion

Background This study aims to compare tooth size ratios (Bolton anterior and overall ratios) and transverse dental arch widths among Class II Division 1, and Class II Division 2 malocclusions using three-dimensional (3D) digital models, and to evaluate their clinical relevance for individualized orthodontic planning.

Materials and methods The study included 120 patients (mean age 14.5 ± 1.1 years) of both sexes, divided equally into three groups: Class I (n = 40), Class II/1 (n = 40), and Class II/2 (n = 40). Intraoral scans were obtained for both the maxillary and mandibular arches. Digital measurements were performed including the mesiodistal width of the teeth for calculating the anterior ratio (AR) and overall ratio (OR), as well as the intercanine (ICW), interpremolar (IPMW), premolar (PW), and intermolar (IMW) arch widths in both arches. Statistical analysis included independent t-tests, ANOVA, and Tukey post-hoc tests (p < 0.05).

Results Males showed significantly greater maxillary and mandibular mesiodistal widths, especially in Class II/2 malocclusion. Whereas Class I subjects showed significantly greater intercanine, interpremolar, premolar, and intermolar widths compared to Class II/1 and Class II/2 groups (p < 0.05). Significant differences were also observed in the Bolton ratios: Class II/1 showed the highest AR and OR values, while Class II/2 showed the lowest ratios.

Conclusion Three-dimensional digital analysis revealed significant differences in tooth size and transverse arch width between Class I, Class II/1, and Class II/2 malocclusions. These findings highlight the need for individualized orthodontic planning of tooth size ratios and arch dimensions during the treatment of Class II malocclusions.