Archform comparisons between skeletal class II and III malocclusions

Wei Zou; JiaQi Wu; JiuHui Jiang; TianMin Xu; CuiYing Li

doi:10.1371/journal.pone.0100655

Archform comparisons between skeletal class II and III malocclusions

PLoS One. 2014 Jun 27;9(6):e100655. doi: 10.1371/journal.pone.0100655. eCollection 2014.

Authors

Wei Zou¹, JiaQi Wu¹, JiuHui Jiang¹, TianMin Xu¹, CuiYing Li²

Affiliations

¹ Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing, China.
² Department of Oral Pathology, Peking University School and Hospital of Stomatology, Beijing, China.

Abstract

The purpose of this cross-sectional research was to explore the relationship of the mandibular dental and basal bone archforms between severe Skeletal Class II (SC2) and Skeletal Class III (SC3) malocclusions. We also compared intercanine and intermolar widths in these two malocclusion types. Thirty-three virtual pretreatment mandibular models (Skeletal Class III group) and Thirty-five Skeletal Class II group pretreatment models were created with a laser scanning system. FA (the midpoint of the facial axis of the clinical crown)and WALA points (the most prominent point on the soft-tissue ridge)were employed to produce dental and basal bone archforms, respectively. Gained scatter diagrams of the samples were processed by nonlinear regression analysis via SPSS 17.0. The mandibular dental and basal bone intercanine and intermolar widths were significantly greater in the Skeletal Class III group compared to the Skeletal Class II group. In both groups, a moderate correlation existed between dental and basal bone arch widths in the canine region, and a high correlation existed between dental and basal bone arch widths in the molar region. The coefficient of correlation of the Skeletal Class III group was greater than the Skeletal Class II group. Fourth degree, even order power functions were used as best-fit functions to fit the scatter plots. The radius of curvature was larger in Skeletal Class III malocclusions compared to Skeletal Class II malocclusions (rWALA3>rWALA2>rFA3>rFA2). In conclusion, mandibular dental and basal intercanine and intermolar widths were significantly different between the two groups. Compared with Skeletal Class II subjects, the mandibular archform was more flat for Skeletal Class III subjects.

Publication types

Comparative Study
Research Support, Non-U.S. Gov't

MeSH terms

Adult
Algorithms
Cross-Sectional Studies
Dental Arch / physiopathology
Female
Humans
Male
Malocclusion, Angle Class I / physiopathology*
Malocclusion, Angle Class II / physiopathology*
Malocclusion, Angle Class III / physiopathology
Mandible / physiopathology

Grants and funding

This work was supported by the National Natural Science Foundation of China (grant numbers 81171006); the Beijing Science and Technology Committee (grant number Z121107001012024). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.