Dentofacial Morphology of Skeletal Class II Malocclusion with Mandibular Retrusion

Authors

Yu-Chun Lin, Department of Orthodontics, Kaohsiung Medical University Hospital; Division of Medical Statistics and Bioinformatics, Department of Medical Research, Kaohsiung Medical University Hospital
Hong-Po Chang, Department of Orthodontics, Kaohsiung Medical University Hospital; Division of Medical Statistics and Bioinformatics, Department of Medical Research, Kaohsiung Medical University HospitalFollow
Yi-Hsin Yang, Department of Orthodontics, Kaohsiung Medical University Hospital; Division of Medical Statistics and Bioinformatics, Department of Medical Research, Kaohsiung Medical University Hospital
Yu-Chuan Tseng, Department of Orthodontics, Kaohsiung Medical University Hospital; Division of Medical Statistics and Bioinformatics, Department of Medical Research, Kaohsiung Medical University Hospital
Chin-Yun Pan, Department of Orthodontics, Kaohsiung Medical University Hospital; Division of Medical Statistics and Bioinformatics, Department of Medical Research, Kaohsiung Medical University Hospital
Szu-Ting Chou, Department of Orthodontics, Kaohsiung Medical University Hospital; Division of Medical Statistics and Bioinformatics, Department of Medical Research, Kaohsiung Medical University Hospital

Abstract

Objective: The aim of this study was to investigate the morphological characteristics of the craniofacial pattern in skeletal Class II adults with mandibular retrusion. Materials and methods: Lateral cephalograms of 80 adults with skeletal Class II malocclusion with mandibular retrusion (∠ANB > 5°, ∠FNB < 86°) compared with 80 adults with normal occlusion (equal sexes in both groups). Thirty five landmarks were identified and digitized. Cephalometric analysis utilizing 30 linear, 29 angular and 4 ratio measurements were undertaken. Statistical comparison of the two groups was performed with Student’s t-test and 2 way-ANOVA. Results: (1) The skeletal Class II sample with mandibular retrusion had longer anterior cranial base length but the internal cranial base angle and the saddle angle were not different from the normal occlusion subject. (2) The sample with mandibular retrusion had longer maxillary length but the maxilla was in normal position related to the cranial base. The mandible was more retrusive and smaller but the ramus width was wider than normal occlusion subject due to compensatory growth. (3) The mandibular retrusion sample had more tilting maxillary plane, mandibular plane, ramus plane and occlusal plane. The sample had longer total anterior facial height, longer upper and lower anterior facial height and shorter posterior facial height (shorter ramus height) than normal occlusion subjects. Hyperdivergent facial pattern and the mandible rotated clockwisely were noted. (4) The mandibular retrusion sample had extrusive but normal inclined upper incisors, more inclined and extrusive lower incisors, smaller interincisal angle, larger overjet and deep overbite. (5) The mandibular retrusion group had more mesial tipping and more extrusive upper 1st molars. Besides, more mesial tipping, more retrusive, and more extrusive lower 1st molars were noted. Conclusion: Multiple variations of skeletodental features were found for skeletal Class II malocclusion with mandibular retrusion.

Recommended Citation

Lin, Yu-Chun; Chang, Hong-Po; Yang, Yi-Hsin; Tseng, Yu-Chuan; Pan, Chin-Yun; and Chou, Szu-Ting (2014) "Dentofacial Morphology of Skeletal Class II Malocclusion with Mandibular Retrusion," Taiwanese Journal of Orthodontics: Vol. 26: Iss. 1, Article 2.
https://doi.org/10.30036/TJO.201403_26(1).0002
Available at: https://www.tjo.org.tw/tjo/vol26/iss1/2

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