Efficacy of Cephalometric Norms as a Predictable Method for Soft Tissue Positioning and Facial Aesthetics After Orthodontic-orthognathic Interventions

Aim: The aim of this study is to verify whether there are morphological differences in the soft tissue profile between individuals submitted to orthodontic-orthognathic treatment and individuals belonging to an aesthetically ideal population. Materials and methods: A total of 578 young Portuguese adults of both genders who attended the Institute of Orthodontics of the Faculty of Medicine of the University of Coimbra were submitted to an examination, and after applying the inclusion criteria previously defined for this study, only 55 were considered for the control group. In this ideal population sample (mean age 22.6 years), lateral cephalograms were obtained in the natural head position and centric occlusion. The sample of the population submitted to orthodontic-orthognathic treatment consisted of 20 young adults (mean age of 22.75 years) who successfully underwent orthodontic-orthognathic treatment of dento-skeletal Class III. The cephalometric analysis was performed using Dolphin Imaging Software/32 (High Quality Digital Imaging Software for Orthodontics, Cosmetics and Medical Imaging, version 8.0.6.12 of Dolphin Imaging Systems Inc., USA), and the cephalometric points were used mainly from the cephalometric atlas of Miyashita and Dixon (1996). For the statistical analysis of the obtained data, a Student's t distribution was used and a significance level 0.05 was adopted; therefore a confidence level of 95% was considered. Results: Among the variables that represent the upper and middle thirds of the face, only TVL: UL (True Vertical Line: Upper Lip) characterize the upper lip in the posterior-anterior plane. These variables were significantly different between the two populations (α=0.05). In the lower third of the face the variables are almost all significantly different between the populations (α ≤0.05). Conclusions: If the cephalometric norms obtained in this study are accepted as the ideal for the Portuguese population, then orthodontic and/or orthodontic-orthognathic interventions based on dento-skeletal norms are not enough to obtain good facial aesthetics. Parole chiave: Cephalometric norms, orthodontic-orthognathic interventions, soft tissue positioning, facial aesthetics