An Investigation of Posttreatment Facial Harmony in Accordance with Steiner Estimates

Abstract

Contemporary orthodontic practices slowly adopt modern technologies, new treatment tools, and soft-tissue-based diagnostic approaches. Classic diagnostic tools, especially those concerning the cephalometric positioning of the incisors, are gradually being discarded from routine use. However, it is important to understand whether any of the classic treatment planning tools have a direct relation to perceived success in facial harmony. In this study, we aimed to evaluate the perceived success in posttreatment facial outcomes in a randomized orthodontic population using several components of the Steiner analysis. Inclusion criteria included an ANB angle ranging from -1 to 6 degrees and an SN-GoGn angle ranging between 26 and 39 degrees at the beginning of the treatment. In addition, to be enrolled in the study, the selected patients were required to have a Class I canine relationship, normal overjet and overbite, standard curves for Wilson and Spee, and absence of visible spacing at the end of the treatment. The records of 119 qualifying orthodontic patients were included in the study. Ten orthodontists were presented with pre-and posttreatment cephalometric radiographs of the sample and asked to review the facial outcomes of the treatment using a ten-point visualized analog scale (VAS). Based on the evaluations of the panel, three groups were formed: ideal (n=20), average (n=82), and below average (n=17). Cephalometric variables from the Steiner analysis were compared between the three groups using a one-way analysis of variance (ANOVA). In addition, Pearson Correlation coefficients were calculated between the evaluations of the judges and the cephalometric variables. The level of significance was set at p.01. Of the cephalometric variables used in this study, the measurements related to the position and inclination of the mandibular incisors and the position of the lower lip were significantly different between the three groups (p.01). Bonferroni post hoc comparisons showed that when the below average group was compared to the other two groups (p.01), significant differences occurred for L1-NB (mm and degrees) and the lower Lip to E line measurements. In addition, there was a significant difference in IMPA measurement between the below average and average groups (p.01). Significant negative correlations occurred between the judges' esthetic scores and the cephalometric variables, including all the mandibular incisor measurements and the posttreatment lower-lip position. Increased lower incisor proclination and protrusion both before and after treatment as well as posttreatment lower lip protrusion had strong affiliations with poor facial outcomes.