ObjectiveThe purpose of this study was to examine whether orthodontic treatment experience affects the individual's perception of smile esthetics and to evaluate differences among orthodontically treated laypersons, non-treated laypersons, and dentists by using computerized image alterations.MethodsA photograph of a woman's smile was digitally altered using a software image editing program. The alterations involved gingival margin height, crown width and length, incisal plane canting, and dental midline of the maxillary anterior teeth. Three groups of raters (orthodontically treated laypersons, non-treated laypersons, and dentists) evaluated the original and altered images using a visual analog scale.ResultsThe threshold for detecting changes in maxillary central incisor gingival margin height among laypersons was 1.5 mm; the threshold of dentists, who were more perceptive, was 1.0 mm. For maxillary lateral incisor crown width and height, the threshold of all three groups was 3.0 mm. Canting of the incisal plane was perceived when the canting was 3.0 mm among non-treated laypersons, 2.0 mm among treated laypersons, and 1.0 mm among dentists. Non-treated laypersons could not perceive dental midline shifts; however, treated laypersons and dentists perceived them when the shift was ≥ 3.0 mm.ConclusionsLaypersons with and without orthodontic treatment experience and dentists have different perceptions of smile esthetics. Orthodontically treated laypersons were more critical than non-treated laypersons regarding incisal plane canting and dental midline shifts. Based on these findings, it is suggested that orthodontic treatment experience improved the esthetic perceptions of laypersons.

Distraction osteogenesis is the biological process of new bone formation between bone segments that are gradually separated by incremental traction. The purpose of this study was to assess dental stability and radiographic healing patterns following mandibular symphysis widening with distraction osteogenesis (MSDO) in 19 non-syndromic patients (10 males, 9 females: mean age at the time of surgery 20 years 11 months). To evaluate dental stability, 13 landmarks were measured on the study models of all patients and healing patterns were classified for 11 subjects according to healing times on periapical or occlusal radiographs at three time points: pre-distraction (T1), post-distraction (T2), and follow-up (T3; average 1 year 6 months). Paired t-tests were used to evaluate the change between T2-T1, T3-T2, and T3-T1. The results of this study showed that although there was a decrease in expansion during treatment, the total amount of surgical expansion was maintained. Arch length was significantly increased and irregularity was significantly decreased (both P<0.001). There was evidence of mineralization of the distraction gap in 11 patients within 3 weeks of the end of activation. Radiographically, healing patterns for the distraction gap were diverse, but radiopacity increased over time. MSDO is dentally stable and the distracted gap is mineralized with time, indicating that MSDO is an efficient and stable treatment method in subjects with skeletal mandibular transverse deficiency.