RESUMO
Objective@#The aim of this study was to investigate the effect of changes in nasal tip protrusion on the sense of upper lip protrusion in different populations and to provide a reference for the improvement of soft tissue beauty.@*Methods @# Informed consent and portrait authorization were obtained from the model. A female model whose face met the criteria was selected, and a 3D model of her was obtained using a 3D stereo camera. Based on the original model, ZBRUSH2019 software was used to simulate changes in nose tip protrusion. Then, 9 segments of facial dynamic rotation videos were produced, and an electronic questionnaire was created through a questionnaire website to evaluate the effect of different nose tip protrusions on perceived upper lip protrusion. Randomly selected orthodontic patients, orthodontics professionals and general adults completed the electronic questionnaire. In the questionnaire, a Visual Analog Scale was used to evaluate the perceived degree of protrusion of the upper lip. The higher the score, the more prominent the upper lip of the model in the image. The questionnaire data were statistically analyzed using a generalized linear mixed model. @*Results @#As the nasal tip position became progressively more retracted, the subjects' upper lip protrusion scores increased. Among male subjects, the results showed that the general population thought that the upper lip protrusion was higher than the patients did when the nasal tip protrusion was +6 mm and +4.5 mm (P = 0.023, P = 0.047). When the nasal tip protrusion was +6 mm, the scores of the general population were higher than those of the orthodontics professionals (P = 0.023). However, when the nasal tip variable was -6 mm, their score was lower than that of the patients (P = 0.003), and there was no significant difference in other retest distances between groups (P>0.05).@*Conclusion @#When the protrusion of the nasal tip decreased, the three groups experienced a visual illusion of upper lip protrusion. When the nasal tip protrusion is too large, the general population perceived the visual illusion of the upper lip protrusion as being more obvious.
RESUMO
Objective@# The present study evaluated the clinical effects of Invisalign-aided molar distalization in the treatment of mild or moderate crowding in anterior teeth. @*Methods@#Eleven adults with class Ⅱ dental malocclusion and a class Ⅰ skeletal pattern were selected as subjects. The patients’ molar occlusion did not exhibit an end-to-end relationship. Subjects were selected for straight profile, mild or moderate crowding in maxillary teeth and normal or mild crowding in mandibular teeth. Nonextraction and Invisalign-aided molar distalization were planned for treatment. Model measurement and cephalometric analysis were performed before and after treatment. A paired t test was used for the statistical analysis.@*Results@#The crowding and class Ⅱ molar relationship were corrected in all 11 patients. The upper first molars were moved distally by 2.32 mm (t = 3.315, P < 0.01) and were inclined distally by 3.35° (t = 3.959, P < 0.01) on average. The central incisors were protruded by 1.72 ° (t = 3.274, P < 0.01) on average. The buccal movement of the upper first molars was 1.32 mm (t = 2.461, P < 0.05) on average. The above differences were statistically significant. @*Conclusion @#Upper molar distalization can be achieved using a class Ⅱ elastic-aided Invisalign technique. The end-to-end molar occlusion can be corrected, and front teeth with mild or moderate crowding can be aligned using our treatment protocol.