ABSTRACT
OBJECTIVES@#To investigate the effect of different soft-tissue morphologies on the treatment of skeletal class Ⅰ malocclusion patients by analyzing measurement data before and after treatment.@*METHODS@#Pre- and post-treatment lateral cephalograms of 55 adult female Angle class Ⅰ patients were collected in the Department of Orthodontics, Hospital of Stomatology, Jilin University from January 2012 to December 2020. Chin soft-tissue morphologies in the lateral cranial radiographs were used to divide the patients into an abnormal chin morphology group (flat and retracted chins, n=27) and a normal chin morphology group (rounded and prominent chins, n=28). Relevant soft- and hard-tissue indexes were selected to study in-group varieties and intergroup differences in the varying chin morphologies before and after treatment.@*RESULTS@#The chin-lip angle, mandibular chin angle, mandibular chin vertex angle, PP-MP, LL-E, UL-E, Po-Pos, and B-B' thickness in the abnormal chin morphology group were significantly higher than those in the normal chin morphology group (P<0.05). Furthermore, m∶BMe and n∶B'Mes in the abnormal chin morphology group were signi-ficantly lower than those in the normal chin morphology group (P<0.05). After treatment, the mandibular chin angle, mandibular chin vertex angle, U1-SN, L1-MP, LL-E, UL-E, SNA, SNB, and B-B' thickness of the abnormal chin morphology group significantly decreased (P<0.05), whereas the nasolabial angle, m∶BMe, n∶B' Mes, and Po-Pos significantly increased (P<0.05). In the normal chin morphology group, the U1-SN, L1-MP, LL-E, UL-E, and B-B' thicknesses decreased significantly (P<0.05), whereas the nasolabial angle significantly increased (P<0.05). Among them, m∶BMe and n∶B' Mes were positively correlated.@*CONCLUSIONS@#Chin morphology affects the formulation of treatment plans. Compared with the normal chin morphology group, the abnormal chin morphology group required a larger retraction of incisors. Although the chin of soft-tissue morphology is related to the morphology of bones, the changes in soft tissue chin after treatment cannot be directly predicted according to the bone changes. Soft-tissue chin morphology affects the aesthetic assessment of the soft-tissue lateral profile and the change in soft tissue before and after treatment. The method of predicting the change in soft-tissue chin after treatment should consider the morphology of the soft-tissue chin.
Subject(s)
Adult , Humans , Female , Chin , Lip , Cephalometry/methods , Esthetics, Dental , MandibleABSTRACT
BACKGROUND:Individuals with different vertical facial types have different chin morphologies. For the individuals with different vertical facial types, what is the most beautiful chin morphology? OBJECTIVE:To evaluate the effects of vertical facial types and chin morphology on facial profile attractiveness. METHODS:Three beautiful females were selected, including one with high mandibular angle, one with average angle and one with low angle. Their facial profile photographs were taken. A series of new pictures were generated by the smal scale (2 mm per unit) modification of soft tissue chin in the sagittal direction and vertical direction. Raters consisting of 17 orthodontists and 35 laypersons were selected for aesthetic ratings, in order to evaluate the facial profile attractiveness of the individuals with different vertical facial types. RESULTS AND CONCLUSION:There was no esthetic difference of vertical change in female with high angle;while slightly protrude chin was perceived to be more beautiful than retruded chin. For the female with average angle, lower chin was more attractive than higher chin;slightly protruded chin was beautiful than excessive protruded chin and retruded chin. For the individual with low angle, higher chin was preferred by raters;slightly protruded chin was more beautiful than excessive protruded chin and retruded chin.The results indicate that the effects of vertical facial types and chin morphology to facial profile attractiveness are different. In clinical orthodontic, vertical facial types should be taking into consideration to change the chin morphology of the patents, in order to obtain better profile attractiveness.
ABSTRACT
This study was undertaken to investigate the difference of chin morphology and mandibular form in relation to different mandibular growth direction. The subject was divided into three group i.e., control group, vertical group, and horizontal group, according to the criteria of Bjork sum, and each group was composed of 15 females and 15 males. Medial axis analysis in addition to the routine cephalometric analysis using P.I.A.S. (personal image analysing system) was carried out to find out the differences of mandibular morphology on each group. The results were as follows: 1. The area of symphysis was larger in horizontal growth group than that of vertical growth group. 2. Protruding chin area was also larger in horizontal growth group than that of vertical growth group. 3. There was a close correlationship between protruding chin area and other form of mandible. 4. Antegonial notch depth and ramus posterior contour depth was deeper in vertical growth group than in horizontal growth group, and antegonial notch depth was more influenced by anterior part of notch than posterior part of notch. 5. Mental medial axis and incisal medial axis length, in relation to corpus medial axis length was larger in vertical growth group than in horizontal growth group.