| Objective:To analyze the sagittal and vertical changes of profile lip position in adult female patients with different vertical facial skeletal types and bimaxillary protrusion after orthodontic treatment with teeth extraction.Studying the relationship between anterior teeth retraction and lip position changes in order to obtain the strongest dental index correlation with the change of lips and the best combination of the two variables in different groups,finally guide the clinical treatment of different patients with bimaxillary protrusion with different vertical skeletal types.Methods:59 adult female patients who have completed orthodontic treatment were selected in accordance with the inclusion criteria,collecting pre-and post-treatment lateral cephalogram.The samples were divided into three groups based on their FH-MP angle.Firstly,The XY axis coordinate system with the sella S as the origin is established by using the Geometer's Sketchpad.Secondly,20 for dental measurement index;16 for measurements index of the soft tissues;6 for measurements index of skeletal tissues.Factor analysis of variance?paired t-test?Pearson correlation tests and multiple stepwise regression analysis were used to analyze theresults of each index.To compare the changes of soft and hard tissue indexes before and after treatment in three kinds of vertical skeletal types,and to evaluate the correlation between soft and hard tissues and the changes of soft tissue of lips in different groups during orthodontic treatment.Results:Experiment 1 showed that before treatment,the differences of soft and hard tissues in the three groups,when low versus high,low versus average,high versus average,and high versus average,the angle of mentolabial sulcus,high>average>low,the difference was statistically significant.After treatment,the results showed that the low angle of FCA was larger than that of the high angle group and the average angle group,and the mental thickness of low angle group was smaller than that of the high angle group and the average angle group.The U1C thickness of low angle is thinner than that of other groups,the vertical distance of upper central incisor,high angle group>average angle group>low angle group,and the inclination of lower incisor in high angle group was greater than that in other groups and the LIC thickness and the inclination of upper incisor in high angle group was less than that in other groups.When average versus low,the thickness of the lower lip on the lower central incisor was thicker than that of the average angle,and the difference was statistically significant.Intragroup comparison showed that,U1-L1 was increased,and the other indexes related to incisor inclination and incisor protrusions were all decreased compared with those before treatment.The difference was statistically significant.The NLA was increased,the cUl thickness and the FCA were all decreased compared with those before treatment,and the difference was statistically significant.In the low angle group,the length of upper and lower lip,the angle of mandibular plane,the angle of mentolabial sulcus were increased,and the thickness of chin was decreased.Comparing the difference before and after treatment showed that the NLA,the FCA,the inclination of upper incisorand the ratraction of upper front teeth in high angle group was higher than that in other groups,and the difference was statistically significant.The change U1-L1 was high angle group>average angle group>low angle group,and the change of the cLl thicknesswas smaller in the high angle group than in the other groups.The difference was statistically significant.The change of SNB was greater in the average angle group than in the other groups,and the amount of ratraction in the lower lip and incisor was smaller in the average angle group than in the other groups.Protrusion of upper incisor,U1C thickness and the change amount of SNA in low angle group were smaller than those in other groups,the thickness of chin,the length of upper and lower lip,the change of mandibular plane angle and the ratraction of lower front teeth in the low angle group was higher than that in the other groups.The change of ANB in low angle group was larger than that in high angle group,and the difference was statistically significant.Multiple stepwise regression was used to find out that the correlation factors of upper and lower lip sagittal changes and the correlation of upper and lower lip sagittal directions were coincident in three groups(P<0.05,r>0),but the predictive factors and the regression equations related to the sagittal change of lips were different.In the low angle group and the average angle group,there was a positive correlation between the vertical change of the upper lip and the vertical change of the upper central incisor and the cervical point(P<0.05,r>0),and the positive correlation between the vertical change of the lower lip and the vertical change of the upper and lower central incisor and the vertical change of the cervical point(P<0.05,r>0).In the high angle group,vertical change of the upper lip and vertical variation of incisor points,cervical points were positively correlated(P<0.05,r>0),lower lip point vertical variation andincisor points and lower cervical point vertical variation was positively correlated(P<0.05,r>0).The predictive factors and regression equations related to vertical changes of upper and lower lip were different in the three groups.Experiment 2 showed that the crown axis of upper incisor was negatively correlated with the change of NLA.The crown axis of lower incisor was negatively correlated with the length of the lower lip.Conclusions:1.The facial profile of patients with bimaxillary protrusion was improved after teeth extraction.2.In low angle,obtains a straight face should be closely related to the mental.High angles should be paid attention to anchorage and vertical control.3.The responding changes of treatment in low angle group were upper and lower lip tension decreasing?mandible rotation clockwise and the improvement of mental shape.In the high angle group,the change is the improvement of mental shape.4.The ratio of sagittal and vertical changes of upper and lower lip and the related factors was different in bimaxillary protrusion patients with different vertical skeletal type,which suggested that before the clinical treatment for those patients,we should refer to its different predictive factors and regression equations to design different orthodontic plans.5.The crown axis of the upper and lower is closely related to the changes of the upper and lower lip soft tissue and the facial beauty of the patients,which suggested that more attention should be paid to the long axis of incisor. |
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