| Objective:In this study,four first premolars were extracted from adult female patients with bimaxillary protrusion for orthodontic treatment.Lateral cranial radiographs and frontal photographs were measured before and after treatment to analyze the changes in the position of incisors and the height and area of upper and lower lips before and after orthodontic treatment.In addition,the correlation between the position change of incisor and the change of lip soft tissue after tooth extraction treatment was analyzed to provide clinical reference for the development of orthodontic treatment for patients with bimaxillary protrusion.Methods:In this study,37 adult female patients(age range: 18-33 years old,with an average age of 25.3 ± 5.3 years old)with bimaxillary protrusion who were treated in orthodontic department of School of Stomatology,Shanxi Medical University from 2016 to 2019 were selected.All subjects selected in this study met the inclusion criteria,and tooth extraction was adopted for the orthodontic program,in which four first premolars were extracted for orthodontic treatment.Straight-wire fixed appliance(Ormoca Damon Q)was used,and implant anchorage was used as an enhanced anchorage to adduct the upper and lower incisors.The extraction space was closed.The orthodontic course was24.3±2.3 months.Lateral cranial radiographs and front photographs were shot and then measured and analyzed before and after treatment for each patient.19 indexes incephalometrics were measured including 12 indexes of tooth tissue and 7 indexes of soft tissue.16 indexes in front digital photographs including 14 indexes of the height of the upper and lower lips and 2 indexes of the area of the upper and lower lips.Results:1.Changes of indexes in cephalometrics before and after orthodontics.The result after treatment comparing to that before tooth extraction treatment to adult female patients with bimaxillary protrusion showed the dental indexes: Y-t U1,Y-c U1,Y-t L1,Y-c U1,?U1-SN,?L1-MP decreased.The differences were statistically significant.X-t U1 and X-c U1 increased compared with that before treatment.Soft tissue indexes Y-UL and Y-LL decreased.Nasolabial angle(NLA)increased.The differences were statistically significant.Sn-St distance increased.There was no significant statistical difference in other items measured.2.Changes of indexes in front lips before and after orthodontics.The height of upper and lower lips decreased compared with that before tooth extraction for treatment to adult female patients with bimaxillary protrusion.The area of upper and lower lips decreased after orthodontics.3.Analysis of correlation between changes of position of upper and lower incisors and indexes of lips after orthodontics.Pearson correlation analysis was conducted between indexes of the upper and lower incisors and the height and area of the upper and lower lips,which showed that there was a weak correlation between changes of incisors retraction and the lateral margin height of individual upper lips.There was a weak correlation between incisors retraction and Up7-15,Up9-17,Up8-16,Up12-20.There was more close correlation between changes of incisors retraction and the changes of the height of lower lips.There was a high correlation between incisors retraction and Lo18-25.There was a weak correlation between incisors retraction andLo17-24,Lo19-26,Lo16-23,Lo20-27,Lo21-28.Conclusion:1.After the extraction of the four first premolars for bimaxillary protrusion of an adult female,the retraction of the upper and lower incisors was obvious.2.After the extraction of the four first premolars for bimaxillary protrusion of an adult female.The upper and lower lips were adducted,and the face shape was improved significantly.3.After the extraction of the four first premolars for bimaxillary protrusion of an adult female.The frontal lip height and the upper and lower lip area were reduced significantly,which suggested that the treatment of tooth extraction to patients with imaxillary protrusion was beneficial to the improvement of facial shape.4.The change of incisor position had less correlation with the change of upper lip height and more correlation with the change of lower lip height. |
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