Analysis Of Mandibular Soft And Hard Tissue Changes In Patients With Skeletal Class ? Treated By Surgery-first Approach

Objective:To explore the mandible stability and relationship between soft and hard tissue before and after operation in patients with skeletal Class III treated by Surgery-First Approach.Methods:Twenty patients with skeletal class?underwent SFA were selected from nearly five years in the department of orthodontic,the affiliated hospital of Qingdao university.All of the patients treated by SFA,which included Lefort I and BSSRO,without Geniuplasty.The lateral cephalometric radiographs were taken before surgery?T₀?,one month after surgery?T₁?and at finish of treatment?T₂?.The changes of SNA,SNB,ANB,point A,B,ANS,Pog,Me,UIE and LIE in the horizontal direction were measured during the period of T₀ and T₂.The changes of hard tissue were analyzed before and after treatment with paired t-test.The changes of Ns-Pn-Pog',Ns-Sn-Pog',point Pn,Sn,Ls,Li,Si,Pog',Me'in the horizontal direction were measured during the period of T₀ and T_2.The changes of soft tissue were analyzed before and after treatment with paired t-test.The ratio of changes of hard tissue and corresponding soft tissue markers in T₀ and T₂ phases was calculated,and the correlation between soft tissue and hard tissue was analyzed by Pearson correlation coefficient.Point ANS corresponds to Pn,A corresponds to Sn,UIE corresponds to Ls,LIE corresponds to Li,B corresponds to Si,Pog corresponds to Pog',Me corresponds to Me'.The changes of B,LIE,Pog and Me points in mandible were measured horizontally during T₁ and T₂ phases,and the stability of mandible after operation was analyzed.Results:During the period of T₀ and T₂,ANS,A and UIE of maxillary hard tissue moved forward 0.28 mm,0.83 mm and 4.08 mm respectively.Point ANS has no statistical significance?P>0.05?.Point A and UIE have statistical significance?P<0.05?.LIE,B,Pog and Me of mandibular hard tissue retreated 2.29 mm,6.13 mm,5.39 mm and 6.38 mm respectively,whicn all have significant statistical significance?P<0.001?.During the period of T₀ and T₂,point Pn,Sn,Ls of maxillary soft tissue moved forward 0.35 mm,0.26 mm and 2.05 mm respectively.Point Pn and Sn have no statistical significance?P>0.05?.Point Ls has statistical significance?P<0.05?.Li,Si,Pog'and Me'of mandibular soft tissue retreated 2.62 mm,4.12 mm,2.86 mm and 2.88 mm respectively,whicn all have statistical significance?P<0.05?.The correlation coefficients r of ANS-Pn and A-Sn were 0.30 and 0.23,which have no correlation.UIE-Ls was 0.62,which has significant correlation.The coefficients of LIE-Li?B-Si?Pog-Pog'?Me-Me'were 0.82,0.83,0.90,0.92 respectively,which have highly significant correlation.During the period of T₁and T₂,the mandibular hard tissue moved forward.Point B,LIE,Pog and Me moved forward 1.63mm,0.60 mm,1.55 mm and 1.60 mm respectively.The recurrence rates were 26.2%,25.7%,29.4%and 24.8%respectively.Conclusion:After SFA treatment,the facial soft and hard tissues of patients with skeletal III improved significantly,and the correlation between soft and hard tissues increased gradually from point Pn to Me'.From the end of operation to the end of treatment,mandible recurrence occurred horizontally,but the degree of recurrence was less than 30%,which within acceptable range,and reserve should be considered in the design of operation.