Study Of Soft And Hard Tissue Changes In Adult With Bimaxillary Dentoalveolar Protrusion Following Treatment With PASS Technique

Objective:The aim of this study was to explore the changes of soft and hard tissues in adult patients with bimaxillary dentoalveolar protrusion treated by PASS,to provide basis for clinical analysis of bimaxillary dentoalveolar protrusion,prediction of curative effect after correction and selection of more efficient and faster correction techniques.Methods:The retrospective study included 32 patients with bimaxillary dentoalveolar protrusion who met the inclusion criteria in the orthodontic outpatient department of the Fifth Affiliated Hospital of Xin jiang medical university,from 2015 to 2017.All the patients were treated with extraction.After the removal of four first premolars and treated by PASS technique.The 29 soft and hard tissue indexes before and after treatment were compared and were evaluated by paired t-test.Results:The changes of hard tissue indexes in adult patients with bimaxillary dentoalveolar protrusion after treatment:SNA,ANB,SN-MP,FH-MP,Yaxis NA-PA,AO-BO angle were reduced compared with those before treatment,but the difference was not statistically significant(P>0.05).SNB,NP-FH,Pog-NB increased compared with before treatment,and the difference was statistically significant(P<0.05).U1-NA angle and distance,U1-SN,L1-NB angle and distance,L1-MP,FH-MP were significantly reduced compared with those before treatment,and the difference was statistically significant(P<0.05).U1-LI increased compared with before treatment,and the difference was statistically significant(P<0.05).The changes of soft tissue before and after treatment:NLA,Ls-Sn-Pos,Li-Sn-Pos,Ls-E,Li-E,H-angle decreased significantly after treatment,and the difference was statistically significant(P<0.05).Po-Pos,Chinlip groove thickness,upper lip thickness,lower lip thickness decreased,but there was no statistical difference(P>0.05).Ns-Sn-Pos,Z-Angle increased compared with before treatment,and the difference was statistically significant(P < 0.05).Conclusion:The soft and hard tissue profile of patients with bimaxillary dentoalveolar protrusion can be significantly improved by using PASS technique after tooth extraction,Good occlusion and soft tissue profile were obtained.