The Evaluation Of Long-term Therapeutic Effects Of Using Protraction Facemask And Straight Wire Appliance In The Treatment Of Skeletal Class Ⅲ Malocclusion

Objective:The purpose of this study was to evaluate hard and soft tissure changes and long-term stability of using protraction facemask and straight wire appliance in the treatment of skeletal Class Ⅲ Malocclusion.The results of this study can help provide theoretical basis for choosing appropriate treatmet plan and treatment time.Methods:The 67 skeletal Class Ⅲ patients treated with protraction facemask and straight wire appliance at the Department of Orthodontics,School and Hospital of Stomatology,Jilin University between 2005 and 2010 were included.34 patients were followed up,including 15 male patients and 19 female patients.The range of age before treatment was 7 to 12 years old with an average age of 9.89±1.41 years old.Lateral cephalometric radiographs before protraction facemask treatment(T1),after straight wire appliance treatment(T2)and follow-up(T3)were measured to quantify the hard and soft tissue changes.SPSS22.0 software package was used for statistical analysis.Paired t-test was used to compare the differences between T1 and T2,also T2 and T3.Result:1、After straight wire appliance treatment,SNA,ANS-Ptm,NA-PA and A-NP(mm)increased significantly.Co-Pog(mm)and Pog to NB(mm)increased significantly too.SN-PP,FH-PP,SN-OP and FH-OP reduced significantly.U 1-SN,U1-PP,U1-NA and U1-NA(mm)increased significantly.There were not difference in others.2、After straight wire appliance treatment,UL-SnP’ and A-A’(mm)increased significantly and facial profile was improved.3、Compared with the condition just after treatment,the long-term follow-up,ANB increased but there was no difference.Ar-Go(mm),Co-Pog(mm),Pog to NB(mm),ANS-Ptm(mm),S-Go(mm),N-ANS(mm),N-Me(mm),ANS-Me(mm)and S-Go/N-Me increased significantly.L1-MP,L1-NB,L1-NB(mm)increased.NA-PA and A-NP(mm)reduced.Overjet and overbite reduced.Upper Lip to E-Plane(mm)reduced significantly.Conclusion:1、The method of protraction facemask therapy combined with straight wire appliance was effective for the treatment of skeletal Class Ⅲmalocclusion with skeletal and dental effects.Both facial profile and occlusal relation were improved.2、At the long-term follow-up,occlusal relation and overjet tented to recur,but without prominent difference.The long-term stability was connected with the growth of mandible and the inclination of mandibular anterior teeth.3、Treatment time,moderate overtreatment and the stable occlusal relation after straight wire appliance were determinant factors to long-term effects.