The Clinical Study Of Molar Distalization By Mini-implant And Sectional Arch Wire Technique

Objective:To evaluate the treatment effects of mini-implant anchorage and sectional arch wire technique and to confirm the clinical usage of the application compared with molar distalization appliance in molar distalization used in Angle classⅡand Angle classⅢcases. To provide theoretical basis for orthodontic clinical research.Methods:47 patients were divided into fourgroups according to age and the malocclusion. GroupⅠ,12 patients(ages,12-14 years) with Angle classⅡmalocclusion and anterior crowding were selected on a nonextraction basis. Then mini-implant anchorage and sectional arch wire technique were used to push maxillary molar distalization. GroupⅡ,16 adult patients(ages,18-32 years,10 were reorthodontic patients) with ClassⅡDivision 1 malocclusion were selected. After the second or third maxillary molars were extracted, mini-implant anchorage and sectional arch wire technique were used for maxillary molar distalization. GroupⅢ,6 patients (ages,12-26 years) of Angle classⅢsubdivision malocclusion were selected. After the mandibular third molars were extracted, mini-implant anchorage and sectional arch wire technique were used to push unilateral mandibular molars disterlization. GroupⅣ,13 Patients(ages,10-13.5 years) with Angle classⅡmalocclusion were selected. They were treated with maxillary molar distalization appliance for maxillary molar distalization. Lateral cephalometric radiographs were used to assess the alteration of molar position and craniofacial hard tissue relationship before and after molar distalization for all the groups.Results:All the mini-implants were stable in groupⅠ-Ⅲ. In groupⅠ, maxillary molars were moved to the distal by 4.27±0.36 mm (P<0.05). The average distances of molar distalization were 1.12±0.12 mm per month. There were no significant difference in SNA,SNB,ANB,U1-NA mm,U1-NA,U1-L1,U1-SN,MP-SN.FH-MP,L6-MP mm and U6-PP mm before and after treatment. (P>0.05).In groupⅡ, maxillary molars were moved to the distal by 4.80±0.30 mm. The average distances of molar distalization were 0.81±0.10 mm per month. There were no significant difference in ANB,SNA,SNB,U6-PP mm,L6-MP mm,FH-MP and SN-MP before and after treatment. (P>0.05). While U1-NA mm,U1-NA,L1-NB mm,L1-NB,U1-SN and L1-MP were statistically significant (P<0.05). In groupⅢ. unilateral mandibular molars were moved to the distal by 3.24±0.25 mm. The average distances of molar distalization were 0.72±0.14 mm per month. There were no significant difference in SNA,SNB,ANB,U1-NA mm,U1-NA,FH-MP and SN-MP before and after treatment. (P>0.05). But L1-NB mm,L1-NB and L1-MP were statistically significant (P<0.05). In groupⅣ, maxillary molars were moved to the distal by 4.67±0.35 mm (P<0.05). The average distances of molar distalization were 1.40±0.14 mm per month. No significant difference was observed in SNA,SNB,ANB,MP-SN,FH-MP and L6-MP(P>0.05) before and after treatment. However, there were significant differences in U1-NA mm,U1-NA.U1-L1,U1-SN and U6-PP mm (P<0.05).Conclusion:Mini-implant anchorage and sectional arch wire technique provide effective molar distalization. Compared with molar distalization appliance, the appliance can reduce or avoid insior proclination. The sectional arch wire can avoid the alternate motion of anterior teeth because of stress break. Also, it can simplify the treatment process and provide more reliable treatment effects. By using it, the force can be better controlled and it can avoid offsetting a variety of intertwined and mutual forces. In this study, the segmental arch wire was 0.46 mm×0.64 mm stainless steel rectangular wire. Various types of loop can be bent on the arch wires,. and adjust the movement of molars in three dimensions. Also, it is very convenient to apply force and reduce the chair side time. Mini-implant anchorage and sectional arch wire technique distalize molars effectively influencing maxillofacial skeletal structure little. The application expands the sutable region of non-extraction othodontic treatment.