The Efficacy Evaluation Of Maxillary Protraction Therapy On Class Ⅲ Malocclusion With Two Different Methods Of Rapid Maxillary Expansion

Objective:To evaluate the clinical efficacy of rapid maxillary expansion(RME)and Alternate Rapid Maxillary Expansion and Constriction(Alt-RAMEC)combined with maxillary protraction in the treatment of skeletal class Ⅲ malocclusion.The treatment effects of the two methods provide a reference for future clinical work.Methods:A total of 40 patients with skeletal Class Ⅲ malocclusion(15 males and 25females)were selected,with an average age of(10.11±0.88)years old.All patients were randomly divided into RME group and Alt-RAMEC group.In the RME group,the expansion screw were opened in a circle every morning and evening,each circle was 0.25 mm,and the expansion was continuous opened for 2 weeks,with a total expansion of 7mm.After finishing the expansion,the maxillary protraction is carried out.In the Alt-RAMEC group,the expansion screw was rotated once in the morning and evening,each circle was 0.25 mm.In the first week,the expansion device was used to expand 0.5mm per day.In the second week,the expansion device was used to close 0.5mm per day.In the following time,the screw was opened for 1 week,then the screw was closed for 1 week,open and close for 3 circles,then the screw was opened for two weeks,with a total expansion of 7mm.Then maxillary expansion combined with maxillary protraction.The completion criterion is a positive overjet.All patients took lateral cephalometric before and after correction.Using SPSS26.0software to evaluate the clinical efficacy of the two treatment methods and compare whether there are differences between the two methods.Results:1.The maxillary protraction time and total treatment time of the two groups: the maxillary protraction time of the patients in the RME and the Alt-RAMEC group were(9.60±0.84)months and(8.45±0.58)months respectively.The difference was statistically significant(P<0.05).The total time of treatment was(10.10±0.83)months and(9.95±0.58)months,respectively.There was no significant difference in the total treatment time between the two groups(P>0.05).2.The development of the two groups: the average age of the patients in the RME and the Alt-RAMEC group was(10.18±0.95)years old and(10.04±0.81)years old;the average bone age of the two groups was(1.9±0.72)and(2.1±0.64).There was no statistically significant difference(P>0.05).The development condition was consistent.3.The malocclusion degree: there was no statistically significant difference(P>0.05).The malocclusion degree was consistent.4.The changes in the Alt-RAMEC group: SNA,A-Y,A-X values increased,and the difference was statistically significant(P<0.01).The maxillary moved significantly forward and downward.SN/PP decreased,the difference was statistically significant(P<0.01),and the palatal plane rotates counterclockwise.SNB and B-Y decreased,the difference was statistically significant(P<0.01),indicating that the mandible moved backward.SN/MP increased,the difference was statistically significant(P<0.01),and the mandible rotated clockwise.The ANB value increased,the difference was statistically significant(P<0.01),and the bone relationship was significantly improved.U1-SN,U1-X,U1-Y,U6-X and U6-Y values increased,and the difference was statistically significant(P<0.01),indicating that the protrusion of maxillary incisors and the first molar moved forward;the LI-Y value decreased,and the difference was statistically significant(P<0.05).The soft tissue face angle,NLA and CLA decreased,FCA increased,the difference was statistically significant(P<0.05).5.The changes in the RME group: The bone and soft tissue changes were similar to the Alt-RAMEC group.The maxillary is moved forward,and the mandible moves backward with counterclockwise rotation;protrusion of the maxillary incisor and the maxillary first molar moved forward;the soft tissue profile improved..6.Comparison of the efficacy of two groups: the SNA value of the Alt-RAMEC and RME group increased by 3.25°and 2.32° respectively,and the difference was statistically significant(P<0.05).The change of A-Y value in the Alt-RAMEC group was significantly greater than in the RME group,and the difference was statistically significant(P<0.05).The ANB value increased by 4.82° and 3.34°respectively,and the difference was statistically significant(P<0.01).The U1-SN values of the two groups increased,and the change value of the RME group was greater than the Alt-RAMEC group,the difference was statistically significant(P<0.05).There is no significant difference in the other measurement items.Conclusion:RME or Alt-RAMEC combined with maxillary protraction can effectively treat the skeletal class Ⅲ malocclusion of maxillary deficiency.The total course of treatment in the Alt-RAMEC group is not significant compared with the RME group.The effect of Alt-RAMEC combined with maxillary protraction on skeletal class Ⅲ malocclusion is better than the RME.