| Objective:To respectively evaluate the effects of maxillary protraction alone or combined with alternating rapid maxillary expansion and constriction(Alt-RAMEC)in treating early skeletal Class III malocclusion.To compare the effects of maxillary protraction alone or combined with Alt-RAMEC,in order to provide reference for clinical applications.Method:According to the inclusion criteria,20 patients were selected,with an average age of 10.16±1.46 years old.The patients were randomly divided into two groups.Group A used maxillary protraction alone.Group B received maxillary protraction with Alt-RAMEC,while using the same method of maxillary protraction as which in group A,the maxilla was expanded twice a day for 1 week(once respectively in the morning and evening,0.5mm per day),then it was contracted twice a day for 1 week(once respectively in the morning and evening,0.5mm per day),repeating alternating protocol,until the end of the treatment.The treatment completion criterion was a class I or class II molar relationship with a positive overjet of 3mm.The lateral cephalometric X-ray ware taken for all the patients before and after the treatment,and Pancherz,common and Wits analysis were used,which were measured by the researcher himself.Using SPSS 22.0 software for statistical analysis of data.Comparing the age,bone age,and common measurement items of patients in two groups before treatment by the independent t-test,to evaluate the consistency of growth and development status and malocclusion degree between the two groups before treatment.The paired t-test was performed on measurement items of each group of patients before and after treatment,to respectively evaluate the efficacy of the two methods.The independent t-test was performed on the changed value of each measurement item before and after treatment,and the treatment course of two groups,comparing whether difference exist between the two methods.Result:1.The consistency of growth and development status and malocclusion degree before treatment in the two groups:There was no significant difference in the age and bone age before treatment between groups A and B(P>0.05).The common measurement items before treatment in the two groups showed no significant differences(P>0.05),except for the U1/NSL.Growth and development status and malocclusion degree of patients were consistent.2.The treatment course of two groups of patients:The average treatment course was 8.59±13.44 months in group A and 5.78±0.97 months in group B.The treatment course of group B was significantly shorter than that of group A(P<0.05).3.The changes before and after treatment in each group of patients:Group A:The jaw,teeth and soft tissue profile changed significantly after treatment.The SNA angle and A/OLP value were significantly increased,and the PP/NSL was decreased slightly,indicating that the maxillary moved forward with counterclockwise rotation.The SNB angle was decreased and ML/NSL angle was increased significantly,indicating that the mandible rotated backward and downward.The ANS/Me value was significantly increased,indicating that the anterior-posterior heights increased.The ANB angle and Wits value were significantly increased,indicating that the sagittal relationship between maxilla and mandible was significantly improved.The U1/NSL angle and Is/OLP-A/OLP value were increased significantly,the L1/ML angle and Ii/OLP-Pg/OLP value were decreased significantly.The overjet and molar relationship were corrected.The soft tissue profile improved significantly.Group B:After treatment,the variation tendency of jaw and soft tissue profiles were similar to those in group A,but the changes in teeth were quite different.There were no significant changes in the U1/NSL angle and Is/OLP-A/OLP value,only the Ll/ML angle showed significantly decreased.The overjet and molar relationship received correction.4.The efficacy of two groups before and after treatment:The difference of measurement items between the two groups before and after treatment showed that Is/OLP,Is/OLP-A/OLP,Mic/ML,ANS/Me value and Ul/NSL angle all increased after treatment,and the change of group A was more significant than that of group B(P<0.05).The OL/NSL angle of group A decreased while increasing in the group B,and the difference between the two groups was significant(P<0.05).The Msc/PP value of group A increased,which decreased in group B,and the difference between the two groups was significant(P<0.05).There is no significant difference in the rest measurement items except which are mentioned above.5.The proportion of dental or bony effects in each group:Correction of overjet is a combination of bony and dental effects.The proportion of skeletal effects reached 54.3%in group A,and the proportion of dental effects was 45.6%.Meanwhile,the proportion of skeletal effects in group B attended 82.4%,and the proportion of dental effects was 17.6%.The proportion of skeletal effects in group B was significantly greater than that of group A,and the proportion of dental effects was significantly reduced.Conclusion:1.The treatment course of maxillary protraction combined with Alt-RAMEC was significantly shorter than that of maxillary protraction alone.2.Maxillary protraction alone or combined with Alt-RAMEC both can effectively treat patients with early skeletal class III malocclusion.3.Compared with maxillary protraction alone,the proportion of the skeletal effects of maxillary protraction with Alt-RAMEC increases significantly,while the proportion of dental effects decreases. |
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