Application of Maxillary Protraction Combined with FRⅢ Appliance in Children with Skeletal Class Ⅲ Malocclusion in Mixed Dentition
Objective To investigate the application effects of maxillary protraction combined with FRⅢ appliance on children with skeletal Class Ⅲ malocclusion in mixed dentition.Methods 92 children with skeletal Class Ⅲ malocclusion who were treated in the author's hospital from December 2019 to June 2021 were selected as the research subjects.According to the correction methods,the children only with maxillary protraction were selected as traction group(n=43),and the children treated with maxillary protraction combined with FRⅢ appliance were included in combined group(n=49).The maxillofacial hard tissue indexes,soft tissue indexes,dental indexes and hyoid bone position of the two groups of children were observed before treatment and after 1 year of treatment.Results After treatment,the sella-nasion-point A(SNA)angle,sella-nasion-point B(SNB)angle,point A-nasion-point B(ANB)angle,maxillary position(A-OLP),mandibular position(Pg-OLP),angle formed with the mandibular plane and the extension line of sella-nasion line(SN)(MP-SN),angle formed with frankfort horizontal plane(FH)(MP-FH),and intersection angle of Y axis and FH plane(Y-axis angle)in both groups were improved compared with those before treatment,and the improvements in combined group were better than those in traction group(P＜0.05).After treatment,the distance from the prominence of the lower lip to the esthetic plane(LL-EP),angle between the lower nasal point,the columellar point and the lower nasal point and the upper lip protrusion point(NLA)and facial convex angle(G-Sn-Pg)were improved in the two groups compared to before treatment,and the improvement status group were better in combined group(all P＜0.05).After treatment,the angle between the long axis of the upper central incisor,the nasal root point and the upper alveolar point(U1-NA),the vertical distance(overlap)of the upper and lower central incisors,and the projection distance(overlap)of the upper and lower central incisors in the two groups were also improved compared with those before treatment,and the improvement status were better in combined group than traction group(all P＜0.05).After treatment,the distance from hyoid anterior superior point H to Y axis(H-Y)and the distance from H to X axis(H-X)in both groups were prolonged compared with those before treatment,and the distances of combined group were longer than those in traction group(all P＜0.05).There were no statistical differences in the distance from H to mandibular plane(H-MP)and the distance from H to FH(H-FH)between the two groups(P＞0.05).Conclusion The combination of maxillary protraction and FRⅢ appliance in children with skeletal Class Ⅲ malocclusion can effectively improve the occlusal relationship and concave profile of children,and promote the normal recovery of position of hyoid bone.
maxillary protractionFRⅢ appliancemixed dentitionskeletal Class Ⅲ malocclusionsoft and hard tissues
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