A Comparison And Correlation Study Of Soft And Hard Tissues Changes In Adult And Adolescent Angle Class Ⅱ, Division2Malocclusion After Orthodontics Treatment

Objective The purpose of this study was to compare the changes of soft and hard tissues and to analyze the correlation of them in adult and adolescent Angle Class II,Division2malocclusion after orthodontic treatment.Method45patients with Angle Class Ⅱ, Division2malocclusion were selected(21adults and24adolescents). They were all treated with the fixed appliance, and some of them needed the combination of plane plate,rocking chair archwire and class II elastics to improve occlusal relationship.Lateral cephalometric radiographs were used to quantify the skeletal,dental and soft tissue changes before and after treatment.All data were analyzed by SPSS13.0software.Results (1) In adolescent group,many indicators changed obviously after treatment. The length of maxillary and mandible increased and the mandibular position moved forward.Anterior facial height and posterior facial height were all increased, and the anterior lower facial height increased obviously. The MP-FH, MP-SN increased significantly and the mandibular plane rotated clockwise. Point B and Po moved forward. The upper and lower incisors labial inclined significantly, OB decreased and OJ increased. The prominence of profile improved and the upper lip length increased.The lower lip length and chin-lip height increased obviously, chin-labial curve shallowed. The thickness of upper and lower lip decreased significantly.(2) The adult group changed less than adolescents group.Mandibular moved forward and rotated clockwise,Anterior facial height and anterior lower facial height increased. The upper and lower incisor inclined labially significantly, OB decreased and OJ increased.With the soft tissue, the changes were similar to but not significant as adolesecent group.(3) Compared with adult group,most changes of soft and hard tissues were more obvious in adolescent group,such as SNB, ANB, NA-PA, MP-SN, MP-FH, ANS-Me, N-Me, ANS-Me/N-Me et al.But the dental compensation was more obvious in adult group.(4) There were obvious correlations between the changes of soft and hard tissues in two groups.But the correlations were very different between the two groups.The correlation of upper lip index on the changes of hard and soft tissues was similar and lower lip index was significantly different between the two groups.Conclusion (1) In adolescent group,many hard tissue index changed more significantly than adult group. But the dental compensation was more obvious in adult group.Early treatment could release the restriction from upper incisors and promote mandibular growth.The upper lip index showed no significant difference, while the lower lip index between two groups was different obviously. The soft tissue profile of adult group improved less than adolescent group.(2)There were significant correlations between soft and hard tissues changes in two groups,but the correlations were very different between the two groups.Treatment in the adolescent period could not only alter hard tissue, but also remodel soft tissue, make soft and hard tissues more coordinated,so as to improve the profile.(3) For Class II,Division2patients,early treatment was beneficial to release the restriction from upper incisors, guide the mandibular growth to normal direction, coordinate the relation between maxillary and mandible and improve soft tissue profile and the shape of lower lip, so as to get harmonious and beautiful appearance.