| Objectives1.To evaluate long-term stability of orthognathic and orthodontic treatment over skeletal Class II malocclusion without idiopathic condylar resorption;2.To clarify skeletal,dental and soft tissue change tendencies during the follow-up;3.To analyze factors correlated with negative post-treatment changes;4.To illustrate changes of tempromandibular joint internal structures after orthognatic and orthodontic treatment and changes during follow-up;5.To analyze influence of pre-treatment disc-condyle relationship on mandibular advancement in patients without idiopathic condylar resorption.Methods1.Inclusion criteria was set to include skeletal Class II patients without idiopathic condylar resorption who received orthognatic and orthodontic treatment in Center of Craniofacial Orthodontics,Shanghai Ninth People's Hospital from Jan.2001 to Dec.2015.37 patients were included,7male and 30 female with TO ANB(°):9.04±2.21,TO OJ(mm):8.17±2.75,age at surgery(yr.):25.95±5.82 and length of follow-up(yr.):6.76±3.06;2.Measurements and analysis of parameters were performed on X-ray lateral cephalometric radiographs and TMJ MR images,Dahlberg's formula was used to check method error;3.Patients were grouped according to B point positional change in sagittal direction during the follow-up.In Group 1,the change was less than 2mm;in Group 2,the change was more than 2mm;4.Patients were grouped according to pre-treatment degree of disc displacement,-10 degrees to+10 degrees as normal disc position,+11 degrees to+50 degrees as disc position of slight to mild displacement,more than 51 degrees as disc position of moderate to severe displacement;5.Mann-Whitney test,Krusal-Wallis test and Pearson correlation analysis were performed;a P value less than 0.05 was considered significant.Results1.Significant differences that the mandible moved backward in sagittal direction and proclination of lower incisors increased were found during follow-up.At B point,mean value of forward movement after treatment was 5.88mm and then moved posteriorly during follow-up with a mean value of 0.81mm;change percentage was 13.78%.At Pog point,mean value of forward movement after treatment was 8.10mm and then moved posteriorly during follow-up with a mean value of 1.32mm;change percentage was 16.30%;At Gn point,mean value of forward movement after treatment was 7.91mm and then moved posteriorly during follow-up with a mean value of 0.89mm;change percentage was 11.25%;2.Proclinati on of lower incisors after treatment,positional change of Co point in sagittal direction after treatment,change of mandibular plane during follow-up and positional change of the maxilla in vertical direction showed significant differences between Group 1 and Group 2.Correlation analysis further verified that increase of lower incisors proclinati on,Co point backward movement after treatment and follow-up change of mandibular plane might correlate with B point backward movement;3.Posterosuperior space of TMJ decreased after orthognathic and orthodontic treatment and the condyle displaced to the concentric position during follow-up;among groups of normal disc position,slight to mild disc displacement,severe disc displacement,there was no significant difference of condylar movement;4.In the group of normal pre-treatment disc position,the disc length decreased and displaced more anteriorly during follow-up;in the group of light to mild and severe pre-treatment disc displacement,change of disc length and disc displacement degree showed no significant difference;5.There existed no significant correlation between pre-treatment disc displacement angle and follow-up B point positional change.Conclusions1.Skeletal deformity was corrected by orthognathic and orthodontic treatment among patients of skeletal Class II malocclusion without idiopathic condylar resorption.Skeletal class II relationship turned to class I relationship and the outcome was stable during follow-up.No significant follow-up tendency of skeletal relapse emerged in the research;2.Increase of lower incisors proclination after treatment,Co point backward movement after treatment and follow-up change of mandibular plane might correlate with mandibular backward movement.3.Posterosuperior space of TMJ decreased after orthognathic and orthodontic treatment and the condyle displaced to the concentric position during follow-up;in the group of normal pre-treatment disc position,the disc length decreased and displaced more anteriorly during follow-up;in the group of light to mild and severe pre-treatment disc displacement,change of disc length and disc displacement degree showed no significant difference;4.No significant correlation existed between the severity of pre-treatment disc displacement and follow-up mandibular positional change. |
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