| Objective: To compare the changes of root length and alveolar bone morphology in maxillary bilateral canine region of adult skeletal class II malocclusion patients after extraction and unconventional extraction of upper anterior teeth,so as to provide an effective reference for safe and effective tooth movement during orthodontic treatment.Materials and Methods: Thirty patients who completed orthodontic treatment in the Department of Orthodontics,Dalian Stomatology Hospital Affiliated of Dalian Medical University were selected.Among them,15 patients were treated with extraction(3males and 12 females,with an average age of 21.55 ± 2.82),and 15 patients were treated with unconventional extraction(7 males and 8 females,with an average age of20.48±2.64).Root length,alveolar bone thickness,height,the amount of rotation and distance of canine roots were measured before and after orthodontic treatment.All subjects were scanned by CBCT(Cone-Beam Computed Tomography)using the computer cone-beam tomography system produced by Ka Vo Company.The three-dimensional data of DICOM were reconstructed by Invivo Dental 5 software to obtain the sagittal and coronal measurement planes required for the experiment.The measurement items included the length of the root,the height of the alveolar bone on the labial and palatal sides,the thickness of the alveolar bone on the labial and palatal sides,the amount of rotation and distance of canine roots were measured before and after orthodontic treatment.SPSS 23.0 statistical software was used to analyze the experimental results,and t-test was used to compare the results within and between groups.Result: We found from our results that 1.In extraction patients,the apical resorption of maxillary canine teeth was observed(p < 0.01),the thickness of alveolar bone at 6 mm,12 mm from CEJ(cemento-enamel junction,CEJ)and the root apex of canine at the labial side was thinner significantly,the thickness of alveolar bone at 12 mm from CEJ and the root apex of canine at the palatal side was thicker significantly(p < 0.01),the height of labial and palatal side and alveolar bone decreased significantly(p < 0.01),and the height of distal middle alveolar bone increased significantly(p < 0.05).The amount of rotation and distance of the labial side of the canine root decreased,while the amount of rotation and distance of palatal side increased(p < 0.05).2.In unconventional extraction patients,the apical resorption of maxillary canine teeth was observed(p < 0.01),the thickness of alveolar bone thinned at 6 mm and 12 mm from CEJ at the labial side was thinner significantly(p < 0.05),the height of labial and palatal side and alveolar bone decreased significantly(p < 0.01),and the height of distal and middle alveolar bone decreased significantly(p < 0.05).3.The thickness of alveolar bone at 12 mm of the labial side from CEJ decreased more in extraction patients than that of unconventional extraction patients(p < 0.05).The thickness of alveolar bone at12 mm of the palatal surface to CEJ and at the apex increased in extraction patients,but the alveolar bone thickness of unconventional extraction patients had no statistical significance(p < 0.05);The distal alveolar bone height of the patients with extraction was increased,while The distal alveolar bone height of the patients with unconventional extraction was decreased(p < 0.05).The labial rotation range and rotation distance of canine teeth were much less than those of unconventional extraction patients(p < 0.05).The total rotation range of canine teeth was larger in extraction patients than in unconventional patients(p < 0.05),with statistical difference.CONCLUSION: After unconventional extraction,the alveolar bone of the labial side absorbed and the alveolar bone height of the labial and palatal side decreased.Compared with the unconventional extraction,the canine teeth were more upright,the root movement was wider,the alveolar bone of the labial side absorbed more,and the alveolar bone height of the distal side increased.Tips:1.In the treatment of skeletal class II malocclusion,attention should be paid to the control of root-lingual torque when addressing canines.2.In the treatment of skeletal class II malocclusion with unconventional extraction,it is suggested that the implant nail should be moved to the distal part of the anterior teeth first,and then the anterior teeth should be adducted to prevent the reduction of the alveolar bone mass.3.Whether extraction or non-conventional extraction,we should pay attention to the rotation range and rotation distance of canines to prevent the reduction of the distal alveolar bone mass of the canine teeth. |
PDF Full Text Request