Objective To study the pre-and post-surgical orthodontic treatment methods of patients with skeletal malocclusion treated through combined orthodontic-orthognathic surgery,and to set some guidance for the future clinical Work.Methods Twenty-five skeletal malocclusion patients in our clinic aged from 17 to 36 were treated by presurgical orthodontic treatment,orthognathic surgery and postsurgical ortho dontic treatment.Presurgical orthodontic treatment included alignment of dental arches,leveling of arches,elimination of rotations,coordination of the arches,and decompensation of anterior and posterior teeth.The postsurgical orthodontic treatment included closing residual spacing,final tooth alignment,maximum interdigitation,finalizing torque,artistic positioning,ideal overjet/overbite relationship and establishment of correct root parallelism.Results The duration of presurgical orthodontic treatment was 14.41 months on average(2～23 months),and the postsurgical orthodontic treatment time was 6.94 months on average(1.5～13.5 months).The duration for the whole active treatment was 21.35 months on average(7～35 months).The maxilla was moved back on an average 5.00 mm in maxillary protrusion cases.The mandible was moved anteriorly on an average 7.25 mm in mandibular retrusion cases.The mandible was moved back on an average 6.55 mm in mandibular protrusion cases.The chin was moved anteriorly on an average 5.33 nan in retrusion of chin cases.Conclusions Pre-and post-surgical orthodontic treatments are important procedures to the surgical treatment for skeletal malocclusion and basic needs to obtain successful treatment results.

Objective To analyse the location of the mandibular canal,providing the theoretical basis for implanting and bone grafting. Methods Mandibular data of 83 Chinese people obtained by cone-beam computed tomography examination were collected. Results The distance from the mandibular canal to mandibular buccal wall was (5.32 ± 1.29)~(7.24 ± 1.29) mm. And the average distance from mandibular canal to mandibular lingual wall or inferior margin were respectively (3.43 ± .99) ~ (3.93 ± 1.17) mm and (8.81 ± 1.90) ~ (10.02 ± 2.19) mm. Significant differences between males and females were found in groups. The anterior loop was observed in 70.9%of all sides. The accessory mental foramen was observed in 10.84% of all sides. Conclusion For the remarkable mutation of the location of the mandibular canal in Chinese people, clinicians should be careful before implant or bone surgery procedures to minimize the risk of inferior alveolar nerve injury.