Safty Study Of The Mandibular Buccal Shed In Adults With Skeletal Class Ⅲ Malocclusion

Objective: In order to evaluate the safety of mandibular buccal shed of skeletal Ⅲ malocclusion adults during implantation of micro-implants,measured by cone-beam computed tomography(CBCT).Methods: According to inclusive and exclusive criteria,31 CBCT images of skeletal type Ⅲ patients were collected from orthodontics department of Hebei medical university stomatology hospital.CBCT image datas were imported into Invivo 5.1.3 software for three-dimensional reconstruction and measurement analysis,and lateral cephalometric images were imported into WinCeph 9.0 software for cephalometric analysis.All of the results were statistically analyzed by SPSS 21.0 software.Results:1.The distance between mandibular canal and alveolar ridge crest of male and female is 17.03±0.40 mm and 16.09±0.33 mm respectively in the space between mandibular first and second molars.The distance between mandibular second premolar and first molar of male and female is 18.56 ±0.34 mm and 17.23±0.39 mm,respectively.There is a significant difference between male and female.2.The distance between mandibular canal and alveolar crest was significantly different between different teeth in the same gender population,the distance between mandibular second premolar and first molar was larger than that between the mandibular first and second molars.3.The narrowest interradicular space in females was larger than that in males.4.The narrowest interradicular space between the first and second mandibular molars was larger than that between the second premolar and the first molar,but there was significant difference only in the section of 10 mm to the crest of alveolar ridge in females.Conclusion:1.The farther the implant site is,the closer it is to the upper edge of the mandibular canal;and the closer it is to the female than the male,the shorter implant can be used in clinical practice.2.The safe distance for the roots are the location of 4 mm away from the crest of alveolar ridge between the mandibular second premolar and the first molar and its gingival sites and the location of 2 mm away from the crest of alveolar ridge and its gingival sites between the mandibular first and second molar in females;the males should choose the location more inclined to the gingival sites about 2 mm.