Objective To investigate the contouring plastic effect of the digital navigation techniques assisted mandibular angle osteotomy,thereby providing surgical reference and evaluation basis for improving the accuracy,efficacy and safety of surgery.Methods From March 2015 to March 2017,15 female cases of the digital navigation aided intral-oral mandibular angle osteotomy in the past 2 years were collected and compared to the pre-operational image and digital design.Results The postoperative effect of navigation-assisted mandibular angle osteotomy was well matched to that of preoperative design.The mandibular angle was smooth and bilateral symmetrical with no obvious complication occurred.Conclusions Navigation-assisted techniques can solve the problem of limited exposure of intra-oral approach and significantly improve the accuracy,effectiveness and safety in mandibular angle osteotomy.

Objective:To study the mechanism of free bone graft survival in calvarial defects.Methods:We simulated the bone autograft reconstruction through transplanting green fluorescent protein (GFP) mice＇ cranium to the nude mice＇ calvarial bone defects. Then gross and histological evaluation were performed to calculate BTA (%) and GFP (%) in graft bone.Results:The results showed that the green fluorescence was getting disappeared from 4 to 24 weeks＇ post-operation. However, a small amount of green fluorescence remained at 24 weeks＇ post-operation (6.69% of the positive control group). In addition, the gross and histological evaluation indicated that the grafted bone survived well at different time points.Conclusions:The survival mechanism of free bone graft in cranium mainly relies on creeping substitution assisted with bony regeneration.