Which kind of miniplate to use in mandibular sagittal split osteotomy? An in vitro study

This study verified the resistance to displacement of six miniplate fixation methods after sagittal split osteotomy (SSO). SSO was performed in 30 polyurethane synthetic mandible replicas. The distal segments were advanced (4 mm) and specimens were grouped according to the fixation method: four-hole standard miniplate; four-hole locking miniplate; six-hole standard miniplate; six-hole locking miniplate; six-hole standard sagittal miniplate; six-hole locking sagittal miniplate. Biomechanical evaluation was performed by applying compression loads to three points on the second molar region, using an Instron universal testing machine until a 3 mm displacement of the segments occurred. Compression loads able to produce 3 mm displacement were recorded in kN and subjected to analysis of variance (P < 0.01) and Tukey's tests for comparison between groups (P < 0.05). The locking sagittal miniplate showed higher resistance to displacement than the regular four- and six-hole locking and standard miniplates. No significant differences were observed between the locking sagittal miniplate and the regular sagittal or the four-hole locking miniplates. Two of the three groups with the best results had locking plate fixation methods. Fixation of SSO with a single miniplate is better accomplished using six-hole locking sagittal miniplates, six-hole standard sagittal miniplates, or four-hole locking miniplates; these methods are more resistant to displacement.     

Effect of self-setting α-tricalcium phosphate between segments for bone healing and hypoaesthesia in lower lip after sagittal split ramus osteotomy

AimsThe aim of this study was to evaluate hypoaesthesia of the lower lip and bone formation using self-setting α-tricalcium phosphate (Biopex^®) between the proximal and distal segments following sagittal split ramus osteotomy (SSRO) with bent absorbable plate fixation.Subjects and methodsThe subjects were 40 patients (80 sides) who underwent bilateral SSRO setback surgery. They were divided into a Biopex^® group (40 sides) and a control group (40 sides). The Biopex^® was inserted into the anterior part of the gap between the segments in the Biopex^® group. Trigeminal nerve hypoaesthesia in the region of the lower lip was assessed bilaterally using the trigeminal somatosensory-evoked potential (TSEP) method. Ramus square, ramus length, and ramus width, the square of the Biopex^® at the horizontal plane under the mandibular foramen were assessed preoperatively, immediately after surgery, and 1 year postoperatively by computed tomography (CT).ResultsThe mean measurable period and standard deviation were 9.3 ± 15.7 weeks in the control group, 5.3 ± 8.3 weeks in the Biopex^® group, and there was no significant difference. Ramus square after 1 year was significantly larger than that prior to surgery and new bone formation was found between the segments in both groups (P < 0.05). In the Biopex^® group, the square of the Biopex^® after 1 year was significantly smaller than that immediately after surgery (P < 0.05).ConclusionThis study suggested that inserting Biopex^® in the gap between the proximal and distal segments was useful for new bone formation and it did not prevent the recovery of lower lip hypoaesthesia after SSRO with bent absorbable plate fixation.     

Effect of bilateral sagittal split ramus osteotomy on temporomandibular joint symptom and condylar position in patients with skeletal class Ⅲ malocclusion by cone beam computed tomography

目的 探讨双侧下颌骨升支矢状劈开截骨后退术（BSSRO）对行正畸—正颌联合治疗的骨性Ⅲ类错牙合患者颞下颌关节（TMJ）症状及髁突位置的影响。方法 选取24例行正畸-正颌联合治疗的骨性Ⅲ类错牙合患者,分别在BSSRO术前、术后1个月、术后12个月按Helkimo指数整理记录关节症状,并行锥形束CT（CBCT）扫描,在三维方向上测量髁突水平位及冠状截面最大径、髁突短轴径、髁突颈部宽度、髁突高度、不同角度（45°、90°、135°）下关节间隙宽度、双侧髁突间距及髁突角度（水平角、垂直角、受力角）,分析不同时期TMJ症状及骨性结构的变化情况。结果 BSSRO术前与术后的Helkimo指数均为Ai、Di 0级或1级,二者之间无差异。与术前相比,术后1个月时髁突水平角、45°及90°下关节间隙宽度增大,135°下关节间隙宽度减小（P<0.05）;术后12个月时,除髁突水平角增大（P<0.05）外,其余测量项目间差异均无统计学意义（P>0.05）。结论 在正畸—正颌联合治疗中,BSSRO不会对Helkimo指数为Ai、Di 0级或1级的骨性Ⅲ类错牙合患者的TMJ症状及髁突位置产生明显的影响。     

The use of mineralized bone allograft as a single grafting material in maxillary sinus lifting with severely atrophied alveolar ridge (1–3 mm) and immediately inserted dental implants. A 3- up to 8-year retrospective study

Objective

The primary aim of our study was to evaluate the efficacy of mineralized bone allograft alone in sinus floor augmentation with simultaneous implant placement in cases with severe atrophy of the residual maxillary bone (bone height <?4 mm).

Methods

Thirty-five dental implants were placed in 29 patients who underwent sinus augmentation via traditional lateral window technique from 2008 to 2013. Patients with residual alveolar height between 1 and 3 mm at the site of implantation were included in the study. The height of residual bone was initially estimated by plain panoramic X-ray and reevaluated intraoperatively by precise micrometric measurement at the site of implantation. Implants of 13 mm height and 3.5 or 4.3 mm in diameter were inserted simultaneously. Mineralized bone allograft was used alone to augment the sinus floor.

Results

No wound dehiscence was recorded. In one case there was a postoperative site infection which subsided with antibiotics without implant failure. One implant migrated during the postoperative period to the maxillary sinus and was removed. One implant failed. The remaining 33 implants were successfully loaded. Follow-up ranged from 3 to 8 years.

Conclusions

Maxillary sinus lift in severely absorbed alveolar ridges with simultaneous implant placement could be safely performed using mineralized allograft alone, rendering the procedure less invasive and less time-consuming.