The relationship between neurosensory disturbance of the inferior alveolar nerve and the lingual split pattern after sagittal split osteotomy.

OBJECTIVE: The aim of this study was to evaluate the relationship between neurosensory disturbance (NSD) and the different types of bilateral sagittal split osteotomy (BSSO) lingual fracture created. STUDY DESIGN: The study group consisted of 45 patients with mandibular deformities (90 sides; 14 males and 31 females). Computed tomography (CT) scans were obtained preoperatively and 1 week postoperatively. All patients were divided into lingual fracture line groups on the basis of their postoperative scans. NSD was tested preoperatively and 1, 3, and 12 months postoperatively by using a sensory touch Semmes-Weinstein (SW) test and the 2-point discrimination (TPD) test. RESULTS: Patients were divided into 2 groups on the basis of their lingual fracture lines after mandibular BSSO; among the 45 patients, 39 sides (43.3%) had short-splits, and 51 sides (56.7%) had long-splits. The short-split group was less affected at all tested times, and the difference between the 2 groups was significant 1 month postoperatively on TPD test but not at other times on the both tests. CONCLUSIONS: The split type did not affect the NSD incidence at 3 and 12 months postoperatively.

Influence of oestrogen deficiency and excessive mechanical stress on condylar head of mandible.

OBJECTIVE: We assessed the aetiology of idiopathic condylar resorption by examining the effects of oestrogen and compressive mechanical stress under a low systemic oestrogen condition in temporomandibular joints (TMJ) caused by an ovariectomy. MATERIALS AND METHODS: Female rabbits were divided into non-ovariectomy (non-OVX) and ovariectomy (OVX) groups. A cortical osteotomy was performed with a custom device that was increased in length by 0.25 mm every 12 hr for 1 week after the operation, during which the TMJs in the rabbits received compressive mechanical stress. Samples from both groups were examined with micro-computed tomography and histological staining. RESULTS: Area and depth of bone resorption were both greater in the OVX group. Furthermore, a significantly earlier and greater prevalence of sub-condylar bone resorption was noted in that group, while cells positive for tartrate-resistant acid phosphatase were increased in the OVX group. CONCLUSIONS: The present findings suggest that oestrogen induced a much greater amount of bone resorption on the anterior surface of the condylar head at an earlier stage in the TMJs of the present model rabbits. Thereafter, restoration of TMJ function appeared to occur in a normal manner.

Histologic and histomorphometric evaluation of the bone regeneration following cortical bone repositioning in a rabbit mandible.

BACKGROUND: Although bone graft (BG) is the gold standard for bone augmentation, its use is hampered by donor site morbidity and limited quantity. PURPOSE: To evaluate the capabilities of bone formation by cortical bone repositioning (CBR) as the healing response following grafting of autogenous bone block without filling biomaterial at the gap between gap and recipient. MATERIALS AND METHODS: Twelve Japanese White rabbits were divided into three groups (postoperative 2, 5, and 8 weeks). A cortical block was freed from the mandibular body, half of the block was positioned and fixed overlapped the original bone surface beside the defect and the other half remained only elevated above the defect. Three areas were decided for the evaluation; BG, CBR, and defect (D) area. Areas were evaluated by micro-CT, histology, and histomorphometric analysis. RESULTS: There is no statistical difference between BG and CBR by evaluating distance and area in histomorphometrical analysis (P < .05). D area showed statistical decrease compared with BG and CBR at week 2. Histologically, new bone was evident at week 2, mature bone was observed in all three areas at week 8, D area disappeared and fused completely with the elevated bone block. CONCLUSION: CBR has potential for bone augmentation as BG induced from its own regenerative ability of healing process.

Timed-release system for periosteal expansion osteogenesis using NiTi mesh and absorbable material in the rabbit calvaria.

UNLABELLED: This study aimed to improve bone regeneration using a timed-release system for periosteal expansion osteogenesis (TIME-PEO) using a shape memory alloy (SMA) mesh device and absorbable thread in a rabbit model. MATERIALS AND METHODS: Twelve rabbits were used in this study. The device was inserted under the periosteum at the forehead, then pushed, bent, and attached to the bone surface and fixed with an absorbable thread. Rabbits were divided into groups C1 (5 weeks postoperatively without dynamic elevation), C2 (8 weeks postoperatively without dynamic elevation), T1 (5 weeks postoperatively from TIME-PEO), and T2 (8 weeks postoperatively from TIME-PEO). Newly formed bone was evaluated histologically and radiographically. RESULTS: The newly formed bone volume to elevated bone volume ratio was 6.1% in C1, 21.9% in T1 15.5% in C2 and 36.0% in T2. These quantitative data indicate that TIME-PEO group had a significantly higher volume than that of the control group (P < 0.05). Histologically, multiple dome-shaped bones, outlined by thin and scattered trabeculae, over the original bone surface were evident in the T group. CONCLUSION: This technique appears to be a promising clinical alternative for alveolar bone augmentation and introduces the new concept of "dynamic guided bone regeneration" for atrophic alveolar bone.