Dynamic contrast-enhanced magnetic resonance imaging for monitoring neovascularization during bone regeneration-a randomized in vivo study in rabbits.

OBJECTIVES: Micro-computed tomography (µ-CT) and histology, the current gold standard methods for assessing the formation of new bone and blood vessels, are invasive and/or destructive. With that in mind, a more conservative tool, dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), was tested for its accuracy and reproducibility in monitoring neovascularization during bone regeneration. Additionally, the suitability of blood perfusion as a surrogate of the efficacy of osteoplastic materials was evaluated. MATERIALS AND METHODS: Sixteen rabbits were used and equally divided into four groups, according to the time of euthanasia (2, 3, 4, and 6 weeks after surgery). The animals were submitted to two 8-mm craniotomies that were filled with blood or autogenous bone. Neovascularization was assessed in vivo through DCE-MRI, and bone regeneration, ex vivo, through µ-CT and histology. RESULTS: The defects could be consistently identified, and their blood perfusion measured through DCE-MRI, there being statistically significant differences within the blood clot group between 3 and 6 weeks (p = 0.029), and between the former and autogenous bone at six weeks (p = 0.017). Nonetheless, no significant correlations between DCE-MRI findings on neovascularization and µ-CT (r =-0.101, 95% CI [-0.445; 0.268]) or histology (r = 0.305, 95% CI [-0.133; 0.644]) findings on bone regeneration were observed. CONCLUSIONS: These results support the hypothesis that DCE-MRI can be used to monitor neovascularization but contradict the premise that it could predict bone regeneration as well.

Evaluation of neurosensory disturbances of the inferior alveolar nerve after intraoral verticosagittal ramus osteotomy.

PURPOSE: To assess the incidence of neurosensory disturbances (NSD) of the inferior alveolar nerve (IAN) after Intraoral verticosagittal ramus osteotomy (IVSRO). MATERIALS AND METHODS: The sensibility of the chin and lower lip of ten consecutive patients undergoing IVSRO was assessed. Evaluations were performed at 7 days preoperatively, 7 days, one month and six months postoperatively. The chin was divided into four quadrants, which were tested separately. The tests used were: two-point discrimination (2-P), brush stroke direction discrimination (BSD) and thermal stimuli (TH). Postoperatively, patients also answered a questionnaire. RESULTS: The values for 2-P showed statistically significant difference when compared to preoperative measurements (P>0.05) in all quadrants, with exception to quadrant D. There was no statistically significant difference among preoperative values and 7 days, 1 month and 6 months postoperative values. For BSD and TH tests, no differences were found among time points. None of the 10 patients reported complete numbness after 1 week. After 6 months, complete recovery of the chin sensibility was reported in all 10 cases. CONCLUSION: This study showed, objectively and subjectively, a low incidence of NSD after IVSRO. Further studies with larger samples are necessary to confirm these results.