Effect of Osteoporosis on Bone Density of Orthognathic Osteotomy Sites in Maxillofacial Region.

OBJECTIVES: The aims of this study were to investigate the availability of Hounsfield unit (HU) measurement of computed tomography (CT) in evaluating the bone density of certain sites by comparing bone density between CT and dual-energy x-ray absorptiometry (DEXA), and to evaluate the effects of osteoporosis on osteotomy sites in orthognathic surgery. METHODS: This retrospective study included 80 patients who had undergone both facial CT and DEXA at our hospital. We selected 7 regions of interest from among the osteotomy sites in bimaxillary orthognathic surgery. The patients were assigned to either the normal (control) group (n = 40) or the abnormal group (n = 40), and HU values were measured in each region of interest. RESULTS: There were statistically significant differences in the mean HU values between 2 groups at all the osteotomy sites in the maxilla and mandible, with the normal group showing higher values than the abnormal group (P < 0.05). In addition, there was a significant positive correlation between T-scores obtained with DEXA and the HU values on CT at the osteotomy sites (P < 0.01). Multiple regression analysis indicated that the abnormal group was more negatively associated with 6 osteotomy sites except for 1 maxillary area, as compared with the normal group. CONCLUSIONS: Measurement of HU values on CT can be valuable in assessing bone density of the maxilla and mandible. It is suggested that osteoporosis may affect bone density at the osteotomy sites in orthognathic surgery, and the preoperative measurement of HU values might be useful in predicting unfavorable fracture or the risks involved in such surgery.

Correlation between clinical symptoms and magnetic resonance imaging findings in patients with temporomandibular joint internal derangement.

OBJECTIVES: The purpose of this study was to clarify which findings in magnetic resonance imaging (MRI) are good predicators of pain and mouth opening limitation in patients with temporomandibular joint (TMJ) internal derangement (ID). MATERIALS AND METHODS: Clinical examinations for pain and mouth opening limitation were conducted for suspected TMJ ID. MRI scans were taken within a week of clinical examinations. On the oblique-sagittal plane image, readings were obtained in terms of the functional aspect of disc position, degree of displacement, disc deformity, joint effusion, and osteoarthrosis. Multiple logistic regression analyses were conducted to identify the predictors of pain and mouth opening limitation. RESULTS: A total of 48 patients (96 TMJs) were studied, including 39 female patients and 9 male patients whose ages ranged from 10 to 65 years. The resultant data showed significant correlations between pain and the MR imaging of the degree of disc displacement (P<0.05). The probability of there being pain in moderate to significant cases was 9.69 times higher than in normal cases. No significant correlation was found between mouth opening limitation and MRI findings. CONCLUSION: We identified a significant correlation between clinical symptoms and MRI findings of ID. The degree of anterior disc displacement may be useful for predicting pain in patients with TMJ ID.

Simultaneous Glossectomy with Orthognathic Surgery for Mandibular Prognathism.

Macroglossia can create dental and skeletal instability after orthodontic treatment or orthognathic surgery for mandibular prognathism. In relevant literature, partial glossectomy is suggested for a good post-treatment prognosis. Most of the published partial glossectomy cases are two-staged surgery, because of concern about postoperative airway obstruction. As orthognathic surgical techniques and fixation method develop, however, concerns about postoperative airway obstruction have lessened. In this case, mandibular setback surgery and partial glossectomy were performed simultaneously, leading to stable recovery without any postoperative respiratory problems. After surgical technique to preserve the tongue tip, we achieved good outcomes without postoperative side effects of lingual hypoesthesia, pronunciation disorder and dyskinesia. We report this case with a literature review.