Tadaharu Kobayashi

Stability of the mandible after sagittal ramus osteotomy for correction of prognathism

The change in the position of the mandible after sagittal ramus osteotomy was evaluated on lateral cephalograms and in dental casts in 44 patients with mandibular prognathism. The postoperative relapse of the mandible at four landmarks was less than 1 mm on cephalograms and 1.1 mm at the first molar on the side with the larger posterior movement. The tendency to relapse was greater in cases in which large posterior and/or lateral movements of the mandible occurred at surgery. The importance of proper postoperative care and avoidance of lateral shift of the mandible to minimize relapse is stressed.

Impact of lymph node metastasis on the pattern of failure and survival in oral carcinomas

BACKGROUND Carcinomas of the oral cavity present a high risk for neck metastases that decrease the disease control and survival. METHODS A total of 106 patients with squamous cell carcinoma of the oral cavity who had metastatic neck nodes were studied. The impact of neck metastasis and treatment modalities on outcome was assessed. RESULTS Thirty-eight patients developed neck recurrence or distant metastasis. The 5-year survival, neck recurrence-free, and distant metastases-free rates were 56%, 84%, and 77%, respectively. Univariate analyses showed extranodal spread (ENS), number of positive nodes, and adjuvant chemotherapy were predictors for survival. In multivariate analysis, ENS and postoperative radiotherapy were of borderline significance. There was no prognostic factor for neck control. The presence of ENS and lower levels of positive nodes and no chemotherapy were associated with high distant failure rates. CONCLUSIONS To prevent distant metastases, patients with ENS should be considered for adjuvant chemotherapy.

Impairment of the inferior alveolar nerve after sagittal split osteotomy.

The incidence and degree of neurosensory disturbance of the inferior alveolar nerve, as well as its recovery course, were studied on 46 sides in 23 patients who had undergone bilateral sagittal split osteotomies, by means of subjective symptoms, light touch, anaesthesiometer and two-point discrimination. The degree of disturbance was classified into mild, moderate and severe grades by the threshold pressure shown in tests with the anaesthesiometer. The disturbance, which was almost exclusively limited to mild (37%) and severe (28%) grades, was observed in 67% of the sample at one week. The disturbance disappeared completely within one to three months postoperatively in most sites with mild disturbance, and within three months to one year in half of the severely affected sites. Although the recovery was delayed in the other half of the severely disturbed sites, the disturbance was of mild grade at one and a half years. The overall incidence of disturbance at one year was 15%. Computed tomographic examination of the ascending ramus showed that the narrowest width between the mandibular canal and the buccal cortical plate ranged from 0 mm to 3.2 mm with a mean of 1.6 +/- 0.9 mm (SD) and it was less than 1.2 mm in 91% of sites with a severe grade disturbance, whereas it was distributed in a range of 0.9 mm to 3.2 mm in sites with no disturbance or with mild or moderate disturbance. The importance of preoperative computed tomography to indicate the location of the mandibular canal and the use of a thin cement spatula for the osteotomy was stressed, to avoid or reduce postoperative development of neurosensory impairment.

Computed tomographic evaluation of bone formation after secondary bone grafting of alveolar clefts

PURPOSE The purpose of this article was to evaluate the initial volume of alveolar clefts and the bone bridges formed in patients who had undergone secondary bone grafting. PATIENTS AND METHODS Fifteen cleft patients were studied. Computed tomography (CT) scans were made at 2-mm slice sections immediately before operation and at 3 months and 1 year postoperatively. The volume of the alveolar clefts and bone bridges was calculated from stored images by using an image scanner and a personal computer. RESULTS The mean cleft volume of the patients was 1.1 +/- 0.3 cm3. The corresponding volume of the bone bridges 3 months and 1 year postoperatively were 1.2 +/- 0.6 cm3 and 1.1 +/- 0.5 cm3, respectively. The value at 1 year was significantly decreased compared with that at 3 months. CONCLUSIONS Adequate bone bridging was maintained for 1 year. However, it is suggested that the grafted site should be restored with a functioning tooth or a dental implant to place it under physiologic stress, because the volume of the bone bridges tends to decrease from 3 months to 1 year.

Predicting factors for distant metastases in head and neck carcinomas : An analysis of 103 patients with locoregional control

PURPOSE This study evaluated the ability of certain clinical and pathologic parameters to predict distant metastases (DMs) in patients with squamous cell carcinoma of the head and neck. MATERIALS AND METHODS A total of 103 patients with histologically proven squamous cell carcinoma of the head and neck were studied. None had persistent or recurrent disease above the clavicle. Of these patients, 48 (47%) had metastatic lymph nodes. The relationships of tumor stage, primary site, clinical growth pattern, tumor differentiation, regional node status, and extranodal spread (ENS) with DMs were evaluated. RESULTS Twenty-one (20%) of the 103 patients developed DMs as the initial treatment failure. The incidence of DMs was significantly higher in patients with neck metastases (40%) than in those without neck metastases (4%) (P < .001). The degree of histologic differentiation and the presence of ENS were also correlated with the subsequent occurrence of DMs. There was no statistical difference in the incidence of DMs based on sex, location, stage of the disease, and clinical growth pattern. On multivariate analysis, only pathologic nodal status and ENS proved to be independent cofactors of DMs. The most common site of DMs was the lungs (56%), followed by bone (16%) and skin (16%). CONCLUSION The presence of pathologically positive nodes is the most critical factor to influence the eventual development of DMs.

Masticatory function in patients with mandibular prognathism before and after orthognathic surgery.

Masticatory function was analyzed in 54 patients with mandibular prognathism before or after orthognathic treatment and in 40 adults with normal occlusion. Masticatory efficiency was evaluated spectrophotometrically by measuring the amount of adenosine triphosphate eluted from masticated adenosine triphosphate granules. Occlusal contact was evaluated by calculating the number and area of occlusal contacts from the illuminated images of a silicone record of the occlusion that was stored in the image analysis system with the aid of a charge-coupled device camera. The mean masticatory efficiency of the preoperative group was approximately half that of the control group. The value for the postoperative group was slightly higher than that for the preoperative group, but there was no statistical difference between the two groups. Likewise, the number and area of occlusal contacts in the preoperative group were also approximately half or less as compared with those of the control group, and they did not show significant changes postoperatively. Statistically, there were correlations between the masticatory efficiency and the number and area of occlusal contacts. The results indicate that although the occlusal relationship of the upper and lower teeth were greatly improved by orthognathic treatment, the postoperative occlusion is not tight enough and may need further adjustment at the end of the treatment.

Changes in oropharyngeal airway and respiratory function during sleep after orthognathic surgery in patients with mandibular prognathism

The aim of this study was to examine the effects of mandibular setback surgery on pharyngeal airway space and respiratory function during sleep. The subjects were 22 patients in whom mandibular prognathism was corrected by bilateral sagittal split ramus osteotomy; either one jaw or two jaw surgery. Polysomnography was performed before surgery and 6 months after surgery, and the apnea hypopnea index (AHI) and arterial oxygen saturation during sleep were measured to assess respiratory function during sleep. Morphological changes were studied using cephalograms taken immediately before, a few days after and 6 months after surgery. As a control, 10 subjects without sleep-disordered breathing underwent the same examinations. AHI was not changed significantly after surgery, although two patients were diagnosed with mild obstructive sleep apnea (OSA) syndrome after surgery. They were not obese, but the amounts of mandibular setback at surgery were large. In conclusion, a large amount of mandibular setback might inhibit biological adaption and cause sleep-disordered breathing, and it might be better to consider maxillary advance or another technique that does not reduce the airway for patients with skeletal class III malocclusions who have large anteroposterior discrepancy and/or maxillary hypoplasia.

Squamous Cell Carcinomas of the Mandibular Alveolus: Analysis of Prognostic Factors

Background: To assess the effect of clinicopathologic factors on local tumor control and survival in patients with mandibular alveolar carcinoma. Methods: Fifty patients with mandibular alveolar carcinoma treated surgically were included in this study. There were 3 patients with T1, 25 with T2, 5 with T3, and 17 with T4 disease. Clinical evidence of bone invasion was noted in 47 patients. A hemi- or segmental mandibulectomy was performed on 37 patients, whereas 10 patients had a marginal mandibulectomy. The impact of clinicopathologic variables on local tumor control and patient survival was assessed by univariate analysis. Variables included T and N stage, dental extraction, treatment modality, tumor differentiation, nodal status, surgical margin, and bone invasion. Results: Eleven patients (22%) develop recurrent disease, including 8 local recurrences, 1 neck, and 2 distant metastases. Overall, the 5-year actuarial rates of local control and disease-specific survival were 85 and 73%, respectively. Most local recurrences after surgical treatment were caused by inadequate resection margins. When resection margins were negative, the survival and local control rate were significantly better than when there were positive resection margins (survival, 91 vs. 11%; local control, 100 vs. 49%; p < 0.01). Neither T and N stages, clinical stage, tumor differentiation, dental extraction, bone invasion, extent of bone resection, nor treatment modality influenced outcome. Conclusions: The status of surgical margins was of major importance for the outcome of patients with gingival carcinoma of the mandible.

The impact of extranodal spread of lymph node metastases in patients with oral cancer

A retrospective study of 61 patients with histologically confirmed lymph node metastases was undertaken to evaluate the prognostic significance of extranodal spread (ENS) of metastases on the patterns of treatment failure and survival. ENS was present in 28 (46%) of the 61 patients and it was significantly associated with N stage. T stage, clinical stage, number of positive nodes, level of metastases, mode of treatment, and histological differentiation, however, did not influence the incidence of ENS. The 5-year disease-specific survival rate was 57%. The values for patients with and without ENS were 40% and 72%, respectively, which were statistically significant. The univariate analysis showed that the presence of ENS was a significant predictor of patient survival (P = 0.008). The number and level of positive nodes and postoperative radiotherapy had no prognostic importance. ENS, however, was also associated with an increased risk of distant metastases.

Surgical treatment of stage I and II oral squamous cell carcinomas: analysis of causes of failure

Sixty-one patients with stage I and II squamous cell carcinomas of the oral cavity treated by surgery alone were analysed to investigate treatment outcome, pattern of failure, and occurrence of second malignant neoplasms. The disease recurred or developed lately in 11 patients. The ipsilateral neck was the most common site of failure. Salvage treatment was successful in only three of these patients. Occult neck metastasis was found in 31% of patients with T2 tumours. Second malignant neoplasms developed in 20 patients and were the cause of death in 8 patients. In conclusion, locoregional control of stage I and II oral carcinomas is achieved by surgery alone. Elective neck dissection is required for patients with stage II tumours, showing a high risk of lymph node metastasis in histology.