Morbidity of harvesting of retromolar bone grafts: a prospective study

20 retromolar bone grafts were harvested in outpatients for augmentation of the implant site from January to June 2000 (10 female, 10 male, 40.9 +/- 12.8 years, minimum 17 years, maximum 66 years). The aim of the study was to assess typical complications of this procedure in a prospective manner. For the determination of the superficial sensory function of the inferior alveolar and the lingual nerve, an objective method was used. The bone grafts were harvested for single tooth reconstruction. In 14 cases a ridge augmentation and in 6 cases an endoscopically controlled crestal sinus floor elevation was performed. Preoperatively, the height of bone above the cranial aspect of the inferior alveolar nerve in the retromolar region was assessed radiologically with known markers. The maximum mouth opening was determined. The superficial sensory function of the inferior alveolar and the lingual nerve was assessed with the Pointed-Blunt Test, the Two-Point-Discrimination Test and the objective method of the 'Pain and Thermal Sensitivity' Test (PATH Test). Moreover, the pulp sensitivity of the teeth of the donor site was determined by cold vitality testing. All tests were repeated 1 week postoperatively. Intraoperatively, the width of the retromolar region was measured with a caliper. The patients rated the operative strain on a visual analogue scale. The height of bone above the inferior alveolar nerve in the retromolar region was 11.0 +/- 2.2 mm. The width of the retromolar area was 14.2 +/- 1.9 mm. Postoperatively, the maximal mouth opening changed significantly (40.8 +/- 3.5 mm preoperatively, 38.9 +/- 3.7 mm postoperatively, P = 0.006). However, the reduction was not relevant clinically. A direct injury of the inferior alveolar or lingual nerve did not occur. A sensitivity impairment could not be detected for either of the nerves by the different test methods 1 week postoperatively. The operative strain related to the donor site was significantly less than the strain generated by the implant placement (rating on a visual analogue scale 2.8 +/- 1.0 and 4.1 +/- 2.0, respectively, P = 0.027). Retromolar bone grafts are a viable method for augmentation of the implant site in conjunction with single tooth reconstruction with low strain on the patient and minimal risk of complications.     

Cancer of retromolar trigone: long-term radiation therapy outcome

BACKGROUND: Cancer of the retromolar trigone is an uncommon head and neck cancer. In this retrospective study, we identified the prognostic factors and evaluated the therapeutic outcomes of patients treated with preoperative radiation therapy (RT), postoperative RT, and RT alone. METHODS: Between 1971 and 1994, 65 patients with histologically proven epidermoid carcinoma of the retromolar trigone were treated at the Mallinckrodt Institute of Radiology; 10 patients received preoperative RT (30-55.2 Gy), 39 received postoperative RT (46-66.6 Gy), and 15 were treated with RT alone (63-74 Gy). Surgery included 44 composite resections and 7 wide excisions. The minimum follow-up was 5 years. RESULTS: The 5-year disease-free survival rates were 90% with preoperative RT, 63% with postoperative RT, and 31% with RT alone. The 5-year disease-free survival rates were 76% for patients with T1 disease, 50% for T2, 72% for T3, and 54% for T4. The 5-year disease-free survival rates were 69% for patients with NO disease, 56% for N1, and 26% for N2. The locoregional recurrence rates were 10% (1 of 10) for preoperative RT, 23% (9 of 39) for postoperative RT, and 44% (7 of 16) for RT alone. On multivariate analysis, the significant factors for disease-free survival were treatment modality (p =.002) and N stage (p =.012); for locoregional control it was treatment modality (p =.046); and for distant metastasis it was N stage (p =.002). The incidence of bone necrosis, soft tissue necrosis, and severe trismus was 12% with postoperative RT, 11% with RT alone, and none with preoperative RT. CONCLUSIONS: Combination surgery with postoperative or preoperative RT offers better locoregional control and disease-free survival than RT alone for epidermoid carcinoma of the retromolar trigone. Lymph node status significantly influences the disease-free survival and distant metastasis rates.     

Radiographic study of the mandibular retromolar canal: an anatomic structure with clinical importance

Introduction

The retromolar canal is an anatomic structure of the mandible with clinical importance. This canal branches off from the mandibular canal behind the third molar and travels to the retromolar foramen in the retromolar fossa. The retromolar canal might conduct accessory innervation to the mandibular molars or contain an aberrant buccal nerve.

Methods

Patients referred for panoramic radiography were consecutively enrolled, provided a limited cone-beam computed tomography (CBCT) scan had also been taken in the area of interest. Radiographs were retrospectively screened for the presence of a retromolar canal, and linear measurements (distance to second molar, height, width) were taken.

Results

One hundred twenty-one sides in 100 patients were evaluated (100 unilateral and 21 bilateral cases). A total of 31 retromolar canals were identified with CBCT (25.6%). Only 7 of these canals were also seen on the corresponding panoramic radiographs. The existence of a retromolar canal was not statistically related to gender or side. With regard to the linear measurements, the mean distance from the retromolar canal to the second molar was 15.16 mm (±2.39 mm), the mean height of the canal was 11.34 mm (±2.36 mm), and the mean width was 0.99 mm (±0.31 mm).

Conclusions

This radiographic study documents a frequency of 25% for the presence of a retromolar canal. The clinician is advised to preserve this anatomic variation when performing surgery in the retromolar area and to consider additional locoregional anesthesia in the case of failed mandibular block anesthesia.     

基于遗传算法优化青少年下颌磨牙后区生长潜力预测方法研究

目的　探讨影响青少年下颌磨牙后区生长潜力的因素,并分析基于遗传算法（genetic algorithms,GAS）优化青少年下颌磨牙后区生长潜力非线性预测方程的准确性。方法　选取2017—2019年于吉林大学口腔医院正畸科就诊的符合纳入标准的初诊患者306例。通过头颅定位侧位片测量下颌磨牙后间隙及颈椎测量指标,采用多元线性回归分析下颌磨牙后间隙与年龄、下颌第三磨牙牙龄、颈椎骨龄等的相关性,选取最强相关因子构建线性回归方程和基于GAS优化的非线性方程,并比较两个预测方程的准确性。结果　（1）不同矢状骨面型患者下颌磨牙后间隙不同,骨性Ⅰ类错牙合畸形组［（9.99 ± 2.53）mm ］与骨性Ⅲ类错牙合畸形组［（10.53 ± 3.53）mm ］比较,差异无统计学意义（P > 0.05）;而骨性Ⅱ类错牙合畸形组患者下颌磨牙后间隙［（8.98 ± 2.71）mm］小于骨性Ⅰ类和Ⅲ类错牙合畸形组,差异均有统计学意义（均P < 0.05）。故将所有患者分为骨性Ⅰ+Ⅲ类错牙合畸形组和骨性Ⅱ类错牙合畸形组。（2）下颌磨牙后间隙（RMS）与下颌第三磨牙牙龄（YL）呈正相关关系,两组分别构建线性回归方程和基于GAS优化的非线性方程如下。骨性Ⅰ+Ⅲ类错牙合畸形组：RMS = 1.489YL + 3.891;RMS = 2.36YL0.81 + 2.686。骨性Ⅱ类错牙合畸形组：RMS = 1.464YL + 1.961;RMS = 2.36YL0.81 + 0.723。基于GAS优化的非线性方程误差值低于线性回归方程,但其差异无统计学意义（P > 0.05）。结论　临床正畸医生进行青少年患者正畸方案设计时,应着重结合患者第三磨牙牙龄及矢状骨面型。应用基于GAS优化的非线性方程预测下颌磨牙后区生长潜力具有较高的预测精度和准确性。     

Controversies in the management of retromolar trigone carcinoma

Our objective is to discuss the current controversies that surround the management of retromolar trigone (RMT) cancer. We conducted this literature review to discuss trigone cancer. RTM and anterior pillar cancers should be studied separately. Preoperative clinical and radiographic assessments need to be further investigated to establish their reliability at predicting bone invasion. In the absence of suspicion of bone invasion, surgery and radiotherapy seem to give similar results, but recent reports indicate a greater benefit if they are used in combination. Some authors have advocated systematic segmental resection for all RMT cancers but marginal mandibulectomy is a reasonable option in selected cases. Standard treatment for RMT cancers with N0 necks is selective neck dissection or radiation therapy, depending on the modality of treatment of the primary. Allowing a better understanding of the evolution of RMT cancer and its response to different treatment modalities requires efforts to report different institutional experience with this rare tumor. © 2008 Wiley Periodicals, Inc. Head Neck, 2009     

带蒂颊脂垫在修复磨牙后区组织缺损中的应用

目的探讨带蒂颊脂垫对磨牙后区肿瘤切除术后组织缺损的修复效果。方法13例磨牙后区肿瘤的患者,肿瘤切除术后在同一创口区分离出带蒂颊脂垫,对磨牙后区组织的缺损进行修复,缺损范围最大4.5 cm×2.5cm。结果全部病例的带蒂颊脂垫均成活,其表面均与正常口腔粘膜相似;有1例粘膜有轻度瘢痕化,但不影响张口度。结论用带蒂颊脂垫修复磨牙后区组织缺损是一种安全、简便的方法。     

Diagnosis and Surgical treatment of Retromolar Trigone Malignant Tumor

目的：磨牙后区的解剖和组织学结构比较特殊,该部位的恶性肿瘤在临床、病理、手术及修复方法等方面与其它部位不同。现就此进行回顾性研究。材料和方法：本文回顾性分析了我院１９８０年６月至１９９７年１２月间收治的４３例磨牙后区恶性肿瘤患者,其中５例采用单纯化疗,１９例采用单一手术治疗,１７例采用化疗后手术的综合治疗,２１例在病灶切除后即刻手术修复。结果：该组病例５年生存率为３７％,但仅使用化疗的５例病人生存期均低于２年。结论：手术切除方法是磨牙后区恶性肿瘤的主要治疗方法。     

Primary typical carcinoid tumour in the retromolar region with prominent squamous differentiation: a case report

Primary carcinoid tumours of the oral cavity are rare, with only one case of atypical carcinoid tumour reported in the literature. In this article, a case of primary typical carcinoid tumour in the retromolar region in a 46-year-old woman is described. Histologically, the tumour was characterized by submucosal proliferation of medium-sized monomorphous epithelioid cells with an organoid and nesting pattern of growth. Mitoses and necrosis were not found. Prominent squamous differentiation was present. Immunohistochemically, the tumour was diffuse positive for cytokeratin (CK) (AE1/AE3), CK7, p63, neurone-specific enolase, synaptophysin, and chromogranin. To the authors’ knowledge, this is the first report of primary typical carcinoid tumour in the oral cavity.