CT Evaluation of Morphology of Transferred Fibula for Implant Placement in Reconstructed Mandible.

BACKGROUND: Dental rehabilitation with osseointegrated implants in reconstructed mandibles remains one of the most challenging procedures for oral and maxillofacial surgeons. Satisfactory outcome requires appropriate assessment of graft morphology. There are few analyses of the morphology of fibulae in reconstructed mandibles, although cadaver studies on fibular shape have been performed. MATERIALS AND METHODS: In this study, we used postoperative computed tomography to retrospectively evaluate the shape, height, and orientation of fibulae transferred after mandibulectomy in 19 patients. RESULTS: The average height of transferred fibulae was 14.3 mm (range, 10.8-20.5 mm). The cross-sectional morphology of transferred fibulae could be classified into 2 types: apex and nonapex. The former type included knife-edged and triangular shapes; the latter included square and circular shapes. CONCLUSION: When implant insertion is planned in a reconstructed mandible, the orientation of the apex of transferred fibula should be evaluated preoperatively to allow for adjustments in implant procedure because the ridge at the apex of the fibula is narrow.

Potential role of post-treatment follow-up FDG-PET CT to detect mandibular osteoradionecrosis: A case report.

It was hypothesized that fluorodeoxyglucose (FDG) uptake on post-treatment follow-up positron emission tomography with computed tomography (PET CT; using PET CT to monitor and rule out recurrence and metastasis of head and neck carcinoma) would be useful for detecting and understanding the disease state of osteoradionecrosis (ORN) of the jaw. The present study included 14 patients who developed mandibular ORN following radiation therapy (RT) for head and neck cancer and underwent follow-up PET CT several times following RT. Areas exhibiting FDG uptake were retrospectively assessed on post-treatment follow-up PET CT images and were classified into three types: Spot type: Only spot accumulation of FDG; localized type: Accumulation of FDG restricted to within the bone resorption area; extensive type: Accumulation of FDG extending into surrounding soft tissue. PET classification at the time of clinical diagnosis of mandibular ORN in the 14 patients demonstrated the extensive type in 43%, localized type in 36% and spot type in 21%. An increased area of FDG uptake around the ORN was revealed retrospectively on post-treatment follow-up FDG PET-CT images in 50% of patients. Alterations in PET classification included spot type to localized type in 36% and localized type to extensive type in 14%. A significantly increased number of patients with extensive-type ORN (P=0.026) required surgery. Post-treatment follow-up FDG-PET CT may be useful for early detection and better understanding of ORN.

Differences between osteoradionecrosis and medication-related osteonecrosis of the jaw.

PURPOSE: The appearance of osteoradionecrosis (ORN) and medication-related osteonecrosis of the jaw (MRONJ) is similar, but clinically important differences between ORN and MRONJ exist. The aim of this study was to compare the clinical data between ORN and MRONJ and to reveal the critical differences between these diseases. METHODS: We retrospectively reviewed the epidemiological data, clinical findings, and treatment in 27 ORN and 61 MRONJ patients. Radiographic signs before the initiation of treatment were also assessed. RESULTS: The median age (P = 0.0474) and the ratio of female to male patients (P < 0.0001) were significantly higher in MRONJ patients. There were significantly more MRONJ patients who reported a history of pain when compared with ORN patients (P = 0.0263). As an aetiological factor, tooth extraction was significantly more relevant to MRONJ than ORN (P = 0.0352). When assessing the radiographic signs on computed tomographic images, periosteal reaction was found only in MRONJ patients (P = 0.0158). Minimal debridement was performed significantly more frequently for MRONJ (P = 0.0093), and by contrast, surgical resection was performed more frequently for ORN (P = 0.0002). CONCLUSIONS: Understanding the clinical and underlying pathological differences between ORN and MRONJ probably contributes to the selection of appropriate treatment for each patient.

Association between pain severity and clinicohistopathologic findings in the mandibular canal and inferior alveolar nerve of patients with advanced mandibular osteoradionecrosis.

OBJECTIVE: Pain is one of the most problematic symptoms in patients with osteoradionecrosis of the jaws. This study investigated the associations between pain severity and morphologic alterations of the mandibular canal and inferior alveolar nerve, in respective computerized tomography images and resected specimens of mandibular osteoradionecrosis. STUDY DESIGN: We assessed 14 lesions in 13 patients who underwent segmental mandibulectomy for surgical debridement and simultaneous reconstruction with free fibula flap (1 patient exhibited bilateral lesions). The extent of the mandibular canal bone defect on preoperative coronal computerized tomography images and the number of inferior alveolar nerve fascicles in resected specimens were evaluated. Comparisons were made between the slight pain and extreme pain groups. In most of the patients in the extreme pain group, either mandibular canal bone defects were absent or entire circumferential defects were present; inferior alveolar nerve fascicles were either distinguishable or completely absent in the resected specimens. RESULTS: Although there was no statistically significant association between extreme pain and computerized tomography or histopathologic findings, the histopathologically indistinguishable inferior alveolar nerve fascicles was significantly associated with slight pain. CONCLUSIONS: The degree of degeneration of mandibular canal and inferior alveolar nerve may be associated with pain severity in patients with mandibular osteoradionecrosis.

Heterogeneity of Necrotic Changes between Cortical and Cancellous Bone in Mandibular Osteoradionecrosis: A Histopathological Analysis of Resection Margin after Segmental Mandibulectomy.

BACKGROUND: This study aimed to analyze differences in necrotic changes between cortical and cancellous bone in resection margins after segmental mandibulectomy for advanced mandibular osteoradionecrosis. METHODS: Anteroposterior bone specimens from eleven patients who underwent segmental mandibulectomy with simultaneous free fibula flap reconstruction for advanced osteoradionecrosis were analyzed histopathologically for the presence of necrotic bone based on the presence of blood vessels within Haversian canals. RESULTS: Ten of eleven (91%) cortices near the inferior border of the mandible at the anterior margins were necrotic. All cancellous bones at the anterior margins were viable. Seven of eleven (64%) cortices near the inferior border of the mandible at the posterior margins were necrotic. Three of eleven (27%) cancellous bones at the posterior margins were necrotic. CONCLUSION: Necrotic changes are more prevalent in cortices than in cancellous bones in mandibular osteoradionecrosis, probably due to a decrease of periosteal blood supply caused by radiotherapy.

Cause and occurrence timing of osteoradionecrosis of the jaw: a retrospective study focusing on prophylactic tooth extraction.

PURPOSE: This retrospective study aimed to analyze the relationship between tooth extraction and osteoradionecrosis (ORN) occurrence. The irradiation field, dose, and time interval between radiotherapy (RT) and ORN were reviewed. We also discuss appropriate guidelines for prophylactic tooth extraction. METHODS: A total of 33 patients treated for grade ≥2 (clinical) ORN in our department from 2002 to 2014 were enrolled. The following epidemiological data were retrospectively gathered: age, sex, histological diagnosis, primary tumor sites, radiation dose, chemotherapy, site of ORN, relationship between tooth extraction and ORN occurrence, and time interval between tooth extraction and the initiation or end of RT. RESULTS: Twenty-one percent of ORN cases resulted from tooth extraction. The most common site of ORN (82 %) was the mandibular molar region. About half of ORN cases (49 %) occurred within 2 years after RT. All patients who received tooth extraction after RT developed ORN (100 %) independently of time interval between tooth extraction and the end of RT (median interval, 37.5 months; range, 27-120 months). In contrast, only 50 % of patients who received tooth extraction before RT developed ORN. There may have been an association between the irradiation field and the site of ORN development CONCLUSIONS: ORN occurrence due to tooth extraction was 21 %. Occurrence timing of ORN did not depend on time interval between tooth extraction and the end of RT. The irradiation field is certainly related to the site of ORN; therefore, prophylactic tooth extraction should be performed in consideration of the proposed radiation field and dose.