Objective:To introduce a novel clinical classification that can be applied to osteoradionecrosis treatment in an easy and considerably acceptable manner through a retrospective analysis of patients with osteoradionecrosis of the mandible (ORNM). Methods:The clinical data of 99 ORNM patients admitted to shanghai Ninth People's Hospital between 2000 and 2013 were summa-rized. A novel classification was established based on bone necrosis and soft tissue lesions. The new staging system was developed based onBandSclassifications. Corresponding strategies and methods of ORNM treatment at different stages were also proposed. Results:A new staging system with four different stages (i.e., stage 0:8 cases;stageⅠ:14 cases;stageⅡ:65 cases;and stageⅢ:12 cases) was proposed. Conservative treatment was applied to stage 0 patients, whereas sequestrectomy was performed in stageⅠcases. Marginal or segmental resection of the mandible was selected for stageⅡpatients;osteocutaneous flap or just soft tissue flap was also reconstructed. Conclusion:This new classification and staging system is easier to use and more acceptable for clinical evaluation than other systems.

Objective:To assess the effectiveness of free vascularized bone flap transfer for treatment of advanced osteoradionecrosis of the mandible (ORNM). Methods:We reviewed 53 patients who were treated for ORNM by radical resection and reconstruction with free vascularized bone flaps in our institute between January 2003 and January 2015. Results:Among the 53 vascularized bone flap patients, 48 (90.57%) had fibula osteocutaneous and 5 (9.43%) had deep circumflex iliac artery (DCIA). Postoperative complications occurred in 5 (10.42%) of the 48 fibula osteocutaneous patients (4 cases of vein thrombosis and 1 case of arterial crisis). In three of these patients, flap was salvaged back to normal in a timely manner by vascular exploratory surgery. However, pectoralis major myocutaneous flap was conducted as a second procedure for the other two patients. Meanwhile, complications occurred in 2 (40%) of the 5 DCIA transfer patients (1 case of vein thrombosis and 1 case of arterial crisis). None of these two flaps was salvaged back. Necrosis transfer bone was finally removed. No obvious donor site complications were noted. The mean follow-up time was 28 months. Our results showed that 88.57%of the patients with ORNM were stable, 85.71%of the patients can open their mouth at 2-3 figures, 85.72%of the patients can eat soft or semi-liquid food, and 80%patients can speak clearly and can be understood by others around them. No significant difference was found in mouth opening and face type of the patients with or without the intact condyle. However, the temporomandibular joint area discomfort of the patients with intact condyle was obviously less than that of patients with removed condyle. Conclusion:Radical resection, followed by vascularized bone flaps, especially fibula osteocutaneous, is still the best way to treat ORNM, as long as the indications are chosen appropriately, intraoperative work is conducted properly, and postoperative complications are controlled.

Objective:The present study was aimed to determine the value of cone beam CT (CBCT) in predicting the risk of lingual bone plate injury during extraction of impacted mandible third molar (IMTM).Methods:The original CBCT data of 150 teeth (50 in vertical, 50 in angular and 50 in horizontal ) in January 2018 to December 2019 in Panzhihua Central Hospital of Sichuan Province were collected and analyzed. The thickness of lingual bone plate in enamel cementum boundary (ECB), root middle (RM) and root tip (RT) of each IMTM was measured by the software of CBCT system, and datas were analyzed by one-way ANOVA.Results:The average thickness of lingual bone plate in ECB of IMTM was (1.36±0.43)mm, (1.21±0.44)mm and (1.28±0.40)mm in vertical, horizontal and angular groups, respectively, with no significant difference ( F=1.07, P=0.35). The average thickness of lingual bone plate in RM of IMTM was (1.48±0.33)mm, (1.06±0.57)mm and (1.11±0.45)mm, respectively, with statistically significant difference ( F=8.78, P<0.01). The average thickness of lingual bone plate in RT of IMTM was (1.44±0.49)mm, (0.84±0.58)mm and (0.86±0.64)mm, respectively, with statistically significant difference ( F=12.35, P<0.01). Compared with the mandibular second molar, there were statistically significant differences in the average thickness of the lingual bone plate in ECB ( F=5.03, P<0.01), the RM ( F=15.13, P<0.01) and the RT ( F=33.12, P<0.01) of the IMTM among the three groups. In addition, the horizontal and angular IMTM, the thinness of lingual bone plate in RT region was more likely to occur than in vertical, and the absence of lingual bone plate was most likely to occur in patients with partial buccal crown. Conclusions:The doctor-patient communication and risk prediction should be sufficient before IMTM extraction when CBCT shows that the lingual bone plate of RT region is thin or absent. At the same time, we should avoid violent operation and thoroughly protect the lingual bone plate in the process of tooth extraction, and guard against serious complications such as perforation or fracture of lingual bone plate of mandible, and root displacement.