The position paper from the American Association of Oral and Maxillofacial Surgeons (AAOMS) initially defined bisphosphonate-related osteonecrosis of the jaw (BRONJ) in 2007, and the Allied Task Force Committee of the Japanese Society for Bone and Mineral Research reported anti-resorptive agent-related osteonecrosis of the jaw (ARONJ) in their position paper in 2016. These position papers included significant modifications in the diagnosis and treatment of BRONJ, respectively. In the 2014 position paper definition, the following characteristics were added: exposed and necrotic bone, or fistulae that probe to bone. The added characteristic of fistulae is an usual finding in osteomyelitis of the jaw. The pathological characteristics of BRONJ conform to those of osteomyelitis of the jaw. In the 2010 Japanese position paper, surgical treatment was indicated only for Stage 3, unlike in the AAOMS position paper, but the 2016 position paper suggested that mobile segments of bony sequestra should be removed regardless of the disease stage. The diagnosis and treatment of BRONJ have been modified according to those for osteomyelitis of the jaw. However, the pathophysiology of BRONJ remains unclear. Stage 0 is considered the key for the elucidation of the pathophysiology of BRONJ.

Obstructive sleep apnea (OSA) is a social problem that can lead to cardiovascular disease, traffic accidents resulting from daytime sleepiness, and other effects due to sleep breathing disorders. Polysomnography (PSG) testing is necessary for the diagnosis of OSA at a professional medical facility but not all medical facilities can perform PSG testing. However, Japan has the highest number of computed tomographic (CT) scanners per capita, and the frequency of CT imaging is high. Therefore, CT imaging was studied to determine whether it can predict the severity of OSA and might be useful for understanding the anatomical pathophysiology of OSA.

　We enrolled 326 consecutive male patients with OSA who were younger than 65 years of age, given a diagnosis of PSG, and consented to CT imaging from April 2014 through March 2015 at the Ota Memorial Sleep Center (Kanagawa). We measured the details of the maxillofacial structure of each OSA patient by three-dimensionally constructing their CT data. All measurements, clinical findings, and patient backgrounds were evaluated by multiple regression analysis. Further, the results were evaluated in OSA patients divided into 2 groups according to their level of obesity.

　The group of non-obese (BMI <25kg/m²) OSA patients included 159 patients. Independent predictors of OSA were the hyoid position, the airway volume of the pharynx, the size of the tonsils, age, the anteroposterior length of the cranium, and the length of the tongue (R²=0.374). The group of obese (BMI ≥25 kg/m²) OSA patients comprised 167 patients. Selected independent predictors were the hyoid position, the BMI, and the anteroposterior length of the mandibular body (R²=0.393).

　A prediction equation created from the maxillofacial CT data can be used to predict the severity of OSA. In the future, we will develop standards for the CT analysis of these data to predict the severity of OSA.

Many patients who have received maxillofacial surgery require enteral nutrition; however, consideration might be necessary because such patients have gastrointestinal symptoms such as diarrhea during nutritional management. We evaluated the effects of a novel concentrated liquid diet, HINE E-Gel (E-Gel), which turns semi-solid in the stomach, on gastrointestinal symptoms as compared with the effects of HINE, which is a marketed and generally used concentrated liquid diet.

　A prospective randomized parallel open-label trial was conducted using E-Gel and HINE in 78 patients who required nasogastric nutrition after maxillofacial surgery. The test diet was administered from the day of surgery through 3 days after surgery (total 4 days) three times daily at a rate of 200 to 300 mL/hour. The dose was determined according to the patient’s sex and body weight. Achievement rates of successful nutritional control, body weight, nutritional parameters, and the occurrence of gastrointestinal symptoms were evaluated. The achievement rate of the successful nutritional control was 67.5% (27/40) in the E-Gel group and 39.4% (15/38) in the HINE group. The incidence of gastrointestinal symptoms such as diarrhea was 25.0% (10/40) in the E-Gel group and 50.0% (19/38) in the HINE group. There were significant differences between two groups in the two endpoints.

　In conclusion, E-Gel, which turns semi-solid in the stomach, improved the achievement rate of successful nutritional control and the rate of gastrointestinal symptoms during nutritional management after maxillofacial surgery.

Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue type, referred to as mucosa-associated lymphoid tissue (MALT) lymphoma, arises as a low-grade B cell lymphoma associated with chronic inflammation. This disease is relatively rare and accounts for 0.3 percent of all malignant lymphomas. In this article, we report a case of MALT lymphoma coexisting with diffuse large B-cell lymphoma (DLBCL) arising in the submaxillary gland along with a literature review. A 67-year-old woman was referred to our hospital because of indolent right submandibular swelling. Palpable 30 × 25 mm mass was observed on the right submandible. Computed tomography (CT) showed a well-defined oval radiopaque mass measuring approximately 30 × 30 mm. We performed submaxillary gland resection with the patient under anesthesia for a suspected submaxillary gland tumor. A diagnosis of MALT lymphoma coexisting with DLBCL was made on the basis of the histopathological examination and immunohistochemical staining. As additional treatment, 3 cycles of rituximab with CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) (R-CHOP) therapy were given after radiotherapy (36 Gy/20 fr) in accordance with the NCCN Guidelines. Currently, the patient is doing well with no recurrence.

We report a case of rhabdomyosarcoma arising in the buccal region of a 20-year-old male. He was referred to our hospital because of swelling in the right buccal region. Clinical examination showed an elastic hard mass with ulceration measuring 25 × 20 mm in the right buccal region. Magnetic resonance imaging revealed a well-defined mass of high signal intensity on T2-weighted images in the right buccal region. We removed the lesion via an intraoral approach.

　Histopathological examination showed that the tumor consisted of the small round and polygonal cells that showed an alveolar structure. Immunohistochemically, the tumor cells exhibited a positive reaction for desmin and myogenin. Based on those findings, the tumor was diagnosed as an alveolar-type rhabdomyosarcoma.

　The lesion was classified in group Ⅰ a of the Postsurgical Grouping Classification and stage 1 of the Presurgical Staging Classification according to the Intergroup Rhabdomyosarcoma Study (IRS) classification. Treatment was performed according to the IRS protocol. The patient received chemotherapy with intravenous injection of vincristine, actinomycin, and cyclophosphamide (VAC regimen) and radiotherapy (36 Gy).

　There has been no evidence of local recurrence or distant metastasis as of 3 years after surgery.

We report a case of Kikuchi’s disease that developed after extraction of a mandibular third molar. A 16-year-old girl visited our hospital because of bilateral gingival pain of the mandibular third molar region. After bilateral extraction of the mandibular third molars, she had bilateral painful submandibular and cervical lymphadenopathy with fever.

　Under local anesthesia, a biopsy of the cervical lymph nodes was performed. Histopathological examination showed proliferation of lymphocytes and histiocytes, apoptotic bodies, and a necrotic lesion. A definitive diagnosis of Kikuchi’s disease was made. The symptoms responded to treatment with prednisolone. There was no sign of recurrence for 8 months.

If the inferior alveolar nerve is resected by surgery for a mandibular tumor, the perception of its dominant area will be permanently lost. When we perform nerve reconstruction, autologous nerve grafting is usually performed, but there is a fault that we produce new neuropathy in the nerve-donor site. The nerve conduit, which is an artificial material, begins to be used for nerve amputation and deficiency, but there is no report about mandibular tumors. The patient was a 20-year-old man with mandibular ameloblastoma. We performed hemimandibulectomy, mandibular reconstruction with a free iliac bone graft, and inferior alveolar nerve reconstruction with a nerve conduit. The postoperative course was uneventful. Neurosensory disturbance of the mental nerve improved 5 months after surgery, and approximately normally status was recovered after 10 months. Currently, 2 years have passed since the operation, and there are no obvious abnormalities.

Arisaema serratum is a perennial plant with a corn-like fruit. However, the plant contains calcium oxalate, a compound that, when eaten, causes acute pain in the mouth and throat, swallowing difficulties, and intense abdominal symptoms, sometimes leading to death. We present the case of a 10-year-old boy in whom edema developed from his lips to his oral mucosa after accidentally eating an A. serratum fruit. He was referred to our emergency department after dramatic swelling of his lips and acute intraoral pain. We diagnosed A. serratum poisoning because of what he ate and provided emergency medical treatment. We performed oral care with saline and applied steroid ointment to his lips. He was hospitalized and was able to talk and eat normally after 6 days and was thus discharged. We need accurate knowledge on natural poisons to respond immediately to affected patients.

Methotrexate (MTX) has become the primary drug used to treat rheumatoid arthritis (RA). A 76-year-old woman visited our clinic for the first time in January 2017 because of ulceration and contact pain in the bilateral buccal mucosa and lingual margin, which had developed while receiving MTX therapy for RA. The patient had difficulty in dietary intake caused by intraoral pain associated with stomatitis and was thus hospitalized to undergo pain control and nutritional care. A diagnosis of MTX poisoning was made based on evidence showing an association with pancytopenia. After the withdrawal of MTX and administration of active folate, pancytopenia and stomatitis improved. Pancytopenia is an adverse side effect of MTX that is often fatal, while stomatitis is considered a prodromal symptom of pancytopenia. Stomatitis caused by MTX can be detected early by an examination performed by a dental or oral surgeon. Accordingly, to avoid an increase in severity in an affected patient, coordination with the attending physician in charge of their RA therapy is important.

We herein report a case of squamous cell carcinoma (SCC) arising in a pectoralis major musculocutaneous (PMMC) flap used for reconstruction after the resection of tongue cancer. A 54-year-old woman underwent resection of tongue SCC, right modified radical neck dissection, and reconstruction with a forearm flap in 2010. Soon after the surgery, another reconstruction was performed with a PMMC flap owing to necrosis of the forearm flap. She was making steady progress, but SCC was found in the center of PMMC flap, and the lesion was resected 5 years after the first surgery. There has been no finding of recurrence for over 1 year. There are some hypotheses on the causes of tumorigenesis in reconstructive flaps, such as chronic stimuli, mucosalization of the skin of the flap, and human papillomavirus (HPV) infection. Our patient showed persistent contact of the flap with the teeth due to immobilization of the flap, and immunohistochemical expression of p16, which is induced by HPV infection in dysplastic epithelium and SCC. Therefore, we considered that multiple factors were involved in the carcinogenesis in the PMMC flap. It is important to remove the stimulus and perform long-term follow up owing to the risk that SCC might develop in the reconstructive flap.