Orthodontic surgery improves stomatognathic functions such as mastication, swallowing, and pronunciation in patients with jaw deformity, as well as improving esthetics in facial features and dentition. It also contributes to the improvement of patients’ psychosocial problems and QOL. Among jaw deformity, 87％ are diagnosed with mandibular protrusion or mandibular retrusion, and most of them require mandibular surgery. Sagittal split ramus osteotomy （SSRO） and intraoral vertical ramus osteotomy （IVRO） are typical mandibular surgeries. However, intraoperative complications such as abnormal fractures and massive bleeding have been reported during these surgeries. Preoperative imaging diagnosis and planning are important for safety. Recently, preoperative evaluation using CT （computed tomography） has become common, in addition to conventional diagnosis and analysis using X-ray images such as cephalometric prediction. Further, preoperative surgical planning using 3D models and 3D simulation of orthognathic surgery using software are becoming popular. In the present review, we describe the key points of preoperative diagnostic imaging for safety and reliability during SSRO and IVRO.

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Many approaches have been used previously for early diagnosis of oral squamous cell carcinoma. Although several diagnostic methods such as vital tissue staining and liquid-based cytology are available, their application has not achieved satisfactory outcomes. Recently, optical devices have emerged as a non-invasive diagnostic approach that can be easily used even in general dental practice. Technological advances have led to rapid innovations in these optical devices, which are expected to become useful tools for early diagnosis of oral squamous cell carcinoma in the future.

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We investigated trends in the number of first-visit patients presenting at the Oral Diagnosis Department of Meikai University Hospital during a three-year period from January 2018 to December 2020 with respect to gender and age group, chief complaints, and systemic medical history, and examined the impact of the coronavirus disease 2019 （COVID-19） pandemic. The total number of new patients decreased in comparison with previous surveys. In April 2020, when the state of emergency was first declared, the number of patients decreased significantly, but thereafter recovered quickly. Toothache was the most common complaint, but before and after the pandemic, the number of patients who visited the hospital complaining of dissatisfaction with treated teeth or an abnormal taste sensation increased. There was no change in the general medical history of patients. The results of this survey suggest that new dental patients continued to visit the hospital for alleviation of oral complaints, despite the pandemic.

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Dental infections, including dental caries, periodontitis, and pericoronitis, are common conditions frequently encountered in routine dental practice. We conducted a study on 153 patients who visited our hospital for oral cellulitis between April 2016 and March 2021. The investigation items were as follows: area, age, gender, cause of tooth, cause of illness, underlying disease, onset period, hospitalization period, body temperature, WBC, RBC, HGB, Hct, Tp, Alb, and CRP. The results of the statistical analysis were as follows. The average age of the patients was 55 years, and oral cellulitis occurred most frequently in males aged 30 years or older. Apical periodontitis of the mandibular molars was the most common cause of oral cellulitis. The occurrence of oral cellulitis was more frequent in summer, and among the 53 hospitalized patients, 33 had underlying medical conditions. Patients with lower Tp and Alb values tended to have longer disease states.

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Impacted supernumerary teeth in the maxillary premolar region are often encountered. However, impacted supernumerary teeth in the molar region are rare. Furthermore, dentigerous cysts derived from impacted supernumerary teeth are very rare. We report the case of a dentigerous cyst derived from a mandibular ramus excess tooth that was removed using an extraoral approach.
The patient was a male in his 40s. CT images showed a dentigerous cyst originating from an impacted supernumerary tooth in the left mandibular ramus. The surrounding alveolar bone showed osteosclerosis. A model was made using a 3D printer before the surgery. After considering intraoral and extraoral approaches, the impacted supernumerary tooth and cyst in the left mandibular ramus were extracted using an extraoral approach under general anesthesia. Postoperative panoramic radiographs were taken, and no fracture of the left mandible was observed.

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Synovitis, acne, pustulosis, hyperostosis and osteitis （SAPHO） syndrome is a sterile, inflammatory disease of the skin and joints. It may also affect the mandible; however, it is difficult to determine whether unifocal mandible involvement is sterile or infectious in origin, often making the diagnosis difficult. We experienced a case of SAPHO syndrome with isolated involvement of the mandible that could only be diagnosed after successful diagnostic treatment. A man in his twenties who had been unsuccessfully treated for severe trismus and swelling of the left cheek and temporal region for about one month at another hospital was referred to our department for detailed examination and treatment. Lesions were found around the left mandible. Although a diagnosis of suppurative osteomyelitis was made and an antibacterial drug was administered after drainage, the symptoms improved and recurred repeatedly. Thus, we suspected a SAPHO syndrome lesion based on the clinical course. After consultation with the internal medicine physician, the symptoms were remarkably ameliorated by administering prednisolone as a diagnostic treatment. The patient has been continuing to receive a combination of drugs with no recurrence of symptoms for two years.

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We report a case in which an agar impression material entered the maxillary sinus. The patient was a 64-year-old woman who was referred to our hospital in October 202X for a detailed examination of a foreign body in the right maxillary sinus. Computed tomography （CT） revealed that the right maxillary sinus had a soft tissue-like radiopaque image, with a high-density amorphous structure in the center. Based on a clinical diagnosis of right maxillary sinusitis and a foreign body in the maxillary sinus, in February 202X, under general anesthesia, removal of the foreign body in the right maxillary sinus and radical surgery for the maxillary sinus were performed. The foreign matter was identified as an agar impression material by Fourier transform infrared spectroscopy.

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We report a case of early diagnosis of amyotrophic lateral sclerosis （ALS） due to dysarthria after prosthetic treatment. The patient was a woman in her 50s who visited our hospital with complaints of dysarthria and dysphagia. After prosthetic treatment at a dental clinic, the patient became aware of difficulty in swallowing and speaking. An intraoral examination at our department revealed fasciculation of the tongue and oral hypofunction. Since the patient’s father had died of ALS, we suspected ALS and referred her to the Department of Neurology, where she was diagnosed with ALS. The present case suggests that dentists may be able to assist in the diagnosis of ALS in the early stage of the disease and contribute to early intervention in oral hygiene management.

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Acute mandibular osteomyelitis is an intractable dental infection with severe pain, fever, and general malaise in the maxillofacial region. It is classified into four stages according to the degree, and spontaneous pain is remarkable in the advanced stage （Ⅱ）. It is said that specific pathological conditions such as Yumikura symptom and Vincent symptom are observed, but there has been no report of a case with allodynia in the same part. We report a case of acute mandibular myelitis with allodynia in the mental nerve region of the apical periodontitis of the right mandibular first molar reaching the mental foramen via the mandibular canal.

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