Advances in medical and demographic change due to aging, dentistry and oral surgery care has changed significantly. In point of the dental care in Japan, hospital dentistry and oral surgery improves the quality of treatment and the patient’s safety and secure. It has become necessary and essential. Hospital dentistry and oral surgery with a seamless cooperation with other departments and different jobs in hospital is believed to be a significant contribution to the future of dentistry.

　As shown in this paper, hospital dentistry and oral surgery according to the needs has various functions. Its significance is noted and necessity. It enhances the knowledge, the technology and the surgical techniques. Advanced oral surgery expertise and the cooperation of local and in-hospital seemed to be a mission of hospital dentistry and oral surgery. It increases the need for hospital dentistry and oral surgery in the future.

　At the same time this was believed to contribute significantly to improve the quality of local dental care and hospital dental oral surgery.

A clinical study was performed in patients with obstructive sleep apnea syndrome (OSAS) to clarify the effectiveness of an oral appliance (OA). In 40 patients, the mean apnea hypopnea index (AHI) was 24.7 ±19.3 /h at baseline, and they were classified into 13 mild (AHI 5 to <15), 18 moderate (AHI 15 to <30) and 9 severe (AHI ≥30) cases of OSAS. The AHI on OA therapy decreased significantly (P<0.0001) to a mean AHI of 5.9±5.1/h, and the improvement rate was 71.0±28.0%. Twenty-one patients (52.5%) had a successful response (AHI <5). There was no significant difference in the AHI on OA therapy among the mild, moderate, and severe groups. The AHI improvement rate was low (51.7%) in patients with a body mass index (BMI) of ≥25 kg/m²; however, there was no significant difference in the AHI improvement rate on covariance analysis assuming that BMI was a covariate. Therefore, the effect of OA did not depend on the BMI. There was no significant difference in the reduction in AHI among groups classified according to age or Epworth sleepiness scale (ESS). These results suggested that OA therapy was effective for mild and moderate OSAS cases and that improvement in AHI can be expected in severe OSAS or obese patients.

Palisaded encapsulated neuroma (PEN) is a benign, distinctive variant of cutaneous neuroma that is composed of normal nerve tissue. It usually presents as a solitary, asymptomatic, normal-colored papule. PEN should be histologically distinguished from other neural neoplasms, including schwannoma, neurofibroma, and traumatic neuroma.

　We present a case of PEN of the lower lip in a 50-year-old woman who visited our department because of an asymptomatic mass on her lower lip. She had no history of trauma. We suspected a fibroma based on clinical findings and removed the mass with the patient under local anesthesia. Histological and immunohistochemical examinations revealed a well-circumscribed spindle-shaped tumor, S-100 protein-positive cells, and neurofilament-positive nerve axons arranged in fascicles. The capsule of the tumor was positive for epithelial membrane antigen. The pathological diagnosis of the specimen was PEN. No sign of recurrence was observed 20 months after surgery.

　Cases of oral PEN, although a relatively common mucocutaneous peripheral nerve sheath lesion, seem to be rarely documented. This suggests that PEN might be misdiagnosed as other types of neural neoplasms. Immunohistochemical staining should be actively conducted for differential diagnosis between PEN and other neural neoplasms.

Basal cell adenoma (BCA) a ccounts for 1.5% to 7.9% of all salivary gland tumors. It frequently occurs in the parotid glands and rarely occurs in minor salivary glands. We report a case of BCA arising in the buccal mucosa. A 50-year-old woman was referred to our department because of a swelling in the left buccal mucosa. Intra-oral examination revealed an elastic-hard mass, approximately 25×20 mm in diameter. Ultrasonography, enhanced computed tomography, and enhanced magnetic resonance imaging showed a well-circumscribed mass. Fluorodeoxyglucose (FDG) -positron emission tomography showed abnormal accumulation of FDG in the buccal lesion. The mass was clinically suspected to be a benign tumor. With the patient under general anesthesia, extirpation of the buccal tumor was performed. Histopathological examination confirmed the diagnosis of BCA. The postoperative period was uneventful. At 18 months, the patient was well, without any complications.

We encountered a case of masticator space abscess caused by oral trauma. The patient was a 72-year-old man with the chief complaint of a remarkable swelling of the left side of his face and neck, sustained after injury due to a fall. Contrast-enhanced computed tomography showed that an abscess had formed in the masticator space and neck, where air had been found. We treated the patient by drainage of the temporal region, submandibular region, lateral upper neck, intraoral incision, and extensive surgical debridement. A large amount of pus was drained from the incision site, and the prognosis was good. Most of the masticator space abscess was caused by odontogenic inflammation. However in this case, there was no obvious odontogenic origin, and the buccal mucosa was lacerated due to a fall. We therefore thought that the abscess in the masticator space and neck was caused by injury of the buccal mucosa.

Trichofolliculoma is a rare benign tumor originating from hair follicle tissue and typically occurring on the face. Clinically, the tumor consists of a small, dome-shaped nodule, commonly with a central pore and an immature wool-like tuft. Histological examination shows a cyst lined by squamous epithelium with associated follicular structures. The keratin-filled, epidermal-lined cyst is a “primary” hair follicle with numerous radiating “secondary” hair follicles. Here we report a case of trichofolliculoma of the upper lip. A 70-year-old woman was referred to our hospital because of swelling of the upper lip and oral vestibule. Computed tomography and magnetic resonance imaging showed an upper lip tumor. Clinical symptoms had been modified by a history of verruca vulgaris in the nasal cavity, thereby precluding diagnosis. We performed resection of the tumor as a dermoid cyst. The histopathological diagnosis was trichofolliculoma. No sign of recurrence has been detected since the treatment.