Teruo Amagasa

Oral and maxillofacial tumours in children: a review

This retrospective review presents our experience of oral and maxillofacial tumours in children. The subjects were 250 children under the age of 15 years (out of a total of 2747 patients with oral and maxillofacial tumours), who were treated after histopathological confirmation of their diagnoses during the 28 years 1965-92. Diagnosis, incidence, and age at presentation were the main outcome measures and the results showed that 232 patients (93%) had benign tumours and 18 (7%) were malignant. The most common benign tumour was haemangioma (n = 69) and the most common malignant tumour sarcoma (n = 14). The most common odontogenic tumour was odontoma (n = 47) and non-odontogenic tumour ossifying fibroma (n = 5). The most common site of soft tissue tumours was the tongue (n = 65) and of bony tumours the mandible (n = 62). About a third of the tumours developed in patients between the ages of 6 and 11 years. Most of the angiomas developed in patients less than 6 years old, and most of the ameloblastomas in those over 12 years of age. Children accounted for 55% of patients with lymphangoma, 41% of those with odontoma, and 22% of those with haemangioma. It is concluded that most of these lesions were probably developmental malformations rather than neoplasms, and that the definition of oral and maxillofacial tumours in children should be reconsidered.

Aetiology of maxillofacial fracture

The aetiological factors associated with maxillofacial fractures, and the trends in these factors over a 13 year period are reported. The First Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Tokyo Medical and Dental University, managed 695 patients with maxillofacial fractures between 1977 and 1989. The male to female ratio was 3.2:1 and the majority of patients were aged between 10 and 30 years old. Road traffic accidents and accidental falls were the main causes of fractures throughout the 13 year study period. Mandibular fractures occurred in 477 patients (68.6%). A high percentage of patients were treated by closed reduction and maxillo-mandibular fixation, or occlusal splinting.

Oral malignant melanoma in Japan.

Clinical examination was performed on 20 cases of malignant melanoma in the oral region encountered at the First Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Tokyo Medical and Dental University, during the 22-year period from 1970 to 1991. In addition, we reviewed 140 cases reported in the Japanese literature since the last major review in 1974. The results of our study revealed that the clinical course of malignant melanoma in the oral region is worse than oral squamous cell carcinoma and that treatment by radiotherapy is effective in prolonging the life of these patients. Clinically, the tumors were classified into five types: (1) pigmented nodular type; (2) nonpigmented nodular type; (3) pigmented macular type; (4) pigmented mixed type; and (5) nonpigmented mixed type. We suggest that oral malignant melanoma might be different from cutaneous malignant melanoma and that new criteria for diagnosis and therapy for oral disease should be considered.

Maxillofacial fractures in children

A clinico-statistical and long-term follow-up study was performed on 81 pediatric fractures seen during the 14 years between 1977 and 1990. Of all maxillofacial fractures, the incidence of pediatric fractures was 14.7%. The ratio of boys to girls was 2.1:1, and the highest incidence involved boys over 13 years of age. Fractures of the upper alveolar bone and mandible were common. Conservative therapy, such as maxillomandibular fixation using orthodontic brackets was usually performed and was found to be successful. The long-term follow-up study revealed that 5 out of 21 patients with alveolar fractures complained of malocclusion and it is suggested that a longer duration of intramaxillary fixation and long-term follow-up might be needed for alveolar fractures in children.

Expression of bone morphogenetic protein genes in the human dental pulp cells

Dental pulp has a potential to induce ectopic bone formation, but little is known about its mechanism. We thought that bone morphogenetic proteins (BMPs), members of the transforming growth factor-beta (TGF-beta) superfamily, are involved in the osteoinductive activity of dental pulp. In order to prove this assumption, we constructed a cDNA library from primary culture cells of human dental pulp (HDP cells), and screened the library with previously cloned cDNAs for mouse BMP-2 and -6 as probes. Three distinct cDNA clones encoding human BMP-2, -4 and -6 were isolated. By Northern blot analysis, specific transcripts of the genes of those BMPs were detected in the HDP cells. It was concluded that the BMPs were expressed in a certain population of dental pulp cells and might play some roles in ectopic bone formation by dental pulp.

Ultrasonography in the diagnosis of palatal tumors

OBJECTIVEnThe purpose of this study was to evaluate the usefulness of ultrasonography for the preoperative evaluation of palatal salivary gland tumors.nnnSTUDY DESIGNnEleven surgically treated patients with salivary gland tumors of the palate were examined retrospectively. Intraoral ultrasonic scanning examinations were performed with a 10-MHz transducer.nnnRESULTSnThe ultrasonographically well-delimited tumors had a complete capsule histologically, whereas the poorly delimited tumors had no capsule or only an incomplete capsule. The tumors that had a reinforced posterior wall echo were associated with pressure bone absorption, and the tumors that had a reinforced posterior echo were associated with bone destruction. Echograms of the tumors were classified into 4 types on the basis of the internal echoes.nnnCONCLUSIONSnIntraoral ultrasonography of palatal tumors can be used to determine the localization and condition of the tumors by close analysis of the echogram. The internal echo pattern on the ultrasonogram of a palatal tumor was found to reflect the pathologic structure of the tumor. Ultrasonography can therefore be a quite useful technique for the preoperative evaluation of palatal salivary gland tumors.

Insulin enhancement of in vitro wound healing in fetal rat parietal bones

PURPOSEnThis study evaluated the effect of insulin on fracture in fetal rat intramembranous bone using an organ culture system in which bone mineralizes in vitro.nnnMATERIALS AND METHODSnTwenty-day-old fetal rat parietal bones were fractured parallel to the frontal plane and cultured in a serum-free medium with or without insulin for 4 to 12 days. They were then processed for light microscopy.nnnRESULTSnIn the specimens not treated with insulin, bony bridges were observed in less than 10% on day 4 and 8, and only 45% on day 12. In bones treated with insulin at 10(-6) mol/L, bony bridges were observed in 73% on day 4 and 100% on day 8 and 12. No callus or cartilage formation was observed during the wound repair process, indicating that intramembranous ossification occurred.nnnCONCLUSIONnThese findings suggest that insulin has a direct effect on bone cells, which enhances the healing of fractures in intramembranous bone.