The 2nd Department of Oral and Maxillofacial Surgery, Faculty of Dentistry Hospital, Iwate Medical University has performed radiation-combined intra-arterial chemotherapy as a preoperative treatment and subsequent mandibulectomy. During a 20 year-period from 1975 to 1994, clinical and histopathological examination of the above therapy was made for its effect and usefulness by using 15 primary cases of mandibular gingival squamous cell carcinoma, which were all identifiable.

Roentgenological examination by bone resorptive pattern (invasive type, erosive type) and by bone resorptive depth (degree 0-Ⅲ) revealed that early infiltration case and advanced case were predominant in the erosive type and the invasive type respectively.

Histopathologically, the therapeutical effect of the radiation-combined intra-arterial chemotherapy on the tumor cells was examined using osteoclast, fibrous connective tissue, osteoblast, new bone, site of neoosteogenesis, and post-treatment site of residual tumor cells as findings in the healing process. The histological therapeutic effect was good on well-differentiated type cases, and the histological effect on osteo-infiltrated region was as good as, or better than on soft tissue region. The cases with good histological therapeutic effect scarcely showed osteoclast, but showed remarkable hyperplasia of fibrous connective tissue, appearance of osteoblast and repair mechanism via neoosteogenesis. Invasive type tumor was persistent in the depth of the mandible, while erosive type tumor showed a tendency to be persistent in superficial layer.

The results suggested that the application of the present radiation-combined intra-arterial chemotherapy to mandibular gingival squamous cell carcinoma is very useful, leading to the improvement in radical curability of the tumor in its primary focus and the preservation of mandibular continuity in surgery.

We prepared a disinfectant-fixing combined solution (NCK) for an alginate impression containing 1%NaClO-0.2%CaCl₂-1%K₂SO₄. Calcium chloride (CaCl₂) inhibited swelling of the impression at a concentration of 0.15%, therefore, the surface roughness of the stone cast was improved. Potassium sulfate (K₂SO₄) itself showed a property that inhibited swelling of the impression. With calcium chloride, K₂SO₄ stabilized the size of the impression for long hours by inhibiting consecutive shrinking of the impression, which was attributed to the uptake of calcium into the impression. Changes in sizes of the impression immersed in a 1%NaClO solution for 60 min and surface roughness of the stone cast set against it were 0.78% and 1.45μm (mean values of 4 products) respectively. However, those values were reduced to -0.16% and 1.04 μm when the impression was immersed in a solution of NCK. The results showed that the values for the solution of NCK were significantly lower than the values for the solution of 1%NaClO.

Accordingly, NCK may be an excellent disinfectant-fixing combined solution for fixing an alginate impression and stabilizing the size of it.

Analyzing the correlation between the electrolyte concentration of the human resting-saliva and the radial bone mineral density (BMD), the following results were obtained. Salivary electrolyte and related indices such as pH₁, △pH₁, △pH_L, [Na⁺], and [K⁺] were measured by means of thin layer sampling.

1. Corresponding to the difference in radial BMD between the female groups of the nontreated osteoprotic patients and the nonosteoporotic patients, a significant difference was found in both the salivary pH₁ and [K⁺].

2. In the nontreated groups plus the nonosteoporotic female and male groups, significant positive correlations were found between radial BMD and pH₁ of the resting-saliva, as well as between the BMD and salivary △pH₁ in the nontreated group of high△pH₁ only in the females.

3. A significant negative correlation was found between the radial BMD and the salivary [K⁺] in the nontreated female group and the treated male group.

4. In the treated female and male groups, no signficant correlation was found in most of the parameters as previously stated.

5. Although no significant difference was found in the male groups, a significant difference in the salivary [Na⁺] was found between the nonmedicated female group and the medicated one. This suggests that the drug improving the bone metabolism can change the function of the salivary gland, in addition to that of the bone tissue.

In order to get information of the oral health status, decayed / missing / filled teeth and community periodontal index of treatment needs were evaluated by using thirty adult patients, aged 26-77 years, undergoing maintenance dialysis in a general hospital in Akita Prefecture. The mean numbers of teeth of patients, aged 26-39 years ,40-59 years, and 60-77 years, were 22.4, 14.3, and 10.6 respectively. The mean numbers of intact, decayed and filling teeth decreased with age, and particularly the decreased number of intact teeth was higher than that of decayed and filling teeth. On the other hand, the mean number of missing teeth increased with age.

All the patients were suffering from periodontal disease. The rate of patients with periodontal pockets decreased with age. The percentages of patients, aged 26-39 years and 60-77 years with shallow pockets, were 80% and 42% respectively, while those of patients, aged 40-59 years and 60-77 years with deep pockets, were 31% and 8% respectively. The rate of patients with no teeth or with no functioning teeth in the sextants increased with age. The mean numbers of sextants with calculus and with periodontal pockets decreased with age, but that of sextants with no teeth or with no functioning teeth increased with age. All patients required both improvement in personal oral hygiene and scaling. The percentages of patients, aged 40-59 years and 60-77 years, requring a high level of treatment, were 40% and 17% respectively. Increased tooth loss over 40 years might be attributed mostly to the progression of periodontal disease rather than to that of carious lesion.

The present study was conducted to investigate the relationship between magnetic resonance imaging (MRI) of the temporomandibular joint (TMJ) and clinical findings of patients having symptoms of temporolnandibular disorders, and to consider the possibility to grasp the internal derangement of the TMJ from clinical findings. Subjects were 80 patients who visited to ask orthodontic treatment, 16 males and 64 females. The average age was 22 years and 4 months. We performed a investigation of both their previous and present illness. In addition, to decide the correct condition concerning the internal derangement of the TMJ, patients were given MRI examinations (G. E. medical system Signa 1.5 Tesla) before orthodontic treatment.

Results were as follows: The three symptoms of temporomandibular disorders-noise, pain, and abnormal mandibular movement, were not related to constant disk displacement. It seemed difficult to infer and obtain the diagnosis of the condition of internal derangement of the TMJ only from clinical findings. In a dental clinics having no medical imaging instrument such as MRI, it was, however, considered that the following items will make it possible to define the condition of internal derangements of the TMJ from clinical findings.

1. As to respects concerning clinical findings, it is necessary to consider the previous illness as well as present illness.

2.TMJ noise indicates a higher relationship to the disk displacement in MRI findings.

3.The temporomandibular joint with plural symptoms indicated a higher incidence of disk displacement examined by MRImaging than that with a single symptom.

We studied the distribution and proportion of oral streptococci isolated from dental plaque and saliva of healthy adults and from subgingival plaque and fluid of gingival pocket of periodontitis patients to clarify the relation betweeen oral streptococci and periodontitis. α-hemolytic sreptococci were isolated from all materials of the healthy adults and the periodontitis patients. The isolation rate of β-hemolytic streptococci from dental plaque of the healthy adults was 20%, and the isolation rates of subgingival plaque and fluid of gingival pocket of the periodontitis patients were 25% and 65%, respectively. The isolation rate of non-hemolytic streptococci from dental plaque of the healthy adults was 35% and the isolation rates of subgingival plaque and subgingival fluid of periodontitis patients were 65% and 60%, respectively.The 670 strains of these isolated oral streptococci on the basis of hemolysis were identified as S. sanguis, S. gordonii, S. oralis, S. mitis, S. salivarius, S. mutans, S. sobrinus, S. anginosus, S. intermedius and S. constellatus through biochemical tests. The species which were identified by the biochemical tests, agree to the species identified by DNA-DNA hybridization. Eight of these strains were not identified by the biochemical tests, but were identified as S. sanguis, S. mitis and S. gordonii by DNA-DNA hybridization. The isolation rates of S. gordonii, S. anginosus, S. intermedius and S. constellatus from periodontitis patients were higher than those from healthy adults. These results suggest that those bacteria may be associated with periodontitis.