Histopathological study of Bioglass granules and calcium hydroxide powder implanted in subcutaneous tissue was made experimentally. The animals used were male Wistar rats, and were sacrified 5, 10, 20, 30, and 40 days after subcutaneous implantation of Bioglass granules and calcium hydroxide powder. The results were as follows: 5 and 10 days after implantations, calcium hydroxide powder and Bioglass granules were surrounded by granulation tissue, but the amount of granulation tissue around the calcium hydroxide powder was greater than that around the Bioglass granules. 10 days after implantiation histiocytes phagocytizing the Bioglass granules were scattered throughout the granulation tissue. 5 and 10 days after implantations, necrosis of the muscle tissue adjacent to the calcium hydroxide powder was noted, but such finding was not noted adjacent to the Bioglass granules. Calcification of calcium hydroxide powder began 5 days after, on the oter hand, such calcification of Bioglass granules began 10 days after. The wound healing was slower in calcium hydroxide powder-implanted cases than in Bioglass granules-implanted cases.

Statistical evaluations of various causes and pathological findings of the maxillofacial defect, as well as a variety of maxillary prosthesis and the reasons for their usage were analyzed from a clinical point of view in 56 cases.

Out of 56 maxillofacial defects, 50 cases were due to malignant tumors (42 maxillary defects and 8 mandibular defects). Results of the pathological findings of the maxillary defects when analyzed using the HS classification, showed 20 cases to be H₄ (45.5%), 27 cases to be S₀ (61.4%), 16 cases to be D₀ (36.3%), and 20 cases to be T₄ (45.5%), each being the largest number in their respective categories. A correlation between defects in the palatum durum and the alveolar bone to the degree of mouth opening revealed that the greater the area of defect the lesser was the degree of opening. Consistency and continuation of those mandibula which underwent tumor extirpation or reconstruction was maintained in most cases and found to be relatively good. ln recent years, the obturation portion of the maxillary prosthesis has shown a gradual increase in the buccal flange type obturators. Regardless of the region or cause of defect, in most cases, the maximum period of time necessary from actual surgery to placement of the maxillary prosthesis was 1 year enabling the patient to a quick return to nomal life.

An experimental study was carried out to evaluate the effectiveness of alveolar bone preservation of submerged-root implants, immediately after tooth extraction in dogs. The mandibular bilateral first molar was extracted, under general anesthesia, and two types of implant materials (single-crystal sapphire and solid hydroxyapatite) were embedded at various depths in the extraction sockets. The animals were sacrified at 3, 12 and 30 months after the start of the experiment. On some occasions, during the experiment, standardized radiography was employed to evaluate the bone modelling around the implant. The radiographs were taken at the start of the experiment and at intervals of 1, 2, 3, 12 and 30 months. The results were as follows:

Radiographical investigation revealed that the 2-types of implants were well retained in the jaw bone throughout the experimental periods, but no statistically significant difference in the height of the alveolar bone was observed between the 2-types when compared with the controls. When the implants were embedded with their tops at 20% of the depth of the socket, they became completely covered with newly formed bone. The significant differences were histopathologically observed. The single-crystal sapphire implants were surrounded by a thin fibrous connective tissue layer, while the solid hydroxyapatite implants were surrounded by newly formed bone no connective tissue layer. During the 3 months from its beginning, contact-microradiographs showed newly frormed trabecular bone developing around the implants. This architecture of bone structure was maintained throughout the experimental periods and was similar to that of normal alveolar bone.

A long-term clinical follow-up study was carried out with ten patients who had been wearing complete dentures after root submergence for alveolar bone preservation. Crowns were removed from 28 selected vital teeth and one endodontically treated tooth at a level with the crest of the alveolar bone, and the submerged roots were covered with mucoperiosteal flaps. Then a 7.5-year clinical and radiographic follow-up was made. The findings obtained in this study are as follows.

The ratio of successful root submergence was about 45%. In the successful cases, the alveolar bone surrounding the submerged roots was maintained at the same height as the amputated root surface. The number of failures was 16,(55%, 16/29).

As the result, however, the ratio of roots that could be retained in a healthy state over a long term by means of the root-submergence procedure was higher than that in previous reports. Therefore, it was suggested that the root-submergence procedure could be useful as a means of preventing residual alveolar ridge reduction. The failure of root submergence during the primary healing period may be associated with poor surgical procedure. The failure during the later healing period may be associated with poor prosthetic procedure. In determining the height of root amputation special attention should be given to the characteristic structure of the alveolar bone surrounding the submerged roots in order to obtain good results. Adequate recall and prosthetic treatment may also increase the rate of successful root submergence.

An experimental study was conducted to improve the prosthetic and surgical results of the root-submergence procedure. Crowns of four mandibulars were amputated at a level 1mm below the original alveolar crest. Vital and endodontically treated roots of nine dogs were submerged and studied histologically over a period of 540 days postoperative period.

In the vital root submergence group, a dentin bridge at the pulp amputated surface, new bone over the root amputated surface, and osteocementum on the dentin amputated surface were formed 4 weeks after the operation. These tissues continued to mature. The tkickness of the new bone 540 days after the operation was less than in the early stage of the experiment.

On the other hand, these reparative processes of hard tissues were somewhat delayed in the endodontically treated submerged roots. The findings obtained in this study suggest the following: A reparative process of the vital submerged root was mostly accomplished in the early stage, 180 days after the operation. It was thought to be good for the formation of dentin bridges if roots were amputated at a level 1mm below the original alveolar crest. In the endodontically treated submerged roots, it was found favorable to place some bio-compatible material on the amputated root canal surface.

Effect of the 24-h fasting on the spontaneous motor activities: vertical (VMA), horizontal (HMA) and wheel-running motor activities (WRA), induced by a single administration of methamphetamine (2mg/kg, s.c.) and apomorphine (0.1mg/kg, s.c.), alone or in combination, to male ddY mice weighing 18-22g, was examined. The results are summarized as follows.

1)With fasting VMA increased markedly and HMA increased slightly, but no increase in WRA was noted.

2)When methamphetamine was administered to fasting mice, VMA increased significantly over that of mice which were fed. While HMA and WRA in fasting mice receiving methamphetamine showed the same patterns as those in mice which were fed.

3)When apomorphine was administered to mice which were fed and fasted VMA, HMA and WRA decreased at an early stage of the experiment.

4)When methamphetamine and apomorphine, in combination, were administered to fasting mice, VMA showed biphasic patterns comprising a decrease and an increase, while HMA showed a decrease and WRA showed an increase.

These results suggest that fasting may modify the activity of the central dopaminergic function.

Differences in surface stress on denture base resin was generated by a difference the heating and cooling condition. The surface stress value was measured by a laser surface stress meter before and after removal from the mold. Also the relation between the discrepancy and the above mentioned conditions was examined.

The results were as follows:

1. The surface stress value after heating increased more during rapid cooling than during slow cooling.

2. The surface stress value had a tendency to increase more at a temperature of 100℃ than at 70°C.

3. The surface stress value remained almost constant before and after removal from the mold and showed no stress relaxation at the alveolar area. Stress relaxation at the palatal area was noted after removal from the moid.

4. The amount of discrepancy was greater at 100℃ than at 70℃ and further increased during the rapid cooling condition.

5. The laser surface stress meter is usable in the direct measuring method of the surface stress generated in a denture.

Lymphoepithelial cyst often occurs in the lateral cervical region but is rarely seen within the parotid gland. This paper reports one case of lymphoepithelial cyst within the parotid gland. The subject is a 59year-old male who appeared at our hospital complaining of a painless swelling of the left parotid gland. A 50 x 40mm palpable tumor was found in the left parotid gland region. Resection of the tumor was performed under general anesthesia and it turned out to be a single vesicle cyst having lymphoid tissue with some follicules. It was diagnosed histopathologically as a lymphoepithelial cyst. There has been no recurrence of the tumor three years after operation.

An autopsy case of doble cancer in the gingiva of the mandible and the esophagus was reported.

The case, an 86-year-old man, had a well differentiated squamous cell carcinoma in the mandibular alveolar mucosa. Autopsy revealed an additional moderately differentiated squamous cell carcinoma in the lower part of the esophagus. The criteria for diagnosis, incidence, age and affected organs were discussed from clinicopathological findings reported in the Annual of the Pathological Autopsy Cases in Japan.

A woman became unconscious during dental treatment with an injection of local anesthetics. Until she was twentyfour years old, she had no trouble when under dental treatment. Because this problem occurs sometimes while under dental treatment, people are not anxious about it. But, we desired to know the reason, so we discussed the reasons for her loss of consciousness. We suspect that the reason for her becoming unconscious was a combination of the following: toxicity of adrenalin (hypersensitivity of adrenalin), an excessive pain reflex, vegetative dystonia and a hyperventilation syndrome.

We had an opportunity to make an oral examination of a 93 years-old woman who still conntinues the old custom of blacking her teeth. A summary is herewith reported, along with an addition of some bibliographic and clinical considerations.

There is a traditional tale from ancient times that women who black their teeth rarely have dental caries.

Our opinions concerning oral examination of the patient were that there were 26 residual teeth and dental caries were not found, however slight mobility was acknowledged in all teeth. A slightly decayed gingiva due to periodontitis and gingival restractlon was acknowledged in one molar tooth. Bone resorption was observed by X-ray diagnosis.

It seems that there were preventive agents in the tooth black that made such conditions possible even at such a great age.