The subsensitivity (Sub s.) of mouse salivary gland induced by the pharmacological denervation was studied applying the parameters, total amount of saliva and maximal salivary flow rate, on pilocarpine-induced salivation. Pilocarpine-induced salivation was measured by a modified Richter’s method.

The results obtained are summarized as follows:

1) The supersensitivity (Super s.) and Sub s. of mouse salivary gland were induced after the withdrawal of the chronic administration of atropine (0.008-5mg/kg/day for 7 days), chlorpromazine (4 and 40mg/kg/day for 7days), amitriptyline (2 and 12mg/kg/day for 7 days), and promethazine (1.25 and 10mg/kg/day for 7 days).

2) The induction of Sub s. of mouse salivary gland was confirmed by the shift of dose-response curves to right.

3) The Sub s. developed only after the induction of the Super s.

4) Duration of the Sub s. was dependent on the dosage of the drugs.

5) Factors, such as the decreased information capacity accompanied by decreased number of binding site in receptor site as well as increased dsappearance rate of chemical mediators from active site, were responsible on the development of Sub s.

The present results show that the Sub s. post denervation is induced on the salivary gland as well as the sweat gland by the pharmacological denervation procedure.

Histological and histochemical studies of the influence of dexamethasone (DXM) on the periodontal tissue during experimental tooth movement were carried out by using forty five male Wistar strain rats. The animals were divided into four groups. The first group was untreated. The second group was intraperitoneally injected DXM in doses of 4 or 8 mg per 100g of body weight without tooth movement. The third group was moved their upper molars by Waldo’s method. The fourth group were injected DXM with experimental tooth movement.

1. In non-administered rats with tooth movement alkaline phosphatase activity at periodontal membrane of pressure side was lower than that of tension side, and acid phosphatase activity at pressured periodontal membrane was higher than that of tension side.

2. In DXM-administered rats with or without tooth movement activity of alkaline and acid phosphatase at periodontal membrane was lower than that in non-administered rats.

3. In DXM-administered rats with experimental tooth movement the apperance of osteoclasts was inhibited.

4. By finishing administration of DXM the number of osteoclasts recovered in control level.

The dentinogenesis in the incisor teeth of adult rats that were orally administered with 0.1, 0.5 or 2.5μg/kg body weight (b.w.)/day of 1α-hydroxyvitamin D₃(1αOHD₃) for 30 days was studied with special reference to osteodentin formation. The decalcified maxillary incisors were examined by light and electron microscopy. Conspicuous osteodentin formation was observed only in the highest dose group. Small defects appeared at some intervals on the pulpal side of dentin in the middle-third of the tooth. The dentinal defects were occupied by many regressive odontoblasts, some of which were embedded in the irregular dentin just above the defects. Moreover, in the middle-third of the pulp, predentinoid tissue was frequently observed in the subodontoblastic area except for the regions where dentinal defects could be seen. Ultrastructurally, predentinoid tissue was composed of dense collagenous matrix containing small round membrane-bound vesicles similar to matrix vesicles. One or two cytoplasmic projections, which were very akin to bonafide odontoblast processes during early dentinogenesis morphologically, were often extended from the proximal aspect of the odontoblasts in contact with the predentinoid matrix.

A mass of osteodentin was observed in the apical-third of the dentin. From these results, we suggest that at least two different processes participate in the formation of osteodentin after the daily overdosage of 1αOHD₃, i. e., the partial regression of odontoblast population and predentinoid formation in the subodontoblastic area.

The antisialagogic effect of chlorpromazine (CPZ) on the salivation controlled by the adrenergic system was examined in mice treated with CPZ chronically. The measurement of phenylephrine (PHE, 20mg/kg, s. c.) -induced salivation in mice was carried out by the modified Richter’s method. CPZ (2 and 40mg/kg, s. c.) and phenoxybenzamine (PBZ, 0.05 and 2.5mg/kg, s. c.) were successively administered to mice once a day for 21 days. The results are summarized as follows. (1) CPZ and PBZ administered singly inhibited PHE-induced salivation dose-dependently. (2) The antisialagogic action of the these drugs did not change during the period of the chronic administration, except for that of a large amount of CPZ (40mg/kg/day×21 days). (3) The change of the antisialagogic action induced by CPZ on the chronic administration may be due to the development of the pharmacological denervation supersensitivity. (4) Thirst and dry mouth induced by clinical long term administration of CPZ may be mediated by not only parasympatholytic action but also sympatholytic action of CPZ.

In order to investigate a transverse patatine fold function, ovserved the course of the transverse palatine folds and teeth eruption in miniature swines.

For the orientation and positional identification of the transverse palatine folds and the teeth, the plaster models and X-ray examination were collected at every week regularly.

The results were as follows:

1. The number of folds in miniature swine ranges from 20 to 25, and the mean number is 22.

2. The number of transverse palatine folds was continuous since the period of the deciduous dentition to the permanent dentition.

3. The most posterior fold is situated a position in the vicinity of the distal side of rear molar tooth.

4. The shapes of the transverse palatine folds are related of the masticatory function and those posterior parts are associated with swallowing.

In order to investigate the precise growth and development of the maxilla, mandible and dentition on the miniature swine. The serial plaster models which were taken every week from 6 males miniature swines from 6.5 month old to 36 month of age were used.

The result were as follows:

1. The length of maxilla increased markedly for the 6.5 to the 24 month, and subsequently it was on the decrease gradually from the 24th month to the 36th month and increasing was completed at this time. The growth value was compared between the ages of a 6.5 month and a 36 month. The growth rate had become 1.5 times.

2. The length of mandible favorably increased until 12 month. The enlargement was remarkably at the regions of the canine.

3. Upper second molar erupted after making the space in which the upper second molar would erupted. However at the lower second molar region, the basal alveolar process length tended to increase during this tooth eruption.

4. The growth center was located at the first premolar region.

Nine cases of several complications arised from the fracture of dens evaginatus occurring in premolars are described. Being studied about the clinical findings and the treatments of these cases, the results were as follows.

The complications were found in patients having an average age of 10.7 years. The most complicalions arised from the fracture of dens evaginatus locating in the central groove on the lower second premolars, Most of cases had incomplately developed roots with wide-open apices and the pulpes were necrotic or inflamed, As to the treatments, the fillings of the pulp canal with Vitapex^® (improved Calcium hydride paste) are successfully for the apical closure of immature pulpess teeth.

Excepting the teeth with complications on the fracture of dens evaginatus, eight cases had the other teeth with dens evaginatus. It was considerated that this fact gives effect to the teeth with the complications.

The Pathological analysis on 22 cases of fibrous lesions of the jaws was performed. These cases were classified according to WHO’s classifications: 4 cases of ossifying fibroma, 5 cases of cementifying fibroma, 6 cases of fibroma, 5 cases of myxoma, and 2 cases of fibrous dysplasia. Majority of clinical symptoms of the patients with these lesions was swelling in the affected area. The lesions showed a striking predilection for the premolar and molar regions of the mandible. Size of the lesions had a tendency to extensive. Sex predilection was unclear.

Anterior maxillary axial occulusal projection is a significant method to visualize anatomical locations of supernumerary, unerupted, and impacted teeth, foreign bodies and the lesions in the anterior maxilla exactly. The purpose of this study is to review the exposure conditions of the conventional anterior maxillary axial occulusal projection and to evaluate the diagnostic performances of the radiograms with a grid and without a grid.

Fuji RX films (screen type) were used with a screen (Kyokko, PS-II), with screen and grid, and without screen and grid. Radiograms of the test chart were performed with these films using a screen with a grid and without a grid under the same exposure conditions. Radiograms of the maxilla of Rando phantom (Alderson Co.) were performed with Fuji RX films using a screen and agrid on tube potential 60 kV, 70 and 80 respectively. Anterior maxillary axial occulusal projections of a patient were performed using the same screen system with a grid and without a grid by dental X-ray exposure unit. All of the radiograms obtained were evaluated for the diagnostic performances by 9 radiological stuffs.

No significant differences of diagnostic performances among radiograms performed on 60,70 and 80kV are exhibited. Radiogram of a patient with a grid has better diagnostic performances than that of without a grid. The results suggested that the application of a grid with screen system is useful to the anterior maxillary axial occulusal projection. For the reduction of dose to patients, dental X-ray unit with variable tube potential is recomended to the projection.

DNase fractions, designated here Fr. I and Fr. Ⅱ were isolated by the lysozyme digestion and Brij 58 treatment from aerobically cultured Streptococcus sanguis I.

Optimal pH value of both enzymes was 8.5 and metal ions such as Mg²⁺, Mn²⁺, Ca²⁺, Cu²⁺ did not have any effect on their activity.

On the other hand, the extracellular DNase activated by the addition of Mg²⁺ or Mn²⁺ but was inhibited by Ca²⁺ or Cu²⁺. DNase activity was inactivated especially with high concentration Cu ion (0.1mo1/ml).

Molecular weight of these DNases was determined hy SDS-PAGE. Fr. I was about 85,000~90,000 daltons and Fr. Ⅱ about 40,000~45,000 daltons. Molecular weight of the extracellular DNase was different from that of cell surface DNase. On 0.8% agarose gel electrophoresis both Fr. I and Fr. Ⅱ hydrolyzed native thymus DNA, lamda DNA, fd DNA, and thermally denatured thymus DNA. The specific activity of Fr. I was higher than that of Fr. Ⅱ when the substrate was native thymus DNA, while in another substrate it was smaller in Fr. I than in Fr. Ⅱ.

From these results it can be concluded that the cell surface DNases have poor uniqueness on enzymatic activity, while the extracellular DNase has special activity that the enzyme hydrolyzed native thymus DNA only. There were differences in the DNase activity between Fr. I and Fr. Ⅱ.