Aqueous solution of NaF, containing 10 to 250 ppm of fluorine was given per os daily to premature rats, which were sacrificed on the 3 rd to 55 th day after the begining of its administration. Macroscopically striation or lack of pigmentation and attrition of the incisor were observed. Microscopic observations were carried out especially on the enamel epithelium. On NaF-intoxication ameloblasts in the stage of matrix formation show in their cytoplasms SH positive substances like enamel matrix, and severe NaF-intoxication leads to a few cyst formation between the layers of ameloblasts and enamel matrix. The cells of the wall of large cyst were reduced in the activities of their alkaline and acid glycerophosphatase and alkaline adenosine triphosphatase together with loss of sudanophilic, acidophilic substance in the infranuclear portion of ameloblasts. Another portions of the enamel epithelium showed no remarkable decrease in an alkaline phosphatase activity. However, acid phosphatase in the stratum intermedium was occasionally reduced in its activity.
In maturation stage several changes of the enamel epithelium were noted; vacuolar degeneration, reduction of Fe-positive granules, presence of coarse Fe-positive granules, occasionally disappearance or nodular proliferation of ameloblasts containing remarkable Fepositive substances.
In long-term intoxication rats were given per os daily aqueous solution of NaF, containing 10 and 50 ppm of fluorine, for the period of 280 days. Macroscopically striation or lack of pigmentation were visible on the incisor of 50 ppmF group rats. But no sigificant change was histologically observed on the enamel organs of all these groups.
Another rats weighing 150-250 g each were operatively extirpated their unilateral salivary glands (parotid, submaxillary and sublingual glands) after 24-hours of fasting, then the rats received intravenous injection of 0.5-2.0 per cent fluoride solution (0.2-0.5cc of aqueous NaF and NaF·HF) . After various intervals, 7 to 60 minutes, the salivary glands of the opposite side were extirpated and histologically investigated. The following changes were observed; increase in the number of secretory granules in the striated tubules, discharge of granules, homogenous secretion in the lumen, irregularity of shape of secretory granules, coarse granules accumulated in the supranuclear portion, diminishing and/or disappearing in number of granules, and striated cells losing their cylindrical shape and elevating the cells from the basal membrane.
A profuse salivation occurred soon after intravenous injection of a toxic dosis of fluoride solution. From the histological finding it may be due to hyperf unction of the sub-maxillary gland. Furthermore, it is noteworthy that the striated tubules show a degenera-tive change.
No remarkable histologic change of the salivary gland was observed on the chronic fluorosis of the rat as given 10 or 50 ppm of fluorine per os daily during 280 days.

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Due to the hardness of complete sterilization of tooth surface, much caution should be concentrated on how to secure the local sterility when pulp chamber is opened aseptically.
The examination how to sterilize the tooth surfaces were carried on an extracted tooth and the result was checked by means of a sterility test medium which enabled to grow both anaerobic and aerobic organisms.
The results obtained from the 1st experiment on the surface sterilization concluded that the grinding off the surface is the surest method to develop the proper effect of disinfectants. To grinding off the whole surface above the rubber dam applied in a mouth, however, is apparently impossible in the practice. The 2nd experiment found that to cover the tooth with thinner film of celluloid was very useful for limitation of the grinding area small enough to bore the dental tissue to reach to the dental pulp. The role of the celluloid film covering the rest area seemed triplicate, i. e. smoothing the tooth surface to make sterilization easy, to prohibit the contamination by immobilization of local flora, and to stope the leak of saliva through the capillary space between the rubber dam and the tooth. The sterilization of rubber dam sheet in an autoclave had practical value but caused slight degradation.
As the final integration of these results, pulp of healthy teeth were removed under the aseptic circumstance indicated above.
1. Application of a sterilized rubber dam sheet on a tooth.
2. Covering the whole surface above the rubber dam and the adjacent of the tooth with celluloid solution, after drying.
3. The suface of small area to be opened toward the pulp chamber was removed with a sterile carborundam point.
4. One per cent Oyalax, kept at 37°C, was applied for the sterilization of the whole operation field, and washed out by sterile water. Desiccation.
5. After boring into the pulp chamber with a sterile bur, dental pulp was pulled out by a sterile barbed broach.
Cultures for sterility tests were taken from initial and final dental dust obtained by boring, the removed pulp and cotton peace used for dressing after the operation. No positive culture was obtainable at every specimens from 9 cases tested.

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Part. 1 Clinical Study
Transplantation of developing teeth were performed in eighty-five cases of the young adults. Fifty-five of them were transplanted autogenously, twehty-f our were transplanted homogenously, and six displaced teeth were surgically corrected their position. Results are as following:
1) Transplantation was succeeeded in seventy-five cases: Fifty-two autogenous (94.5%), seventeen homogenous (70.8%) and six surgical-orthodontical (100%) . Two months after operation, they were tightly held in alveolar bones, and they became to be able to stand the masticatory function.
2) Seventy-two per cent of transplanted teeth indicated vital reaction to the electric pulp tester eight months after the operation, and the teeth which had halfly developed roots on transplantation showed the highest per centage of vital pulps in this test The teeth homogenously transplanted did'nt show vital reaction.
3) In the cases of autogenous and surgical orthodontical transplantations, the formations of periodontal membrane and root apex was observed roentgenographically. In homogenous transplantation, however, no development of periodontal membrane and teeth were found although the reestablishment of alveolar bones.
4) The elongation of the root were not markedly.
Part 2. Experimental Study
1) The wounds of the homogenous and autogenous transplantation healed well on the histological observation, the epithelial attachments were located at cement-enamel junction, and no down growth of the epithelium to the apical were observed.
2) In the cases of autogenous transplantation; the osteoid and secondary dentin (in only apical portion) were added to the dentin surfaces of transplanted teeth narrowing the pulp chamber and the apical foraminae were formed by the addition of new cementum. Their alveolar socket walls and periodontium were also rebuild getting normal condition.
3) In the case of homogenous transplantation; the alveolar bone were build excessively resulting bony union with transplanted teeth and the periodontal membrane were not regenerated. Some resorption of the apical root surfaces of the transplanted teeth were observed after two months.
From these observations, it is considered that the autogenous and surgical-orthodontical transplantations should be performed more in clinic and that those teeth are expected to serve with a fairly good eternity.
The teeth with halfly developed roots are considered to be in the best conditions for transplantation.
The permanency of the homogenously transplanted teeth is considered less than expect of the autogenously transplanted teeth.

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There are two methods to determine the IEP of teeth substance (ampholyte), one is the method by means of color stuff buffer, the other is electro-cataphoresis. Dental enamel and calculus contain many inorganic substances, and it is difficult to dye, therefore the electro-cataphoresis is a propriety which determine the IEP of the same. The author determined the IEP by means of microscopic electro-cataphoresis apparatus and he devised glass measurements tube.
The results obtained are as follows.
1. At the IEP of dental enamel 3.8 is the highest depending on the histogram. Its average value is 3.744 ± 0.024.
2. According individual age we find out the difference in second teeth: 0-30=1, 31-50=2, 51- =3, and the results is that there is no difference between 1-2, but we find out the difference between 2-3, 1-3, (the dangerous rate 10%) . We find out a conscious difference between the primary and second teeth, (dangerous rate 5%) .
3. There was no conscious and sexual difference between male and female, and the same is of alveolar pyorrhoe and caries teeth.
4. There was no difference among the teeth of same men, therefore you may think of some individual difference in them.
5. According to the histogram of dental calculus the 4.1 and 4.2 was same percentage, its average value is 4.13 ± 0.07.
6. There was no difference between the IEP of salivary calculus and serum calculus in my experimental results at least.
7. It seems to me that the formation factor of the dental calculus is related to the IEP of teeth and various ingredients in saliva.

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The observation as to blood pressure and psychogalvanic phenomenon in the 153 examples of outpatients (extracting teeth) and those of 124 indoor patients shows the following results.
1. The fluctuation of blood pressure in the course of operation of extracting teeth can classify as the following five types. Type A: No fluctuation of blood pressure can be observed before, and in the course of, and after the operation. Type B: Rising of blood pressure after the operation. Type C: Falling and then rising of blood pressure in the course of operation. Type D: Falling of blood prassure after the operation. Type E: Falling of blood pressure soon after rising in the course of operation.
2. Major fluctuation of blood pressure is not found in the course of operation (extracting teeth), when 10cc of 1 per cent hydrochloric procain was injected for the purpose of anesthesia, with or without a drop of 0.1 per cent of adrenaline.
3. As to the patients (to extract teeth), when observed by psychogalvanic phenomenon, spiritual excitement is closely connected with the fluctuation of blood pressure.
4. As to the indoor patients, no sudden falling of blood pressure is not observed soon after the commencement of operation. Shedding of blood and anesthesia exercise great influence on the patients and generally an inclination of rising of the blood pressure in the beginning of operation, and falling in the course of operation and again rising in the last stage of operation is observed.

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The rare three superanumerary teeth were presented at the lower bicuspid region in an individual. Two of them were situated bilaterally at the medial of the first bicuspid, and one was at the distal of the second in the left side.
On their anatomical form, the former were showed much the same to the first bicuspid crown, but the latter was conical.

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A twenty five years female is presented, diagnosed as a dermoid cyst in the mouth floor, consisting of keratinous stratified squamous epithelial lining and loose connective tissue, with sebaceous gland scattering in the subepithelial layer.

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This is a statistical observation of 214 patients who visited our clinic with jaw fractures during the period from April 1934 to February 1957.
The results are summarized as follows:
1) The rate of frequency of fractures at mandibles and maxillae was three to one.
2) Fractures were found more in males than in females.
3) Fractures were found particularly often in the males of 20-30 years of age. However, 11.7% of all fractures were observed in the children under 9 years of age.
This frequency was very high in comparison with the reports of foreign observers.
4) The greatest part of the causes of those fractures were traffic accidents, and the next was labour accidents. Pathologic fractures due to chronic diseases were 6 cases and a fracture occured at tooth extraction.
5) The frequency of fractures was higher in May, June, September and October than in other months.
6) The fractures due to traffic accidents were frequent at 10-12 o'clock a.m. and 4-6 o'clok p.m. and those due to labour accidents were frequent at 10-12 o'clock a.m. and 2-4 o'clock p.m.
7) The direction of the fracture lines in mandibles are not always parallel with the axes of the teeth.
Most of them ran obliquely from supro-anterior to infro-posterior. Some of them ran paraller to the tooth axes. The smallest part of them ran from supro-posterior to infroanterior.
Most of the fractures lines beginning at the alveolar region between right and left cuspids ended at the lower edges below right or left 1 st bicuspids.
Those beginning at the wisdom teeth ended at mandibular angles.
Subcondyle fractures, coronoid fractures and a part of fractures in mental regions occured by the indirect shocks.
8) Most of chosen cases were successfully treated by traction gum elastics and the open reduction were used for old fractures.
9) For the fixation, the multiple loop wiring with 18-8 stainless steel have been applied since 1952 with good results.
10) Recently, severe infective complication is rare due to application of antibiotics.

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