In order to investigate thc distribution of tissue mast cells (TMC) in the tongue, histological study was made in 10 Wister-strain male rats. The histological sections were stained with 0.1% solution (pH4.5) of toluidine blue (TB group) and orcein-water blue solution (OWB group). The number of TMC in TB group was 60.6±8.2mm²/5μ in the tip, 36.8±7.7mm²/5μ in the middle and 16.7±3.8mm²/5μ in the root, and that in OWB group was respectively 39.5±5. 0mm²/5μ,19.2±4.7mm²/5μ and 10.3±3.0mm²/5μ. As to the distribution of TMC in the tongue, there were significant differences from the tip on both groups (p<0.001).

It is known that the addition of vasoconstrictors to local anesthetic solution raises the pain threshold and prolongs the duration of anesthesia as compared to the anesthetic efficiencies of the soluttions without vasoconstrictors. In the present study, the depth and duration of anesthesia of a 2% lidocaine solution with norepinephrine (ranging from 1: 12,500 to 1: 50,000), phenylephrine (1: 5,000 to 1: 20,000) and methoxamine (1: 5,000 to 1: 20,000) were compared to those of the solution with epinephrine 1: 100,000, using the method of mental nerve block in guinea pigs as reported by Murai et al. The results obtained were summarized as follows: The depth and duration of anestesia of a 2% lidocaine solution increased markedly by the addition of norpeinephrine, phenylephrine and methoxamine to the solution, but the magnitude of such anesthetic efficiences were less than that of the solution with epinephrine 1: 100,000, except that the depth of anesthesia produced by the additon of methoxamine 1: 5,000 to the solution showed the same efficiency level as that of the solution with epinephrine 1: 100,000. However, no correlation was noted between the depth and duration of anesthesia of a 2% lidocaine solution, with or without the three vasoconstrictors.

This experiment was made to investigate the difference of total DNA content and nuclear size between multinucleate, mononucleate and mitotic cells which treated with cytochalasin B in culture.

Measurement of the DNA and nuclear size in each cells was done by means of the scanning microdensitometer utilizing on Nikon-Vickers M85 (Nippon Kogaku, Co., Ltd.).

The results obtained were as follows.

1) The DNA content was high in the followmg descending order: mononucleate cell, mitotic cell and multinucleate cell.

2) There was no significant difference between DNA content and nuclear size of mononucleate cells. On the other hand, in the multinucleate cells DNA content was in proportion to nuclear size but in mitotic cells there was no proportional relation between DNA content and nuclear size.

3) The frequency of polyploid cells in multinucleate cells increased together with the concentration of cytochalasin B and its incubation period. It was indicated that polyploidization in this strain was performed by the formation of multinucleate cells.

4)The frequency of polyploid mitotic cells increased with multinucleate cells. It was indicated that polyploid and multinucleate cells was endowed with karyokinetic activity.

The progressive muscular dystrophy (PMD) is an independent disease and so called one of the progressive muscular atrophy and dystrophy. Since 1968, the Japan Welfare Ministry have been started the study on the cause and treatment of PMD. This study was done a part of this project.

The study was made on the 51 PMD Patients using lateral head plate, plaster cast, and oral examnaition at Iwaki National Sanatorium. In majority an anterior open bite and posterior open bite were shown as a characteristic pattern and observed an exsistence of the cross bite of molar segment.

On the analysis of dental cast, inter molar distance on the mandibular arch was extermly wide, while arch length was shortenning oviously on the madibular.

According to the lateral head X-ray film, in many cases, observed steep mandibular plane, extensive Gonial angle and Gnathion came to downwards on the angular measurement, while cranial base and mandibular ramus were apparently undergrown on the liner measurement.

These findings suggested that there exists a definite correlation between a disorder of muscles and anomalies of Maxillo-facial bone structure.

With the devolution of maxillo-facial-cranium in the course of the progress of mankind, malocclusion with impacted teeth appears frequently. It is suppoused that the difference between the devolution of tooth size and denture base will develope more rapidly, and the incidence of impacted tooth will be appeared higher from now on.

We investigated that is about the stability of impacted tooth after treatment and the factors that influence on the condition after treatment. The results are as follows:

1. After the impacted tooth is retracted and guided into the dental arch in correct position, the conditions of the retracted tooth and tissues around it are stable, and are continued.

2. When retracted, the factor which has most important effect on the stability after treatment is curved root of impacted tooth. And it also suggested that retracted distance, the amount of axial change of tooth, and the ages when tooth is retracted are also important factors which have influence on the condition after treatment.

The purpose of this study is to compare SM-susceptible of strains of S. mutans with SM-resistant ones as to biological and serological properties, particularly adherent ability to glass surface and production capacity of insoluble glucan. As reference strains five S. mutans (E49, Fa-1, GS5, 6715 and LM7) were used and 10 strains isolated from dental plaque of carious patients were used as wild strains.

Results were as follows:

1. In both reference and wild strains colonial morphology and biological and serological properties of SM-resistant strains were similar to those of SM-susceptible strains.

2. SM-resistant strains of S. mutans GS 5 had higher adherent ability to glass surface and produced a large amount of insoluble glucan-1 in adherent-1 fractions than SM-susceptible strains.

3. Seven of 43 SM-resistant strains selected from S. mutans Fa-1 had higher adherent ability to glass surface than SM-susceptible ones.

4. Eighty-five of 141 strains of S. mutans isolated from dental plaque of patients of Oral Surgery Department developed colonies on Mitis-Salivarius agar plate containing SM 50μg/ml. Adherent ability to glass surface of those strains was higher than that of SM-susceptible strains.