It is generally acknowledged that premature contact causes occlusal trauma and temporomandibular joint dysfunction. However, there are numerous points yet to be clarified concerning the changes premature contact would initiate in regards to the activities of the masticatory muscles.

In the present study, we, with the assistance of electromyography, detected masseteric excitation (periodontal-masseteric reflex) which is induced by pressure stimulation applied to the periodontaI membrane in dogs and human beings. Through the detection we clarified the influence of premature contact upon the masseter. We also discussed changes in the masseteric functions following the elimination of premature contact.

The results show that information generated from the periodontal membrane by premature contact will influence masseteric excitement and that this reflex will be formed and eliminated at arelatively early stage. Our findings also indicate that the information produced by pressure stimulation upon the periodontal membrane has the possibility of not only influencing the excitation of the masticatory muscles but also influenclng mandibular movement.

An aim of this study was to clarify the relationship between the difference in facial types and the movements, and the morphology of the temporomandibular joint (TMJ). The subjects were 46 persons (32 males and 14 females) aged from 22 to 34 years, who had no particular abnormality about the masticatory system. Facial types were classified into three: Brachyfacial type (B), Mesofacial type (M), and Dolichofacial type (D), by tracing the lateral roentogenographic cephalograms. The movements of mandibular condyle were recorded by the condylar movements recording system (CADIAX®), Gamma CO. Ltd., Wien, Austria), and the movements of articular disc were analyzed by using a magnetic resonance imaging (MRI). Morphology of the TMJ was also measured by using a computed tomography (CT) and standardized radiographs of TMJ. The results obtained were as follows:

1. No difference in quantity of condylar translation in protrusive movement at the most protruded position (QCTP) was shown between the three. But the inclination of sagittal condylar path (ISCP) was steeper in B than in D.

2. Quantity of condylar translation in opening and closing movement at the maximum opening position (QCTO) and quantity of the maximum condylar rotation in opening and closing movement (QCRO) were larger in B than in D.

3. B was larger than D in quantity of non-working side condylar translation in lateral movement (QCTL) at the eccentric position.

4. Quantity of articular disc movement was larger in B than in D.

5. Maximum cross-sectional area (MCSA), horizontal condylar angle (HCAN) and angle of posterior slope of the articular eminence (APSE) were larger in B than in D.

6. Some significant TMJ correlation was found between items of movement and items of morphology.

These results suggest that facial types will be related to TMJ movements and its morphology.

The purpose of this study was to confirm the localizations of basic fibroblast growth factor (bFGF), FGF-receptor (FGF-R) and transforming growth factor-β₁ (TGF-β₁) on the periodontal tissues during experimental tooth movement, by means of immunohistochemistry, using polyclonal antibodies. Male S. D. rats were used, and experimental tooth movement was performed under ether anesthesia according to the technique by Waldo. Orthodontic elastics were inserted between the left upper lst and 2nd molars. The rats were killed at 6 and 18 hours, and 3 and 7 days after the experiment. Paraffin sections 5μm in thickness cut from the left upper 1st molars and alveolar bones were stained immunohistochemically.The sections cut from the right upper molars were used for a control. On the tension side, there were immunoreactivities for bFGF and TGF-β₁ on the osteoblasts at 18 hours, 3 and 7 days. There were immunoreactivities for FGF-R on the osteoblasts at 6,18 hours. On the pressure side, there were immunoreactivities of the osteoclasts to bFGF and TGF-β₁ at 18 hours, 3 and 7days. There were immunoreactivities of the osteoclasts to FGF-R at 6,18 hours. These results indicated that bFGF, FGF-R and TGF-β₁ controlled alveolar bone resorption and formation during the experimental tooth movement.

We investigated the relationship between the acoustical characteristic of the nasalized vowels and the velopharyngeal incompetence (VPI) of cleft palate patients. Subjects were five male adult patients who had palatoplasty in their infancy. Cephalograms, digital recordings of Japanese vowels and magnetic resonance imaging (MRI) of head and neck were taken from sublects. MRrs were obtained while the patients pronounced single vowels nonnally. We employed the A-b-S (Analysis-by-Synthesis) method for the acoustical analysis of the / i / sound with our original software in a work station. The velopharyngeal opening areas were measured with a personal computer by using MRI’s of the velo-pharyngeal closure portion.The results showed that the antiformant frequencies were related to the velopharyngeal opening area, and the antiformant frequencies will be a useful index to VPI case. The acoustical estimation of the velopharyngeal opening area will apply to the training of speech improvement.However, to fully determine the relations between the antiformant frequencies and the velopharyngeal opening area, the followings are required, 1) measuring the entire area of the vocal tract including asymmetrical anomalous nasal passages and paranasal cavities, and 2) avoiding the artifact of MRI.

The aim of the present study was to clarify the morphological changes and location of the preexisting and neovasculatures, associated with the growth of tumor, by three-dimensional reconstruction of the distribution of arteries changing with the lapse of days after transplantation of the VX2 cancer into the rabbit tongue.

Serial sections of the specimens injected with India ink were prepared 3,7 and 14 days after transplant. The sections were observed with a light microscopy and photographed. The micrographs were inputted into a computer as image data. Tumor vessels were then reconstructed three-dimensionally using image analysis software VoxelView. The morphology and number of furcations of tumor vessels were examined. The diameter of these vessels were also measured.

In the specimens after 3 days, tumor growth inside the vertical muscle of the tongue, dilatation and tortuousness of the preexisting capillaries adjacent to the periphery of the tumor were observed. In the specimens after 7 days, cancer nests formed by the tumor and capillaries invading the stroma were observed. These capillaries took a basket-mesh-like running course different from the capillary network in stroma surrounding the tumor, which clearly indicated that they were neovasculatures. In the specimens after 14 days, dilatations of the dorsal lingual branches and precapillary arterioles, the reduced number of furcations and precapillary arterioles inside the tumor nest were observed, accompanied by the neovasculatures. In addition, dilatation and tortuousness of the preexisting capillaries observed at 3 and 7 days after tumor transplantation were identified in the surrounding tumor stroma in association with the tumor growth.

It is suggested that the changes of tumor vessels induced by transplanted VX2 cancer into the tongue will pass through three phases: dilatation, tortuousness of the preexisting vessels and angiogenesis in order.

The author has developed a new simple method with device for collecting the submandibular saliva in rats without taking tracheotomy which helps then breathe. The device makes it possible to use the identical rat, repeatedly.

1) To use special plate for fixing a non-tracheotomized rat was kept at an angle of 16.4 degrees, and the saliva was naturally dropped through a cannula inserted into a ductus of the submandibular gland in a urethane-anesthetized rat without taking tracheotomy. Furthermore, whether the identical rat are able to use repeatedly was examined by the comparison of amount of the submandibular saliva induced by sialogogues. The results are as follows.

The amounts of the saliva induced by pilocarpine (1.0~4.0 ㎎/ kg, s. c.), phenylephrine (1.25~5.0 ㎎ / ㎏.s.c.) and isoproterenol (0.156~2.5㎎ / ㎏, s. c.) increased in the dose-dependent manner respectively, at the first and the second experiments. No significant fluctuation was shown between the amounts of the saliva and the patterns of the salivary response at the first experiment and the ones at the second experiments.

2) Wet weights of the submandibular and sublingual glands in the rats 90 min after the injection of pilocarpine showed both at the first and the second experiments no significant fluctuations. These results indicate that it is possible to be used the identical rat repeatedly in the experiments of the response to the salivary secretion induced by sialogogues, by using the method with a special plate for fixing a rat.

The clinical symptoms of temporomandibular disorders (TMD) were examined in 306 primary school and 679 high school children in Mutsu City, Aomori Prefecture. These symptoms are classified into three types; joint sounds, pain and dysfunction, according to palpation and inquiry. In primary school children, 4.2% of TMD sounds and 0.7% of pain were observed. On the other hand, in high school children were examined 23.4% of sounds, 2.7% of pain and 2.4% of mandibular movement dysfunction. One or more combined symptoms of TMD was 13.0% in high school children. Incidence of normal occlusion in these subjects was 83.0% in primary school and 68.5% in high school children. Of the high school subjects with malocclusion was observed 16.9% of crowding; 11.0% of anterior cross bite; and 1.9% of maxillary protrusion.

In comparison with another report, the frequency of TMD in this district was almost the same percentage in primary school children, data in the high school children was shown to be less than that of another report which was surveyed in Tokyo. However, in high school children, the frequency was increased approximately 11%, compared to the report based on the data from the oral health examination of 1988 in Chiba Prefecture. From these findings, TMD in the young generation had a recogniźed tendency of increasing.

This study was done to examine the effects of protein and fat contents in the diet of mice on the resistance to demineralization of a tooth and the distribution of calcium and phosphorus in the enamel and dentine. Since the maternal generation, the mice were bred and given a diet of different contents;group H (high-protein: high-fat diet), group L (low-protein: low-fat diet) and group C (normal content diet). Electron probe X-ray microanalysis (EPMA) was used to determine the amount of calcium and phosphorus in the tooth.

The results were as follows: 1) The resistance to demineralization of the tooth was lower in a low-protein and low-fat diet, and increased with the additional content of protein and fat in the diet.Reach and over some amount, the tooth size had a tendency to increase becauSe of the diet, but the increase of resistivity was not remarkable. 2) Among the three groups, no particular difference of the concentrations in weight percent of both calcium and phosphorus was confirmed. 3) In all groups, both of the elements increased in the concentration in weight percent, from the surface to the inner limit of one third of the outer enamel layer. In the area of two thirds of the inner enamel layer decreased slightly toward the dentinoenamel junction. In the dentine layer, these two elements gradually increased in the concentration toward the depth of the tooth. 4) The resistance to demineralization of tooth group L was significantly lower than group H or group C. It is suggested that the intake of protein and fat in the formative period of a tooth may influence the resistance to demineralization.

During the last 7-year period from 1991 to 1997, β-hemolytic streptococci, Haemophili and in Moraxella (Branhamella) catarrhalis in throat of healthy school children in Morioka were examined. The results were summerized as follows. 1. The rates of isolation of β-hemolytic streptococci in lower-grade children were higher than in upper-grade children. 2. In the isolated β-hemolytic streptococci, group A streptococci were the most prevalent. The isolation rates of the group were from 61.3% to 96.6%, followed by group B, group G and group C streptococci. 3. Type T3 and T12 were dominant in this period: the isolation rates of type T3 were at the top in 1993 and 1994, and those of type T12 were high in 1991, 1992, 1996 and 1997. Although type T1, T4 and T28 were low epidemic T types, these types were isolated almost every year. A similar tendency was seen in the results of clinical specimens. 4. Genome typing of type T3 group A streptococci, which were isolated dominantly, was performed by pulse-field gel electrophoresis (PFGE). These were divided into two PFGE types. The two types were provisionally designed as type I and Ⅱ. Most of the isolates tested belonged to type I, and isolates of type H were observed only in 1994.5. The average rate of isolation of Haemophili was 6.3% regardless of the grade or year. 6. The rates of isolation of M.(B.) catarrhalis were higher in the lower grades than in the upper grades: 49.9% in the first grade and 17.7% in the 6th grade. 7. In the isolated M.(B.) catarrhalis, the production rate of penicillinase positive isolates was 87.4% and that of cephalospolinase positive was 81.7%.

Bacteria that are adhered to alginate impression material remains in the impression material, and the treatment to disinfect should be done during removal of the impression and cleaning of the tray. Therefore, experimental tray cleaner (EX) containing the surface active agent, (Sodium alkyl di-aminoethyl glycine), which has antibacterial effect is produced.

The purpose of this study was to examine antibacterial effect of EX, solutions of each component of EX (1.00% EDTA-2Na, 0.50% EDTA-4Na, 1.26% Na₃PO₄, 0.25% Na₂CO₃, and 0.04% ADEG-Na), Super Tray Cleaner^® (SP, SHOFU), and Treclean^® (TC, GC) to Staphylococcus aureus (IFO 14462).The results are as follows:

1. The surface active agent, ADEG-Na, showed stronger antibacterial effect than any other component of EX.

2. The EX was stronger antibacterial effect than the EX without ADEG-Na.

3. The EX had stronger antibacterial effect than SP and TC. It suggested that the ADEG-Na played an important part for antibacterial effect in EX.