Shika Kiso Igakkai zasshi = Japanese journal of oral biology最新文献

Difference in the activity of masticatory muscles between subjects with normal teeth alignment and occlusion and patients with disorders at the oral region was investigated using a differential Lissajous EMG method. Surface EMGs were recorded from the right and left temporal and masseter muscles during peanut and chewing gum mastications. The difference of the integrated EMGs between both sides was obtained in both the temporals and masseters, then two differences were synthesized to a Lissajous figure. The figures generally showed the following: 1) In the normal subjects, the muscle behavior varied from stroke to stroke in peanut mastication, while it was constant in chewing gum mastication. 2) Activity of some muscles of the patients was quietly weak, while that of the normal subjects was totally balanced. 3) In the patients, combination of use between the temporal and masseter muscles and contraction order among the muscles tended to be reversed compared to the normal subjects.

Rabbit buccal epithelial cells were studied by scanning electron microscopy. The cell surface was covered with type 4 microridges. The surface was also segmented by cellular borders and attached borders. Small area enclosed by the attached border was often elevated from the surrounding areas. The intervals of the microridges of this small protrusion were narrower than those of the surrounding area and resembled those of type 5 microridges. These findings suggest that exposure of the cell membrane to the external environment induces morphological changes in the microridges. The area surrounded by cellular borders, which was considered to have become small protrusions, was also observed. These observations suggest a staggered lamination of cell stacks and the penetration of a part of cell surface of the lower layer into the cellular space of the upper layer, forming an interdigitation. This cell arrangement is considered to enhance the strength of the binding of the cells.

Successive changes in the vascular pattern during the osseous healing of extraction wounds were investigated by studying microvascular casts under a scanning electron microscope. The casts were prepared utilizing the plastic injection method, after the extraction of the upper four incisors of the Japanese monkey (Macaca fuscata). Five days after extraction, vascular buds have sprouted from a pre-existing blood vessel on the alveolar wall into the blood clot, and leakage of the plastic injected was found from the tips of these buds. One week after extraction, newly-formed vessels have extended widely to the socket center, and dilated vessels have arborized towards the socket opening. Two weeks after extraction, the socket was filled with thick, newly-formed vessels. In the socket fundus, the woven bone was formed between irregular vascular networks, but was arranged different in the socket wall. Four weeks after extraction, the new bone forming on the socket wall became thickened and converted to a lamella-like bone. Inside it the woven bone was raised from the fundus, and blood vessels leaving it were decreased in their thickness and passed toward the socket center. Five weeks after extraction, the new bone structures came up to the level of the socket opening, the surface of which appeared as a shallow concavity (pivot), from which vascular bundles were directed to the socket opening. A beginning of the bone-remodeling was seen in osseous trabeculae in the socket fundus. Six weeks after extraction, almost all of the socket became filled with new trabeculae, between which, fine vascular networks were sorted out and communicated with the periosteal vascular network beyond the socket margin. The interalveolar septum between the extraction sockets was thickened by deposition of the lamella-like bone to be remodeled to a cancellous bone. It can be said that microvascular patterns formed through all stages of the osseous healing of the extraction wounds contributed to a woven bone formation and its development.

The external carotid artery and its branches were investigated in hens by an acrylic plastic injection method. The common carotid artery of hens bifurcated into the internal and external carotid arteries at the level of the second cervical vertebra. The external carotid artery advanced antero-superiorly within the platysma, stylohyoid, and occipitomandibular muscles at the postero-lateral side of the pharynx. Thereafter, it bifurcated into the anterior palatine and facial arteries between the pharynx and capitis rectus muscle at the posterior side of the medial mandibular process of the articular bone. The external carotid artery sent out the following branches: the occipital, hyomandibular, anterior temporal, sublingual, anterior palatine, and facial arteries.

The frequency of three rooted mandibular first molars was surveyed. Subjects were of 1,353 male and female students trained in radiology at Fukuoka Dental College whose average age was 24.3 years old. Dental (complete radiographic survey using 14 films) and panoramic radiographs of their mandibular first molars were taken during a period of 9 years from 1978 to 1986. The results were as follows: 1) The number of the three-rooted mandibular first molars was 440 (18.8%) of 2,331 teeth, including 240 (20.6%) of 1,163 in the right side and 200 (17.1%) of 1,168 in the left. 2) 274 (11.8%) of the three-rooted mandibular first molars were identified by radiographs of the premolar region, 42 (1.8%) by radiographs of the molar region, 124 (5.3%) by radiographs of both the premolar and the molar region. 3) Panoramic radiography identified 70 (15.9%) out of 440 three-rooted mandibular first molars. 4) 136 (12.7%) of 1,070 subjects who had bilateral mandibular first molars had three-roots on both sides 127 (11.9%) of 1,070 had them on one side.

In this study, we elucidated some characteristics of soluble sialidases in the rat salivary glands, brain, liver and kidney. 1) Soluble sialidases in the submandibular and parotid glands were inactivated by about 75 and 60%, respectively, and the enzymes in the brain, liver and kidney were also inactivated by 16-48%, when preincubated at 40 degrees C for 1h. When preincubated at 60 degrees C, the enzymes in all tissues were completely inactivated within 10 min. 2) Ca2+ ion in low concentrations tended to activate soluble sialidases in both the submandibular and parotid glands, but had no apparent effect on the enzymes in the brain, liver and kidney. The enzyme in the submandibular gland tended to be activated also by low concentrations of Mg2+. Both Cu2+ and Hg2+ ions caused a marked inhibition on the soluble sialidases in all tissues. 3) The molecular weight of soluble sialidases in the submandibular and parotid glands was determined to be about 68,000 and 46,000, respectively, by means of Sephadex G-200 gel filtration. The molecular weight of the enzymes in the brain and liver was almost similar to that of the enzyme in the parotid gland. In the kidney, soluble sialidase was separated into two enzymes, one having high (more than 500,000) and the other having low (about 46,000) molecular weight. 4) By isoelectric focusing analysis, three isozymes were detected in the submandibular gland and brain sialidases and two isozymes detected in the enzymes of other tissues. The isoelectric point of the major isozymes in the submandibular and parotid glands was 6.4 and 6.9 respectively. In the brain, liver and kidney sialidases, the isozymes with isoelectric point in the range of 4.4 to 6.7 were detected.

Tooth germs of rat incisors were examined by lectin-histochemistry in the portion from the apical end to enamel forming stage. Tissue sections were prepared from paraformaldehyde-fixed and paraffin-embedded tissues with or without EDTA-decalcification. They were stained with fluorescein-isothiocyanate-labeled (F- for short) lectins and observed by a fluorescent microscope. The boundary between inner enamel epithelia and dental papilla cells was stained with F-Con A, F-MPA and F-PNA. The boundary between the epithelia and dentin was stained with F-Con A and F-MPA. Stratum intermedium cells were stained with F-Con A, F-MPA and F-PNA, and were different in the time when they began to be stained with each lectin during their development. Distal cytoplasm of secretory ameloblasts and odontoblasts were stained with F-MPA and F-Con A, respectively. The staining with these lecting became stronger gradually from the apical to the incisal side. These results suggest that F-MPA and F-Con A are useful as a marker indicating the time when enamel and dentin begins to form, respectively. Distal cytoplasm of secretory ameloblasts was also stained with F-Con A and F-PNA. The odontoblastic layer was stained only with F-Con A, but the dental papilla was stained with F-Con A, F-MPA, and F-PNA. Stellate reticulum and outer enamel epithelia were stained with F-Con A and F-MPA. The comparison of the results from decalcified and non-decalcified tissues showed that the EDTA-decalcification scarcely affected these lectin bindings.

In order to clarify the bacteriological similarities of bacterial deposits formed on transistor pH electrodes (pH-ISFET) and enamel surfaces in vivo, bacteria were allowed to accumulate on indwelling electrodes in four human mouths, and the predominant bacteria were then isolated and characterized. Both the total number of bacteria accumulated per unit area and the population of predominant bacteria were similar for the electrodes and enamel surfaces, indicating that pH changes in the bacterial deposits formed on the electrodes can be representative of those occurring in natural dental plaque formed on enamel surfaces. Obligate anaerobes were predominant (68%) among the 346 isolates, and almost all the isolates were acidogenic. This may be a good reason why rapid pH-drop to pH 4 level was observed in every subject when 1% glucose or sucrose was applied to the bacterial deposits.