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

In the forming initial dentine, each odontoblast extended a thick process perpendicularly to the basal lamina, and the collagen fibrils formed were divided into two groups based on their orientation. One was a group of fibrils running parallel to an odontoblastic process to organize the peri-process fibril bundles to organize the inter-process fibril bundles. This pattern of fibril orientation was similar in both crown and root. The diameter of each collagen fibril ranged from 30-100 nm in the crown and from 30-180 nm in the root.

As this study subjects, upper and lower dentitions of 49 mongrel dogs were used. X-ray films of the upper and lower dentitions of the dogs were taken. These films were from the collection of the Department of Pedodontics, School of Dentistry, Aichi-Gakuin University. Although the data on the sex and age of the dogs were not available, the dental ages were judged to range from the deciduous dentition to the early mixed dentition. Molars were not dealt with in this study for two reasons: 1) the molars of many of the subjects had not yet been calcified, and 2) the upper second and/or lower third molars, if present, had frequently been sacrificed when the jaws were separated. Numerical anomalies were observed in 16 dogs (32.7%). And infranumerary teeth were observed in 14 dogs (26.8%). Incidences of infranumerary teeth were higher in the secondary dentitions than in the primary ones. Most of the infranumerary teeth were found in both the upper and lower premolars, but not in the upper incisors and the upper and lower canines. Infranumerary teeth often occurred symmetrically whereas supernumerary teeth occurred asymmetrically. This investigation suggests that tendency of the reduction of the upper third premolar was considered to be caused by the reduction of the maxilla through the process of domestication. These results are inconsistent with Fujita's terminal reduction theory.

Histological changes in periodontal tissues of the first maxillary molars of immature rats following perforation down through the floor of pulp chamber were observed with light and electron microscopes. One and two weeks after perforation, ovally shaped epithelial islands were frequently observed in the apical end of the roots. Cellular cementum was being formed rapidly around the islands and the amorphous layer, containing scanty collagen fibrils and microfilaments, was observed between the epithelial islands and cementum. Four and eight weeks after the treatment, the islands were embedded in the cellular cementum and undergoing degeneration. In the bifurcational area, destruction of the periodontal tissues and subsequent proliferation of epithelium derived from the gingiva were observed. The epithelial rests of Malassez were characterized by enlargement of nucleus and cytoplasm. The results indicate that inflammatory stimulation induced histological changes of the odontogenic epithelial cells and enhances the formation of cementum. The possibility that the epithelial cells are associated with the formation of cementum is also suggested.

Lysosome formation was studied in rat junctional epithelium (JE) by detection of acid phosphatase (ACPase) using the cerium reaction method after intravenous injection of horseradish peroxidase (HRP). Intravenously injected HRP was endocytosed by the whole JE, especially at the coronal portion. ACPase activity was also observed in numerous organellae (vacuoles, dense bodies, multivesicular bodies and Golgi cisternae) in the junctional epithelial cells. These ACPase positive organellae often fused with each other, and their contents were mixed in the fused structures. The numbers of the ACPase-positive organellae in the HRP-exposed JE were more numerous than those in the JE without HRP, especially at the coronal portion. Thus, the distribution of the ACPase-positive products in the JE was closely related to that of HRP-positive products. These findings indicated that the whole JE has not only endocytotic ability but also intracellular digestion ability by the lysosomal enzymes.

Human cementum formation is a continuous process which occurs throughout life. Young cementocytes are situated near the periodontal membrane and old cementocytes towards the cementodentinal junction. Electron microscopic observations on 110 cementocytes of human permanent teeth were carried out to analyze the morphological and morphometric changes due to ageing. Cementocytes with ageing showed a rapid decrease in the number of the cell and a gradual decrease in the size of the cell, nucleus and cytoplasm. The location of the nucleus was changed from the periodontal side to the dentinal side and was hyperchromatic. Organelles showed a decrease in the size of the mitochondria, the rough-surfaced endoplasmic reticulum and the Golgi apparatus, meanwhile showing a gradual increase in the number of vacuoles and lysosomes. The cell death with ageing showed a rapid increase in number and their lacunae contained nuclear remnants, mitochondrial-like structures and fine fibrillar materials. Two distinct types of age changes were recognized: cytoplasmic swelling with scanty organelles and pronounced vacuoles, and cytoplasmic atrophy preserving the rough-surfaced endoplasmic reticulum in the narrowing cementum lacuna.

The localization of vasoactive intestinal peptide (VIP)- and substance P (SP)-like immunoreactivities within the submandibular salivary glands (SMG) of Balb/c male mice at 4 to 5 weeks of age were investigated. Two immunocytochemical methods using polyclonal, monospecific antibodies, the indirect immunofluorescence and peroxidase-antiperoxidase (PAP), were used to elucidate the localization of VIP- and SP-like immunoreactivities in the SMG. Both VIP- and SP-like immunoreactivities were positive in the SMG of Balb/c male mice at 4 to 5 weeks of age. The VIP-like immunoreactivity was found in the dense plexuses around the salivary duct and in the small scattered nerves surrounding glandular acini, and particularly in the nerve cell bodies of the submaxillary ganglion. The SP-like immunoreactivity was conspicuously abundant in the excretory ducts with a rich supply of SP-positive nerves, but also very scanty in the acinus areas close to the striated ducts and interlobular excretory ducts. It could be conclusively observed that the localization of the VIP- and SP-like immunoreactivities were different in the submaxillary ganglion, in the nerves around blood vessels and acinus areas, but very similar in the areas of the excretory and striated duct of the SMG.

The characteristics of the glycoproteins contained in the secretory segments of the three major salivary glands of adult male rats and the secretion of these various glycoproteins in response to autonomic agents were examined by micro-disc electrophoresis. Characterization of the glycoproteins showed that the acinar segments from the three major salivary glands and the segments of the convoluted granular tubules from the submandibular gland each contain characteristic species of glycoproteins. The glycoproteins characteristic of the acinus of the submandibular gland were secreted into saliva in response to carbachol or dobutamine, those characteristic of the parotid gland by carbachol, methoxamine, or dobutamine, and those of the sublingual gland by carbachol, whereas glycoproteins characteristic of the convoluted granular tubules of the submandibular gland were only elicited by methoxamine. The secretory response of carbachol, methoxamine and dobutamine, respectively, were almost completely reduced by pretreatment with atropine, prazosin and metoprolol. The relative proportions of glycoproteins secreted into the oral cavity from secretory cells of the three major glands varied significantly with the nature of the stimulant.

For better bacterial recovery from endodontic lesions, several bacterial culture conditions were studied. Samples taken from endodontic lesions of 26 freshly extracted teeth, and the bacterial growth was determined in 11 kinds of growth media under aerobic (in air with or without addition of 5% CO2) or anaerobic conditions (in an anaerobic glove box). Among the media tested, bacteria of endodontic lesions were most efficiently recovered in brain heart infusion medium containing 4% sheep blood (BHI-Blood) under anaerobic conditions. For routine dental practice, serum can be substituted for blood which makes the media opaque, resulting in clear media, and thus bacterial growth can be judged more easily.