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

Effects of lidocaine-HCl on extrafusal muscle fibers in the masseter muscle of developing mice were studied histologically and morphometrically. In the affected region, many extrafusal muscle fibers were circular and smaller in diameter than unaffected extrafusal muscle fibers, and the SDH activity of the affected fibers was very irregular. In lidocaine-HCl injected groups, the ratios of extrafusal muscle fibers with central nuclei to total extrafusal muscle fibers were higher than those in the saline solution-injected groups. The diameters of extrafusal muscle fibers in the masseter muscle treated with lidocaine-HCl were smaller than those in the saline solution-injected groups. These changes in the muscle with lidocaine-HCl continued for 45 days after a single injection. Five injections of lidocaine-HCl into developing mice caused long-term degeneration of the masseter muscle. Thus, the present study suggests that a local anesthetic agent caused degeneration of immature muscle fibers of the masseter muscle in developing mice and may result in long-term decrease of masticatory capacity. Therefore, lidocaine-HCl may inhibit the synchronized development of masticatory organs in developing animals.

Hyaline bodies in odontogenic cysts were examined by using histochemical and immunohistochemical techniques and transmission electron microscopy in order to study their origin. These methods revealed no evidence of keratinization, erythrocytes, and endothelial cells in the hyaline bodies. Ultrastructurally, epidermoid cells were attached to the hyaline bodies by hemidesmosomes and induced numerous vesicles in their cytoplasm. Electron probe X-ray microanalysis demonstrated a resemblance between components of the vesicles and that of the hyaline bodies. This close relationship of both structures supports the hypothesis that hyaline bodies are a secretory product of odontogenic epithelium.

This investigation was made on the ramifications and distribution territories of the posterior auricular artery of fifty adult dogs utilizing the plastic injection method, comparing with those of the cat. In general, the posterior auricular artery of the dog arose independently from the posterior wall of the external carotid artery at a position where it passed across the superior margin of the digastricus muscle, distal to the origin of the facial artery. In six cases of all examples observed, the posterior auricular artery arose independently from the external carotid artery at a position where it passed across the inferior margin of the digastricus muscle, proximal to the origin of the lingual artery. As principal branches, the posterior auricular artery gave rise to the parotid glandular, the digastric muscular and the strong, cervical branches in this order. It finally terminated to the temporal muscular and the major auricular branches after giving off the occipital branch and the stylomastoid artery. The distribution territories of the posterior auricular artery of the dog, being similar to those of the cat, were not only the auricule but also the muscles of the mastication, the salivary glands, the middle ear and the retromandibular regions.

The purpose of this study was to obtain information on the developmental changes of the infraorbital margin and the form of infraorbital suture. 136 Indian craniums were divided into five developmental groups according to the stage of eruption of the teeth. The anterior view of the skull was observed photographically. The results are summarized as follows: 1. The infraorbital margins were divided into three types according to the shape of the infraorbital suture. Type I: Infraorbital suture was independent. Type II: Infraorbital suture and zygomatico-facial suture coincided. Type III: Infraorbital suture and zygomatico-facial suture were joined. Type I was the basic type of infraorbital suture. 2. The frequency of type I was 90% at the pre-eruption stage, 31.8% at the eruption stage, 41.7% at the deciduous dentition stage, 56.3% at the mixed dentition stage, and 62% at the permanent dentition stage. 3. On the distance between the median line and each point of the infraorbital margin the growth rate is expressed in values relative to a standard that was based on the pre-eruption stage. The growth rate was greatest at the highest point of the superior margin in the infraorbital foramen (1.79 times), the middle rate was at the position of the infraorbital suture (1.72 times) and the smallest rate was 1.63 times at the position of the zygomatico-facial suture. Each measuring point moved towards lateral side.

A transistor pH electrode (pH-ISFET electrode) was placed in each of four human mouths and bacteria were allowed to accumulate on it for 1, 2 or 3 days. Changes of plaque pH were measured in situ after application of sucrose solution (0.1, 1 or 3%) and, then, quick pH recovery by mouth-rinses with water was estimated. Although the acidic pH after application of 0.1% sucrose was easily and quickly recovered from by a few mouth-rinses with water, rather frequent mouth-rinses with water were required to recover from the acidic pH of 2- or 3-day-old plaque after the application of a 1 or 3% sucrose solution. For example, 15 (mean, n = 4) mouth-rinses with water were required for the 3 day-old plaque pH to recover after the application of 3% sucrose solution.

Mandibular condylar cartilage from normal and low phosphate-vitamin D deficient rats were investigated by lectin histochemistry utilizing wheat germ agglutinin (WGA). We obtained the following results: 1) The cartilage from low phosphate-vitamin D deficient animals consisted predominantly of hypertrophic chondrocytes with abundant extracellular matrix. 2) The territorial matrix of the hypertrophic cell zone of normal cartilage was intensely labelled with WGA, whereas the binding affinity of this region in low phosphate-vitamin D deficient animals was significantly diminished. 3) Compared to normal cartilage, WGA binding sites were demonstrated in the inter-territorial matrix of low phosphate-vitamin D deficient animals to a moderate degree. 4) Abolishment of the territorial WGA binding affinity in low phosphate-vitamin D deficient animals was presumed to indicate the accumulation of chondroitin sulfate which is believed to be a strong chelator of calcium ion.

The present study was designed to compare the process of structural changes which appeared in the alveolar bone and cortical bone of the frontal maxilla and mandible after extraction of the incisors. Twelve adult dogs whose upper and lower incisors on the same side were extracted at the same time were kept for 29-181 days. The dogs were injected continuously with tetracycline during the first half of the experimental period and with calcein during the latter half. Labio-palatal and labio-lingual longitudinal ground sections were first micro-radiographed and, then, examined by fluorescence microscopy. From a montage of fluorescence micrograms, color tracings of the labelling sites were made on thin plastic sheets. The two images of the control and experimental sides were precisely compared The structural changes which appeared in all the parts of the alveolar bone and cortical bone after extraction of the incisors were more prominent in the maxilla than in the mandible. New bone formation in the extraction socket appeared and was completed earlier in the maxilla than in the mandible. Secondary internal remodelling of the alveolar bone proper and the newly formed bone in the extraction socket progressed more quickly in the maxilla than in the mandible. The remodelling of cortical bone and the resorption of the alveolar crest was made very actively in the upper labial side, whereas these process very slight in the upper palatal side and in the lower labial and lingual sides, so that the contour of the frontal maxilla, especially in its labial side, was more prominently deformed than the mandible.

A microperoxidase (MP, molecular weight 1,900; molecular diameter 20 A) or a horseradish peroxidase (HRP, molecular weight 40,000; molecular diameter 40 A) was intravenously injected into healthy rat junctional epithelium (JE) to investigate the endocytosis of foreign substances. By light microscopy, intravenous HRP was taken up throughout the JE, and the uptake was marked at the coronal portion of the JE. On the other hand, MP was taken up by only the coronal portion of the JE. At the electron microscopic level, the tracers were taken up by endocytotic organellae (phagosomes and micropinocytotic vesicles) of junctional epithelial cells (JE cells). HRP-positive endocytotic organellae in the JE cells were more numerous than MP-positive organellae. Thus, JE, especially its coronal portion, exhibited strong endocytotic activity for HRP compared with that for MP. These findings suggest that the JE has selective endocytotic ability for foreign substances, and plays an important role in protecting periodontal tissue.

The purpose of this study was to examine the effects of chewing a hard and soft diet on acquisition of conditioned avoidance response in mice and rats. 76 C57BL mice and 38 Wistar rats were divided into 2 groups respectively 20 days after birth. One group was fed a solid diet and another was fed a powder diet containing the same components as the solid one (Nihon Crea Company, CE-2). Using the avoidance conditioning system of Gunma University, conditioned avoidance experiments started at the age of 8 weeks and the rate of avoidance (number of avoidance/number of trials) was measured. The mean percentage of avoidance rates in the solid diet group were significantly higher than those of powder diet group at level of 1% in mice and 5% in rats. These results suggest that mastication of a hard diet in younger animal may facilitate their brain function more than that of a soft diet.