Shika gakuho. Dental science reports最新文献

Investigation of the physicochemical characteristics of reinforcement ceramic implant materials which have needle crystal produced the following results. 1. Simple diopside and hydroxyapatite with diopside have enough dynamic intensity of both the implant in point of bending intensity and the breaking toughness. 2. Simple diopside and hydroxyapatite with diopside go well as biomechanics because of their Young's modulus being close to the surrounding bone. 3. Diopside in pseudo-body fluid developed hydroxyapatite on surface like bioglass, and this resulted in high possibility of direct bond with bone. 4. The results of this study indicate that the diopside and hydroxyapatite with diopside have enough dynamic intensity and are bioactive dental implant materials.

Clonal cell lines established from human periodontal ligaments were used in vitro experiments to ascertain periodontal ligament responses, on the cellular level, to mechanical stretching. A procedure developed by Hasegawa et al. (1985) was used in applying mechanical stretching. Unstretched cultures were used as controls. All cultures were processed for investigations of fine structures, histochemical and cytochemical detection of ALPase activity, and localization of alpha-tubulin. Cultured cells to which mechanical stretching was intermittently applied showed little change in overall appearance, cell shape and arrangement, and distribution of alpha-tubulin. Although fine structural characteristics remained unchanged in both stretched and unstretched cultures, mechanical stretching force clearly increased the intensity of ALPase activity. Histochemical and cytochemical examinations indicated that the added intensity resulted from increases in numbers of cells demonstrating enzymatic activity.

The present work used 2 groups of Wistar rats, weighing 100g each. Rats in the first group served as the controls; those in the second group were given 2 mg/kg of vinblastine in single intravenous injections. The animals were then fixed by perfusion with a mixture of 0.1% glutaraldehyde and 4% paraformaldehyde. After having been dissected out of the jaws, upper incisors were demineralized in EDTA and prepared into longitudinal sections (3 microns thick) for immunohistochemical demonstration of alpha-tubulin by means of indirect methods using an anti-alpha-tubulin monoclonal antibody as the primary antibody and peroxidase-labeled anti-mouse sheep IgG as the secondary antibody. 1. Control group. In controls, diffuse alpha-tubulin reaction was observed in the distal cytoplasm of inner enamel epithelial cells, differentiating ameloblasts, and ameloblasts in the stage of matrix formation. In the ameloblasts, the reaction was especially strong in the distal ends and Tomes processes in the matrix-formation stage. It gradually decreased until the transitional stage, in which the ameloblasts regained intense reaction to alpha-tubulin. Reaction to alpha-tubulin was generally low in the enamel-maturation stage in both smooth-ended and ruffle-ended ameloblasts but grew somewhat intense in the stage in which ferritines were precipitated in the cells. Although dental papilla cells reacted only faintly to alpha-tubulin, when they started differentiating into odontoblasts, reaction grew stronger in their distal end regions and in processes extending from the distal ends into the dentin. But this reaction decreased and ceased at a middle dentin level. Fairly high reaction was observed in the cells of the outer enamel epithelium, the stratum intermedium, the stellate reticulum, the papillary layer, the pulp and the dental sac. 2. Experimental group. Reaction to alpha-tubulin described in the preceding sections generally decreased in from 1 to 6 hours after vinblastine administration. Reaction recovery appeared to begin at from 12 to 24 hours and almost reached control degree by 48 hours after administration. Following the decrease of alpha-tubulin reaction in ameloblasts and odontoblasts, their shapes and polarities changed dramatically. In other cells, however, in spite of decreased alpha-tubulin reactions, no noticeable morphological alteration took place.

Unlabelled: We observed 173 cases of 20K gold alloy inlay restorations on young permanent premolars and molars and investigated the emergence age of all these teeth. The observation period of inlay restorations was from 1 year to 11 years and 6 months. Clinical evaluations were made by exploring with an explorer, roentgenography and color photography.

Results: 1. Changes in inlay restorations occurred in 1 case (0.6%) of discoloration and 4 cases (2.3%) of inlay dislodgement. 2. Changes in teeth occurred in 8 cases (4.6%) of secondary caries, 15 cases (8.7%) of new caries and 4 cases (2.3%) of pulpitis. 3. Clinical failures occurred in 32 cases, and 24 of those cases were restored within 2 years after tooth emergence. 4. Almost clinical failures occurred on the maxillary and mandibular first molars. 5. In 27 cases (15.6%), repeat restoration was necessary. In 10 of these cases, the original 20K gold alloy inlay restorations continued in use.

Single subcutaneous injections of sodium fluoride (84 mg/kg NaF) were administered to male Wistar rats weighing 100 g each. After 6, 12, and 24 hours and then after 2 and 5 days, the animals were fixed by perfusion with a mixture of 2.5% glutaraldehyde and 2.0% paraformaldehyde; and their upper incisors were subjected to optical microscopy, microradiography, and electron microscopy. 1. Changes in ameloblasts in the matrix-formation stage: Large vacuoles and dark globules, which frequently appeared to be stacked within the cell, could be seen in the distal one-third of the ameloblast 6 hours after NaF injection. These globules and vacuoles disappeared 24 hours after injection. Distortion of the Tomes' processes and separation of the ameloblasts from the enamel surface too could be seen. The separated areas gradually expanded to form cystic cavities, which developed toward the end of the formation stage of amelogenesis. But these cavities never extended to ameloblasts in the transitional stage. 2. Changes in ameloblasts in the transitional stage: Transitional ameloblasts may be divided into 2 stages: the early transitional stage, during which the proximal portion of the Tomes' process persists, and the late transitional stage, during which all trace of the Tomes' process has disappeared and a basement membrane-like structure has been produced. The appearances of ameloblasts in these two stages altered after NaF injection. In the early transitional stage, 6 hours after the injection, large vacuoles and dark globules appeared in the distal portion of the cell. Similar to vacuoles appearing during the matrix-formation stage, these vacuoles and globules disappeared 24 hours after injection. Traces of the Tomes' process, however, persisted and assumed an irregular, wavy form. The adjacent enamel adapted to and interdigitated with the cel surfaces without a structure resembling the basement membrane. NaF injection caused slight changes in the late transitional stage: small vacuoles appeared at the distal ends of the cell and disappeared 24 hours later. 3. Changes in the ameloblasts in the enamel-maturation stage: Six hours after the injection, small vacuoles appeared at the distal portion of the cell close to the striated border which was poorly developed. These vacuoles disappeared, and the striated border resumed its usual features 24 hours after the injection. 4. Changes in the enamel: In the forming enamel, a calciotraumatic line consisting of hypermineralized and hypomineralized layers could be seen. Another hypermineralized line appeared at the enamel surface adjacent to the transitional stage. Electron microscopy showed that this hypermineralized layer consisted of crowded, disoriented, needle-shaped crystals.

Unlabelled: This study was investigated on the mechanism of the sedative state, tranquilization induced by bradykinin (BK) and kallikrein (KAL). The drugs used in this study were as follows: KAL as endogenous BK promoter; prostaglandins (PGs) as a material of analogous action of BK; indomethacin and mepacrine as the inhibitors of PG-synthesis; eugenol as the OH- scavenger and the PGE-synthesis potentiator; angiotensin converting enzyme inhibitor as BK potentiator B. All drugs were dissolved in Hartmann's solution (lactate Ringer's solution) and 10 microliters of solution was injected into the lateral ventricle of rats, according to the Myers' procedure. Then, the rat behavior was estimated, by means of monitoring spontaneous movement. A high performance liquid chromatography (HPLC) was used for detecting alteration of monoamines and prostaglandins in the rat brain on sedative state after BK or KAL injection.

Results: 1) A 2-phase alteration of spontaneous movement was occurred within 30 min after BK or KAL icv-injection with behavioral specificity as follows: two exciting states and one sedative state. 2) A great increase of spontaneous movement evoked by BK or KAL was accompanied by exciting state as follows: jumping, wet dog response, struggle and scratching response, rearing and exploration. 3) A great decrease of spontaneous movement evoked by BK or KAL was accompanied with sedative state as follows: crouching with piloerection and closed eyes, catalepsy, preening and moisturizing and grooming. 4) PGE1 icv-injection was also carried out to clarify the involvement in the BK- or KAL-induced behavioral alteration. Consequently caused PGE1 the similar result to BK or KAL. 5) ACEI elongated and enhanced the exciting state or sedative state evoked by BK or KAL. 6) It was clear that BK reduced levels of monoamines in the rat hypothalamus: levels of norepinephrine(NE), epinephrine(E), dopamine(DA) and 5-hydroxytryptamine (5-HT) were decreased to 72.5%, 53.5%, 71.2% and 75.0% of control, respectively. Reduction of catecholamines in the hypothalamus was produced by increase of PGs and subsequently occurred sedative state of rats. 7) BK- or KAL-induced exciting state was enhanced by PG- synthesis inhibitor, especially the cyclo-oxygenase inhibitor indomethacin, but the sedative state was weakened. On the contrary, eugenol, an OH- scavenger, elongated and intensified the sedative state. Detection with HPLC showed remarkable increase of levels of PGs in the rat brain during the sedative state: the level of PGE2 was 27.5% increase of control and the level of PGE2 alpha was also 54.8% increase of control, respectively.

In order to elucidate their cranial and facial morphological features, frontal and lateral cephometric analysis was made of parents of 86 children with cleft lip with or without cleft palate [CL (P)] and 14 children with cleft palate (CP). Similar analysis was made of 30 control male and female volunteers who demonstrated no maxillofacial anormalies and had no blood relatives affected by CL(P) or CP. In addition, discriminative analysis was performed. Results (1) Maximum cranial breadth values in the 4 parent groups, both father groups [CL(P)-F, CP-F] and mother groups [CL(P)-M, CP-M] were lower than those in controls. Differences were significant in the CP-F and CP-M groups. The shapes and sizes of the cranial base, however, in all parent groups showed no distinct difference from those in the control group. (2) Inner canthal distance and maximum piriform aperture breadth in all parent groups and outer canthal distance, zygoma breadth, and maxillary alveolar base breadth in the CL(P)-F, CL(P)-M, and CP-M groups were all greater than those in controls. The differences were significant in the case of inner canthal distance and maximum piriform aperture breadth in the CL(P)-F group and in both inner and outer canthal distances and maximum piriform aperture breadth in the CL(P)-M group. (3) SNA angle in all parent groups was slightly greater, but occlusal plane angle and maxillary incisor angle were smaller than those in the control group. Significant difference was noted in occlusal plane angle in the CL(P)-F group. In all parent groups, depth values at various upper facial points in the lateral aspect of hard tissue tended to be greater and height values smaller than those of the control group. (4) In all parent groups, upper facial height, upper labial thickness, upper labial bending degree, and anterior nasal angle in the lateral aspect of the upper facial soft tissue tended to be smaller and upper labial height greater than those in the control group. A distinct difference between subjects and controls was observed in upper labial height in the CL(P)-F and CL(P)-M groups and in upper labial bending degree in the CP-F and CP-M groups. (5) Although no distinct difference was observed between controls and the parent groups in terms of facial angle and SNB angle, mandibular plane angle and gonial angle were relatively large and incisor axial angle was small in the parent groups.(ABSTRACT TRUNCATED AT 400 WORDS)

A dark field microscopic examination of subgingival microorganisms and gas chromatographic analysis of volatile sulphur compounds were employed to investigate the role of subgingival microflora in the production of bad breath. Subjects (11 female, 13 male; aged 24 to 61) were divided into the following 2 groups on the basis of apparent bad breath by the olfactory judgement; bad breath group (group B, n = 13), and no bad breath group (group N, n = 11). A gas tight syringe was employed to withdraw 5 ml mouth air samples, which were injected directly into the gas chromatograph. Volatile sulphur compounds produced in mouth air were analyzed by gas chromatograph to determine volumes of CH3SH. Subgingival plaque samples were taken with sterilized paper points from the deepest site of probing depth in each subjects. The samples were examined by means of dark field microscopy and 100 bacteria in randomly selected fields were classified on a percentage basis into one of the following morphological categories: (1) spirochetes, (2) motile rods, (3) filaments, (4) fusiforms, (5) straight rods, and (6) coccoid cells. Total cell counts per 1 ml were calculated from bacterial counts of each categories. Comparison of 2 independent means from each groups were carried out by Wilcoxon's rank sum test for nonparametric values. Correlations of bacterial data with CH3SH values in mouth air were determined by means of Spearman rank correlation cofficient. Results were as follows; 1. Significant differences existed in the microbial flora between the 2 groups: percentage of spirochetes and motile rods in group B were significantly higher than those in group N (p less than 0.01). Total cell counts of group B were significantly greater than group N, and there were statistically significant differences (p less than 0.01). 2. CH3SH values in mouth air had positive correlations with the percentage of spirochetes, the percentage of motile rods, and total cell counts. These results are consistent with the view that subgingival microorganisms play a certain role in the production of bad breath. Moreover, it was suggested that spirochetes and motile rods are related to the mechanism of bad breath production.

This report contains a statistical study of 874 cases of epulis diagnosed by the Department of Pathology of Tokyo Dental College from 1966 to 1986. 1. Of the 874 cases, 344 were epulis fibrosa, 217 were epulis granulomatosa, 78 were epulis fibromatosa, 74 were epulis fibrosaosteoplastica, 51 were epulis hemangiomatosa, 43 were epulis fibrosa teleangiectaticum, 15 were epulis cementoplastica, 14 were epulis osteomatosa, 3 were congenital epulis, 2 were giant cell epulis, and 1 was epulis cementomatosa. 2. As has been reported in other literature, there is a marked tendency for this condition to occur in females (331 male cases and 539 female cases). 3. Our data indicate a higher occurrence rate in people in their fifties, although the occurrence rates were similar in people in their twenties and in people in their sixties. 4. The epulis was observed most frequently in the maxillary incisor region.

The present work was designed to elucidate crystallographic changes in enamel that had been demineralized in a 0.01 M acetate buffer (pH 4.0) for 2 days at 50 degrees C and then remineralized in a solution containing 1 mM Ca, 0.6 mM P, and 0.05 mM F for 1 or 2 weeks at 37 degrees C. The demineralized and remineralized enamel samples were observed by means of high-resolution electron microscopy, electron-probe analysis, and small area X-ray or electron diffraction. Before remineralization, demineralized enamel had been composed of sparsely arranged apatite crystals with either a central perforation or lateral surface defects or both. Measurements of crystalline (001) planes indicated that crystals in demineralized enamel were significantly larger than those in intact enamel, thus suggesting that crystal growth had taken place during demineralization. Small, newly formed, hexagonal crystals occurred in remineralized enamel. In some cases, precipitation of such small crystals together with localized enamel-crystal regrowth restored central perforations and lateral defects. A number of the small, newly formed crystals and preexisting enamel crystals aggregated to form a group with a roughly hexagonal outline. After the growth and fusion of these grouping crystals, a large, regular-hexagonal crystal formed. Such various kinds of lattice defects as edge dislocation, small-angle grain boundary, and lattice displacement were frequently detected in fusing crystal boundaries. Prolonging remineralization duration seemed to reinforce these lattice defects. Electron-probe and X-ray diffraction studies led to the assumption that the large hexagonal crystals were fluoroapatite. These results indicate that remineralization of demineralized enamel proceeds through several stages, including formation and growth of new crystals and regrowth of preexisting enamel crystals.