The purpose of this study was to evaluate the effects of a fibrin tissue adhesive material (FAM) on periodontal tissue regeneration.
Fourteen dogs were used in the experiment. Evaluation of buccal mucoperiosteal flaps were followed by removal of buccal alveolar bone. The bone of the 3rd and 4th premolar was removed to 4 mm from the cement-enamel junction. The periodontal ligament and cementum were removed by root planing. FAM was applied between the root surface and the flap, before suturing, at each experimental site. The control sites were srepared in a similar manner but without FAM. Histological and histometric observations were made at 2, 4 and 8 weeks after surgery.
The histometric measurements of the experiment showed that FAM inhibits the apical migration of epithelium (P<0.05). The experimental sites showed a significant increase in new cementum formation (P<0.005). The new bone formation were more prevalent in experimental sites than in control sites (P<0.05).
It is concluded that FAM may facilitate for periodontal tissue regeneration.

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Histological study of elastic fiber in the lymph node is relatively limited, although there are many reports on the elastic fibers in various tissues. No evidences on the elastic fiber in the lymph node surrounding the salivary gland are reported. The present study investigated histologically the appearance of the elastic fiber of the capsule and the pulp of the submandibular lymph node in Sprague-Dawley rat by aging.
The lymph nodes were obtained from 0 day-, 1, 2, 3, 5, 9, 26, 30, 52 and 78 weeks-aged rats. Thin sections were made, and stained with Lithion-Carmin for the nucleus and with Weigert's Resorcin-Fuchsin for the elastic fiber. The appearance of the fiber in the capsule, the marginal sinus, the outer and the deep cortex layers, the outer layer of the germinal center, the germinal center and the medulla were observed and photographed with a transmitted light microscope.
In 0 day-and 1 week-aged rat, the elastic fibers were not found in the capsule, the cortex, and the medulla of the lymph node. When grew up into 2 weeks of age, a few fine fibers appeared at the surface layer of the capsule. At 3 weeks of age, the fibers run meanderingly through the capsule into the marginal sinus. After 26 weeks of age, many elastic fibers appeared in the capsule. In addition, the elastic fibers were seen in the outer cortex layer, the deep cortex layer and medulla adjacent to the lymph nodule. The shapes showed a straight or a meandering structure, and some of the fibers formed networks. Especially, the elastic fibers were observed clearly in the germinal center of the lymph nodule at 26 weeks of age. The number of the fibers gradually increased and its shape became thicker with the aging. Many fibers were observed more clearly in all parts of the lymph node at 78 weeks of age.
These results suggest that the appearance of the elastic fiber in the lymph node by aging may participate in the control of lymphatic circulation in the submandibular lymph node.

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By using scanning electron microscopy, the different crystals formed on basal crystals were observed in human dental calculus. In early calculus, polygonal column and triangular plate-shaped crystals of brushite or dicalcium phosphate dihydrate (DCPD) were formed on the mass of fine needle or sandygrain-shaped biological apatites (AP). In old calculus, elongated ribbon and plate-shaped crystals of octacalcium phosphate (OCP) were arranged on the glomerate structures of AP crystals; in addition, the alternation of these crystal layers were frequently observed. Hexahedrally based crystals of whitlockite (WH) were induced on the surfaces of OCP crystals and on the mass of AP crystals, while rod-shaped AP crystals were induced on the surfaces of WH crystals. Their appearances suggest that the epitaxial growth and transformation of DCPD, OCP, AP, and WH crystals easily occur in the microenvironment of dental calculus.

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It is known that calcified deposits showing an aster-like structure on the sectioned and fractured surfaces are present in human supragingival calculus. In a tonsillolith collected from an old female, aster-shaped calcified deposits were also found. In both stones, the central regions showed a glomerate structure composed of fine needle or sandygrain-shaped crystals of biological apatites formed mainly by the extracellular calcification, and the marginal regions showed a radial arrangement of elongated ribbon and plate-shaped crystals of octacalcium phosphate. It is suggested that the deposits of the tonsillolith are formed in the sites surrounded with organic matter, and that the sites are similar to that of dental plaque where the deposits of dental calculus will be formed.

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The purpose of the present study was to evaluate the clinical performance of a newly developed surface grazing agent (BRT-II) for resin composite restorations. Forty-seven cavities were restored by commercial resin composites, followed by an application of this surface grazing agent according to manufacturer's instructions. Short-term detailed examinations were performed. No complications up to one month were shown as a result of use of BRT-ll. It is concluded that application of the new surface grazing agent for resin composite restorations is clinically acceptable.

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The purpose of this study was to examine the three dimensional arrangement of collagen fibrils organizing compact bone and Sharpey's fibers with a high-resolution scanning electron microscope. The materials were diaphyses of tibiae of young adult men. The specimens to observe the surface of compact bone were dissected free the fibrous layers of ectoperiosteum, and incubated in 1% trypsin solution to digest both osteoblasts and amorphous organic matrix. The specimens to observe collagen fibrils in compact bone and Sharpey's fibers were cut or freeze-cracked, and decalcified with 10% EDTA. All specimens were followed by conductive-staining, dehydration, critical point drying, ion sputter coating, and examination with a field emission type scanning electron microscope.
The results we examined were as follows :
(1) Most surface of compact bone were composed of reticular collagen fibrils and collagen fibril bundles. Collagen fibril bundles were running in parallel along the long axis of the long bone.
(2) Collagen fibrils forming each lamellae of external basic lamellae were running perpendicularly to the collagen fibrils composed of adjacent lamellae.
(3) Collagen fibrils composed of external basic lamellae formed bundle structure.
(4) Sharpey's fibers entered into the bone matrix between collagen fibril bundles. Most Sharpey's fibers showed the dense bundles outside the bone matrix, and some of these were spiral structures.
(5) Parts of Sharpey's fibers entered into bone matrix from the long and narrow spaces between dense collagen fibril bundles.
(6) Sharpey's fibers inside the bone matrix formed extremely dense bundles, and were running straight toward the deep layer of bone matrix.

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The effect of the Pd content in a powder alloy which was triturated with a commercial Ga-containing liquid alloy was evaluated by measuring its mechanical properties and by its clinical performance in class I restorations. Experimental powder alloys were prepared by reducing the Pd content of a commercial powder alloy, which contained 10 wt % Pd, to either 3 wt % or 0 wt % (Pd-free alloy). The clinical performance of the restorations was significantly improved by decreasing the Pd content to 3 wt %, and the degree of marginal integrity correlated with the creep. Therefore, these results suggest that the Pd content in the commercial alloy should be reduced to 3 wt % to improve its clinical longevity.

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Changes in the contractile tension and muscle length of rat superficial masseter muscles were measured together with postnatal increases in body weight from the age of 3 to 11 weeks to establish control data during growth. Isolated masseter muscle fiber bundles were used for precise measurement of contractile tension and muscle length. Up to the age of 5 weeks, female rats showed a greater contractile tension than male rats. At the 6th weeks, the level of contractile tension in male and female rats was similar. The tension development curve in 6-to 9-week-old males was sigmoidal, while that in 6-to 8-week-old females showed a linear increase. Male and female rats reached maximum contractile tension at 9 and 8 weeks of age, respectively. The most remarkable changes in contractile tension from the age of 6 to 9 weeks correlated with rapid changes of body both weight and muscle length. Statistically significant relationships were observed between contractile tension and both body weight and muscle length. These findings suggest that the changes in the contractile tension were influenced by morphological changes as well as by individual growth. These findings will also be useful as control data regarding the rat superficial masseter muscle contractile tension.

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The purpose of this study was to determine the three-dimensional accuracy of a duplicated cast made with the silicone duplicating impression system.
Three kinds of silicone duplicating impression systems were selected : Rema-Sil, Wirosil and Deguform. A partially edentulous maxillary dentition epoxy model (Kennedy class III) was used as the master model. Five measuring point (A, B, C, D, E) were assigned to the abutment teeth and the medial parts of the floor of the mouth. All materials used in this study were handled according to each manufacturer's instructions. Three duplicated casts and metal bases were made by each silicone duplicating system. The coordinates of each measuring point on the duplicated casts were measured using a three-dimensional measuring system. This measuring system was a non-contact type. The dimensional changes of the duplicated casts were calculated from the obtained coordinates of the assigned measuring points. In addition, the lengths of the perpendiculars dropped to the segment A-B from point E and respectively referred to as H. Furthermore, permanent strain, compressive strain and dimensional change of the silcone duplicating impression materials were determined.
The duplicated casts made with Rema-Sil and Deguform showed almost the same dimensions as the master model in a horizontal direction (A-B, A-C, A-D, B-C, B-D, C-D) to the occlusal plane and were larger than the master model in a vertical direction (H), while the duplicated cast made with Wirosil was slightly larger overall than the master model.
Wirosil showed a different tendency from the other two systems. This difference may be attributed to the presence of a flask upon production of the duplicated cast. In Wirosil, the flask is removed after making the duplicating impression, and then the investment is poured and allowed to set. Thus, Wirosil was not influenced by the inhibition of the expansion of the investment.

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Effects of manipulative variables such as the type and volume of chips in a barrel on the barrel polishing were examined. It was found that these significantly affected the amount of polishing and the surface texture of the workpiece. The highest amount of polishing was obtained when using RK chips which had an irregular shape. Then the surface roughness of the workpiece after polishing was about 1.5 μm Rmax. The smallest amount of polishing was obtained when using SA chips which had a spherical shape and wasn't good enough to form the smooth surface. The worst polishing efficiency was obtained at 80 vol % with all chips. Larger amounts of polishing were obtained when using RK chips and UP chips at 20 vol %. In this study, the best dimensional change and surface texture of the workpiece was produced by UP chips which had a columnar shape at 60 vol%.

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