To determine the role of actin filaments in osteoclastic function, osteoclastic multinucleated cells were suspended on dentine slices and cultured for 24 hours in the presence or absence of cytochalasin D (CD), a specific and potent inhibitor of actin filament elongation to determine the role of this cytoskeleton. Cultured cells and co-cultured dentine slices were examined by means of backscattered-and immuno-electron microscopy. Unlike those in control cultures without CD, osteoclasts in CD-treated cultures became spherical in shape and lacked microvilli on their basolateral cell surfaces. CD treatment induced a complete disappearance of the ruffled border-clear zone complexes in osteoclasts, which resulted in strong inhibition of the formation of resorption lacunae in a dose dependent manner. CD treatment also reduced intensity of immunoreaction of anti-actin in the ruffled borders of osteoclasts. These results suggest that the cytoarchitecture, as well as the bone-resorbing function, of the osteoclast is highly regulated by the F-actin-containing microfilamentous cytoskeleton in the ruffled border-clear zone complex

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To investigate metabolic changes of periodontal ligament (PDL) fibroblasts and osteoblasts in insulin-deficient diabetes, adult Sprague-Dawley rats were administered a streptozotocin (STZ) and, at 1-16 weeks after STZ administration, their lower mandibles were examined ultrastructurally. By inducing diabetes, PDL fibroblasts became flattened in cell profile and contained many autophagosomes including various cytoplasmic inclusions. In addition, multinucleated fibroblasts appeared in PDL exhibited various atrophic cellular structure. In electron microscopic autoradiography of ³H-proline utilization by PDL osteobalsts, STZ-induced diabetes resulted in marked reduction of ³H-proline incorporation and its secretion towards newly-formed osteoid by atrophic fllattened osteoblasts. These results suggest that diabetes-induced structural abnormalities and suppression of procollagen synthesis by PDL fibroblasts and osteoblasts are important risk factors in local periodontal diseases.

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Rod-shaped deposits composed of hexahedrally based crystals, identified as whitlockite, were occasionally found in the dentinal tubules of the attrited cervical dentin of cariesfree human teeth. It is suggested that the deposits were formed by using the collagen fibers within the tubules for the initial matrix.

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The purpose of this study was to examine the morphological findings of human sound and carious enamel and dentin cut by the powder jet of aluminium oxide (Al₂O₃). Twenty human permanent teeth including carious teeth, premolars and third molars, were used for this study. As a cutting device, Kinetic Cavity Preparation (KCP) -2000, which was developed by American Dental Laser Co. was used. The diameter of powders was 27 um and 50, um. The velocity of Al₂O₃ powders was 80 psi (5. 6 kg/cm₂), 120 psi (8. 4 kg/ cm₂) and 160 psi (11. 2 kg/cm₂). Keeping one or two mm distance from the tooth surface, the cavity preparation was carried out by the fine tip of 0. 34 mm in diameter. The specimens were observed by Nikon HFX-IIA and JEOL JSM-T220A SEM after the dehydration and metal coating. As a result, the discoloration on the tooth surface which was cut by KCP-2000, could not be found by the naked eye and light microscopic observation. The detail morphological findings did not depend on the size and velocity of Al₂O₃ powders, but the cavity surface showed the smooth findings like a sandy beach. Almost Al₂O₃ powders were removed by the air blast of KCP device from the cavity, but a little bit amount of powders were entered into dentinal canals and the cut surface was paved with the powders or debris. The size or morphology of these particles were irregular and variable. It was concluded that this newly developed KCP-2000 had an excellent cutting ability and could be put into the clinical dental practice.

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Effects of an atmosphere in the melting chamber during melting on the hardness of titanium castings were investigated using an argon arc melting and gas pressure casting apparatus. CP titanium was cast into both calcia and copper molds under the conditions such as the increase of the number of repetitions of an exhaust and an argon gas inflow, the elongation of exhausting time and the use of a new rotary pump with powerful exhausting. Hardness of the castings was examined.
The increase of the number of repetitions were found obviously to decrease the hardness of the castings because of the lower residual oxygen concentration in the melting chamber. However, the elongation of exhausting time did not show the obvious effect to decrease the hardness of the castings. Therefore, the increase of the number of the repetition of an exaust and an argon gas inflow was found to be more effective than the elongation of exhausting time to get purer titanium castings with less contamination.
The rotary pump could make the working time for melting ingots shorter than a pump equipped in the casting apparatus due to its higher ability of exhausting.
Moreover, titanium castings obtained from the calcia mold at 1000°C with the rotary pump showed thinner hardened layer than those with the equipped pump. Therefore, it was concluded that the use of the powerful pump was useful to fabricate titanium castings with high quality.

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Clinical application of plasma sprayed hydroxylapatite coated dental implants (Integral ^(R) ) are reported. The subjects consisted of 14 males and 16 females ranging in age from 22 to 73 years. They were treated with 162 Integral^® implants from April 1988 through May 1990.
The details observed were
: 1) intra-and postoperatively transient paralysis of the mental nerve in 6 cases ; premature exposure of the implant in 5 cases ; and perforation to the maxillary sinus in 3 cases. However, there were no severe complications.
2) At the time examined (from 2 years and 8 months to 4 years and 9 months : the mean period was 3 years and 5 months after implantation), the survival rate for implants was 97. 5% (158/162) and for superstructures settled, 97. 4% (38/39). Three of the four failed implants were in cleft palate patients.
3) Failed implants were associated surgically with : (1) poor quality and/or quantity of bone ; (2) lack of attached, keratinized gingiva ; or (3) implantation in the wrong direction.
Results of the present study indicate that Integral^® is clinically useful. Accurate preoperative evaluation and adequate surgical techniques are needed to achieve a higher succes rate and decrease intra-and postoperative complications.

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The purpose of this study was to investigate sex difference of the Japanese nose. The subjects were 64 men and 79 women who were physically normal and ranged in ages from 18 to 38.
Photographs were taken their faces in mandibular rest position with the moiré camera.
Their noses were measured and classified 4 types of the dorsalnose and 4 types of the roof of a nose.
Result
The nasal length, nasal breadth, dorsalnasal length and nasal depth in man were larger than those in woman. The nasal angle was no significant in both sex.
L-B index and B-D index in man were larger than those in woman. The dorsalnasal forms were many straight forms in both sex, but in woman, concavity forms were observed in about 30% of all cases.
The shapes of the roof of a nose were many featureless types in both sex, but in some cases, man's nose showed the type of the good developmental roof of a nose, but on the contrary, woman's nose showed the type of the bad developmental roof of a nose.

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A rare case of Warthin tumor occurred in the deep lobe of the parotid gland was reported. A 42-year-old man was referred because of a mass of the left parotid area. The initial examination using ultrasound and CT revealed a tumor in the left parotid gland. In the operation the tumor was located in the deep lobe of the parotid gland and was completely extirpated. The pathological diagnosis was Warthin tumor. In the literature there were some case of Warthin tumor occurred in the superficial lobe of the parotid gland, however, no case in the deep lobe.

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