This paper examined the adhesive strength of paint-on resin to crown and bridge composites after soaking in water and thermal-cycling. Three shades of paint-on resin were coated on three kinds of crown and bridge composite under four surface treatment conditions (a combination of sandblaster and pretreatment liquid). These specimens were soaked in water at 37°C for 1 day, 1 month, and 1 year, and at 4°C and 60°C alternatively for 1-minute periods for 10, 000 cycles by thermalcycling machine. The adhesive strengths were obtained by shear test. There were no significant differences among the adhesive strengths of three shades of paint-on resin to three composites after storage (p>0.05). The adhesive strengths to composites with sandblasting showed higher values than those without it (p<0.01).

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This study investigated the effects of scratch load, scratch speed, and storage period of specimen on the scratch hardness of stone models. Types 4 and 5 stone specimens were made from vinyl silicone rubber and alginate impressions respectively. After specimens were stored in a desiccator with silica gel at room temperature for 24 hours or 1 week, scratches were created on the surface with three different scratch loads (1N, 2N, and 3N) and two different scratch speeds (50 and 100mm/min). Then, the depths of scratches were measured.
Scratch depth of stone specimens increased with increasing scratch load. Scratch depths of Type 4 stone specimens after 1-week storage were smaller than those after 24-hour storage at a speed of 100mm/min. However, the effect of scratch speed on scratch depth did not follow a specific trend.

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The purpose of this study was to compare root-end sealing using 4-META/MMA-TBB resin with that using conventional retrograde root filling technique, and thereby determine if 4-META/MMA-TBB resin offers long-term prevention against dye leakage from the root canal of human teeth. Thirty-five teeth had the apical 2.5mm of the root resected. In the Sealing (SB) group, 4-META/MMA-TBB resin was applied to the resected surface. In the Filling (Am and EBA) groups, a root-end cavity was prepared and retrofilled with high copper amalgam alloy or reinforced zinc oxide-eugenol cement. Root canals were filled with methylene blue dye solution. Then, dye leakage outside the root canal was measured for 50 weeks.
The integrated amount of leakage in SB group was significantly lower than those in Am group (p<0.05) and EBA group (p<0.05). Therefore, it can be concluded that root-end sealing using 4-META/MMA-TBB resin resulted in better, long-term sealing than conventional retrograde root filling.

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This study evaluated the microhardness and Young's modulus of a photocurable bonding resin, Clearfil SE Bond (SE), cured with four curing units at different distances. The curing units used were: Candelux (Quartz-tungsten halogen), Lux-O-Max (Blue light emitting diode), Arc-light (Plasma-arc), and Rayblaze (Metal halide). Discs of bonding resin were prepared using vinyl molds and were photocured at the top surface with light tip at three different distances (contact, 2 and 4mm). After 24 hours of storage in water at 37°C, the specimens were sectioned into halves, embedded in epoxy resin, and polished. The microhardness and Young's modulus of this bonding resin were measured using a nanoindentation tester. Six specimens were prepared for each group. The data was statistically analyzed using two-way ANOVA test and Tukey multiple comparison test (p<0.01). The microhardness of SE was affected by light source and distance, as was Young's modulus. Candelux and Rayblaze presented the highest hardness and Young's modulus results. Both properties presented high values when the curing unit tip was maintained in contact with the irradiated surface. Increasing the distance between the curing unit tip and the irradiated surface decreased the hardness and Young's modulus of SE.

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The light-attenuating effect of dentin on the mechanical properties of light-activated composite resins was evaluated using a simple experimental filter. The filter was designed to simulate the light transmittance and light diffusion characteristics of 1.0-mm thick dentin. The depth of cure, surface hardness, and flexural strength for 13 shades of three light-activated restorative resins were examined. These resins were cured either using direct irradiation with a light source, or indirect irradiation through the filter. The attenuation of light intensity by 1.0-mm thick dentin reached 85-90% in the 400-550nm wavelength region. For all materials, the values of depth of cure, surface hardness on the top and bottom surfaces, and flexural strength of specimens irradiated indirectly through the simulated 1.0-mm thick dentin filter decreased by 37-60%, 16-55%, 50-83%, and 44-82% in comparison with those by direct irradiation, respectively. Recovery from mechanical properties' reduction was achieved when materials were irradiated 1.5-4 times longer than the standard irradiation time.

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The mechanical properties of six 35Ag-30Pd-20Au-15Cu alloys containing different contents (2% and 4%) of Sn, Ga, or In and a 35Ag-30Pd-20Au-15Cu alloy without additives were evaluated. These alloys were subjected to four different heat treatments before a mechanical test. The distribution of the elements and their contents were analyzed. The mechanical properties of 35Ag-30Pd-20Au-15Cu alloy changed in wide-ranging ways with different heat treatments and with different additive contents. The effects of heat treatment on tensile strength and hardness significantly varied with different additives and their contents. These different changes could be attributed to the formation of different phases in these alloys. Based on the high strength and wide-ranging changes in the mechanical properties when subjected to softening and hardening heat treatments, the 2% Sn-added, 2% In-added, and 4% Ga-added alloys can be recommended for different dental restorations such as crown & bridges, inlays, and denture frameworks.

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The purpose of the present study was to evaluate the relationships among three flexural strengths of recent dental ceramics using 3-point and 4-point bending tests and biaxial flexural test. Three brands of porcelain for veneering (d⋅SIGN, Supper porcelain AAA, Vintage Hallo), two injectable ceramics (Empress 2, OPC 3G), and one castable ceramic (Crys-Cera) were used. Twenty bar-shaped and 10 disc-shaped specimens of each ceramic type were prepared according to manufacturers' instructions, polished, and subjected to 3-point and 4-point bending tests and biaxial flexural test, respectively. Three flexural strengths for each ceramics were compared using one-way analysis of variance and Tukey comparison, and also investigated by Weibull analysis. The biaxial flexural strength and 3-point bending strength of all ceramics, except OPC 3G and Crys-Cera, were significantly greater than the corresponding 4-point bending strength. As for OPC 3G and Crys-Cera, their biaxial flexural strengths were significantly greater than their 3-point bending strengths, which is contrary to the other ceramics. The Weibull moduli ranged from 6.6 to 20.8. The Weibull moduli of examined ceramics, except Crys-cera, were statistically insignificant regardless of test methods.

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Ti-6Al-7Nb alloy was cast into three differently designed, removable partial denture frameworks: Palatal strap (PS), Anterior-posterior bar (AP), and Horseshoe-shaped bar (HS). The vertical displacement and local strain of Ti-6Al-7Nb alloy frameworks were investigated to compare against those of Co-Cr alloy frameworks. Vertical loading force of 19.6N was applied at two locations, 10 and 20mm, from the distal end of the framework. Although higher vertical displacement and local strain were observed for Ti-6Al-7Nb alloy frameworks than those for Co-Cr alloy frameworks, the PS framework appeared to show the least deformation. In addition, the strain at 10-mm location was higher than that at 20-mm location for AP and HS frameworks. This study thus proved that design had a significant influence on the deformation properties of denture frameworks. The PS design was evaluated to be a suitable design for the removable denture framework with Ti-6Al-7Nb alloy.

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Electrochemical buffing, a combined process of electrochemical and mechanical polishing, was applied to titanium casting. Mixture of α-Al₂O₃ suspension (average grain diameter of 5μm) and 5% KNO₃ solution was used as abrasive slurry. Specimen and experimental wheel buff were respectively connected to the positive and negative poles of a DC source, whose potential ratings ranged from 0V (MEP) to 10V (ECB10). Surface roughness, hardness, color, and cleanness were investigated. ECB10 surface produced a gold color and attained a mirror finish, as its roughness value was only one-quarter that of MEP. High amount of aluminum was present in MEP surface. Its bond state entirely differed from that of α-Al₂O₃, hence indicating surface alteration due to chemical reactions with the abrasive material. At higher potentials, reaction products might be dissolved anodically, so that the surface was chemically clean to some extent. The surface also became rich in OH^-.

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The purpose of the study was to investigate the biocompatibility of experimental elastomers, E580 and E590. The experimental elastomers and the control - a clinically used elastomer - were implanted into the subcutaneous tissue of rats. The tissue reactions were examined histologically on the 3rd, 7th, 14th, 28th, and 56th day after implantation. It was found that there were some irritant responses in the tissues adjacent to the implanted elastomers during the first week. However, the inflammatory tissue reaction subsided substantially from the second week onwards. The stable fibrous capsule surrounding the elastomer was formed after eight weeks. The tissue responses of the control, E580, and E590 were similar. The results suggested that the long-term tissue irritation of the experimental elastomers was so low such that they have the potential to be applied clinically.

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The purpose of this study was to investigate the effect of long-period exposure of 30% hydrogen peroxide on bovine enamel. Polished labial surfaces were scanned using an atomic force microscope after bleaching for 120 hours. Compositional change and microhardness of the enamels were evaluated using a Fourier transform Raman spectrophotometer and Vickers hardness tester. The same tests were performed on enamels stored in distilled water. In the FT-Raman spectra of both the unbleached and bleached enamels, peaks remained unchanged except for negligible decrease in intensity. As for microhardness, it significantly decreased after bleaching when compared to the original value (p<0.0001). However, the microhardness values of enamels stored in the bleaching agent and distilled water did not show any statistical difference. Based on the results of this study, the use of 30% hydrogen peroxide solution for dental bleaching should be safe due to its negligible effects on tooth morphology and structure.

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This study investigated the effect of 10% carbamide peroxide gel on human tooth color, vibrational mode, and mineral loss. The exposed enamels were bleached for two weeks (six hours' bleaching and 18 hours' storage in distilled water per day). Color change was calculated from the CIE L^*a^*b^* color values. Vibrational mode in Fourier transform Raman spectrum and mineral content were also estimated. The bleached enamels showed an apparent color change (ΔE^*=5.35). Within the test period, their whiteness increased linearly as the period increased. A slight decrease in Raman peak at 1068cm^-1 - compared with the peak at 430cm^-1 - was observed after bleaching. The total mineral content was decreased from 90.39 to 86.01 after bleaching. Also, the calculated Ca/P ratio decreased from 2.10 to 2.07. However, these changes were negligibly different from the enamels stored in distilled water except for a color change.

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The aim of this study was to investigate the effects of water immersion and repeated loading on the mechanical properties of a glass fiber-reinforced composite (FRC) material. Measurements for three-point flexural tests were made at three different temperatures and cross-head speeds, while measurements for fatigue tests were made under three different loads in air or water at 37°C after each cycle. The flexural strength and elastic modulus of the immersed specimens were significantly lower than those of the dry specimens at the same cross-head speed and temperature. On the whole, the values were inferior to those of metal. The deflection increased significantly as the load increased, but there were no significant differences between the values of dry and immersed specimens. With increasing load and number of cycles, the permanent deformation of both specimens increased significantly. The permanent deformation was similar to that of Co-Cr alloy. Based on the results of this study, it is recommended that more effort be devoted to exploring and devising shapes that would render FRC clasp arms with mechanical and physical properties that differ favorably from those of metal

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Though reputed for attaining the highest bonding strength, dentin bonding systems that use self-etching primer pose a grave concern. This is because the low pH environment induced by self-etching primer may have negative effects on polymerization reactions. In this study, we used electron spin resonance spectroscopy (ESR), high performance liquid chromatography (HPLC), and dynamic viscoelastic (DV) to analyze the effects of self-etching primer on the polymerization of bonding agents. The results of ESR revealed a lower concentration of polymerization radicals in a sample consisting of bonding agent and self-etching primer than in a sample consisting of bonding agent alone. However, in the results of HPLC and DV, the quantity of unpolymerized monomers decreased and the polymer produced was highly viscous in the sample with self-etching primer. It was suggested that hydroxyethyl methacrylate copolymerized as a plasticizer of Bis-GMA and that it formed the copolymer in the interface between the primer and bonding agent.

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The aim of the present study was to evaluate the dimensional accuracy and surface property of titanium casting obtained using a gypsum-bonded alumina investment. The experimental gypsum-bonded alumina investment with 20mass% gypsum content mixed with 2mass% potassium sulfate was used for five cp titanium castings and three Cu-Zn alloy castings. The accuracy, surface roughness (Ra), and reaction layer thickness of these castings were investigated. The accuracy of the castings obtained from the experimental investment ranged from -0.04 to 0.23%, while surface roughness (Ra) ranged from 7.6 to 10.3μm. A reaction layer of about 150μm thickness under the titanium casting surface was observed. These results suggested that the titanium casting obtained using the experimental investment was acceptable. Although the reaction layer was thin, surface roughness should be improved.

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Plasma irradiation on surface of heat-cured acrylic resin prior to processing self-curing acrylic resin is likely to effectively increase the adhesive strength between these materials for short-term period. However, long-term reliability of adhesive strength between these materials has not been clarified yet. In the present study, these materials were stored in water for a long period (100 days), and the effect on their shear bond strength was investigated. Forty-four test specimens with flat bonding test surface were made with heat-cured acrylic resin. They were divided into four groups according to treatment procedures for bonding surface: plasma treatment, adhesive primer application, adhesive primer application after plasma treatment, and no treatment (for control). Self-curing acrylic resin was processed against all bonding surfaces. After storage in water for 100 days, shear bond strength values between heat-cured and self-cured acrylic resins were measured. Specimens in plasma treatment group exhibited higher shear bond strength value than those in control, although the difference was not significant.

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The purpose of this study was to measure the bond strength of dual-cure resin cement at different regions of root canal dentin using three kinds of curing method. Thirty-six extracted bovine teeth were used. Each root was sectioned vertically into halves. Their pulpal dentin walls were polished flat and then applied with two dual-cure resin cements (Bistite II, Panavia F), and divided into three curing strategy groups: multi-direction light, one-direction light and no-light. The bonded specimens were sectioned perpendicularly to the long axis of the root into approximately 0.7mm thick slabs within two-third of the root from the coronal end, and prepared for microtensile bond strength (μTBS) test. Knoop hardness of the cements was also measured. Within each curing strategy for both dual-cure resin cements, there were no significant differences between the μTBS values at the coronal third and mid third regions. The effect of curing method on bond strength and KHN was found to be dependent on the material.

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The effect of acidic fluoride solution on NiTi arch wires was examined by testing crystal structure, tensile strength, morphology after fracture, and element release from wire under four different test solutions after 1 or 3d immersion. Threeday immersion in a 0.2%/pH4 solution did not form any new crystal structure. However, tensile strength after immersion was changed compared to the as-received wires. 3M wires showed increased tensile strength whereas G&H and Ormco wires showed decreased strength. Significant difference in tensile strength was associated with the immersion period. The fractured wires showed dimple patterns in the inner part of the wire, and ductile features on the outer part. Element release in the test solution increased as NaF concentration and the period of immersion increased, and as pH valued decreased. Wires immersed in a 0.2%/pH4 solution released several-fold greater amount of elements than wires in a 0.05%/pH4 solution. Tensile strength and element release were affected by acidic fluoride solution. In particular, NaF concentration, pH value, and the period of immersion were the factors affecting these properties.

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The aim of this study was to investigate the setting characteristics of seven silicone-based resilient denture liners during setting. Maximum extrusion force -at the flow rate of 1cm/min- ranged from 0.183 to 1.26MPa. Working time and setting time ranged from 2.0 to 5.0 minutes and 1.9 to 6.8 minutes respectively. Consistency as described in JIS T6519-2000 was 32.4 to 46.5mm. As normal load of 1kgf was applied to a specimen held between two glass plates after mixing, the time at which film thickness reached up to 1mm was 4.0 to 13.0 minutes at 23°C and 2.2 to 5.5 minutes at 37°C. These results suggested that the reaction rate of materials used in this study differed from one brand to another. Against this backdrop of differing reaction rates amongst brands, it is therefore vital that a denture liner material's setting characteristics be carefully considered whenever it is used in clinical dentistry to prevent any undesirable or unexpected results and outcome.

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Full crowns were fabricated from three different materials (titanium, ceramic, and resin composite) at different rest diameters using a dental CAD/CAM system, and then their marginal discrepancy measured. The deflection of cylindrical specimens at 500gf was measured using the same materials and diameters as for the accuracy measurement. Marginal discrepancy decreased as rest diameter increased, and at the same rest diameter the titanium crown had lower marginal discrepancy than ceramic and composite crowns. A significant correlation was found between marginal discrepancy of the crowns and deflection of the materials. This correlation was aptly expressed in the regression equation, MG=4.54DF+53.9, where MG represented marginal discrepancy and DF represented deflection. This equation can be used as a good measure for new materials which have different modulus of elasticity.

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The aim of this investigation was to compare the tensile strength, microleakage, and Scanning Electron Microscope (SEM) evaluations of SSCs cemented using different adhesive cements on primary molars.
Sixty-three extracted primary first molars were used. Tooth preparations were done. Crowns were altered and adapted for investigation purpose, and then cemented using glass ionomer cement (Aqua Meron), resin modified cement (RelyX Luting), and resin cement (Panavia F) on the prepared teeth. Samples were divided into two groups of 30 samples each for tensile strength and microleakage tests. The remaining three samples were used for SEM evaluation. Data were analyzed with one-way ANOVA and Tukey test.
The statistical analysis of ANOVA revealed significant differences among the groups for both tensile strength and microleakage tests (p<0.05). Tukey test showed statistically significant difference between Panavia F and RelyX Luting (p<0.05), but none between the others (p>0.05).
This study showed that the higher the retentive force a crown possessed, the lower would be the possibility of microleakage.

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The purpose of this study was to evaluate the durability of tubules occluded with FTLA treatment by toothbrush abrasion test on the applied surface and by measuring fluoride release from the FTLA components. Dentin specimens with simulated hypersensitive surfaces were treated with APF containing tannic acid. After which, the specimens received lanthanumchloride-with-powdered-fluoroapatite-glass-ceramics treatment. The specimens were subjected to toothbrush abrasion test up to 6, 000 strokes. SEM observation revealed that dentinal tubules of the FTLA treated specimens were completely occluded with fine deposits even after toothbrush abrasion of 6, 000 strokes. EPMA analysis revealed that fluoride, lanthanum, and aluminum were the main FTLA components on the dentin surface after 6, 000-stroke abrasion. To measure fluoride release from the FTLA components, a slurry was enclosed in a cellulose tube and suspended in deionized water at 37°C. After fluoride was dialyzed against deionized water, a high concentration of fluoride was found to be released from FTLA the components, indicating FTLA treatment's prominent durability.
These results suggested that FTLA treatment has a superior resistance against toothbrush abrasion and a high fluoridereleasing performance. These characteristics lend much weight to showing that the FTLA method is an effective and durable medicament for dentin hypersensitivity.

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The distortion of laser welded titanium plates was assessed for different operating conditions of the laser welding device, and with different welding parameters (in terms of weld point and prewelding). In this study, Nd: YAG laser welding device was used to join the titanium plates. The results showed that distortion increased stepwise after each welding point along the welding zone (one-side welding), but decreased consecutively as the welding proceeded on the second side of the weld (two-side welding). In the case of one-side welding, the dependence of distortion on current and spot diameter presented maxima - due to changes in the welding pool characteristics. For two-side weld the same parameters exercised little influence on its distortion recovery, due to the effect of solidified weld pools from the first side. Current and spot diameter determined the weld pool, which in turn regulated distortion based on shrinkage. Four-point prewelding significantly decreased the final distortion for both one- and two-side welds. Alternating two-side welding of prewelded assembly showed lower distortion than a classic two-side weld.

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Specimens (such as metal inlays) with 30° or 45° marginal bevel were prepared by casting with a 12% Au-Pd-Ag alloy or a gold alloy. A form of the marginal bevel was traced on a profile projector before and after sandblasting, and the length of the abraded margin measured. All the blasting conditions abraded the marginal bevel, while the blasting at 20mm for 2 seconds brought about the least abrasion of approximately 10μm in the 45° specimen cast with Au-Pd-Ag alloy. The gold alloy specimens were abraded more than the Au-Pd-Ag alloy ones; those with marginal bevel of 30° were abraded more than those of 45°.
On the other hand, the effect of different blasting conditions on the bond strength of units bonded with resin cement was evaluated (under selected blasting conditions known to cause relatively less damage to the marginal bevel). Specimens treated by sandblaster exhibited a comparable tensile bond strength, while specimens without sandblasting but applied with only an alloy primer showed a statistically low value.

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The purpose of the present study was to determine the ability of interdental brush to withstand repeated use and to relate this property to clinically observed fractures of such brushes. The stem durability test was conducted according to ISO (International Standards Organization) standard by using a bending at 90° under a 500-g controlled load (ISO/TC106/SC7/WG3). Two sizes (ss, m) of each of the five commercially available interdental brushes (D, B, P, I, S) were used. The cycle number at the time of fracture was noted for all interdental brushes. The fractured surfaces of the stem wire following the stem durability test were also observed under a scanning electron microscope. The specimens, when ranked in decreasing order of the number of cycles at which fracture occurred, were D-m, D-ss, B-ss, B-m>P-m, P-ss, I-ss, I-m, S-m, S-ss (P<0.05). L-type interdental brushes (P-m, P-ss, I-ss, I-m, S-m, and S-ss) showed significantly decreased fracture resistance when compared with straight-type interdental brushes (D-m, D-ss, B-ss, B-m). In all cases, the fracture was found to be of ductile nature.

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The purpose of this study was to evaluate histologically the reaction of soft and hard tissues in rats toward a composite membrane consisting of oriented needle-like apatite crystals and biodegradable copolymer. Histological findings regarding the soft tissue reaction showed that the membrane with or without apatite was covered by fibrous connective tissue at four weeks after implantation. In the case of hard tissue, the defect in dura mater -which was covered with an apatitecontaining membrane- was fully filled with new bone at four weeks after implantation. As for the membrane without apatite, there was some indication of a granulation tissue reaction around the membrane. These results suggested that the biodegradable composite membrane containing oriented needle-like apatite had excellent biocompatibility with both soft and hard tissues.

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New types of self-setting calcium phosphate cement (N-CPC), which do not contain tetracalcium phosphate, were recently developed. N-CPCs harden in 10 minutes with phosphate solution as the cement liquid, and form hydroxyapatite as the set product. The objectives of the present study were to evaluate the biocompatibility (Study I) and cell enzyme activity of N-CPCs and a conventional CPC (Study II). Four experimental cements were tested: (1) dicalcium phosphate anhydrous (DCPA) and calcium oxide; (2) DCPA and calcium hydroxide; (3) tricalcium phosphate and calcium carbonate; and (4) DCPA and tetracalcium phosphate. Phosphate solution was used as the cement liquid for cements (1)-(3), and water for cement (4). Sintered hydroxyapatite particles (5) were used as a control. The test materials were implanted subcutaneously in rats. Four weeks after operation, the animals were sacrificed and histopathological observations were performed. Cements (2) and (3) showed no inflammatory reaction, and were surrounded only by very thin fibrous connective tissues. The histopathological reactions of N-CPCs were nearly identical and were similar to (4) and (5). In addition, effects of alkaline phosphatase (ALP-ase) activity - invoked by the presence of cements (3) and (4) - on osteoblast-like cells derived from dog alveolar bone were also examined because ALP-ase activity is closely related to new bone formation. These results indicated that (3) and (4) were highly compatible with subcutaneous tissues and suggested that these cements may enhance new bone formation.

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To establish a method of determining the machinability of dental materials for CAD/CAM systems, the machinability of titanium, two titanium alloys (Ti-6Al-4V and Ti-6Al-7Nb), and free-cutting brass was evaluated through cutting force and spindle motor current. The metals were slotted using a milling machine and square end mills at four cutting conditions. Both the static and dynamic components of the cutting force represented well the machinability of the metals tested: the machinability of Ti-6Al-4V and Ti-6Al-7Nb was worse than that of titanium, while that of free-cutting brass was better. On the other hand, the results indicated that the spindle motor current was not sensitive enough to detect the material difference among the titanium and its alloys.

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The aim of this in vitro study was to evaluate the pH value of intact and carious dentin in primary teeth using a pH-imaging microscope (SCHEM-100, HORIBA Ltd., Kyoto, Japan). Bucco-lingual cut sections of extracted human primary teeth, which had either mild or severe dentinal caries lesions, were placed on the pH-imaging sensor of the microscope. The pH values were compared statistically by Levene's test for equality of variances and Tukey HSD multiple comparison test (p<0.05). For both mild and severe lesions in primary dentin, the lowest pH values in the carious lesions were lower than those of intact dentin (6.6, range 6.3-6.9). There were statistical differences between the lowest pH value within the mild lesions (6.2, range 5.8-6.4) and that of the severe lesions (6.0, range 5.9-6.2) (p<0.05). It was concluded that SCHEM-100 was able to distinguish the pH-value distribution of intact and carious dentin in primary teeth.

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The purpose of this work was to investigate the far infrared spectral characteristics of bamboo charcoal powder and its effect on cancer cells for use in the dental field. To analyze the effects of the powder, HeLa and WI-38 cells were used and then assessed by cell adhesion assay and WST-1 assay. The powder emitted far infrared rays at wavelengths between 4 to 16μm. The multiplication rate of WI-38 cells showed no significant differences between the conventional culture (control group) and culture on the powder (FIR group). However, at six days after incubation, HeLa cells of FIR group had a significantly lower multiplication rate compared with the control group. Based on the far infrared rays emitted in this study, bamboo charcoal powder proved to be a promising dental filler material for cancer prevention.

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The centrifugal shooting type polishing machine is a recently developed apparatus that seeks to improve the efficiency and environment of polishing removable prostheses. In an attempt to optimize the effectiveness of this apparatus, this study examined the influence of the shooting angle of polishing particle on the surface roughness of cobalt-chromium alloy casting specimens. Polishing was performed for three minutes under five shooting angle conditions: 90°, 60°, 45°, 30°, and 15°. Surface roughness (Ra, Sm) was measured after each polishing stage. There were significant differences (p<0.01) in Ra between shooting angle of 90° (0.95μm) and shooting angles of 45° (0.62μm) or less, and in Sm between 90° (207μm), 60° (350μm), and shooting angles of 45° (868μm) or less. These findings indicated that excellent surface texture was produced when shooting angle was 45° or less.

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It has been reported that the adhesive resin layer of all-in-one adhesives is permeable and allows the formation of a water channel or water tree. The effects of a smear layer on the ultra-structure of bonding interface created with three all-in-one adhesives and a resin composite were evaluated in this study. Dentin surface was ground with of 180-, 600-, or 2000-grit SiC paper to produce different smear layer thickness. The bonding interfaces were observed under a transmission electron microscope without demineralization. Voids of various sizes and water channels were found at the bottom of the adhesive resin layer along the bonding interface of SiC 180-grit dentin, while SiC 2000-grit dentin did not produce any voids. The results showed that the voids were possibly related to water that had penetrated from the underlying dentin. A smear layer may have an adverse influence on the bonding performance of all-in-one adhesives to dentin.

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Our previous study reported that an osteopontin-derived peptide SVVYGLR activates the adhesion, migration and tube formation abilities of endothelial cells in vitro. The present study investigated angiogenesis due to synthetic SVVYGLR and mutant peptides in vivo. Mutant peptides (n=7) were synthesized by substituting alanine (A) for one of the 7 amino acids comprising SVVYGLR. In dorsal air sac assay, mouse dorsal skin 5 days after implantation of a chamber filled with SVVYGLR had approximately the same number of newly formed blood vessels to that filled with vascular endothelial growth factor (VEGF). The ability of angiogenesis due to SVVAGLR was significantly lower than that due to other 6 mutant peptides and SVVYGLR. This indicates that tyrosine (Y) plays an important role in angiogenesis due to SVVYGLR.

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This study examined the possible correlation between the strength of glass ionomers and their adhesive strength to bovine teeth. The shear bond strengths of three different brands of glass Ionomer mixed at four different P/L ratios to bovine teeth were measured 24 hours after the cement specimens were prepared. The correlation between shear bond strength and mechanical strength reported in our previous study was also examined. No significant (p>0.05) increases in the bond strength to bovine teeth were found in any of the cements when the mixing ratio increased. The present study showed no significant (p>0.05) correlation between mechanical strength of cement and its bond strength to bovine teeth. Rather than trying to increase the strength of the cement, it would be more effective to enhance the adhesive bond strength through procedures such as surface conditioning or cleaning of the tooth structure when glass ionomers are used as luting agents.

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