Biomedical subjects
Publications and source records attributed to M Atsuta.
1. Pitting corrosion provides undercuts suitable for retaining a resin facing. 2. Using a cathode with a proper shape, pits were uniformly distributed on the surface of a metal casting. The size of pits varies, depending on the time of pitting treatment. 3. The retentive pits were excellent in both retentive strength and marginal sealing when compared with spherical powder and beads.
Macro- and microscopic studies were made of an interfacial microstructure which developed between a bifunctional monomer and a PMMA rod (or beads) during polymerization. The microstructure consisted of a white band and a blue transparent zone.
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1. Nine different sizes of spherical powder were prepared, and their effectiveness as retentive devices was evaluated against those available commercially. 2. Smaller-diameter spherical powder (No. 5) gave the best results of all retaining devices tested. 3. The physical properties of the resins play an important role in the retentive strength with No. 5 retention beads. The retentive strength was reduced when brittle resin was used. 4. The retentive strength of the resin veneer was greatly affected by the angle of stress at the incisal resin. The retentive strength increased as the angle between the longitudinal axis of the specimen and the direction of stress decreased.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
OBJECTIVES: The purpose of this study was to evaluate the effect of acidic primers on bonding between methacrylic resins and SUS 316 stainless steel. METHODS: The primers were single liquid metal conditioners containing either a phosphate monomer (Cesead opaque primer, CO; Metal primer, MP) or a carboxylic monomer (Super-Bond liquid, SB; Acryl bond, AB; MR bond, MR). Disk metal specimens were air-abraded with alumina followed by priming. The disks were bonded with a methacrylic resin using a brush-dip technique (Super-Bond C & B, CB or Repairsin, RE). Specimens were thermocycled in water and bond strengths were determined. RESULTS: Shear bond strengths after the thermocycling were 11.9 MPa for CO-CB, 7.6 MPa for CO-RE, 4.9 MPa for SB-RE, 3.9 MPa for MP-RE, 3.3 MPa for AB-RE, 2.5 MPa for MR-RE, 1.9 MPa for None-CB, and 0 MPa for None-RE. The two systems primed with CO primer showed greater bond strengths than the other groups (P < 0.05). Of the two systems conditioned with CO primer, CB resin demonstrated higher value bond strength as compared with RE resin (P < 0.05). CONCLUSION: Among the systems examined, CO primer used together with CB resin exhibited greater bond strength to SUS 316 stainless steel than other systems after the ageing test. Reduction in bond strength by thermocycling, however, was remarkable for all groups.
Dental resin composites with antibacterial activity may be useful for preventing the secondary caries frequently seen around restorations. Three types of silver-supported antibacterial materials (Novaron, Amenitop and AIS) inhibited the growth of the major oral pathogen Streptococcus mutans. Minimum inhibitory amounts in suspensions of Novaron, Amenitop and AIS against S. mutans were 40, 30 and 400 microg/ml, respectively. These antibacterial materials were incorporated into TEGDMA-UDMA-based light-activated resin composite, and the antibacterial activities of these composites were examined. Composites incorporating 5 wt% (N-5) or more of Novaron and 7 wt% (AM-7) or more of Amenitop inhibited the growth of S. mutans, whereas composites incorporating up to 10 wt% of AIS did not. No significant difference in either compressive or flexural strength was observed between the control and N-5 composites after 1 day and 6 months of storage in water. However, for AM-5 composite, there was a significant difference in either strength parameter between the two immersion periods. There was no or extremely little release of silver ions from the N-5 and AM-5 composites after 1 day or 6 months of immersion in water. These results indicated that a light-activated resin composite incorporating silver-supported antibacterial material such as Novaron may be clinically useful due to its inhibitory effect against S. mutans and favorable mechanical properties.
PURPOSE: The objective of the current study was to investigate the surface morphologic characteristics of prosthodontic composite materials treated with an acidulated phosphate fluoride (APF) agent. MATERIALS AND METHODS: Seven composite materials (Artglass, Axis, Belleglass, Cesead II, Dentacolor, Solidex, and Targis) were examined. Each material was packed into a split plastic mold and was polymerized with a laboratory photo-curing unit. Half of each composite disk surface was coated with a varnish, and the entire surface of the sample was treated with an APF agent. After removal of the varnish, surface roughness values (Ra) for the treated and untreated (ie, previously varnish coated) sides of all specimens were recorded with a surface analyzer and observed with a scanning electron microscope. RESULTS: Ra values for Cesead II, Solidex, and Targis showed a significant increase as a result of treatment with the APF solution. Microphotographs demonstrated that the macroinorganic fillers in the Cesead II and Solidex materials showed substantial dissolution caused by the APF agent. There were no significant statistical differences in the Ra values between the treated and untreated halves for any of the materials containing inorganic fillers composed entirely of diameters up to 1.0 microm. In particular, microphotographs of prepolymerized silica composite (classified as microfilled materials in Axis and Dentacolor) did not reveal any change of the specimen surfaces. CONCLUSION: The APF agent attacked inorganic fillers in the composite materials. Microfilled material surfaces were insensitive to the agent in comparison with macroinorganic filled material surfaces.
The purpose of this study was to evaluate the effect of etching and silane priming on bond strength to a feldspathic porcelain (VMK 68) of a composite resin (Clearfil APX). Two hydrofluoric acid etchants (2.5% and 5%) and seven different etching times (0, 30, 60, 90, 120, 150, and 180 seconds) were used to etch the porcelain specimens respectively. A self-curing bonding agent containing a silane coupler (Clearfil Porcelain Bond) was used on both etched and unetched porcelain surfaces. Etched relief patterns were observed by means of a scanning electron microscope, and the bond strengths between the photocured composite resin and the porcelain were determined. Scanning electron micrographs revealed complicated etching patterns with increased etching time periods. Shear testing results showed that the bond strength to the unetched porcelain of the composite resin was very low, and that etching periods for more than 30 seconds effectively enhanced the bond strength. Of the two etching agents applied to the unsilanated porcelain, the buffered 2.5% etchant produced higher bond strengths than the 5% etchant for all etching time periods except for 180 seconds. Silane priming was effective and critical for improving bond strength to the porcelain. Application of the silane bonding agent to the porcelain after hydrofluoric acid etching appeared to be suitable for achieving consistent bonding between the composite resin and the porcelain.