Biomedical subjects

W Yukitani

Publications and source records attributed to W Yukitani.

6 recordsLinked to original sources

PubMed1994

Efficacy of various commercial dentin bonding systems.

OBJECTIVES: The purpose of this study was to test the bonding efficacy of fifteen commercial dentin bonding systems and also to determine the effect of various commercial dentin cleaners on bonding and dentin hardness. METHODS: Each commercial bonding system was examined by two methods: 1) measuring the maximum contraction gap of a light-cured composite in a cylindrical dentin cavity; and 2) determine the tensile bond strength to a flat dentin surface. In addition, various commercial dentin cleansers were investigated to determine if dentin hardness was reduced after cleaning. As a control, the dentin surface was cleaned with neutralized EDTA prior to the combined application of an experimental dentin primer, a commercial bonding agent, and a commercial light-cured composite. RESULTS: The study demonstrated that complete marginal adaptation was obtained by the experimental dentin bonding system used as the control. However, it was not possible to completely prevent gap formation with the commercial dentin bonding systems tested. A high correlation (R = 0.88) was observed between maximum contraction gap width and reduction of hardness only in the group in which the dentin was rinsed after cleaning. SIGNIFICANCE: It is very important to combine optimal dentin cleansers, primers, and bonding agents to compensate for the polymerization contraction stress of the composite. Therefore, it was speculated that the commercial dentin bonding systems tested in this study consisted of unsuitable materials.

Acid Etching, Dental↗

PubMed1994

Self-etching dentin primers containing phenyl-P.

The dentin bonding efficacies of two commercial dentin bonding systems and experimental self-etching dentin primers composed of methacryloxyethyl hydrogen phenyl phosphate (Phenyl-P) and either hydroxyethyl methacrylate (HEMA) or glyceryl methacrylate (GM,2,3-dihydroxypropyl methacrylate) were examined. The wall-to-wall polymerization contraction gap width of a commercial light-activated resin composite in a cylindrical dentin cavity and the tensile bond strength to a flat dentin surface were measured. Changes in dentin hardness were determined by Micro Vickers Hardness measurement, and an SEM observation was performed after priming. Formation of a contraction gap was completely prevented by the application of Phenyl-P diluted in HEMA or GM solution combined with a commercial dentin bonding agent, although gap formation was evident in nearly half of the specimens with both commercial dentin bonding systems. The mean tensile bond strengths of the tested groups varied from 16.3 to 20.7 MPa, and there were no significant differences between groups. Based on the measurement of Micro Vickers Hardness and SEM observation after priming, a slight reduction in dentin hardness was observed. However, this reduction in dentin hardness due to self-etching priming did not significantly correlate with either contraction gap width or tensile bond strength.

Acid Etching, Dental↗

PubMedDate not supplied

Effect of mechanical properties of resin composites on the efficacy of the dentin bonding system.

This study determined the relationship between marginal adaptation to dentin cavity preparations, tensile bond strength of the restorations, and mechanical properties of the composites. Contraction gaps, tensile bond strengths, flexural strengths, and Young's modulus of eight commercial resin composites were determined. Eight resin composites (Clearfil AP-X, Estelite, Estio LC, Litefil II-A, Prodigy, Progress, Silux Plus, and Z-100) were applied to dentin cavities or flat dentin surfaces mediated with an experimental dentin bonding system consisting of 0.5 M EDTA dentin conditioner, priming with 35% glyceryl mono-methacrylate solution, and a commercial dentin bonding agent application (Clearfil Photo Bond). The contraction gap of the resin composite in a cylindrical dentin cavity was prevented completely for three of the resin composites tested (Clearfil AP-X, Estelite, and Silux Plus). The measured tensile bond strength correlated significantly not only with the tensile strength (r2 = 0.506; 0.01 < P < 0.05), but also with the flexural strength (r2 = 0.871; P < 0.001) and Young's modulus (r2 = 0.712; 0.001 < P < 0.01) of the composites, whereas the contraction gap did not correlate significantly with the measured tensile bond strength, the tensile strength, the flexural strength, or Young's modulus (P > 0.05). However, the results did indicate that the higher tensile bond strengths measured in the traditional test may be related to the higher mechanical properties of the resin composites because of the number of specimens that exhibited cohesive failure.

Analysis of Variance↗

PubMedDate not supplied

Effects of soft-start irradiation on the depth of cure and marginal adaptation to dentin.

Marginal adaptation of four resin composites, Clearfil APX, Estelite, Silux Plus and Z-100 cured with two irradiation methods (soft-start or high-power start) of a commercial soft-start halogen lamp unit (Elipar Highlight) were evaluated by measurement of the wall-to-wall contraction gap width. One-hundred and sixty cylindrical cavities, 3 mm in diameter and 1.5 mm in depth, were prepared in extracted human molars. The 80 cavity walls were treated with the Megabond system and each 20 cavities were filled with one of four resin composites. Then, each 10 fillings were irradiated by the soft-start method (soft-power light for 10 seconds followed by high-power light for 30 seconds) or high-power light for 40 seconds. The other 80 cavity walls were treated with an experimental bonding system consisting of 0.5M EDTA as a conditioner, 35% glyceryl mono-methacrylate as a primer and Clearfil Photo Bond as a bonding agent. The cavities were restored wtih the four resin composites and two irradiation methods, the same as the Megabond group. The contraction gap was measured with a light microscope and expressed in % of the cavity diameter. In addition, the curing capability of these two light sources was evaluated by measurement of the curing depth of the four resin composites using a split Teflon mold 4 mm in inner-diameter and 8 mm in height. Marginal gap formation of Clearfil APX, Estelite and Silux Plus with the experimental bonding system was completely prevented regardless of the kind of irradiation methods used. The deterioration of marginal adaptation caused by the Megabond system could not be improved by use of the soft-start method programmed in Elipar Highlight.

Composite Resins↗

PubMedDate not supplied

Depth of cure and marginal adaptation to dentin of xenon lamp polymerized resin composites.

Marginal adaptation of four resin composites (Clearfil APX, Estelite, Silux Plus and Z-100) cured with two xenon lamp units (Plasma Arc Curing System or Apollo 95E) or a halogen lamp unit (Witelite) were evaluated by measuring the wall-to-wall contraction gap width. A cylindrical dentin cavity (ø3 mm x 1.5 mm) prepared in an extracted human molar was treated with the Megabond system or an experimental bonding system consisting of 0.5 M EDTA, 35% GM and Clearfil Photo Bond prior to composite filling and was irradiated for three seconds (xenon lamp) or 40 seconds (halogen lamp). The contraction gap was measured with a light microscope. In addition, the curing capability of these three light sources was evaluated by measuring the curing depth of the composites filled in a split Teflon mold (ø4 mm x 8 mm). There was no marginal gap formation for Clearfil APX, Estelite and Silux Plus treated with the experimental bonding system regardless of the type of light sources. The curing depth of the xenon lamp was significantly higher than the halogen lamp, while marginal adaptation did not suffer any significant deterioration.

Analysis of Variance↗

PubMedDate not supplied

Marginal adaptation of dental composites containing prepolymerized filler.

Marginal adaptation to cylindrical dentin preparations of five commercially available dental composites--Charisma, Estelite, Herculite, Pertac, and Silux Plus--and seven experimental dental composites containing prepolymerized filler was evaluated by measurement of the wall-to-wall polymerization contraction gaps. The experimental composites were prepared with varying amounts of spherical inorganic filler particles, irregularly shaped prepolymerized filler particles, and a base resin matrix composed of BIS-GMA and TEGDMA. Cylindrical dentin preparations, approximately 3.0 mm in diameter and 1.5 mm deep, were prepared in the exposed approximal dentin surfaces of extracted human molars. These cavity preparations were pretreated with an experimental dentin bonding system consisting of 0.5 mol/L EDTA, 35% glyceryl methacrylate, and Clearfil Photo Bond, then restored with each composite. Complete marginal adaptation was observed in two composites (Silux Plux and Estelite). Wall-to-wall contraction gaps were significantly related to the amount of ashed inorganic component in the composites (0.01 < P < 0.05) and to the spherical inorganic filler content by volume (P < 0.01).

Bisphenol A-Glycidyl Methacrylate↗