Integrated electromyographic activity and biting force during rapid isometric contraction of fatigued masseter muscle in man.
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Adult↗
Biomedical subjects
H Yatani
Publications and source records attributed to H Yatani.
Effects of thermocycling on the tensile bond strength between resin cement and dentin surfaces after temporary cement application.
PURPOSE: In a previous study the authors found that 2 of 3 tooth conditioners examined were able to reduce the negative effect of temporary cement on the bond strength between resin cement and teeth. The aim of this study was to evaluate the bond durability with the conditioners, as well as their capability for temporary cement dissolution. MATERIALS AND METHODS: After eliminating the temporary cement with a curette from the bovine dentin surface, a conditioner (ethyl dihydrogen phosphate, EP; or methacryloxyethyl dihydrogen phosphate, MEP) was applied to the surface and a resin cement was adhered. Tensile bond strength measurement, scanning electron microscopic observation, and energy-dispersive analysis were carried out without thermocycling and after thermocycling. RESULTS: The tensile bond strength gradually decreased with an increase in the number of thermocycles. However, specimens treated with EP or MEP showed significantly higher tensile bond strength values compared to those that did not receive conditioner application (P < 0.0001); EP showed significantly higher tensile bond strength values compared to the specimens that did not receive both temporary cement and conditioner application (P < 0.0001). The scanning electron microscopic, energy-dispersive, and solubility analyses suggest that both conditioners have the capability of dissolving temporary cement remnants. CONCLUSION: Both EP and MEP have potential value as conditioners to reduce the negative effect of temporary cement on the bond strength between resin cement and dentin and to improve the bond durability.
Analysis of Variance↗
The influence of blood contamination on bond strengths between dentin and an adhesive resin cement.
The objective of this study was to determine in which step of adherent surface treatments blood contamination affects the bond strength between an adhesive resin and dentin. The coronal part of bovine incisors was polished flat to expose the dentin. The specimens were randomly divided into three groups and specific surface treatments were applied to each group: (1) a self-etching primer application (SP group); (2) 38% phosphoric acid etching followed by primer (non-HC group); (3) acid etching followed by 10% sodium hypochlorite solution application and primer (HC group). The dentin surface was contaminated by human blood before or after either step of the surface treatments. The contaminated surfaces were washed with water after 30-second exposure and air-dried. A stainless-steel rod was adhered on the dentin surface with Panavia 21 after completing the surface treatment(s), and the tensile bond strength was measured. Fifteen subgroups including control groups were tested. If blood contamination occurred before collagen fibers were exposed by either phosphoric acid etching or self-etching primer application, the contamination presented almost no influence on bond strength. Blood contamination of the dentin surface where collagen fibers had been exposed decreased the bond strength. However, when the contaminated collagen fibers were dissolved or when the contamination occurred after the exposed collagen fibers were dissolved, the bond strength was maintained. The bond strength was markedly decreased when the contamination occurred after the primer application (Scheffé's Comparison, SP group: p = 0.0003, non-HC group: p < 0.0001), but was restored by reapplication of the self-etching primer. This study revealed that the effects of blood contamination on the bond strength of adhesive resin to dentin vary greatly depending on the adherent surface conditions.
Acid Etching, Dental↗
Effect of dissolution of collagen on adhesion to dentin.
A new method of adherend surface treatment was evaluated to determine the effect of adhesion between dentin and adhesive resins. The pretreatment method consisted of the application of 40% phosphoric acid solution to dentin to remove the smear layer and decalcify the superficial dentin layer, followed by 10% sodium hypochlorite to dissolve and remove the exposed dentinal collagen and provide a fresh dentin apatite surface to which adhesive resin is applied. This method features a direct adhesion between the adhesive resin and dentin, with no resin-reinforced layer of dentinal collagen and adhesive resin. The adhesive tensile strength after storage in water at 37 degrees C for 24 hours measured 6.7 MPa with the phosphoric acid treatment alone, while the test method produced an initial adhesive strength as high as 9.7 MPa. After 10,000 thermal cycles (4 degrees C to 60 degrees C), the adhesive strength was 6.2 MPa, which was approximately 1.5 times greater than the value obtained with the method using the phosphoric acid solution alone.
Acid Etching, Dental↗
Temporary cement remnants as an adhesion inhibiting factor in the interface between resin cements and bovine dentin.
This study investigated the effect of temporary cement remnants on freshly prepared dentin in the adhesion of resin cements. The tensile bond strength of three types of resin cements to dentin were measured in a control group and after the application of two types of temporary cement. Scanning electron microscopy and energy dispersive x-ray spectroscopy were used to confirm the presence of temporary cement remnants. Overall results suggest that temporary cement application significantly decreased the tensile bond strength in all adhesive systems (P = 0.0001, analysis of variance). Scanning electron micrographs presented granular elements on the dentin surfaces treated with temporary cement even after preconditioning. Energy dispersive x-ray spectroscopy results showed the presence of zinc peaks in the specimens that was not present in the control.
Adhesiveness↗
Improvement in the tensile bond strength between resin cement and dentin surfaces after temporary cement application.
PURPOSE: The aim of this study was to evaluate the efficacy of three tooth conditioners in restoring the reduced bond strength between resin cement and teeth resulting from remaining temporary cement. MATERIALS AND METHODS: Ethyl dihydrogen phosphate, methacryloxyethyl dihydrogen phosphate, and 2-methacryloxyethyl hydrogen maleate were evaluated as conditioners. After eliminating the temporary cement with a curette from the bovine dentin surface, the conditioners were applied onto the surface of the specimen and a resin cement was adhered. Stepwise scanning electron microscopic observation and tensile bond strength measurement were carried out. RESULTS: Granular substances were present on the dentin surface even when the temporary cement was carefully eliminated with a curette. When primer and resin cement were applied on this surface without conditioner application, no resin tag or hybrid layer was observed and the mean bonding strength between tooth and adhesive resin cement was 1.8 MPa. In contrast, resin tag and hybrid layer were observed after primer and resin cement application when the dentinal surface was treated with conditioner. Mean tensile bone strength values increased to 6.2 MPa for specimens treated with 20% methacryloxyethyl dihydrogen phosphate for 60 seconds. CONCLUSION: The authors recommend methacryloxyethyl dihydrogen phosphate as it provides high tensile bond strength values and requires no additional rinse step.
Analysis of Variance↗