The influence of configuration factors on cavity adaptation in compomer restorations.
(9/474)
The effect of configuration factor (C-factor) on cavity adaptation was investigated in three compomer and one resin composite restorations. Eighty-four cylindrical dentin cavities (C-factor: approximately 2.5, 3.0 or 4.0) prepared on flat coronal dentin surfaces were filled with the materials in combination with their proprietary adhesive systems. Cavity adaptation was microscopically examined after 15 minutes storage in water at the top surface and at other four sites along the cavity walls. Additionally, indentation testing was performed for each material at 20 minutes and 24 hours after irradiation. Regression analysis revealed no relationship between C-factor and gap dimension in compomer restorations at any of the measuring sites, while a logarithmic relation was found only at the cavity floor of the composite fillings. All materials showed maturation of mechanical properties. The elastic component of the indentation was smaller in compomers than in the composite. It was concluded that C-factor had no influence on the cavity adaptation for compomer restorations. This might be due to reduced stress generation at the bonding interface caused by relatively low mechanical properties immediately after curing, less elasticity, and water absorption in compomers. (+info)
Inhibition of carious lesions in vitro around gallium alloy restorations by fluoride releasing resin-ionomer cement.
(10/474)
A new fluoride releasing resin-ionomer cement was used for bonding of gallium alloy restorations in vitro. Etching, priming, and fluoride releasing resin-ionomer cement were used in the experimental group (ARG), prior to placement of the gallium alloy restorations. Three different controls were used: gallium alloy only (G), no etching, fluoride releasing resin-ionomer cement, gallium alloy (RG), etching, priming, non-fluoride cement and gallium alloy (ACG). The mean shear bond strengths of ARG group to enamel and dentin were higher than those of the three control groups. Artificial secondary caries lesions around the restorations in the experimental group and the control groups were produced, using a strep. mutans culture. The microradiographs were examined for presence of a caries inhibition zone near the restoration. Caries inhibition zones were clearly detected around RG and ARG, but not around G and ACG. The results indicate that the fluoride releasing resin-ionomer cement provided good adhesion and caries inhibition in enamel and dentin. (+info)
Effect of carboxyl group in O-methacryloyl-N-acyl tyrosines on adhesiveness to unetched human dentin.
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We have reported that the carboxylic group plays an important role in the adhesion of methacryloyl amino acid--2-hydroxyethyl methacrylate type restorative resin to dentin surfaces. However, our study so far has been limited to the methacryloyl amino acid that has only one carboxylic acid. In this investigation, three new O-methacryloyl-N-acyl tyrosines (MAATY) that have one or two carboxylic groups in the acyl group, and thus two or three carboxylic groups in MAATY, were prepared and evaluated for their bond strength to unetched dentine. Higher bond strength was observed when the MAATY contained larger number of carboxylic acid groups. Factor analysis of the bonding strength revealed that the hydrogen bond ability of the carboxylic acid and the hydrophile-lipophile balance (HLB) affected the bond strength. (+info)
The effect of primers on bond strength of polyacid-modified resin composites (compomers).
(12/474)
This study evaluated the effect of primer on shear bond strength and marginal gaps of six new compomers immediately after light-activation. A resin-modified glass ionomer cement, a conventional glass-ionomer cement and a microfilled composite were used for comparison. The marginal gap widths of each of the four compomers and a microfilled composite used with the primer were significantly smaller compared with those used without the primer. The bond strength values of five compomers used with the primer were significantly higher than those used without the primer. The bond strength of conventional glass-ionomer was not affected by the primer (or the conditioner). (+info)
Effect of functional monomer in commercial dentin bonding agents use of an experimental dentin bonding system.
(13/474)
The objective of the present study was to understand the role of the functional monomers in dentin bonding agents of an experimental dentin bonding system by measuring the wall-to-wall contraction gap and tensile bond strength measurement. The efficacy of three commercial dentin bonding agents after using EDTA for conditioning and GM for priming was evaluated by measuring the contraction gap of the resin composite in a cylindrical dentin cavity, and by measuring the tensile bond strength of the composite to a flat dentin surface. The effect of the functional monomers was demonstrated by the contraction gap measurement alone. The value of the contraction gap was significantly different between the commercial dentin bonding agents and these agents without functional monomers (p < 0.05). It was concluded that the functional monomers were essential to obtaining the marginal integrity of the resin composite in the dentin cavities. (+info)
Adhesion of a new commercial self-etching/self-priming bonding resin to human caries-infected dentin.
(14/474)
We have examined the adhesive properties of a new commercial self-etching/self-priming bonding resin (Unifil Bond, UB) to normal and caries-infected dentin of human extracted molars using scanning electron microscopy (SEM) and a micto-tensile bonding strength (MTBS) test. In this study, 7 human extracted molars with moderate occlusal caries were used, and flat surfaces including occlusal dentin caries were prepared from the teeth. After the application of UB to the surfaces, a composite resin was built up, and subjected to the measurement of MTBS and SEM observation of the interfacial morphology between UB and dentin. The MTBS of UB to normal dentin was 33.4 MPa, but that to caries-infected dentin was 11.0 MPa. There was a significant difference between the MTBS to normal and carious dentin. SEM observation revealed that the typical hybrid layer was not formed in caries-infected dentin. These results suggested that resin infiltration into caries-infected dentin was not sufficient to allow perfect sealing of the restoration. (+info)
The effect of food simulants on enamel-composite bond strength.
(15/474)
The effect of food simulants upon the enamel-composite bond strength of two orthodontic adhesive composites was studied. Thirty extracted premolars were used in each experimental group. Orthodontic brackets were bonded with either Transbond (3M Unitek) or Right-On (TP orthodontics) and were then exposed to either distilled water (control), 8 per cent ethanol (aqueous food), 50 per cent ethanol (alcoholic food), buffered lactic acid pH4 (acidic food), or corn oil (fatty food) for 12 weeks. Bond strength and Adhesive Remnant Index was recorded. It was found that 50 per cent ethanol had a significant effect upon the bond strength of both Transbond and Right-On. Right-On was affected to a greater extent. The clinical significance of this finding is that alcoholic mouth rinses, and alcohol-containing foods and drinks may be a causative factor in bond failure. However, the use of an alcoholic mouthrinse late in treatment may aid bracket removal. This potential use requires more research. Refereed Scientific Paper (+info)
The science of bonding: from first to sixth generation.
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BACKGROUND: Adhesive dentistry has revolutionized restorative dental practice during the past 30 years. Improved adhesive materials have made resin-based composite restorations more reliable and long-standing. CLINICAL IMPLICATIONS: This article reviews the evolution of bonding from the first generation to current bonding materials. It discusses the composition and effectiveness of the various iterations. Current products are highlighted to improve clinical use and performance of the materials. (+info)