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This paper reports the effect of dentin bonding agents on marginal leakage in cervical cavities without the classical cavity preparation design. Wedge-shaped cervical cavities were cut on extracted teeth with the gingival cavosurface margin of each cavity involving dentin. The specimens were randomly assigned to three groups of 40 each: Group 1 (control), restored with Fuji glass ionomer; Group 2, restored with Scotchbond 2 adhesive and Silux Plus resin and Group 3, restored with Tenure adhesive and Perfection resin. Half of the specimens in each group were thermocycled. All specimens were then stored in basic fuchsin dye after which microleakage of the restorations was assessed by dye penetration. A grading scale of 0 to 3 was used as the scoring criteria. The results showed that differences were more pronounced at the gingival margin. The control group specimens exhibited the least microleakage. There was no significant difference between thermocycled and non-thermocycled specimens for each category of materials used. There was, however, a significant difference between the experimental groups and the control groups. The dentin adhesives tested did not completely eliminate microleakage at the gingival margin of cervical cavities.

The purpose of this research effort was to investigate the microleakage of cervical restorations lined with a light-cured glass-ionomer liner. Wedge-shaped cervical cavities were cut on extracted teeth with the gingival cavosurface margin involving dentin. The cavities were randomly assigned to each of each of three groups: (1) restored with a microfilled composite resin, (2) restored with a light-cured glass-ionomer liner and microfilled resin as in the "sandwich" technique, and (3) restored entirely with the light-cured glass-ionomer liner. Half of the specimens in each group were thermocycled. Microleakage of these restorations was assessed by dye penetration. The results showed that differences were more pronounced at the gingival margin. Composite restorations inserted over the glass-ionomer liner demonstrated significantly less leakage than when the liner was not used.

Differences in microleakage at occlusal and cervical margins have been attributed to variations in the microstructure of enamel. The lack of homogeneity in dentin may have similar influences on the effectiveness of composite bonding. This study examined marginal contraction gaps occurring at the occlusal, cervical, mesial, and distal margins of dentin cavities restored with a composite restorative material, with and without the use of dentin bonding agents. Results showed that marginal contraction gaps at the dentin-restoration interface among the four sites in both treated and untreated cavities are not statistically different in size. Adhesion of composite restorative materials to dentin is not affected by the location of the margins.

There is a tendency to interchange dentine adhesives and composite resins when using composite resins for restorations. This study used marginal contraction gaps to test the effect of changing composite resins with a dentine adhesive. Cylindrical butt-joint cavities were prepared entirely in dentine using extracted human teeth. Two groups of control cavities (30 cavities per group) were restored with Prisma-Bond/Prisma-Fil and Heliobond/Heliomolar respectively. Two groups of test cavities (30 cavities per group) were restored using the dentine adhesive. Prisma Universal Bond with Prisma-Fil on one group and Prisma Universal Bond and Heliomolar in the other. Following thermocycling the marginal contraction gaps were measured and assessed. The results showed a significant reduction in marginal contraction gaps when using either composite resin with Prisma Universal Bond. This indicates a compatibility of both resins with the adhesive in this instance.

Polymerization shrinkage remains an inherent problem in composite restorations. Dentin adhesives generally improve bonding to dentin but do not consistently provide leak-free restorations. This study evaluated a dentin adhesive that bonds to dentinal calcium and another that bonds to dentinal collagen when used separately and in combination. The measurement of contraction gaps at the restoration-dentin interface was used as the means of testing the effectiveness of dentin adhesion. The effect of thermal stress on the dentin-polymer bond was also investigated. Results showed that the bisphenyl A glycidyl methacrylate (BISGMA)-based dentin adhesive was more effective when compared with the hydroxyethyl methacrylate (HEMA)-based adhesive. When used in combination, the mean contraction gaps of cavities were not found to be significantly better than those treated with only the BISGMA-based adhesive. Thermal stress reduced the effectiveness of dentin adhesives whether applied individually or in combination.

This study was undertaken to test the effectiveness of using two dentine adhesives in combination. One of the dentine adhesives used adhered to the calcium in the dentine while the other dentine adhesive adhered to the organic portion of the dentine. It was hoped by using them in combination that their actions would complement each other producing composite restorations with gap free margins. Results showed an increase in the number of gap free restorations but the marginal contraction gaps were not entirely eliminated.

Previous studies have shown that dentine adhesives reduce or eliminate contraction gaps in composite restorations. This study examined the relationship between cavity site and contraction gaps when two dentine adhesives were used in combination with two composites. One hundred and fifty-two cavities, each measuring 2.0 mm diameter and 1.5 mm depth, were prepared on side surfaces of extracted teeth, with each surface classified into three levels: upper, middle and lower. The dentine adhesives and composites were randomly assigned to the cavities. Four pre-determined, diametrical measurements of contraction gaps were made for each restored cavity using a Nikon Measurescope. Measurements yielded overall mean contraction gaps of 0.229, 0.262, and 0.260 for upper, middle and lower levels on the crown; the differences between means were not statistically significant. Type of dentine adhesives and composites influenced the size of contraction gaps rather than cavity site.