William P. Kelsey

Bond strength of an adhesive resin system with various dental substrates.

A laboratory study was conducted to evaluate the Panavia 21 resin-based adhesive system as a bonding agent between a variety of dental substrates. Panavia 21 resin was bonded directly to enamel and dentin and placed between nickel-chromium-beryllium (Ni-Cr-Be) specimens and enamel, dentin, other Ni-Cr-Be samples, and type III gold. Panavia 21 resin was also used to bond amalgam to dentin. Shear bond strengths were determined at 24 hours and after thermocycling at 3 months. The results of this study at both the 24-hour and the 3-months test periods indicate that the enamel bond strengths of Panavia 21 resin (24 hours, 19.3 +/- 5.5 MPa; 3 months, 23.7 +/- 4.4 MPa) exceeded its dentin bond strengths (24 hours, 7.8 +/- 1.4 MPa; 3 months, 8.8 +/- 3.2 MPa). The bond strengths between Panavia 21 resin and Ni-Cr-Be alloy (24 hours, 16.3 +/- 3.4 MPa; 3 months, 17.6 +/- 2.7 MPa) and those for Panavia 21 resin between Ni-Cr-Be alloy and dentin (24 hours, 18.7 +/- 4.2 MPa; 3 months, 19.8 +/- 5.3 MPa) were comparable to adhesive enamel bond strengths. High bond strengths were also generated by Panavia 21 resin between Ni-Cr-Be alloy and type III gold (24 hours, 39.3 +/- 5.9 MPa; 3 months, 35.5 +/- 7.1 MPa). The greatest bond strengths observed during both test time periods for Panavia 21 resin were between Ni-Cr-Be alloy and enamel (24 hours, 54.2 +/- 10.7 MPa; 3 months, 56.4 +/- 7.1 MPa) and between two samples of Ni-Cr-Be alloy (24 hours, 55.1 +/- 5.6 MPa; 3 months, 49.1 +/- 8.6 MPa). Panavia 21 resin produced high bond strengths between a variety of dental substrates commonly used for the placement of fixed prosthodontic restorations.

Enamel cavosurface bevels finished with ultraspeed instruments

Rating scores ranked the straight fissure bur first for producing the smoothest and most distinct bevel. The 40-fluted and 12-fluted finishing burs ranked second and third, respectively, and the superfine diamond stone was judged to produce the roughest and least distinct bevel. In selecting an instrument for finishing an external enamel cavosurface bevel, the results of this study suggest that a straight fissure bur will produce the most distinct and smoothest bevel when ultrarotational speeds are used. Results also indicated the superfine diamond stone to be the least desirable instrument for preparing a bevel in enamel.