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The purpose of this study was to evaluate the effect of thermal cycling on the surface texture of restorative materials. Disk-shaped specimens made of seven resin composites (Beautifil: BF; Esthet-X: EX; Filtek Supreme: FS; Inten-S: IS; Point 4: PT; Solare: SR; and Venus: VS) were finished with 1-μm alumina suspension, and then thermocycled between 4 and 60 ℃ in distilled water for 20,000 or 50,000 cycles with a dwell time of 60 seconds. Staining susceptibility and mean surface roughness, Ra, were examined, and surface texture was observed by scanning electron microscopy. Dye penetration test showed that the surfaces of all resin composites were more stained after thermal cycling. Mean Ra of all resin composites, except PT, significantly increased after 50,000 thermal cycles. Dislodgement of filler particles was observed for all resin composites after thermal cycling, except FS. It was concluded that thermal cycling significantly affected the surface texture of the seven examined resin composites.

Specimens reinforced with 1.2 mm diameter stainless steel wires or Co-Cr-Ni wires resulted in significantly higher loads to fracture as compared to specimens without reinforcement. The use of pure titanium wire, woven metal wire, and woven glass fiber did not improve the fracture loads.

This study evaluated the effects of metal primers on the bonding of adhesive resin to four pure metals (Au, Pd, Ag, Cu) and two noble alloys for porcelain fusing (high-gold and high-palladium content alloys). Bonding surface was polished with 600-grit silicon carbide paper and primed with one of the three metal primers (V-Primer, Metaltite, and M.L. Primer). Bonded specimens were fabricated by applying adhesive resin (Super-Bond C&B) on the primed surface. Shear bond strength (SBS) was determined both before and after thermocycling (4-60°C for 2,000 cycles). The highest SBS values to each pure metal after thermocycling were 33.5 MPa for Au by M.L. Primer, 35.0 MPa for Ag by V-Primer, and 34.4 MPa for Cu by Metaltite. SBS to high-gold content alloy after thermocycling was 33.3 MPa by M.L. Primer. None of the primers was effective for pure Pd and high-palladium content alloy after thermocycling.

The purpose of this study was to evaluate the effectiveness of resin coating as a means of preventing marginal leakage beneath full cast crowns which were emplaced using different cements. Standard full cast crown preparation was made on 64 extracted premolars.These samples were then divided into four groups, with half of each group coated with dentin coating material after preparation.Crowns were cemented onto the teeth using zinc cement, Fuji I, Vitremer, or C&B Metabond. The samples were thermal-cycled for 10,000 cycles. They were then immersed in erythrosine solution, sectioned, and observed under a microscope.Microleakage analyses were performed using a 0-4 point system. The data were statistically analyzed. There were significant differences between the coated specimens and the uncoated specimens using Fuji I and Vitremer.The results showed that a resin coating could decrease the amount of marginal leakage when applied with these two cemPntfi_