[ effect of three different curing methods on the microleakage of Clv posterior composite restorations]

Light-cured composites have become almost universal in modern clinical dentistry. Unfortunately, these materials have demonstrated critical limitations such as postoperative sensitivity and polymerization shrinkage. The aim of this study was to evaluate the effects of three curing modes on the microleakage of class V composite restorations. In this experimental in vitro study, class V cavities were prepared on the buccal surfaces of 90 extracted human molar and premolar teeth and were randomly divided into 3 groups. All teeth were etched followed by bonding and composite filling. Three different methods were used for curing: conventional, 750 mw/cm2/40s; pulse delay, 400 mw/cm2/5s-5 minutes delay-750 mw/cm2/35s; and soft start, beginning at 150 mw/cm2 and increasing to 750 mw/cm2 during 15 seconds and remaining for another 35 seconds. After polishing, the specimens were stored in a 37°C incubator, thermocycled [500 cycles] and immersed in basic%0.5 fushin. Longitudinal buccolingual sections of all teeth were scored for marginal dye penetration under a stereomicroscope. Kruskal-Wallis test was used for statistical analysis. Leakage was observed in all groups but no significant difference was found in the microleakage scores among the three light-curing techniques, used in this investigation. These findings suggest that the 3 studied light-curing methods may have no effect on the microleakage of class V posterior composite restorations

effect of saliva contamination on shear bond strengths of two kinds of one-bottle adhesives during bonding procedures

Saliva contamination of dentin surface during restoring teeth is one of common problems in restorative dentistry that may affect the shear bond strength of adhesive. The aim of this in vitro study was to investigate the effect of saliva contamination on shear bond strengths of two kinds of common one-bottle adhesives in Iran - [Excite] and [Single Bond] during different bonding procedures. Ninety extracted sound human premolar teeth [closed apex] with prepared flat dentinal surfaces were randomly divided into three groups of thirty as control group [without saliva contamination], Group with saliva contamination after etching and Group with saliva contamination after cured resin; and each group was randomly divided into two groups of fifteen for each adhesive. Composite via plastic mold was mounted on specimens and specimens were thermocycled. Finally shear bond strengths were measured. One way ANOVA test was used to compare shear bond strengths of different groups and Tukey test was used for 2 by 2 comparisons of bond strengths between groups. No statistically significant difference was found between different groups [P=0.673], and between two kinds of [Excite] and [Single Bond] adhesives, [p>/0.05]. Saliva contamination of dentin after etching and after cured resin had no adverse effect on shear bond strengths of [Excite] and [Single Bond] adhesives, and no significant difference was found between shear bond strengths of [Excite] and [Single Bond] adhesives too