Influence of the curing time for the adhesive on the oxygen-inhibited layer thickness and the shear bond strength to dentin

Abstract

Objectives : This study investigated the hypothesis that increasing light-curing time would leave the oxy- gen-inhibited layer (OIL) of the adhesive thinner, and in turn, result in lower shear bond strength (SBS) than those obtained by the routine curing procedures. Methods : 120 human extracted posterior teeth were randomly divided into three groups for bonding with three adhesives: All Bond 2 � , One Step � , and Adper Prompt � . They were subsequently divided into four subgourps with different light-curing time (10, 20, 30 and 60 s). The assigned adhesives were applied on superficial occlusal dentin according to the manufacturer' s instructions and cured with one of the four cur- ing times. Composite resin cylinder, 2.35 mm in diameter, were built on the cured adhesive and light-cured for 40 s. SBS were measured after 24 h from the bonding using a universal testing machine (crosshead speed 1.0 mm/min). The relative thickness of the OIL and the degree of conversion (DC) were determined from the adhesive on a slide glass using FT-NIR in an absorbance mode. Data were analysed with One- way ANOVA and Duncan' s multiple test (p 0.05), those of All Bond 2 decreased significantly (p 0.05). Although the DC of All-Bond 2 were statistically not different with increasing cure time (p > 0.05), those of One-Step and Adper Prompt showed an increasing trends with increasing cure time (p < 0.05). Conclusions : Increasing light-curing time did not affect on the relative thickness of the OIL of the adhe- sives, and in turn, on the SBS to dentin. (J Kor Acad Cons Dent 29(2):177-184, 2004) ABSTRACT