Enamel adhesion of light- and chemical-cured composites coupled by two step self-etch adhesives

Abstract

This study was to compare the microshear bond strength (μ SBS) of light-and chemically cured composites to enamel coupled with four 2-step self-etch adhesives and also to evaluate the incompatibility between 2-step self-etch adhesives and chemically cured composite resin.Crown segments of extracted human molars were cut mesiodistally, and a 1 ㎜ thickness of specimen was made. They were assigned to four groups by adhesives used: SE group (Clearfil SE Bond), AdheSE group (AdheSE), Tyrian group (Tyrian SPE/One-Step Plus), and Contax group (Contax). Each adhesive was applied to a cut enamel surface as per the manufacturer' s instruction. Lightcured (Filtek Z250) or chemically cured composite (Luxacore Smartmix Dual) was bonded to the enamel of each specimen using a Tygon tube. After storage in distilled water for 24 hours, the bonded specimens were subjected to μ SBS testing with a crosshead speed of 1 ㎜/minute. The mean μ SBS (n=20 for each group) was statistically compared using two-way ANOVA, Tukey HSD, and t test at 95% level. Also the interface of enamel and composite was evaluated under FE-SEM.The results of this study were as follows; 1. The μ SBS of the SE Bond group to the enamel was significantly higher than that of the AdheSE group, the Tyrian group, and the Contax group in both the light-cured and the chemically cured composite resin (p < 0.05). 2. There was not a significant difference among the AdheSE group, the Tyrian group, and the Contax group in both the light-cured and the chemically cured composite resin. 3. The μ SBS of the light-cured composite resin was significantly higher than that of the chemically cured composite resin when same adhesive was applied to the enamel (p < 0.05). 4. The interface of enamel and all 2-step self-etch adhesives showed close adaptation, and so the incompatibility of the chemically cured composite resin did not show. [J Kor Acad Cons Dent 32(3):169-179, 2007]

Effect of pre-heating on some physical properties of composite resin

“…In general, filler loading level, irregular surface contour, and the type of filler size distribution may impact the ability of particles to easily slide past one another 30) . Heating would not directly affect the glassy particle itself, because, within the temperature range imparted at clinically relevant temperatures, the viscosity of the filler particle remains unchanged.…”

“…Therefore, when using composite resin in the clinic, preheating the composite resin could be recommended to have enhanced physical properties of it. [J Kor Acad Cons Dent 34(1): [30][31][32][33][34][35][36][37] 2009] …”