Document Type

Article

Publication Date

2021

Abstract

This study evaluated the effect of pre-heating a dual-polymerized adhesive and a dual-polymerized core build-up resin composite on their dentin micro-shear bond strength (mSBS), degree of conversion (DC%) and ultimate tensile strength (UTS). For mSBS, 45 human molars were divided into 9 groups (n ¼ 5) according to two factors: (1) Adhesive temperature (25 C/32 C/40 C) and 2- Resin composite temperature (25 C/32 C/40 C). Dual-polymerized adhesive (Futurabond U/FBU) was applied over occlusal dentin at each temperature following the manufacturer’s instructions. Four dual-polymerized composites (Rebilda DC/RDC, VOCO) micro-cylinders (1.2 mm diameter 1 mm height) were built-up over each dentin disc, after being pre-heated at each temperature. After storage (48 h/37 C), mSBS testing was run at a crosshead speed of 1 mm/min. DC% of FBU/RDC was evaluated at each temperature after 48 h using FTIR. Hourglass-shaped specimens were fabricated from both materials at each respective temperature and pulled apart to evaluate UTS after 48 h storage. Data were analyzed by ANOVA/Tukey’s test/Pearson’s correlation (p ¼ 0.05). Neither adhesive/composite temperature nor their interaction had a significant effect on mSBS. No significant difference in mSBS between groups, except within 40 C FBU. Predominant failure mode was a mixed type. No significant difference in DC% of FBU groups. RDC at 40 C had significantly higher DC% than 25 C. No significant difference in UTS of FBU and RDC groups. Application of both dual-polymerized adhesive and resin composite at 40 C seemed to reduce mSBS. Raising the temperature to 40 C improved DC% of resin composite, with no effect on adhesive. Pre-heating did not influence the UTS of both materials.

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