Immediate and delayed micro-tensile bond strength of different luting resin cements to different regional dentin

Abstract

We sought to evaluate immediate and delayed micro-tensile bond strength of Panavia F2.0 and Multilink Sprint resin cement to superficial, deep and cervical dentin. Thirty-six freshly extracted non-carious human molars were sectioned in the mesiodistal direction to expose three different dentin regions including superficial dentin (1 mm below the dentine-enamel junction), deep dentin (1 mm above the highest pulp horn) and cervical dentin (0.5 mm above the cemento-enamel junction and 0.5 mm below the dentine-enamel junction). Resin cements were applied on dentin surfaces and composite blocks were luted under constant seating pressure. Each group was divided into three subgroups according to time intervals. Specimens were sectioned to obtain sticks of 1 mm(2) in diameter and subjected to microtensile bond strength testing at a cross head speed of 1 mm/min. Both resin cements showed higher micro-tensile bond strength to superficial dentin than that to deep or cervical dentin (P < 0.001). Micro-tensile bond strengths of Panavia F2.0 were higher than those of Multilink Sprint at different dentin regions (P < 0.001). Immediate micro-tensile bond strengths were higher than those of delayed micro-tensile bond strengths for both resin cements (P < 0.001). It was concluded that resin cements with different chemical formulations and applications yield significantly different micro-tensile bond strengths to different dentin regions.

Keywords: immediate and delayed micro-tensile bond strength; luting resin cements; regional dentin.

Fig. 1. Schematic diagram of the tooth-composite stick.

Fig. 2. Scanning electronic microscopy showing the failure pattern exhibited after microtensile bond strength of fractured beams treated with Panavia F2.0 (4,000×).

A: specimens stored for 24 hours. B: specimens stored for 6 months. The fractured surface showed adhesive/cohesive failure at the top of the hybrid layer after 24 hours &6 months at 26.7 Mpa & 16.5 Mpa respectively. The consistent layer of adhesive resin still sealing the dentinal tubules. Higher magnification of A&B, showed resin tags, which appear with porous structure and cracks.

Fig. 3. Typical SEM micrograph of fractured beams treated with Multilink Sprint (4,000×).

A: specimens stored for 24 hours. B: specimens stored for 6 months. The fractured surface showed adhesive/cohesive failure at the top of the demineralized deep dentin after 24 hours &6 months at 10 Mpa & 4.5 Mpa respectively. The consistent layer of adhesive resin still sealing the dentinal tubules. Higher magnification of A&B, showed resin tags, which appear with porous structure and cracks.