Objectives: The purpose of this study was to evaluate and compare the effect of endodontic irrigation protocols on the micro-tensile bond strength of total-etch and universal adhesives to coronal dentin.
Materials and Methods: forty teeth were collected and their occlusal surfaces were flattened until middle dentin was exposed. They were divided into four groups according to surface treatment of dentin (untreated (control), NaOCl, EDTA and combination of the two irrigants). Two different adhesives were selected for the current study (total-etch adhesive and universal adhesive). Adhesives were applied according to manufacturers' instructions, then composite restoration was built up incrementally. Resin/dentin specimens were sectioned for micro-tensile bond strength (µTBS) testing. A specimen from each group was randomly selected and investigated under scanning electron microscope (SEM).
Results: Regarding the total-etch adhesive; the control group showed the highest value of µTBS, followed by the group irrigated with NaOCl + EDTA, EDTA and NaOCl; respectively. Regarding the Universal adhesive; dentin irrigated with a combination of EDTA+NaOCL was found to give the highest value of µTBS. It was followed by that irrigated with EDTA and control group. Irrigation with NaOCl resulted in a dramatic decrease in the µTBS in comparison with the other groups (p < 0.001).
Conclusions: the use of a combination of NaOCl and EDTA as a regular endodontic irrigants in dental clinics was found to highly improve the quality of bond strength between dentin and both the total-etch and universal adhesives used for bonding the coronal composite restoration.