Primer application technique and remaining dentin thickness affected microtensile bond strength of contemporary dentin adhesives under simulated pulp pressure

Objectives To evaluate the effect of application techniques, type of adhesives and remaining dentin thicknesses on micro-tensile bond strength (mu TBS) of 3 adhesive systems. Materials and methods 112 flat occlusal dentinal surfaces of third molar were randomly allocated into 16 groups based on 2 remaining dentin thicknesses (RDT), 2 application techniques, and 3 adhesive systems (Optibond FL, OFL; Clearfil SE Bond, CSE; and Single Bond Universal, SB); SB was applied in either etch-and-rinse (ER) or self-etch (SE) mode. Simulated pulpal pressure was performed during restorative procedure and water storage. The stick-shaped specimens from each tooth underwent mu TBS testing. The data were evaluated using a paired t test and ANOVA followed by a post hoc test. The fractured specimens were evaluated for mode of failure using a stereomicroscope. Results The mean mu TBS values were significantly affected by RDT, application technique, and types of adhesives. Neither RDT nor application technique affected mu TBS of SB in ER mode, whereas application technique affected both conventional and universal self-etch adhesives. RDT also influenced mu TBS of OFL. Conclusions RDT and application technique differently affected the mu TBS of dentin bonding which was product-related. Etch-and-rinse systems had higher bond strength to superficial than to deep dentin, whereas self-etch systems were more sensitive to both RDT and application technique.