Purposes: To evaluate (1) the effect of a desensitizing paste containing 8% arginine and calcium carbonate on the microtensile bond strength between dentin and etch-and-rinse adhesive systems; and (2) to examine the dentin tubules occlusion quantitatively.
Methods: 48 freshly extracted intact human mandibular third molars were divided randomly into three groups. The mid-coronal dentin of each tooth was exposed and treated. Group A: no treatment; Group B: specimens were polished with a desensitizing paste containing 8% arginine and calcium carbonate using a rotary cup operating at a low speed for 3 seconds, followed by an additional duration of 3 seconds (total operation time of 6 seconds), according to the manufacturer's instructions; Group C: specimens were handled in the same way with the exception of an increased operation time of 9 seconds, twice (total operation time of 18 seconds). Each group was randomly divided into two subgroups in order to evaluate the effectiveness of two different adhesive agents. A two-step etch-and-rinse adhesive agent (Adper SingleBond 2) and a three-step etch-and-rinse adhesive agent (Adper ScotchBond Multi-purpose) were applied to dentin surfaces. Then, microtensile bond strengths of the six subgroups were tested. Dentin surfaces were analyzed using field-emission scanning electron microscopy (FESEM) and laser scanning confocal microscopy (LSCM).
Results: There was no significant difference in microtensile bond strength between the control group and the experimental groups treated with the 8% arginine and calcium carbonate desensitizing paste during the application of etch-and-rinse adhesives. Both FESEM and LSCM showed that the desensitizing paste occluded dentin tubules effectively.