Effects of the application sequence of calcium-containing desensitising pastes during etch-and-rinse adhesive restoration

Objectives To evaluate the effects of different application sequence of calcium-containing desensitising pastes on bonding effectiveness and tubule occlusion during etch-and-rinse (E&R) adhesive restoration. Methods Seventy molars were sectioned parallel to the occlusal plane, polished and randomly divided into seven groups (n = 10). Group 1 was etched with 35% phosphoric acid for 15 s. Groups 2-4 were treated with different calcium-containing desensitisers, including an arginine-calcium carbonate (Arg-CaCO ₃)-containing paste, a casein phosphopeptide-amorphous calcium phosphate (CPP-ACP)-containing paste and a calcium-sodium phosphosilicate (Novamin)-containing paste, respectively. Afterward, these groups were etched with 35% phosphoric acid for 15 s. Groups 5-7 were initially etched and then treated with Arg-CaCO₃-, CPP-ACP- and Novamin-containing desensitisers, respectively. In each group, samples were equally distributed into two subgroups (n = 5) to bond with either a two-step E&R adhesive Adper SingleBond 2 (SB) or a three-step E&R adhesive Adper ScotchBond Multi-Purpose (SBMP). The microtensile bond strengths (MTBS) were tested and fracture modes were analyzed by stereomicroscopy and field-emission scanning electron microscopy (FESEM). Eight additional dentine disks were prepared to evaluate tubule occlusion prior to bonding using FESEM. Results The application sequence of calcium-containing desensitising pastes did not significantly affect MTBS irrespective of two-step SB (P > 0.05) or three-step SBMP E&R adhesives (P > 0.05). Effective dentinal tubule occlusion was observed in the mode of etching-desensitising. Conclusions Applying calcium-containing desensitisers (particularly Arg-CaCO₃- and Novamin-based) after etching during E&R adhesive restoration could achieve effective tubule occlusion without affecting the bonding strength.