Integrating oxalate desensitizers with total-etch two-step adhesive

Compromised bonding of total-etch adhesives to dentin treated with oxalate desensitizers results from the interference of a surface layer of acid-resistant crystals of calcium oxalate. We hypothesize that effective tubular occlusion and dentin bonding may be simultaneously achieved by depleting dentin surfaces of calcium with acids before desensitizer application. Dentin specimens treated with 4 oxalate desensitizers before or after being acid-etched were bonded with a two-step adhesive. Microtensile bond strengths (μTBS) were significantly lower, compared with the control, when oxalates were used before the specimens were acid-etched; in contrast, when oxalates were used after acid-etching. μTBS were similar to nonoxalate-treated controls. Dentin surfaces and tubular orifices were covered with a surface layer of crystals when desensitizers were applied to fractured dentin and smear-layer-covered dentin before specimens were acid-etched. However, when the dentin was acid-etched prior to the application of oxalate desensitizers, the crystals were largely limited to the subsurface of dentinal tubules, where they did not interfere with subsequent resin bonding.