Effect of postbleaching application of an antioxidant on enamel bondstrength of three different adhesives

ABSTRACT

Objectives: The aim of this study was to compare the shear bond strength (sbs) of three different adhesives on bleached enamel imm ediately after bleaching, bleached/delayed for 1 week, and bleached/applied antioxidizingagent. Study Design: The enamel surfaces of 144 freshly extracted incisors without any caries and restorations were flattened and divided into 12 groups. The following adhesives were investigated Optibond FL (OFL) (three-stepetch&rinse), Optibond Solo Plus (OSP) (two-step etch&rinse), Optibond All-in-One (OA) (one-step self-etch),(Kerr, Orange, USA ). Unbleached enamel groups were prepared as negative controls. The remainder surfaces were bleached with 20% Opalescent PF (Ultradent, USA ) 6 h/d for 5 consecutive days. Specimens were bondedimm ediately after bleaching, after 1 week or after using 10% sodium ascorbate gel for 6 hours. After 500 rounds of thermocycling, sbs was measured and data was analyzed with Kruskall-Wallis and Mann-Whitney U-tests (á= 0.05).Results: The sbs decreased for the adhesives after bleaching except for OFL. The effect of applying sodium ascorbatesubsequent to bleaching was not equal for the studied adhesives. While for OFL, sbs of the sodium ascorbategroup was significantly higher than the unbleached control group, for OSP, the sodium ascorbate group had nostatistically significant difference with the unbleached control group and for OA, sbs was significantly lower thanthe unbleached control group.Conclusions: Different adhesives demonstrate different degrees of reversed bond strength subsequent to applyingantioxidant. It seems the method of application and the chemical composition of the adhesives could affect the antioxidant as a reducing agent (AU)