Influence of chlorhexidine concentration on microtensile bond strength of contemporary adhesive systems

Abstract

The purpose of this study was to investigate the influence of chlorhexidine (CHX) concentration on the microtensile bond strength (muTBS) of contemporary adhesive systems. Eighty bovine central incisors were used in this study. The facial enamel surface of the crowns was abraded with 600-grit silicon carbide paper to expose flat, mid-coronal dentin surfaces. The tested materials were Scotchbond Multipurpose (SMP), Single-Bond (SB), Clearfil SE Bond (CSEB) and Clearfil Tri S Bond (CTSB). All the materials were applied according to manufacturer's instructions and followed by composite application (Z250). The teeth were randomly divided into 16 groups: for the etch-and-rinse adhesives (SMP and SB), 0.12% or 2% CHX was applied prior to or after the acid etching procedure. For the self-etch adhesives (CSEB and CTSB) 0.12% or 2% CHX was applied prior to the primer. Control groups for each one of the adhesive systems were also set up. The specimens were immediately submitted to muTBS testing and the data were analyzed using Analysis of Variance and the Tukey post hoc test (alpha = .01). The failure patterns of the specimens were observed using scanning electron microscopy. The effects of 2% CHX were statistically significant (p < 0.01) for the self-etch adhesives but were not significant for the etch-and-rinse adhesive systems. Analysis of the data demonstrated no statistical difference between the etch-and-rinse adhesive systems. CHX-based cavity disinfectants in concentrations higher than 0.12% should be avoided prior to the self-etch adhesive systems evaluated in this study to diminish the possibilities of reduction in bond strength.

Effect of chlorhexidine on the bond strength of a self-etch adhesive system to sound and demineralized dentin

“…Nevertheless, these results do not agree with earlier reports showing decreased bond strengths when self-etch adhesive systems were applied after CHXbased cavity disinfectant. 7,8,10 This divergence may be due to the different adhesive tested in the earlier studies (two-step self-etch Clearfill SE Bond), which has a composition different from that of the twocomponent all-in-one self-etch All-Bond SE, thus interacting differently with CHX and the smear layer. Our data also diverge from those of another study, which demonstrated increased bond strength of a self-etch adhesive system after carious dentin was treated with a 5% CHX solution.…”

“…The remineralizing solution contained 1.5 mM of calcium (CaCl 2 ), 0.9 mM of phosphate (KH 2 PO 4 ), sticks with a cross-sectional area of approximately 0.8 mm², measured with a digital caliper. 11 Each stick was glued with cyanoacrylate-based adhesive (Zapit Base and Accelerator, Dental Ventures of America Inc., Corona, USA), attached to opposing arms of the testing device and finally stressed until failure with a tensile force in a microtensile testing machine 8 (Micro Tensile Tester, T-61010 K, Bisco, Schaumburg, USA) at a crosshead speed of 1 mm/ minute. The bond strength (MPa) of each specimen was determined as the failure load (N) divided by the cross-sectional area of the bonded interface.…”

“…6 However, the scientific literature reports conflicting results, since in vitro studies have demonstrated decreased bond strengths with self-etch adhesive systems applied after CHX-based cavity disinfectant, [7][8][9] while analysis of other data [9][10][11] demonstrated no adverse effect on dentin bonding compared with a control group. In the most commonly encountered clinical situations, especially when a cavity disinfectant is applied, bonding procedures are carried out in abnormal dentin, such as caries-affected dentin.…”

Bonding efficiency and durability: current possibilities

“…74,85,86,87 The use of 2% CHX solution as an effective and nonspecific protease inhibitor primer, after acid-etching, is attractive from a clinical point of view, since it is already used in other oral health situations as an antimicrobial agent. 88 Compared to control, aged CHX-treated dentin relates to higher bond strength values 73,74,77,78,79,80,89,90,91,92 which are interestingly equivalent to each other in most of the immediate evaluations. 93 Especially when two step etch-and-rinse adhesives are used, reduction of bond strength values for conventionally treated dentin over one to two years is of approximately 50%; when CHX is applied after acid etching, total reduction is around 20% 72 to 84.9%.…”

“…73 Regarding the effectiveness of self-etch adhesives, and even the moment or how CHX must be applied, are conflicting. 74,90,117,118,119 Recent systematic reviews show that an aging-associated decline in dentin bond strength of both categories of adhesives can be lessened by CHX application. 74,118,119 In this sense, a growing predisposition among clinicians in properly applying 0.2-2% CHX for 15-60 s for re-wetting the collagen network on acid-etched dentin 77,79,89,120 to minimize degradation of resin-dentin bonds, can be currently appreciated.…”