Theconcept of adhesion was introduced into the field of dentistry by Buonocore in1955 (1). Adhesive dentistry rapidly expanded treatment possibilities andrevolutionized the way direct and indirect restorations were traditionallyperformed. Paralleling the growing demand for adhesive restorations, dentinebonding systems too have undergone an evolution to improve their bond strengthsas well as to reduce their technique sensitivity.Dentin bonding agents have evolved from the gold standard – etch andrinse fifth generation adhesives to the present universal adhesives.The different generations of dentin bonding agents have witnessed a change inchemistry, mechanism of action, procedural steps and a varying degree ofclinical efficiency(2).
A recent innovation in the one bottle adhesive systemsis their expansion to a more universal bond with 10-Methacryloyloxydecyldihydrogen phosphate (MDP) as the active ingredient. These universal bondingagents can be used in all etch modes for both direct and indirect restorations.Single Bond Universal(SBU),marketed as Scotchbond Universal in USA, was the first commercialuniversal adhesive and is popularly used by the clinicians worldwide (3,4,5,6). SBUapart from MDP, also has methacrylate-modifiedpolyalkenoic acid copolymer (PAAC) in its composition.( Table/Figure 1) Mitra and co-workers have reported that PAACbonds chemically to calcium in hydroxyapatite showing excellent long-termclinical performance thereby further improving the bond strength (7).
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Tetric N Bond Universal (TNBU)is a relatively new Universal adhesive which has its matrix based on a combination of monomers of hydrophilic, hydrophobicand intermediate nature allowing it to reliably bridge the gap between thehydrophilic tooth substrate and the hydrophobic resin restorative.( Table/Figure 1) However studies using this bonding agent are scarce (8,9,10).Oneof the major problems associated with the use of adhesive systems is thedifficulty in obtaining a moisture-free clean tooth surface for adequatebonding (11). Moisture control in the working field is particularly difficultin situations such as equigingival or subgingival cavity margins, seating ofindirect restorations, newly erupted molars or when patients have limited mouthopening (12). Contamination during the bonding process from sources such asgingival crevicular fluid, hand piece oil, blood and saliva, can adverselyaffect the quality of the bond predisposing it to microleakage at thetooth-restoration interface. As a consequence, loss of the restoration,recurrent caries, postoperative sensitivity and discoloration may occur (13).
Studies in the past have shown that salivary contamination has adeleterious effect on bonding (14,15,16,17,18). But manufacturers are claiming that universal bonding agents areresistant to salivary contamination. In accordance to this, study bySantschi and colleagues concluded that saliva contamination did not affect thebond strength of SBU (19). Inthe event of contamination, use of an appropriate decontaminating agent torestore bond strengths has been advocated (20,21).
Workby Yoo et al. and Santschi et al. has shown that for all-in-one adhesives, washing, dryingand adhesive reapplication was the most effective decontamination protocol (12,19).However,to date, studies which have investigated the effect of salivary contaminationon the universal bonding agents are scant and conflicting(19, 22). Hence the aim of this study was to evaluate the influence ofsalivary contamination and water rinsing as a decontamination method on theshear bond strength of universal bonding agents.