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The
concept of adhesion was introduced into the field of dentistry by Buonocore in
1955 (1). Adhesive dentistry rapidly expanded treatment possibilities and
revolutionized the way direct and indirect restorations were traditionally
performed. Paralleling the growing demand for adhesive restorations, dentine
bonding systems too have undergone an evolution to improve their bond strengths
as well as to reduce their technique sensitivity.

Dentin bonding agents have evolved from the gold standard – etch and
rinse fifth generation adhesives to the present universal adhesives.
The different generations of dentin bonding agents have witnessed a change in
chemistry, mechanism of action, procedural steps and a varying degree of
clinical efficiency(2). A recent innovation in the one bottle adhesive systems
is their expansion to a more universal bond with 10-Methacryloyloxydecyl
dihydrogen phosphate (MDP) as the active ingredient. These universal bonding
agents can be used in all etch modes for both direct and indirect restorations.

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Single Bond Universal(SBU),
marketed as Scotchbond Universal in USA, was the first commercial
universal adhesive and is popularly used by the clinicians worldwide (3,4,5,6). SBU
apart from MDP, also has methacrylate-modified
polyalkenoic acid copolymer (PAAC) in its composition.( Table/Figure 1)  Mitra and co-workers have reported that PAAC
bonds chemically to calcium in hydroxyapatite showing excellent long-term
clinical performance thereby further improving the bond strength (7).

Tetric N Bond Universal (TNBU)
is a relatively new Universal adhesive which has its matrix based on a combination of monomers of hydrophilic, hydrophobic
and intermediate nature allowing it to reliably bridge the gap between the
hydrophilic tooth substrate and the hydrophobic resin restorative.( Table/Figure 1) However studies using this bonding agent are scarce (8,9,10).

One
of the major problems associated with the use of adhesive systems is the
difficulty in obtaining a moisture-free clean tooth surface for adequate
bonding (11). Moisture control in the working field is particularly difficult
in situations such as equigingival or subgingival cavity margins, seating of
indirect restorations, newly erupted molars or when patients have limited mouth
opening (12). Contamination during the bonding process from sources such as
gingival crevicular fluid, hand piece oil, blood and saliva, can adversely
affect the quality of the bond predisposing it to microleakage at the
tooth-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 a
deleterious effect on bonding (14,15,16,17,18). But manufacturers are claiming that universal bonding agents are
resistant to salivary contamination. In accordance to this, study by
Santschi and colleagues concluded that saliva contamination did not affect the
bond strength of SBU (19).

In
the event of contamination, use of an appropriate decontaminating agent to
restore bond strengths has been advocated (20,21). Work
by Yoo et al. and Santschi et al. has shown that for all-in-one adhesives, washing, drying
and adhesive reapplication was the most effective decontamination protocol (12,19).

However,
to date, studies which have investigated the effect of salivary contamination
on the universal bonding agents are scant and conflicting
(19, 22). Hence the aim of this study was to evaluate the influence of
salivary contamination and water rinsing as a decontamination method on the
shear bond strength of universal bonding agents. 

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