Universal or Multi-mode Adhesives: Why and How?

Abstract

A new generation of one-bottle dental adhesives is currently being used. The literature refers to them as universal or multi-mode adhesives (UA). UA are indicated as either self-etching (SE) or etch-and-rinse (ER) adhesives. Additionally, manufacturers also recommend an alternative “selective enamel etching” technique. Some UA contain 10-MDP (methacryloyloxydecyl dihydrogen phosphate), which has been shown to bond ionically to hydroxyapatite through nanolayering.18 Taking into account that MDP-mediated nanolayering may be responsible for the clinical success of the two-step SE adhesive Clearfil SE Bond (Kuraray) at 8 years,11 expectations exist regarding the clinical success of MDP-containing UA. Nevertheless, etching dentin with phosphoric acid removes calcium, leaving behind a 2to 5-μm-thick area of denuded collagen fibers. It is not clear at this point if (and how) MDP-containing adhesives are able to bond ionically to calcium-deprived etched dentin through nanolayering. Clinical studies and laboratory evaluations have, in fact, demonstrated that some UA may perform at the same level of previous materials.1,3,5,10 However, enamel etching with phosphoric acid is still recommended for UA. The enamel μTBS values obtained with Scotchbond Universal (3M ESPE) were 28.7 MPa (self-etching) and 40.1 MPa (etched enamel).9 Even when UA are applied with a rubbing Fig 1 UA bond strengths by application protocol. ABU: All-Bond Universal; GBP: G-Bond Plus/G-aenial Bond; SBU: Scotchbond Universal; Fut-U: FuturaBond U. SE-passive: self-etching, passive application; SE-active: self-etching, active application; ER: etch-and-rinse.