Dentin Surface Pretreatment with Dimethyl-Sulfoxide Primer

Despite the evolution in adhesive dentistry over the past decades,¹ degradation of tooth-bonded interfaces still contributes to the reduced long-term clinical success of adhesive restorations.²
Etch-and-rinse approach still relies on traditional wet-bonding technique to couple relatively hydrophilic adhesives to the hydrated dentin substrate in clinically relevant protocols. A partially wet dentin substrate has been consensually advocated to maintain the demineralized collagen matrix expanded for proper resin infiltration by relatively hydrophilic monomers.³Nevertheless, management of adequate moisture is not easily accomplished, and either excess or lack of dentin moisture may compromise resin–dentin bonding.^{4, 5}
Recently, dimethyl sulfoxide (DMSO) has been introduced as a new potential solvent to be used in adhesive dentistry.^{6, 7}DMSO [(CH3)2SO] is a polar aprotic solvent that dissolves both polar and non-polar compounds. It is a polyfunctional molecule, with a highly polar S=O group and two hydrophobic methyl groups , fully miscible in most solvents and monomers used in adhesive dentistry .⁸ DMSO is perhaps the best currently known penetration enhancer for medical purposes⁹ with the ability to dissociate the highly cross linked collagen into a sparser network of apparent fibrils.¹⁰ In addition, dissociation of water self-associative tendency by DMSO ¹¹ improves wettability of demineralized dentin ,¹² monomer diffusion into the collagen matrix ⁶and concomitantly re-expands collapsed collagen to a fairly modest level.¹³