Effect of Dimethyl Sulfoxide on Bond Strength of a Self-Etch Primer and an Etch and Rinse Adhesive to Surface and Deep Dentin

Statement of the problem: composite bond to dentin is crucial in many clinical conditions particularly in deep cavities without enamel margins due to insufficient penetration of adhesive into demineralized dentin. purpose: the aim of this study was to assess the shear bond strength (sbs) of a methacrylate-based and a silorane-based composite resin to surface and deep dentin after pretreatment with dimethyl sulfoxide (dmso). materials and method: eighty extracted human premolars were randomly divided into two groups of flat occlusal dentin with different cuts as a: surface group (sections just below the dentinoenamel junction (dej) and b: deep group (2 mm below dej). each group was randomly assigned to 4 subgroups and their samples were restored with adper single bond (asb) and filtek z350 or silorane system adhesive (sa) and filtek p90 composite resins, using a 3×3mm cylindrical plastic mold. following these steps , the subgroups were assigned as subgroupa1: surface dentin+ silorane system primer (ssp)+ silorane system bonding (ssb)+ p90; subgroup a2: surface dentin+ 37% etchant (e37%) + adper single bond (asb)+ z350; subgroup a3: surface dentin+ dmso+ ssp+ ssb+ p90; subgroup a4: surface dentin+ e37%+ dmso+ asb+ z350; subgroup b1 : deep dentin+ ssp+ ssb+ p90; subgroup b2 : deep dentin+ e37%+ asb+ z350; subgroup b3: deep dentin+ dmso+ ssp+ ssb+ p90; subgroup b4:dentin +e37% +dmso +asb +z350. the specimens were thermocycled at 5± 2/55± 2°c for 1000 cycles and then tested for sbs. results: using dmso as dentin conditioner increased sbs of asb to deep dentin (p< 0.001) and sbs of sa to surface dentin (p= 0.003) but had no effect on sbs of sa to deep dentin (p= 1.00). conclusion: the ability of dmso to increase sbs of asb to deep dentin provides a basis for improving bonding of this composite resin in deep cavities.