Bond strength of restorative materials to human dentin: influence of post-extraction time

This study was undertaken to determine if the time after which teeth are extracted influences the tensile bond strength of a glass ionomer (Fuji II: GC) and a dentin bonding agent (Scotchbond Self Cure; 3M) to dentin. Within 20 min of extraction, 14 teeth were bonded with glass ionomer and 13 teeth with Scotchbond Self Cure plus a composite material (Clearfil; Kuraray), by attachment of orthodontic brackets to prepared dentin surfaces. The bonds were fractured in tension, and yielded values of 3.7 MPa for glass ionomer and 1.08 MPa for Scotchbond Self Cure + Clearfil. These data were significantly different (P less than 0.002) from data previously obtained from the use of old teeth, from which values of 2.20 MPa and 1.82 MPa for glass ionomer and Clearfil + Scotchbond Self Cure, respectively, were obtained. It was concluded that the time after extraction can significantly change bond strengths to dentin, but that the direction and magnitude of these changes depend on the adhesive system used.