The durability of a fluoride-releasing resin adhesive system to dentin

The durability of a fluoride-free (SE Bond) and a fluoride-containing (KBF) self-etching primer/ adhesive system were compared by measuring the microtensile bond strengths (microTBS) of these adhesive systems to human dentin in vitro. After bonding, the restored teeth were serially sectioned into multiple slabs that were trimmed to a 1 mm2 cross-sectional area at the bonded interface. For the three and six month specimens, half were fully covered with nail varnish (SE+, KBF+), while the other half were incubated at 37 degrees C in water without any protective varnish (SE-, KBF-). The microTBS of the one-day specimens were 44.6 +/- 11.2 MPa for SE Bond and 39.8 +/- 8.0 MPa for KBF (p > 0.05). When unprotected specimens were incubated in water for three and six months, the microTBS fell to 26.3 +/- 8.8 MPa and 23.6 +/- 10.7 MPa for SE-, respectively, but did not change in the specimens protected with nail varnish (SE+, 41.9 +/- 12.8 MPa and 41.8 +/- 9.8 MPa, respectively). In contrast, in specimens bonded with a fluoride-containing resin, KBF, the bond strengths of the unprotected specimens did not change over three and six months KBF-. Values were 32.4 +/- 6.1 MPa and 36.8 +/- 2.3 MPa, respectively. Similarly, varnish-protected KBF+ specimens did not change over three and six months (39.3 +/- 13.6 MPa and 40.9 +/- 14.7 MPa, respectively). The results indicate that decreases in bond strength over six months' storage are water-dependent but can be prevented by using fluoride-containing resins.