Bond Strength of SE Adhesives with Phosphoric Acid Etching

Objective: There is concern that etching of uncut enamel with Phosphoric Acid (PA) when bonding with self-etching (SE) adhesives will result in lower bond strength (BS) to peripheral dentin.  The purpose of this study is to determine the long-term BS of several adhesives to dentin after total-etching with PA.  Methods:  The test method has previously been described in J. Dent. Res. V. 80 Abst. # 1272, Jan. 2001.  Two adhesives were evaluated in this study, Clearfil SE Bond (CSE) and Optibond FL (OFL).   Molar teeth, n=128, were selected and divided into 4 groups of 32 teeth (subgroups of 8 ea. for long-term data).  In Group 1, the dentin was etched with PA (15 sec.), rinsed with water (5 sec.) and air dried (5 sec.).  CSE was applied and cured (Herculite XRV Enamel restorative).  In Group 2 the dentin  was bonded with CSE without etching.  In Group 3, the dentin was etched with PA as in Group 1 and bonded with  OFL .  In Group 4, the dentin was bonded with the SE procedure for OFL without etching.  OFL Primer was applied with agitation (30 sec.), airflowed gently and light cured (20 sec.).  OFL Adhesive was then applied as the adhesive.  The samples were stored in 37ºC water and two subgroups were tested for this study (24 hrs. and one month after thermocycling 2,500 X between 5-55ºC).  The data were analyzed with anova (p<0.05).  Results:  The data for this study are attached. There was a slight reduction in BS after one-month for OFL with PA etching, but the BS of all groups remained high. Conclusion:  After short-term, PA etching of dentin only slightly affected the bond of two SE adhesives (study to continue; funded by Kerr Corp.).