Bond Strength to Oxalate-treated Dentin Saturated with Water versus Ethanol

Objectives: To evaluate the effect of potassium oxalate treatment on the microtensile bond strength (mTBS) of experimental primers applied to acid-etched dentin saturated with water or ethanol. Methods: Sixty human teeth had their dentin surface exposed, acid-etched (35% phosphoric acid ) and rinsed. Half of those surfaces were further treated with potassium oxalate (Bis-Block/Bisco) for 30 s, while the other remained untreated (control). Oxalate-treated dentin surfaces were washed with water and gently blot-dried or saturated with 100% ethanol. Two experimental primers containing (%v/%v) 35%HEMA/65%Water (H35/W65) or 35%HEMA/65%Ethanol (H35/ET65) were applied to both untreated and oxalate-treated dentin surfaces that were saturated with water (Water-wet bonding technique) or with ethanol (Ethanol-wet bonding technique). After a dwell time of 30 s, excess solvent was evaporated and the primed-dentin surfaces were bonded with a neat bonding agent (Scotchbond Multi-Purpose, 3M/ESPE). Resin composite build-ups were incrementally constructed. Specimens were prepared for mTBS and tested in tension at 0.5mm/min.

Results:

Conclusions: In general, bond strength to ethanol-saturated dentin was higher than to water-saturated dentin. Application of potassium oxalate tended to decrease the bond strength of the experimental primers, regardless of dentin was saturated with water or ethanol. Nevertheless, decrease of bond strength for oxalate-treated dentin was significantly higher for specimens that were saturated with water. Further studies may investigate whether the ethanol-wet bonding technique may provide durable in vivo bonds.