A fluid filtration and clearing technique to assess microleakage associated with three dentine bonding systems

Objectives: The aims of this in vitro study were to (a) measure fluid flow through teeth restored with one of the dentine bonding systems and a resin composite restoration; (b) measure the distribution of a silver tracer through the same teeth, and make a comparison with fluid flow; and (c) investigate the effect of thermocycling on both measurement types. Methods: Coronal segments of 30 premolars, randomly allocated to three equal groups, were assessed by fluid filtration. Each group was restored with a resin composite restoration in conjunction with Fuji Bond LC (FBLC), Scotchbond Multi-Purpose Plus (SMP+) or Prime&Bond 2.1 (P&B2.1). Fluid filtration rates were measured in the intact crown and then after cavity preparation, conditioning, dentine bonding, restoration and at 2 and 24 h, 1 week and 1 month following restoration. Six specimens from each group were thermocycled at 1 week. After final filtration measurements the specimens were perfused with silver nitrate and cleared before scoring tracer penetration. Results: No significant differences (P>0.05) in fluid filtration rates were found amongst the different bonding systems or at any restoration stage. Thermocycling was not associated with any significant (P>0.05) increase in fluid filtration. Final fluid filtration and tracer distribution showed a weak and not statistically significant correlation (P>0.05). The penetration of silver stain indicated a failure of the restorations to seal the cavity and demonstrated a possible pathway by which in vivo post-operative sensitivity could occur. Conclusions: Although not statistically significant, conditioning of the cavity increased the dentinal permeability but this effect was variable. Thermocycling had no statistically significant effect on microleakage.