Nanoleakage expression after 1-year aging of adhesives applied with ElectroBond

Objectives: The use of ElectroBond-assisted application of dental adhesives has been shown to increase immediate bond strength and reduce nanoleakage expression. Aim of this study was to analyze the effect of 1-year storage on nanoleakage expression of different adhesives applied with or without electricity.

Methods: Non carious extracted human molars were selected for the study. Specimens were then randomly assigned to the following adhesives: 1) Scotchbond 1XT (3M ESPE); 2) XP-Bond (Dentsply De Trey); 3) Clearfil S3 Bond; 4) XENO III. All adhesives were applied on middle/deep dentin disks under the effect of electric impulses generated by ElectroBond 3.0 (ver 2005) or in accordance with manufactures' instructions. Filtek Flow Z-250 was used to create a 1 mm thick resin composite layer. Specimens were cut to expose the bonded interface and analysis of the nanoleakage expression was performed after 24 hours or after 1 year of storage in artificial saliva at 37°C. Specimens were immersed in silver nitrate solution, photodeveloped and observed either with light microscope (LM) or transmission electron microscope (TEM).

Results: Irrespective to their formulation, all tested adhesives showed immediate reduced nanoleakage expression if applied with ElectroBond. After 1-year aging, nanoleakage of all tested adhesives increased due to degradation phenomena of the hybrid layer, nevertheless the use of ElectroBond contribute to reduce silver uptake.

Conclusions: Since the use of ElectroBond reduced nanoleakage of all tested adhesives in comparison with the control application technique irrespective from storage, this study support the hypothesis that electricity may favourably contributes to stabilize the adhesive interface over time. How much ElectroBond improve bonding in vivo is currently under investigation.