Effect of ethanol-wet bonding and chlorhexidine on resin-dentin bond durability

Ethanol-wet bonding has been recently proposed as a bonding technique to effectively infiltrate hydrophobic monomers into acid-etched dentin for a more durable bond. Chlorhexidine (CHX) has also been shown to maintain hybrid layer morphology and bond integrity. Objectives: To evaluate effect of ethanol-wet bonding (EW) and CHX on same-day and 1 year resin-dentin bond strength. Methods: 64 sound human molars were randomly divided into water-wet (WW) and EW groups. All teeth were flattened with a carbide bur in the CNC Specimen Former (University of Iowa) to expose coronal dentin. For EW, the etched and water rinsed dentin was subsequently rinsed with absolute ethanol for 15 s X 3 before primer (50% resin/50% ethanol) application. CHX was applied to ½ of the teeth before priming for both EW and WW groups. After solvent removal, pure adhesive (Bis-GMA/TEGDMA) was applied and resin-based composite (Z100, 3M ESPE) incrementally built-up. Four dumbbell-shaped specimens with a round cross-sectional area of 0.5 mm², 1 mm gage length and 0.6 mm radius of curvature were formed per tooth. One-half of the specimens were immediately tensile tested to failure at 1 mm/min in a passive gripping device while the remaining specimens are stored for 1 year at 37°C in PBS before testing. Results: Seventeen water-wet teeth and one ethanol-wet tooth failed to produce 4 testable specimens and were replaced. Same day dentin uTBS (MPa±SD): WW-CHX = 32.77±11.15, WW = 29.91±15.13, EW-CHX = 47.49±14.01, EW = 51.45±10.18. EW, regardless of CHX application, had a significantly higher uTBS than WW groups (P<0.0001). No significant difference was found between CHX and non-CHX application in both techniques. Conclusion: The ethanol-wet bonding technique showed significantly higher dentin µTBS than water-wet bonding, while CHX application had no significant effect on bond strength at 1 day.

[Bisco, Inc. provided the adhesive]