Incompatibility Profiles of All-in-one Adhesives. I. True vs Apparent Incompatibility

Objectives: Some manufacturers claim that their all-in-one adhesives may be used for bonding of indirect restorations. This study examined the compatibility of some of these adhesives to auto-cured composites, using deep dentin from extracted human third molars as a permeable bonding substrate, and processed composite as an impermeable bonding substrate. Methods: Four all-in-one adhesives were examined. Xeno III (XE, Caulk-Dentsply), Adper Prompt (AP, 3M ESPE) and One-Up Bond F (OU, Tokuyama) are recommended to be used with light-cured composites only, while iBond (IB, Heraeus-Kulzer) is claimed to be suitable for indirect restorations. An auto-cured composite (Bisfil 2B, Bisco) was coupled to both hydrated dentin (H) and processed composite (C) using these adhesives. The control consisted of an experimental dual-curable version of BisFil 2B that was bonded to hydrated dentin using the light-activation mode (HL). Microtensile bond strength evaluation was performed after 24 h of water storage, using beams of approximately 0.9 mm² in cross-sectional area. TEM was performed following exposure to ammoniacal silver nitrate.

Results: Microtensile bond strengths (X±SD, n=20 in MPa; Kruskal-Wallis/Dunn’s). For each column, different superscripts indicated significance difference at P<0.05.

In group H, XE, IB and OU contained silver-filled water blisters along the adhesive-composite interfaces. They were not observed when dentin was replaced with composite in group C. Groups H and C in AP did not bond to the auto-cured composite.

Conclusion: Of the four all-in-one adhesives, only AP demonstrates true adverse acid-base reaction when coupled with auto-cured composites. When bonded to hydrated dentin, the “apparent” incompatibility of XE, IB and OU with auto-cured composites is due to their inherent permeability that permit water movement from the bonded dentin.