Incompatibility Profiles of All-in-one Adhesives. III. Ternary Catalyst and Resin-Coating

Objectives: Although ternary catalysts such as the salts of aryl sulphinate, barbituric acid and aryl borate are effective in eliminating true incompatibility between ionic adhesive monomers and auto-cured composites, they do not contribute to reducing the permeability of all-in-one adhesives. This study compared the use of an add-on ternary catalyst with the use of a light-cured resin-coating on the coupling of an auto-cured composite to dentin bonded with four all-in-one adhesives.

Methods: A 1.8% solution of the sodium salt of p-toluene sulphinate was used with the respective all-in-one adhesive, Xeno III (XE, Caulk-Dentsply), Adper Prompt (AP, 3M ESPE), One-Up Bond F (OU, Tokuyama) and iBond ((IB, Heraeus-Kulzer), and applied to either hydrated dentin (HB) or dehydrated dentin (DB). The same adhesives were applied as a control to hydrated dentin without the ternary catalyst (H), or with an additional coat of D/E resin (Bisco; HR). The bonded teeth were coupled to an auto-cured composite (Bisfil 2B, Bisco). Microtensile bond strength and TEM were evaluated.

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.

TEM revealed that when a ternary catalyst was used, effective coupling only occurred when bonding was performed on dehydrated dentin. Conversely, neither water blisters nor decoupling occurred when an adjunctive resin-coating was used on hydrated dentin.

Conclusions: The beneficial effect of incorporating or using add-on dual-cured catalysts in all-in-one adhesives is masked by the intrinsic permeability of these adhesives. Conversely, the use of an additional light-cured resin-coating, which invariably involves an extra bonding step, converts these adhesives to 2-step self-etch adhesives, and is effective in eliminating both true and apparent incompatibility with auto-cured composites.