Shear Bond Strength of Liner Materials to Caries-Free and Caries-Affected Dentin

Dental liners are used on caries-free dentin to attenuate postoperative sensitivity and caries-affected dentin to promote remineralization and for antibacterial effects. The shear bond strength of liners to caries-affected and caries-free dentin is a significant clinical property in the restoration of teeth with large caries lesions. Objective: The aim of this in vitro study was to compare the shear bond strengths (SBS) of different liners to caries-free and caries-affected dentin.

SBS specimens were prepared according to ISO 29022:2013(E) (n=10/ group). Caries-free dentin specimens were ground to superficial dentin. For caries-affected dentin, grinding to proximity of carious dentin was performed, remaining caries-infected dentin was removed with a polymer bur, and sanding to 320 grit was conducted to achieve a flat surface. 150-micron thick tape was centered over caries-free or caries-affected dentin, and five different liners (new RMGI-based calcium silicate liner [RMGI/ CS], Biodentine, Lime-Lite Enhanced, TheraCal LC, Vitrebond Plus) were applied to dentin and leveled with the tape. Specimens were treated with adhesive, cured, and bonded with resin composite using the Ultradent fixture. Specimens were stored in 37°C water for 24 ± 2 hours and debonded at 1 mm/min. SBS was analyzed by two-way analysis of variance (ANOVA) and the Tukey post hoc test.

There was a significant difference in SBS among materials for both caries-affected and caries-free dentin (p<0.01). Tukey post hoc analysis grouped materials into significantly different groups for caries-free dentin (Lime-Lite Enhanced, Biodentine < TheraCal LC < Vitrebond Plus, RMGI/CS) and caries-affected dentin (Lime-Lite Enhanced, Biodentine, TheraCal LC < Vitrebond Plus, RMGI/CS). There was no difference in SBS to caries-free and caries-affected dentin for Lime-Lite Enhanced (p=0.359), Biodentine (p=0.522), Vitrebond Plus (p=0.406), or RMGI/CS (p=0.165). SBS was significantly greater to caries-free dentin with TheraCal LC (p<0.01).

RMGI/CS and Vitrebond Plus produced higher SBS to caries-free and caries-affected dentin than the three other materials. There was a higher bond to caries-free dentin than caries-affected dentin for TheraCal LC, but not for any of the other liners tested. Clinicians should balance biologic advantages of liner materials with a decrease in bond strength.