Laboratory evaluation of three visible light-cured resinous liners

Objectives: The aim of the present study was to evaluate the composition and the laboratory performance of three visible light-cured resinous liners (Cavalite, Ionoseal and Timeline). Methods: Monomers were separated from fillers and were analysed by HPLC. Set pastes were analysed by FTIR spectroscopy and diametral strengths and water solubility were measured. Results: The monomers identified in the liners were BisEMA/2-HEMA (Cavalite), BisDMA/BisGMA (Ionoseal) and UEDMA (Timeline). Significant variations were found in the filler content but the mechanical response as assessed by the diametral tensile strength showed no statistical differences. The curing efficiency ranged from 24.2 to 31.0% (top surfaces) to 26.0–54.0% (bottom surfaces) of remaining C = C bonds. No positive correlations were found between curing efficiency and optical properties. The bond strength of the liners to dentine was negligible compared with that to composite. All the liners demonstrated extensive gap formation and debonding at the liner-dentine interfaces in marginal adaptation testing. Statistical differences were noticed in the water absorption and water solubility values of the products. Ionoseal showed extensive hydrolytic degradation compared with the other liners. No evidence of acid-base reaction was found in the set products.