The effect of surface treatment on the adhesive strength of chairside hard liners to dental polymers used for the conventional, additive, and subtractive fabrication of complete dentures

Abstract

Objectives: The aim of this in vitro study was to evaluate the tensile bond strength of two hard denture relining materials on denture bases fabricated from conventional, subtractive, and additive polymers. In addition, this study assessed the effect of a polymer to resin primer on the tensile bond strength of hard denture liners to different denture bases. Methods: A total of 120 hard relined denture base samples were fabricated, 40 per denture base group (Lucitone 199, Ivo Base CAD, and NextDent Denture 3D+). For each denture base group 20 samples were hard relined with one of two chair side hard denture liner (GC Reline, MucoHard). Among the hard reline groups, 10 of each group was primed with a composite to PMMA primer (Visio.link). All samples underwent thermocycling. The adhesive strength was evaluated through tensile testing. The surface contact angle was measured on each denture group sample to evaluate the wettability of the material. The data was analyzed using Inverse-variance weighted linear regression. Results: In this study overall the denture bases relined with MucoHard denture liner had significantly higherbond strength than the GC reline groups (P<0.016). The highest tensile bond strength was achieved by combining MucoHard denture liner and primed 3D printed denture base, followed by the non-primed conventional denture base, and non-primed milled denture base to MucoHard denture liner. The surface primer used in this study (Visio.Link primer, Bredent UK Ltd. Chesterfield, UK.) had a significant effect on the tensile bond strength of all tested groups (P<0.0003). However, the primer only positively influenced the bond strength of the 3D printed denture base to MucoHard denture liner, while the other groups were inversely affected. Conclusion: There was no significant difference in the tensile bond strength of chairside denture liners to denture bases fabricated using additive, subtractive, and conventional methods (P>0.05). The highest bond strength was achieved with the combination of MucoHard denture liner and primed 3D printed denture bases. MucoHard denture liner has overall significantly higher tensile bond strength in comparison to GC reline. (P<0.016) The primer only positively influenced the bond strength of MucoHard to 3D printed denture bases. The primer significantly alters the wettability of the denture bases.