Effect of sealer coating on mechanical and physical properties of permanent soft lining materials

Objective: To evaluate the long-term effects of sealer coating on tensile bond strength and surface roughness of soft liners. Background: Failure of the bond between resilient liners and denture base significantly compromise the dentures' longevity. In addition, surface roughness contributes to bacterial adherence on prosthetic materials, increasing the risk of oral infections. Methods: Specimens were manufactured from four reliners [Mucopren Soft (MS), Dentuflex (DF); Soft Comfort Denso (SC) and Ufi Gel SC (USC)], distributed into 10 groups (n = 10), according to material and coating treatment. Tensile bond strength was performed after one year of ageing, while surface roughness was evaluated at 0, 1, 3, 6 and 12 ageing months. Bond strength data were submitted to two-way ANOVA and Tukey-HSD tests, while roughness data were submitted to mixed model analysis for repeated measurements (p <= 0.05). Results: MS and DF without sealer coating presented the highest tensile bond strength. After coating, DF and SC presented increased tensile bond strength. No surface roughness difference was observed in the non-coated groups over time, acrylic-based reliners presented higher roughness. Among coated groups, only SC presented increased surface roughness. Acrylic-based materials presented reduced roughness at three months. Conclusion: Surface coating was effective for acrylic reliners in maintaining their initial properties. However, sealer coating should be re-applied every 3 months.