Effect of Different Surface Treatments and Thermocycling on Bond Strength of a Silicone-based Denture Liner to a Denture Base Resin

Abstract

Aim:The aim of this study is to evaluate the effects of three different surface treatments and thermocycling on the tensile strength of a silicone lining material to denture resin. Materials and methods:A total of 96 cube-shaped specimens were fabricated using heat-cured polymethyl methacrylate (PMMA) denture base resin. Three millimeters of the material was cut from the midsection. The specimens were divided into four groups. The bonding surfaces of the specimens in each group received one of the following surface treatments: no surface treatment (control group), airborne particle abrasion with 110 µm alumina particles (air abrasion group), Er:yttrium aluminum garnet laser irradiation (laser group), and air abrasion + laser. After the lining materials were processed between the two PMMA blocks, each group was divided into two subgroups (n = 12), either stored in distilled water at 37ºC for 24 hours or thermocycled between 5 and 55ºC for 5,000 cycles. The specimens were tested in tensile and shear strength in a universal testing machine. Data were analyzed with two-way analysis of variance and Tamhane's post hoc tests (α = 0.05). The mode of failure was determined, and one specimen in each group was examined by scanning electron microscopy. Effect of Different Results:Surface-treated groups demonstrated significantly higher tensile strengths compared to the control group (p < 0.001). Nonetheless, no significant differences were found between surface-treated groups (p > 0.05). The tensile strength was significantly different between thermocycled and waterstored specimens (p = 0.021). Conclusion:Altering the surface of the acrylic denture base resin with air abrasion, laser, and air abrasion + laser increased the tensile strength. Thermocycling resulted in decrease in bond strength of silicone-based liner to surface-treated acrylic resin.Clinical significance: Pretreatment of denture base resins before applying the soft liner materials improves the bond strength. However, thermocycling results in decrease in bond strength of soft denture liner to surface-treated acrylic resin.

Soft Denture Liner Adhesion to Conventional and CAD/CAM Processed Poly(Methyl Methacrylate) Acrylic Denture Resins-An In-Vitro Study

“…This was further substantiated by the findings of Akin et al [ 40 ], who reported that 120 µm Al 2 O 3 particles are the best particle size to enhance bond strength compared to 50 µm, 60 µm, and 250 µm Al 2 O 3 particles. The outcome of the present study is in agreement with those studies [ 16 , 18 ] reporting an increased bond strength following airborne-particle abrasion.…”

“…On the contrary, Usumez et al [ 18 ] showed that airborne-particle abrasion of the PMMA resins before liner application showed higher mean TBS than the control group. Similarly, Nakhaei et al [ 16 ] reported that airborne-particle abrasion of PMMA resins with 110 µm alumina enhances the adhesion between resilient liners and denture base. These conflicting results between studies could be due to the differences in the acrylic resins and soft-liners used, different sizes of abrasive particles, and the pressure [ 18 ].…”

“…Previous studies have suggested using different techniques to enhance the adhesion of resilient liners to the denture base. These include the introduction of surface roughness to denture base by airborne-particle abrasion, chemical etching, acrylic bur roughening, and lasing [ 8 , 14 , 15 , 16 , 17 , 18 ].…”

The Effect of Sandblasting on Bond Strength of Soft Liners to Denture Base Resins: A Systematic Review and Meta-Analysis of In Vitro Studies

“…[ 84 , 85 ] However, this result contradicts a number of studies that showed higher bond strength after sandblasting. [ 29 , 30 , 73 , 75 , 76 ] Several different parameters and strategies are used for sandblasting, and this could obscure getting the real impact of this procedure on the bond strength. Factors that could affect the bond strength values between the liner materials and denture base resin are the type of lining materials, particle size of sands, blasting pressure and time, test methods, thermocycling, speed of head of testing machine, and thickness of lining material.…”

“…The rationale for these findings is that the size of roughening by sandblasting with 50 µ m Al 2 O 3 particles may not be sufficient to allow liner material penetration. [ 31 , 62 , 76 ] As the penetration coefficient of the liners is inversely related to their viscosity, liners with higher viscosity have less penetration into PMMA surface pores. [ 35 ] On the other hand, sandblasting with large size particles (250 µ m) also reduces the bond strength due to stress concentration of large size particles.…”