Effect of adhesives and mechanical surface treatments on the hard relining of CAD‐CAM denture bases

Abstract Purpose The aim of this study was to evaluate the impact of mechanical roughening, adhesive applications, and aging on the bonding between CAD‐CAM denture base materials with distinct chemical contents and hard relining material. Materials and Methods A total of 300 denture base specimens were produced by additive, subtractive, and conventional heat‐polymerization techniques ( N = 100). The specimens have been classified into five subgroups based on the particular surface treatments administered ( n = 20): (1) Hard relining material's adhesive application (control); (2) Tungsten carbide bur application for 1 min, and hard reline material's adhesive application; (3) Airborne‐particle abrasion (APA) with 110 μm Al 2 O 3 , and hard reline material's adhesive application; (4) Scotchbond Universal application; and (5) Visio.link application. Representative specimens from each subgroup were examined under a Scanning Electron Microscope (SEM). Subsequently, self‐cure hard relining material was condensed in the center of the specimens. Half of the specimens were thermally aged with 5000 cycles at 5°C–55°C. The shear bond strength (SBS) test was performed, and failure loads were recorded. The data was evaluated by Robust ANOVA and Bonferroni test ( p < 0.05). Results No statistically significant difference was obtained between the production techniques ( p = 0.051). The lowest SBS was observed in the control group among surface treatments, while mechanical surface treatments and universal adhesive showed the highest SBS for both aged and non‐aged groups. Aging caused a significant decrease for all test groups ( p = 0.001). Conclusions Mechanical surface treatments and universal adhesive applications are more effective for maintaining adhesion across all production techniques.