Effect of Surface Textures and Fabrication Methods on Shear Bond Strength Between Titanium Framework and Auto-Polymerizing Acrylic Repair Resin

The aim of the study was to evaluate the effect of airborne particle abrasion (using different sizes of alumina particles) on the shear bond strength (SBS) between cast and milled titanium metal frameworks and auto-polymerizing acrylic repair resin. Forty flat cylindrical titanium disks were divided into two main divisions: cast and milled titanium. The two divisions were further subdivided into four groups based on metal surface treatment. Three particle sizes of aluminum oxide air abrasive powders (50µm, 110µm, and 250µm) were used for metal surface treatment by airborne particle abrasion. One group was the control group with no surface treatment. Auto-polymerizing acrylic repair resin was applied to all titanium disks. The specimens were subjected to SBS testing using a universal testing machine (Instron Corporation, Norwood, Massachusetts, United States). Surface evaluation was performed using a scanning electron microscope. One-way ANOVA was used for statistical analysis. The results showed a significant increase in SBS after airborne particle abrasion of both milled and cast titanium groups (p<0.001). The SBS was directly proportional to the size of the aluminum oxide particles. The milled titanium group showed higher SBS values than the cast group when the surface was not treated with alumina particles (p < 0.001) and when the surface was treated with the smaller particle sizes of 50 µm, whereas the cast group demonstrated higher SBS values than the milled group (p < 0.01) when the particle size was increased to 110 µm and 250 µm. It could be concluded that SBS between titanium metal frameworks and auto-polymerizing repair acrylic resin was directly related to the size of the alumina airborne particle abrasives. The fabrication method of the titanium framework also influenced the SBS as the untreated milled frameworks demonstrated favorable SBS values compared to the untreated cast frameworks.