The shear strength of polymethyl methacrylate bonded to titanium partial denture framework material

Premachined titanium frameworks are used in implant-supported fixed complete-arch prostheses. Traditionally, retentive mechanisms are incorporated in the wax patterns to provide retention between polymethyl methacrylate and the cast framework. Nontraditional forms of retention are needed with machined frameworks. This study determined whether three different surface characteristics of titanium improve the bond shear strength of polymethyl methacrylate. Thirty rod shaped specimens of titanium were divided into three equal groups: group 1 received no pretreatment; group 2 was pretreated with 110 microns alumina air abrasive; and group 3 was pretreated with 110 microns alumina air abrasive plus silane (clear). Denture resin was processed around each specimen. A Shell-Nielsen shear test was then performed at a crosshead speed of 0.5 mm/minute to determine the bond shear strength in kilograms per square centimeter. The bond shear strength of group 3 was 63% greater than group 1 (significant, p < 0.01; ANOVA-Scheffé interval 63 kg/cm2). The results of this study indicated that surface pretreatment of titanium with 110 microns alumina air abrasive plus silane coating significantly enhances the bond shear strength of polymethyl methacrylate.