Effect of surface treatments on the shear bond strength of veneering composite resin to CpTi, Ti6Al4V, and BioHPP framework materials: an in vitro study

Abstract

Abstract Background Durable bonding between veneering composite resin and prosthetic framework materials is essential for the performance of veneered restorations. This study evaluated the effects of different surface-conditioning protocols on the shear bond strength (SBS) of veneering composite resin to commercially pure titanium (CpTi), Ti6Al4V alloy, and Bio High-Performance Polymer (BioHPP). Methods Forty-five specimens of CpTi, Ti6Al4V, and BioHPP ( n = 15/material) were divided into three surface-conditioning subgroups ( n = 5): air abrasion with 110-µm Al₂O₃, 98% sulfuric acid etching, and sequential air abrasion followed by sulfuric acid etching. Following material-specific primer application and composite veneering, specimens were stored in distilled water for 24 h and subjected to 5,000 thermocycles. SBS was measured using a universal testing machine. Representative surface morphology was evaluated using scanning electron microscopy (SEM) and atomic force microscopy (AFM), and failure modes were assessed stereomicroscopically. SBS was analyzed using two-way ANOVA followed by Tukey’s HSD test (α = 0.05). Results Framework material (F = 15.20, p < 0.001, partial η² = 0.458) and surface-conditioning protocol (F = 13.02, p < 0.001, partial η² = 0.420) significantly influenced SBS. A significant material × surface-conditioning interaction was also observed (F = 3.17, p = 0.025, partial η² = 0.261). Ti6Al4V subjected to combined air abrasion and sulfuric acid etching demonstrated the highest mean SBS (10.60 ± 4.09 MPa), whereas sulfuric acid-etched BioHPP exhibited the lowest (1.18 ± 1.00 MPa). Air abrasion and combined treatment produced significantly higher SBS than sulfuric acid etching alone (both p < 0.001), with no significant difference between air abrasion and combined treatment ( p = 0.886). All specimens exhibited adhesive failure. Conclusions Framework material and surface-conditioning protocol significantly influenced SBS, with a material-dependent treatment response. Air abrasion, alone or followed by sulfuric acid etching, produced higher SBS than sulfuric acid etching alone. Because material-specific bonding systems were used, inter-material differences should be interpreted as reflecting the complete bonding protocols rather than the isolated effect of framework material alone. Further long-term laboratory and clinical studies are required before definitive clinical recommendations can be made.

The authors' abstract, as published at the source. BMC Oral Health, 2026 · DOI ↗