Effect of Surface Treatments on Bond Strength of CAD/CAM Dental Restorative Materials: A Review

Abstract

Introduction: The longevity of computer-aided design/computer-aided manufacturing (CAD/CAM) dental restorations relies heavily on the interfacial bond strength between the restorative material and resin cements. Surface treatments are essential to enhance micromechanical retention and chemical adhesion, particularly for materials such as hybrid ceramics, lithium disilicate glass-ceramics (LDGC), zirconia-reinforced lithium silicate (ZLS), polymer-infiltrated ceramic networks (PICN), zirconia, provisional polymers, and emerging 3D-printed resins.

Objectives: This review synthesizes evidence from in vitro studies (2003–2025) on the effects of various surface treatments—including hydrofluoric acid (HF) etching, sandblasting (Al₂O₃ or silica-coated), silanization, laser irradiation (Er:YAG/Er,Cr:YSGG), tribochemical coating, and universal adhesives—on shear bond strength (SBS), micro-tensile bond strength (µTBS), four-point bending strength, and repair bond strength in CAD/CAM restoratives, with emphasis on immediate and aged conditions.

Methods: A narrative review was conducted by synthesizing data from 25 peer-reviewed articles identified through databases such as PubMed, ScienceDirect, MDPI, and others. Inclusion focused on experimental studies with universal testing machine assessments, thermocycling/water storage ageing, and failure mode analysis via SEM/stereomicroscopy. Qualitative synthesis addressed material-specific trends, resin cement types, and ageing effects due to protocol heterogeneity.

Results Surface treatments significantly improved bond strength across materials. For silica-based ceramics (e.g., LDGC, hybrids), HF etching combined with silane or universal adhesives yielded the highest SBS (up to 45.49 MPa in experimental protocols; 32.96 MPa in systematic reviews for IPS e.max CAD), with cohesive/mixed failures predominant. Sandblasting or tribochemical coating enhanced bonds to non-silica materials like zirconia and titanium (15–29 MPa), while lithium disilicate veneering outperformed feldspathic porcelain (18.81 vs. 11.40 MPa). In novel CAD/CAM materials, sandblasting + HF + MDP-containing universal adhesive achieved superior four-point bending strength (100.31 MPa for LDGC). For 3D-printed resins, meta-analysis confirmed significant immediate and aged bond enhancements with sandblasting/silane (p<0.007) or HF/sandblasting (p<0.001). Resin-matrix CAD-CAM ceramic repairs benefited from combined mechanical (alumina blasting, silica coating) and chemical treatments, with lasers as viable alternatives. Ageing (thermocycling/water storage) generally reduced SBS, except in resilient materials like PEEK; etch-and-rinse cements outperformed self-adhesive types in most scenarios. Failure modes shifted from adhesive to cohesive/mixed with optimized treatments.

Conclusions: Combined mechanical-chemical surface treatments (e.g., sandblasting + HF + silane/universal adhesive) are most effective for durable bonding in CAD/CAM restorations, with protocols tailored to material composition (silica-based vs. non-silica). These strategies minimize debonding, chipping, and repair failures, supporting clinical longevity. Future clinical trials are needed to validate in vitro findings and standardize protocols for emerging additively manufactured materials.