Adhesion of Newly Developed Composite Resin Splinting Materials to Enamel: Effect of Enamel Surface Treatment.

BACKGROUND/AIM To evaluate the shear bond strength (SBS) of newly developed composite resin materials intended for dental splinting to enamel and to determine whether phosphoric acid etching alone provides reliable adhesion.

MATERIAL AND METHODS Four experimental materials (G-Fix, Light Fix, Ortho Connect, and Ortho Connect Flow) were compared with conventional composite resins applied to phosphoric acid-etched enamel, with or without a universal adhesive. After thermocycling, SBS was measured and failure modes were assessed. Wettability was evaluated by contact angle measurement, and the resin-enamel interfacial microstructure was examined using atomic force microscopy.

RESULTS Across all materials, application of a universal adhesive did not increase SBS. SBS was significantly reduced for Light Fix and Ortho Connect Flow when the adhesive was used. When applied directly to etched enamel, all experimental materials achieved clinically acceptable SBS. Interfacial analyses supported that adhesion was predominantly mediated by functional monomer-driven chemical interactions rather than enhanced micromechanical retention.

CONCLUSIONS For the tested splinting composites, phosphoric acid etching followed by direct composite application provided reliable enamel adhesion, and the additional use of a universal adhesive was unnecessary and may be detrimental for selected materials. This simplified protocol may be suitable for clinical splinting procedures.