Surface Conditioning Critical for Successful Repair of 3D-Printed Dental Resins: Study

A new study published in the Journal of Dentistry showed that the surface conditioning procedure utilized prior to adhesive restoration has a major impact on the repair performance of 3D-printed dental resins.

Despite their growing popularity for dental restorations, 3D-printed resins are still prone to wear and localized fractures. An economical and conservative substitute for total replacement is intraoral repair. However, the availability of reactive groups is restricted by the highly cross-linked structure of additively made polymers, making the chemical bonding that is usually used in traditional composite repairs more difficult.

To produce a solid adhesive contact, adequate surface conditioning—often combining mechanical abrasion with chemical primers—is required. Chemical compatibility and adhesion are also greatly influenced by the choice of repair material, such as utilizing the same 3D-printed resin vs a traditional composite. To create trustworthy clinical repair procedures for 3D-printed dental resins, this study assesses the shear bond strength (SBS) of different surface treatments and repair materials because the available data does not support appropriate protocols.

For final restorations, disc-shaped specimens measuring 10 mm by 2 mm were created using a 3D-printed resin (Crowntec, Saremco Dental AG). Nine surface treatments, two repair materials (flowable composite or 3D-printed resin), and two aging conditions (before/after thermocycling) comprised the 36 groups (n=10) in the study design. Heliobond, a hydrophobic adhesive resin, was used for repairs. 

Surface treatment and repair material significantly impacted SBS, but age had no significant effect (p = 0.539).

Tribochemical silica coating + primer and aluminum oxide air abrasion + primer achieved the greatest SBS values (>25 MPa), especially for 3D-printed resin repair (up to 31.27 ± 4.75 MPa).

Minimal surface conditioning techniques produced substantially lower SBS values (<12 MPa).

Failure mode analysis revealed mixed/cohesive losses in high-SBS groups and adhesive failures in low-SBS groups.

Overall, the repair bond strength of 3D-printed resins is mostly determined by surface conditioning, and the most promising outcomes come from a combination of primer application and mechanical treatments, particularly tribochemical silica coating or Al2O3 air abrasion.

Furthermore, when the same 3D-printed resin is used for the repair, shear bond strength tends to increase. These adhesive qualities are stable and do not significantly deteriorate from thermocycling under the measured aging circumstances

Reference:

Beher, L., Tonin, B. S. H., Özcan, M., & Dascanio, R. (2026). Adhesion of resin composites to 3D-printed dental resins: A study on the effect of surface conditioning methods and repair materials. Journal of Dentistry, 174(106873), 106873. https://doi.org/10.1016/j.jdent.2026.106873