Dose-dependent effects of electron beam irradiation on dental materials: a systematic review of in vitro evidence.

BACKGROUND

Electron beam irradiation (EBI) is a non-chemical technique proposed for modifying dental materials, but evidence is contradictory. Some studies report gains in mechanical performance, others document discoloration, structural breakdown, or cytotoxicity at higher doses.

OBJECTIVES

To systematically review effects of EBI on mechanical strength, surface characteristics, chemical stability, and biological responses in dental materials, and identify dose ranges where effects shift from beneficial to harmful.

METHODS

PubMed, Scopus, and Web of Science were searched for laboratory studies published January 2001-March 2026 using the terms "electron beam irradiation" and "dental materials." Two reviewers independently screened records; a third resolved disagreements. Eligible studies were laboratory-based experiments evaluating dental materials under EBI. Data were extracted on post-irradiation mechanical, physicochemical, biological, and appearance outcomes. Risk of bias was assessed using RoBDEMAT and QUIN; certainty was rated using a modified GRADE approach.

RESULTS

Of 897 records identified, 18 studies met inclusion criteria. Materials tested included composites, nanocomposites, fiber-reinforced composites, denture base polymers, orthodontic bracket materials and adhesives, alloy-resin bonding systems, monolithic zirconia, acrylic resins, glass ionomer cement, dental irrigants, cast titanium, and zinc oxide eugenol. Doses ranged from 1 to 200 kGy, with acceleration energies of 25 kV-10 MeV (two studies did not report beam energy). At low-to-moderate doses, most polymer-based materials showed improved flexural strength, fracture toughness, Vickers hardness, and wear resistance, whereas higher doses caused polymer degradation, discoloration, loss of structural integrity, and genotoxic/cytotoxic effects. QUIN classified 4 studies (22%) as low risk, 12 (67%) as medium risk, and 2 (11%) as high risk of bias.

LIMITATIONS: All evidence was in vitro; studies were heterogeneous in materials, doses, and outcomes; irradiation parameters were inconsistently reported; modified GRADE certainty was very low across all outcomes.

CONCLUSIONS

Current in vitro evidence indicates EBI modifies dental material properties, with mechanical improvements most consistent for dimethacrylate-based polymer systems at low-to-moderate doses (1-100 kGy), while color instability and dose-dependent degradation remain important barriers. Because the evidence base is entirely in vitro and of very low certainty, findings are preliminary; dose-optimization and in vivo studies are needed before clinical recommendations can be made.

SYSTEMATIC REVIEW REGISTRATION: https://doi.org/10.17605/OSF.IO/HAVT8.