Eugenol Interference — MFDS Part 1 MCQ

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ModerateDental MaterialsEugenol InterferenceMFDS Part 1

A cavity has been temporarily restored with zinc oxide–eugenol cement. If residual eugenol remains in direct contact with the definitive restoration, the setting of which restorative material is most likely to be impaired?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: A — Composite resin

The correct answer is A, composite resin. Eugenol is a phenolic free-radical scavenger and can inhibit the polymerisation of methacrylate-based resin materials, reducing their degree of conversion when sufficient residual eugenol is present at the interface. Direct contact between an eugenol-containing material and an unset resin composite should therefore be avoided. This effect does not apply to amalgam, which sets by amalgamation and crystallisation, or conventional glass ionomer and zinc phosphate cements, which set principally through acid–base reactions. A cast gold alloy is fabricated outside the cavity and does not undergo an intraoral polymerisation or cement-setting reaction. The original key was correct, but the categorical claim that zinc oxide–eugenol must never precede a composite restoration was overly broad because the clinical effect depends on residual contamination, concentration and the restorative protocol.

Reference: Alrahlah A et al. Influence of Eugenol and Its Novel Methacrylated Derivative on the Polymerization Degree of Resin-Based Composites. Polymers. 2023;15(5):1124. https://pubmed.ncbi.nlm.nih.gov/36904361/