Composite Water Sorption — MFDS Part 1 MCQ

Instant feedback + full explanation. One question, done properly.

ModerateDental MaterialsComposite Water SorptionMFDS Part 1

During prolonged exposure of a methacrylate-based resin composite restoration to oral fluids, which combination of material changes is most characteristically associated with water sorption?

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

Reveal the answer and explanation

Correct answer: C — Hygroscopic expansion and progressive mechanical degradation

Explanation lettering: D = shown as A · C = shown as B · A = shown as C · B = shown as D

A is correct. Water diffuses predominantly into the polymeric phase of resin composite, producing hygroscopic expansion. With prolonged exposure, water can plasticise the resin and contribute to hydrolytic deterioration of the filler–matrix interface, progressively reducing mechanical performance. Water uptake therefore does not cause contraction or strengthening, excluding B and C. It does not alter the radiopaque filler content, so D is incorrect. Although delayed hygroscopic expansion may partly offset dimensional deformation or stress arising from polymerisation shrinkage, it does not reduce the polymerisation contraction occurring during light curing or increase monomer conversion; therefore E is also incorrect.

Reference: Heckel L, Belli R, Schüssler T, et al. Water sorption of dental resin composites: Is a new method the future? European Journal of Oral Sciences. 2026;134(3):e70090. https://pubmed.ncbi.nlm.nih.gov/21111476/