skip to main content

Composite Polymerisation — ORE Part 1 MCQ

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

HardDental MaterialsComposite PolymerisationORE Part 1

In relation to polymerisation shrinkage of a resin-composite restoration, which statement best defines the configuration factor (C-factor) and its clinical relevance?

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

Reveal the answer and explanation

Correct answer: E — It is the bonded-to-free surface ratio; a higher value increases shrinkage-stress constraint

C-factor is the ratio of bonded cavity surfaces to unbonded, free composite surfaces. During polymerisation, free surfaces permit some material flow and stress relief. A high C-factor therefore means greater restraint of shrinkage and a greater tendency for polymerisation stress at the tooth–restoration interface; however, actual stress also depends on factors such as cavity compliance, material properties and curing kinetics. B confuses cavity configuration with depth of cure. C describes composite formulation, which can influence mechanical properties but is not C-factor. D describes degree of conversion, not cavity geometry. E concerns thermal behaviour and marginal dimensional change after temperature variation, rather than polymerisation-shrinkage constraint.

Reference: Davidson CL, de Gee AJ, Feilzer AJ. Determining the direction of shrinkage in dental composites by changes in surface contour for different bonding configurations. American Journal of Dentistry. 2001. https://pubmed.ncbi.nlm.nih.gov/11507797/