Polycarboxylate Bonding — MFDS Part 1 MCQ
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Correct answer: D — Coordination bonding between polyacrylate carboxylate groups and calcium in hydroxyapatite
Zinc polycarboxylate cement adheres principally through chemical interaction between ionised carboxylate groups of the polyacrylate and calcium at the hydroxyapatite surface. This is commonly described as chelation or ionic/coordination bonding. It is not dependent solely on acid-etch microporosities and resin-tag formation, so B is incorrect. No established covalent bond forms between the cement and dentinal collagen, excluding C. Hydrogen bonding may contribute weak secondary interactions but is not the principal adhesion mechanism, excluding D. Zinc participates in formation of the cement matrix, but adhesion to tooth is not primarily produced by zinc–phosphate bonding, excluding E. The stored answer was therefore correct, but the wording and reference have been repaired for mechanistic precision and direct evidential support.
Reference: Iioka A, Araki Y, Matsuda K, Ohno H. Adhesion mechanism of polyelectrolyte cements to tooth structure—polyelectrolyte behavior of the cement polymers obtained by potentiometric titration in the presence of calcium ion. Dental Materials Journal. 1989;8(2):236-242. https://pubmed.ncbi.nlm.nih.gov/2490597/