Resin bonding failure after haemostatic contamination — ORE Part 1 MCQ

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HardRestorative DentistryResin bonding failure after haemostatic contaminationORE Part 1

A 58-year-old patient receives an adhesive ceramic onlay on a vital lower molar. The dentist used ferric sulphate for gingival bleeding, rinsed briefly, and bonded to a moist contaminated enamel-dentine surface. The onlay debonds two weeks later with no fracture of ceramic or tooth. What is the most likely cause?

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Reveal the answer and explanation

Correct answer: A — Contamination interfering with adhesive bonding

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

The correct answer is E. Ferric sulphate is a hydrophilic chemical haemostatic agent that alters the microchemical structure of enamel and dentine, impairing resin monomer infiltration and adhesive bond formation. Although the dentist rinsed briefly, ferric sulphate residue remains on the tooth surface and prevents proper wetting and resin tag formation by adhesive systems. This results in adhesive layer failure—early debonding without fracture of the ceramic or tooth—consistent with the 2-week failure observed. A is incorrect because thermal expansion mismatch causes cohesive or fracture failures after thermal cycling, not isolated adhesive debonding. B is incorrect because pulp necrosis is a slow process and does not explain early adhesive failure on a vital tooth. C is wrong because ferric sulphate contains no fluoride, and fluoride release would not cause acute debonding. D is implausible because ceramic allergy is rare and would present as inflammation, not mechanical debonding.

Reference: Ebrahimi SF, Shadman N, Abrishami A. Effect of ferric sulfate contamination on the bonding effectiveness of etch-and-rinse and self-etch adhesives to superficial dentin. J Conserv Dent. 2013 Mar;16(2):126–130. https://pubmed.ncbi.nlm.nih.gov/23716963/; Rodríguez-Priego ME, Bolaños-Carmona MV, González-López S, et al. Ferric sulphate alterations on primary dentin and the adhesive interface. J Adhes Dent. 2014 Aug;16(4):347–356. https://pubmed.ncbi.nlm.nih.gov/24892120/