Impression Disinfection — MFDS Part 1 MCQ
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Correct answer: B — Rinse it under cold running water until visibly clean, then use a compatible impression disinfectant according to the manufacturer's instructions
The correct answer is B. SDCEP advises immediately rinsing an impression under cold running water until saliva, blood and debris have been removed, followed by disinfection with a product suitable for the purpose and used according to its manufacturer's instructions. Compatibility is important because immersion can affect the dimensional stability of some impression materials; spray disinfection may be used where appropriate, with the specified contact time. A universal recommendation for 1% sodium hypochlorite or unspecified chlorhexidine is therefore inappropriate. A fixed 70% ethanol protocol is not recommended for every impression material. Conventional impressions should not undergo dry-heat or steam sterilisation because heat can damage or distort them. Sending an impression without disinfection improperly transfers the clinical team's decontamination responsibility to the laboratory. The laboratory should also be informed that disinfection has been completed.
Reference: Scottish Dental Clinical Effectiveness Programme, Practice Support Manual, 'Disinfection of impressions and appliances before dispatch', reviewed June 2026. https://www.psm.sdcep.org.uk/topics/infection-prevention-and-control/disinfection-of-impressions-and-appliances-before-dispatch/