The effect of disinfecting alginate and addition cured silicone rubber impression materials on the physical properties of impressions and resultant casts.

Four commercially available disinfectants were tested and the dimensional stability and detail reproduction of impressions and their resultant casts were measured according to ANSI/ISO specifications. Results showed that alginate impressions immersed in chlorhexidine exhibited considerable dimensional change if not poured immediately. Moreover, alginate impressions soaked in a paraldehyde agent (Virkon) for more than 2 minutes produced casts of inferior surface quality whilst those sprayed and left in contact with phenol derivatives (C&J Spray) for 30 minutes resulted in casts which demonstrated statistically and clinically significant dimensional changes. Addition cured silicone impressions exhibited minimal dimensional change regardless of the disinfection regime employed and the resultant casts were accurate with acceptable surface quality.