Effects of immersion disinfection on polyethers and silicone impression materials

Objective: The effect of immersion disinfection on polyether impression materials is not fully understood. This laboratory study investigated the effects of immersion disinfection on the surface detail reproducibility and the surface hardness of one ‘hydrophilic' addition-cured silicone and three polyether impression materials and their subsequent gypsum casts. The effect of immersion disinfection on the dimensional accuracy of the best performing polyether was also investigated Methods: Using an addition-cured silicone; Aquasil Ultra LV (Dentsply Caulk) and three polyethers; P2 Polyether (Haraeus Kulzer), Impregum Penta (3M ESPE) and Impregum Penta Soft (3M ESPE) impressions were made of a ruled test block. These impressions were either left untreated, immersed in Perform- ID or in sterile water, for 10 minutes. Subsequently they were poured in dental stone (Suprastone–Kerr Dental). Impressions and casts were examined for the reproducibility of the ruled lines. Surface hardness of the casts was assessed using a Wallace Hardness machine. Dimensional stability of casts made from the best performing immersion disinfected Polyether was assessed using a Reflex Microscope. Results: Immersion in perform ID and water had a statistically significant (p<0.05) adverse effect on the ability of the P2 Polyether's surface detail reproduction. The surface hardness of casts made from P2 Polyether, Impregum Penta Soft and Aquasil Ultra LV were reduced as a result of Perform-ID immersion (p<0.05). Impregum Penta casts made from impressions which had either been immersed in Perform ID or water showed no statistically significant difference (p<0.05). Conclusion: Impregum Penta, maybe a more suitable material for immersion disinfection than previously thought. Of concern is that the new more ‘hydrophilic' addition-cured silicones may not be as resistant to Perform ID immersion disinfection as compared to their more traditional counterparts.