Accuracy of polyether and addition silicone after long-term immersion disinfection.

STATEMENT OF PROBLEM

Some studies have demonstrated that short-term immersion disinfection does not affect the accuracy of polyether or addition silicone materials. Impressions are often disinfected for longer than recommended time periods.

PURPOSE

This study evaluated these materials after simulating overnight disinfection.

MATERIAL AND METHODS

Impressions were made of a master model with Extrude Extra material with Extrude Wash addition silicone and Impregum F material in combination with Permadyne Garant polyether material. Nondisinfected impressions served as controls, whereas the disinfected samples were immersed for 18 hours in a full strength 2% acid glutaraldehyde solution. Anteroposterior and cross arch dimensions of the working cast and occlusogingival, mesiodistal, and buccolingual dimensions of working die were assessed. The data were analyzed with one-way analysis of variance at "alpha" = 0.05.

RESULTS

No significant differences were observed for anteroposterior and cross arch dimension when compared with the master model. However, significant differences were found for occlusogingival dimension at 18 hours of disinfection for both materials. The addition silicone 18-hour disinfection group was significantly less accurate in the mesiodistal dimension.

CONCLUSION

Accuracy of both impression materials was adversely affected with 18 hours of immersion disinfection. Long-term (18 hours) immersion disinfection will affect the fit of fixed partial prostheses.