Context: Dental impressions are principal route for cross–contamination, as they come in contact with patient’s blood and saliva and thus they should be disinfected before handling. Disinfection procedures employed for dental materials may affect their dimensional accuracy which would further affect the quality of the final restoration.

Aim: The aim of this in vitro study is to evaluate the effect of disinfection on the dimensional accuracy of addition silicone and polyether impression materials.

Methodology: A standard reference die was milled with four tapered abutments and occlusal grooves onto it. Addition silicone and polyether impressions were divided into group I & II respectively, which were further dividedinto subgroups A, B& C for control group, immersion and spray disinfection respectively.15 impression  were made out of which 10 were treated with the disinfectant and 5 were taken as control group. All the casts were scanned by using 3D scanner.

Results: In the present study, the statistical analysis was performed using statistical product and service solution (SPSS) version 18 for windows (SPSS inc, Chicago, IL). ANOVA test for the inter–abutment distances among subgroupIA, IB &IC showed non–significant p value.Tukey’s post–hoc multiple individual pair wise comparison test was done after ANOVA test,non–significant statistical differences were found between Subgroup IA &IB, IA &IC &Subgroup IB &IC. ANOVA test for the interaction between second group showed significant p value.Tukey’s post–hoc multiple individual pair wise comparison test showed significant statistical differences for the second group.

Conclusion: This in vitro study shows that polyvinylsiloxane and polyether rmaterials display acceptable accuracy for clinical use with immersion and spray disinfection. Thus disinfection of the impressions had no detrimental effects.