A Comparative Study of Different Spray Disinfectant i.e. 2 % Glutaraldehyde and 0.5% Sodium Hypochlorite on Impression Compound and Irreversible Hypochlorite Alginate Dental Impressions. in terms of colonial growth of Gram +ve and Gram -ve micro oraganisams,for The Changes in physical properties to linear dimensions and hardness. Hence, no significant changes occurred in the physical properties, So, the disinfection of impression should be done with spray disinfectants.