Dental luting agents provide the link between a fixed prosthesis and the supporting prepared tooth structure.Failure of fixed partial dentures is most frequently caused by caries. Thus, physically superior cement materials can play an important role in caries prevention. Furthermore, it would be advantageous if such materials possessed effective antibacterial properties. The purpose of this present study was to assess and compare the incessant antibacterial activity of six luting cements against Streptococci mutans and Lactobacillus acidophilus using DCT and ADT.