Statement of problem. The oral environment and its bacteria play a major role in the success or failure of dental prosthodontics. Purpose. This study aims to in vivo compare the bacteria around three types of dental crown materials ( metal ceramic – zirconia(monolithic) – E max full ceramic ). Material and Methods. The sample consisted of 60 patients with good general and oral health who have a posterior tooth (premolar or molar) that needs a crown. The sample was divided into three groups; twenty patients each according to the material of the crown (ten patients the tooth was prepared with a supragingival chamfer finish line and the other ten a subgingival chamfer). The first group; zirconia(monolithic), the second metal ceramic, and the third E- max. Bacterial samples were taken for each tooth before preparation, after a week of the crown's application and then after a month. A comparison was made between them. Results. The results of the study showed a difference in the number of the bacterial colonies between the different materials of the research after a week of the crowns' application and no difference after a month. In addition, there were no difference in the number of bacterial colonies between natural tooth's surface and the crowns' surface after a month of its application. Conclusions. within the limitation of this study, it can be concluded that there is no difference in the bacterial presence around the crowns of different materials in prosthodontics, and that the adhesion of bacteria to the surfaces of crowns, regardless of the type of material, was not different from the surface of the natural tooth.