In response to increased attention to oral hygiene, materials of artificial dental implants and denture frameworks having antibacterial effects are increasingly valued. According to our literature review, most of the bacteria in the oral cavity are Streptococcus mutans, which causes tooth cavities. Therefore, in this paper, we discuss suitable materials for preventing the growth of Streptococcus on denture frameworks. We performed experiments to determine the antibacterial effects of different materials. In this experiment, the international standard method was used to detect the S. mutans culture, and the antibacterial method used solid and liquid media. The problem of the failure of the S. mutans culture was discussed. We used a 3D printing machine to manufacture Ti6Al4V alloys and a coating machine to deposit Ag films on Ti6Al4V alloy substrates (Ag/Ti6Al4V alloys), and we compared the antibacterial effects of Ti6Al4V, Co–Cr–Mo, and Ag/Ti6Al4V alloys with different Ag film thicknesses. Additionally, we observed films of Ag/Ti6Al4V alloys with different thicknesses by scanning electron microscopy (SEM). X-ray diffraction measurements of theAg/Ti6Al4V alloys revealed diffraction peaks of Ag (200), Ag (111), and Ag (200) for a 2.552-μm-thick Ag film for 4 min coating time. Results also showed that the growth rate was 0.0106 µm/s for 4 min coating time. Subsequently, we observed the sterilized test pieces after 18, 24, and 48 h to determine the antibacterial effect on S. mutans. We found that the antibacterial effects of Ti6Al4V and Ag/Ti6Al4V alloys were significantly greater than that of Co–Cr–Mo alloy. As a result, we propose that 3D printing is a suitable method for manufacturing Ti6Al4V alloy, which we found to be the most suitable material for making denture frameworks.