When dental materials are placed in the oral cavity, exposure in the mouth presents a unique surface what can interact with indigenous host bacteria, leading to a plaque formation. So considering the fact that the intraoral conditions provide the ideal environment for corrosion occurrence, it was assumed that oral microorganisms may influence the galvanic corrosion phenomenon in association with dental metallic materials. In this study, we used the following electrolytes: Ringer's solution as a control electrolyte (R), Ringer's solution mixed with viable Streptococcus mutans (M), tryptic soy broth culture media (C), culture media mixed with S. mutans byproducts (B), and 1% lactic acid (L). The tested metallic materials included CpTi grades II and III, Ti-6Al-4V and TiNi alloys, ASTM Type 316L and 17-4 PH-type stainless steels, Co-Cr-Mo alloy, Ni-Cr alloy, Type IV Au alloy, 70Au-10Ag-4Pt-10Cu alloy, and 50Ag-12Au-20Pd alloy. The galvanic couples of CpTi with different dental metallic materials (listed above) were investigated under various ratios of surface areas of anodic and cathodic sides. It was found that (1) the less noble materials (except CpTi grade II) showed their inferior corrosion resistance when they were exposed to media containing bacteria byproducts, (2) the effects of surface area ratios showed the significant influences under the presence of bacteria byproducts, and (3) overall, if CpTi were coupled to precious metals, it was recommended to be coupled with Ag-Au-Pd dental alloy and the surface area ratio should be less than 50% (in other words, less than the equal exposed surface areas).