ObjectiveVarious studies have indicated the application of Coenzyme Q10 and probiotic bacteria such asLigilactobacillus salivarius (L. salivarius)andLactiplantibacillus plantarum (L. plantarum)in combating periodontal disease. Considering the positive effect of these two on oral health, and the destructive effect ofS. mutans, in this study, we investigate the outcomes of the administration of probiotics and Q10 on infected HEp-2 cell viability andS. mutansadhesion in different settings.MethodsA 3-week-old human epidermoid laryngeal (HEp-2) cell line was cultured and exposed to two different probiotics and 3 different doses of Q10 doses. Samples were contaminated byS. mutansimmediately (therapeutic setting) and after 3 hours (preventive setting). Eventually, the viability of HEp-2 cells was investigated by MTT. Also, the number of adheredS. mutanswas explored by direct and indirect adhesion assays.ResultsL. plantarum and L. salivarius protect epithelial cells againstS. mutansin both therapeutic and preventive settings, albeit not fully. In contrast, Q10 completely preserves the viability of infected Her HEp-2 cells at all concentrations. The effects of the coexistence of Q10 and probiotics were not quite equal, among which L. salivarius and 5 μg of Q10 form the best results. The microscopic adherence assay ofS. mutansrevealed that samples containing Q10 had significantly lower adhesion of probiotics andS. mutansto HEp-2 cells. Similarly, plates containingL. salivariuswith5μg orL. plantarumwith 1μg Q10 or sole presence ofL. salivariushad the lowestS. mutansadherence among others. Also,L. salivariuswith5μg Q10 had one of the highest probiotic adherences.ConclusionIn conclusion, co-administration of Q10 and probiotics especially in presence ofL. salivariuswith5μg Q10 could have remarkable effects on HEp-2 cell viability,S. mutans, and probiotic adherence. Nevertheless, our study, for the first time, showed that Q10 might have an anti-bacterial activity by suppressing the adhesion of tested bacteria to HEp-2 cells. This hypothesis, if correct, suggests that due to their different mechanisms, co-prescription of Q10 and probiotics may lead to better clinical responses, especially in the mentiond dose.