Formulation and effectiveness testing of mouthwash (Gargarisma) combination of guava leaves (Psidium guajava L. folium) and bay leaves (Syzygium polyanthum folium) extracts as an antibacterial agent against Streptococcus mutans

The dental caries disease is the result of the bacterial infection by Streptococcus mutans bacteria which cause the decay of the teeth. The extraction of guava leaves (Psidium guajava L. folium) and bay leaves (Syzygium polyanthum (Wight) Walp.) has secondary metabolites with antibacterial action. This research is intended to investigate the effect of combination of both plant extracts as the inhibitors of Streptococcus mutans by making the mouthwash in the three concentrations of F1, F2, and F3. Plant identification, phytochemical testing, physical testing, and disc diffusion test are done in order to identify the identity of the plants, metabolite content of plant, physical quality of the formulation, and antibacterial activity of the formulation. Statistical analysis used for the inhibition zone diameter (IZD) value is one-way ANOVA. From the phytochemical test result, both of plant extracts have secondary metabolites of alkaloid, flavonoid, tannin, and phenol. Physical quality of the F1, F2, and F3 formulations remained stable until the four weeks of storage period. Antibacterial assays revealed that F3 exhibited the highest inhibitory activity against Streptococcus mutans with an IZD of 8.67 ± 0.764 mm, followed by F2 at 7.67 ± 0.577 mm and F1 at 4.33 ± 3.786 mm. One-way ANOVA demonstrated significant differences in IZD between groups (F = 17.135; p < 0.001), following the order of F3 > F2 > F1. Post hoc analysis using the Games-Howell test showed that F2 and F3 had significantly higher antibacterial activity than the negative control. However, the differences in effectiveness among F1, F2, and F3 were not statistically significant.