B ackground: Oral and dental problems are still common in Indonesia, one of themis dental caries. One way to deal with caries is by using restoration material. Idealrestorative material should be able to release fluoride ions and is able to increasebacterial growth or reduce bacterial colonization. Glass ionomer cements andalkasite contain fluoride which can inhibit the demineralization of teeth.Objective: To understand the difference of fluoride in GIC and alkasite forinhibiting the growth of Streptococcus mutans biofilms. Methods: The object ofthis study consisted of alkasite restoration materials and glass ionomer cementwith a diameter of 6mm and 2 mm thick, then immersed in Streptococcus mutansfor 24 hours. Measurement of the number of bacteria carried out by the BHI-B(Brain Heart Infusion Broth) method which was measured using a microplatereader (600nm). Results: There was a difference in the number of Streptococcusmutans biofilms after soaking with alkasite restoration material and GlassIonomer Cement. With a significance value of P<0.05 which means that there aresignificant differences in the subject. Conclusion: There is differenceeffectiveness fluoride between the alkasite restoration material and the glassionomer cement against the Streptococcus mutans biofilm.