Purpose: The purpose of this study was to perform an in vitro evaluation of the protective effects of anticavity agents applied to enamel, by themselves and in combination with Er:YAG. Materials and Methods: In this study 150 extracted third molars were used. Measurements were made using DIAGNOdent, and samples with scores of 0–13 were included in the study. These were divided into 15 groups (n = 20). Use of the agents sodium fluoride (NaF), tricalcium phosphate (Ca3PO4), titanium tetrafluoride (TiF4), Tooth Mousse (CPP-ACP), MI Paste Plus (CPP-ACP), and NovaMin (bioactive glass), individually and then in combination with Er:YAG laser, was assessed based on their effects on microhardness values. After treatment, the groups were exposed to a demineralisation solution. Statistical analyses were conducted using SPSS 20.0 package software. Results: The highest test result value was observed in the TFL (TiF4/Er:YAG laser) group. Statistically significant differences were determined among all the groups (p < 0.05). When the groups in which the agents were applied alone were compared with those involving combined use of Er:YAG laser, combined use provided significantly higher microhardness values, with the exception of the TML group (Tooth Mousse/Er:YAG laser) (p < 0.05). Conclusion: Within the limits of this study, the combined use of remineralisation agents and Er:YAG laser elicited better results than using the agents alone. The most effective remineralisation agent was TiF4/Er:YAG laser, which may be considered an alternative method for protecting the enamel against demineralisation.