Cariogenic bacteria in tooth and resin restorations lead to caries and secondary caries. Biofilms typically develop on diverse surfaces such as indwelling medical devices and implants, natural and portable pipework for water systems, fermentation containers, food businesses, and living tissues. The effect of the biofilm on the degradation of the interfacial adhesion between the composite and the tooth structure has been demonstrated. Demineralization refers to the process by which organic acids produced by plaque microorganisms destroy the mineral content from the surface of HA crystals. The most stable form of hydroxyapatite exists in an environment with a pH of 7.4. There is a constant chemical equilibrium between the hydroxyapatite in the enamel (Ca10(PO4)6(OH)2) and the dissolved hydroxyapatite in the plaque biofilm. Saliva protects against demineralization due to its cleansing effects and mineral composition, buffering pH changes and promoting remineralization. Dentin recovery is more complex than enamel due to the reconstitution of organic type I collagen and inorganic apatite. Remineralization alone is insufficient for full recovery, as it requires restoring collagen matrix structure and linking both phases.