What is the first biochemical change in dental caries formation?

In the process of dental caries formation, the first biochemical change that occurs is enamel demineralization. This is primarily due to the actions of acids produced by bacteria that metabolize dietary sugars in the biofilm (plaque) present on the tooth surface. When dental plaque accumulates, bacteria such as Streptococcus mutans and Lactobacillus spp. are involved in the fermentation of carbohydrates, which leads to a drop in pH at the tooth surface.

When the pH falls below a critical threshold (around 5.5), the calcium and phosphate ions that make up the hydroxyapatite crystals of the enamel start dissolving, leading to mineral loss from the tooth structure. This demineralization is an early indicator of caries, and if it progresses without intervention, it can lead to cavitation and advance to affect the underlying dentin.

Biofilm formation is indeed crucial in the caries process as it is the stage where the bacteria colonize the tooth surface, but it precedes demineralization itself. Dentin decay occurs later in the carious process, following enamel demineralization, when the decay advances beyond the enamel into the dentin. Gingivitis is unrelated to caries formation