Acid pH of saliva in dental caries of pre-school children repressed phagocytic capacity of neutrophil

In Indonesia dental caries is one of the most important issues in children's health. Caries is one of common dental diseases in children who consume sugar-rich diets. Caries cause decalcification of tooth enamel and dentin. The bacteria involved in caries can converge on the dental pulp tissue and spread to other organs. Under adverse conditions, complications such as phylogenetic osteomyelitis and bacterial endocarditis can occur. This study aimed to investigate the effects of oral cavity pH on neutrophil and lymphocyte cell activity in order to eliminate S. mutans. Neutrophil and lymphocyte cells were isolated from the saliva of 30 preschool children, with and without caries, from the city of Surabaya, Indonesia. The dental condition was verified by a dentist based on the def-t index. Obtained results indicate that the number of activated neutrophils (CD11b⁺CD35⁺) from children in the caries group was significantly higher than the caries-free group at an acidic pH, but was unchanged at an alkaline pH. The activated neutrophils triggered naïve T cells to become effector T cells (CD4⁺), which produce cytokines to respond the infection. However, the increased CD11b⁺CD35⁺ were unable to enhance the phagocytic activity of neutrophils in the caries group, especially in acidic pH conditions. An acidic pH was found to repress the phagocytic capacity of neutrophils. This study provides a basis for future strategies to prevent dental caries by promoting phagocytic activity and maintaining a neutral pH in the oral cavity.