The study found that the antimicrobial peptide LL‑37 is present in the saliva of all children, with higher levels in older kids, girls, and those with mixed or permanent teeth, while kids with lots of cavities have lower levels. This suggests LL‑37 may help protect against tooth decay.

Antimicrobial peptides are important components of innate immunity, especially in the unique environment of the oral cavity. Lack of the human cathelicidin LL-37 has been implicated in severe periodontitis, whilst high salivary levels of LL-37 seem to increase caries resistance. Limited data exists about the concentration of LL-37 in saliva of young children. In this study, the salivary concentration of LL-37 was examined in relation to age, gender, type of dentition (primary, mixed or permanent) and caries experience of children. Unstimulated whole saliva was collected from 49 systemically healthy and gingivitis free children aged 2-18 years old. Their caries activity was recorded. The salivary LL-37 concentration was determined by enzyme linked immunosorbent assay (ELISA). LL-37 was detected in all saliva samples. Its concentration varied widely, with girls exhibiting higher peptide levels than boys. A positive correlation of the LL-37 concentration was observed with age. Children with primary dentition had significantly lower peptide concentration than those with mixed or permanent dentition. Significantly lower concentrations of LL-37 were also found in children with high caries activity, compared to caries free children or to children with low to moderate caries activity. Our results reinforce the belief that LL-37 is an important molecule of immunity in the oral environment and it seems to play a protective role against caries.