Melatonin levels in periodontitis vs. the healthy state: A systematic review and meta-analysis

The aim was to provide a comprehensive qualitative and quantitative assessment of any potential differences in melatonin levels in periodontitis vs. the healthy state. The keyword combination "melatonin" AND "periodontitis" was searched in Web of Science, PubMed, and Scopus. Qualitative analysis and quantitative analysis were performed on articles satisfying the inclusion criteria. Only 14 studies were included in the systematic review, out of which only 10 had quantitative data compatible with a meta-analysis. Ten studies demonstrated low melatonin in periodontitis, three studies demonstrated an initial reduction in melatonin levels followed by elevation with worsening of periodontitis, and one study showed an elevation in melatonin levels in the transition from a healthy state to periodontitis. Grading of recommendations assessment, development, and evaluation revealed that all the included studies had low to very low overall evidence. The meta-analysis revealed a significant reduction (p < .0001) in salivary melatonin levels in chronic periodontitis (3.26 ± 3.44 pg/ml) compared with healthy controls (5.27 ± 5.39 pg/ml), with a mean difference of 2.65 ± 7.84 and a confidence interval of 1.94-3.36. The significantly lower salivary melatonin levels in periodontitis must be inferred with caution given the low quality of the included studies.