{'fraction_non_alphanumeric': 0.031628532974428, 'fraction_numerical': 0.023553162853297442, 'mean_word_length': 5.327659574468085, 'pattern_counts': {'":': 0, '<': 1, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Melatonin levels in periodontitis versus the healthy state: A systematic review and meta-analysis.

OBJECTIVES
To provide a comprehensive qualitative and quantitative assessment of any potential differences in melatonin levels in periodontitis versus the healthy state.


MATERIALS AND METHODS
The keyword combination "melatonin" AND "periodontitis" was searched in Web of Science, PubMed, and Scopus. Qualitative and quantitative analysis was performed on articles satisfying the inclusion criteria.


RESULTS
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, 3 studies demonstrated an initial reduction in melatonin levels followed by elevation with worsening of periodontitis, and 1 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<0.0001) in salivary melatonin levels in chronic periodontitis (3.26±3.44 pg/ml) compared to 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.


CONCLUSION
The significantly lower salivary melatonin levels in periodontitis must be inferred with caution given the low quality of the included studies.