Poor oral hygiene is the primary cause of common oral diseases and has been found to be associated with low-grade inflammation, suggesting its potential link to metabolic syndrome (MetS).
Metabolic syndrome (MetS), a clustering of abdominal obesity, hyperglycemia, hypertension, and dyslipidemia, represents a growing public health concern globally . Besides socioeconomic status (SES) , smoking , diet , and physical activity , oral diseases, such as periodontal diseases and dental caries, are associated with MetS . Poor oral hygiene is the primary cause of common oral diseases and is associated with low-grade inflammation , suggesting its potential link to MetS .
Although several epidemiological studies have reported the association of oral hygiene status  and care  with MetS, some studies found no such association . To date, there has not been a systematic review conducted on the topic. A summary of evidence can provide a better understanding of the potential relationship and help healthcare practitioners deliver more targeted care. This systematic review and meta-analysis aimed to evaluate the associations of oral hygiene status and care with MetS.
Briefly, a systematic search of the PubMed and Web of Science databases from inception to 17 March 2021, and examination of reference lists was conducted to identify eligible studies. The inclusion criteria include observational studies that examined the association of oral hygiene status (e.g., oral hygiene index, plaque index, plaque score) or care (i.e., tooth brushing, interdental cleaning, and dental visit) with MetS. Two authors independently conducted study selection, data extraction, and quality assessment of the studies. Any ambiguities or disagreements were resolved by consensus. Meta-analysis was conducted separately for different types of exposure (i.e., oral hygiene status, tooth brushing, and interdental cleaning). A random-effects model was applied to pool the effects of oral hygiene status and care on MetS. Potential sources of heterogeneity were assessed using prespecified subgroup analyses by study design and country.