The potential association between periodontitis and non-alcoholic fatty liver disease: a systematic review

Many animal and human studies have shown associations between periodontitis and non-alcoholic fatty liver disease (NAFLD). Hence, the present systematic review sought to investigate such a potential association. PubMed/Medline, Scopus, Embase, and Web of Science databases were thoroughly searched to identify all relevant studies. The eligibility criteria were all observational (cross-sectional studies, case-control, cohort studies, and case reports) and interventional studies that assessed the relationship between periodontitis and NAFLD in humans. Due to remarkable heterogeneity and inconsistency among the included studies, no statistical analyses were conducted. A total of 12 studies comprising 53,384 patients were included in the present systematic review. The sample size in the individual studies ranged from 52 to 24,470 patients. All studies except one found significant associations between clinical and/or microbial periodontal parameters and NAFLD. Eight studies found significant associations between clinical periodontal parameters and NAFLD. Four microbial studies found a significant association between periodontal pathogens, especially Porphyromonas gingivalis and NAFLD development and progression. The available evidence suggests that periodontitis may be a risk factor for development and progression of NAFLD. However, due to limited number of prospective cohort studies included in this review along with the substantial heterogeneity among the included studies, further well-designed prospective cohort studies are highly warranted. Given the potential association between periodontitis and NAFLD, it can be assumed that healthy periodontium may be essential for liver health.