Teeth, gums and lifespan

A systematic review pooled 7 good-or-fair-quality cohort studies of periodontal disease (covering periodontitis, tooth loss, gingivitis and bone loss) and incident coronary heart disease in the general adult population. Summary relative risk estimates across different definitions of periodontal disease ranged from 1.24 (95% CI 1.01–1.51) to 1.34 (95% CI 1.10–1.63), independent of the traditional CHD risk factors and socioeconomic status [1]. A later consensus report from the periodontology and cardiology societies treats periodontal disease as a legitimate target for cardiovascular prevention, not just a correlated marker [8].

In 161,286 adults from Korea’s National Health Insurance System followed for a median 10.5 years, frequent tooth brushing (3 or more times a day) was independently associated with 10% lower risk of atrial fibrillation (hazard ratio 0.90, 95% CI 0.83–0.98) and 12% lower risk of heart failure (0.88, 0.82–0.94), after adjusting for age, exercise, smoking, diabetes, blood pressure and more. Professional dental cleaning tracked with 7% lower heart failure risk (0.93, 0.88–0.99), while having 22 or more missing teeth tracked with 32% higher heart failure risk (1.32, 1.11–1.56) [4].

A systematic review and meta-analysis of 75 cohort studies (44 pooled quantitatively) found a lower number of teeth consistently linked to higher risk of atherosclerotic cardiovascular disease and all-cause mortality. Pooled multiple-adjusted hazard ratios for the incidence rate of death ranged from 1.02 to 1.30 across studies, and pooled risk ratios for cumulative death incidence ranged from 1.76 to 2.27 [6]. An earlier, smaller review of the same question found a similar direction but could not establish whether replacing lost teeth (dentures, implants) itself reduces mortality, since no study has tested that directly [9].

A systematic review and meta-analysis of 23 longitudinal studies found poor periodontal health (periodontitis, deep pockets, bone or tooth loss) carried 21% higher dementia risk (hazard ratio 1.21, 95% CI 1.07–1.38) and complete tooth loss 23% higher (1.23, 1.05–1.45), with a similar 1.23 for cognitive decline specifically [3]. A separate dose-response meta-analysis of 14 cohorts put complete tooth loss at 40% higher dementia risk (hazard ratio 1.40), with each additional missing tooth adding roughly 1% [2]. Both reviews rate their own evidence as low quality and flag a real risk of reverse causation: early, undiagnosed dementia makes people stop brushing and skip dental visits, which would produce this same pattern without gum disease causing anything.

In a randomized trial, 120 patients with severe periodontitis were assigned to community-based periodontal care or intensive periodontal treatment, with blood-vessel (endothelial) function measured by brachial artery flow-mediated dilatation before treatment and at 1, 7, 30, 60 and 180 days after. Twenty-four hours after intensive treatment, blood-vessel function was temporarily worse and inflammatory markers (CRP, interleukin-6) were significantly higher than in the control group — an acute inflammatory spike from the treatment itself. But by 60 and 180 days, the intensively treated group had significantly better blood-vessel function than the control group (difference at 180 days: 2.0 percentage points, 95% CI 1.2–2.8, p<0.001), with the degree of improvement tracking how much the gum disease itself had improved [5].

Porphyromonas gingivalis, the bacterium most strongly linked to periodontitis, and its toxic enzymes (gingipains) were found in the brain tissue of deceased Alzheimer’s patients at higher levels than in people without Alzheimer’s, and gingipains were found alongside tau protein pathology. In mice, an oral P. gingivalis infection led the bacterium to colonize the brain, and a small-molecule gingipain inhibitor reduced bacterial load, blocked a key toxic protein fragment, and rescued neurons in the hippocampus [7]. This is mechanistic and animal-model evidence, not a human mortality or incidence trial; the same lab that ran it went on to test a gingipain-inhibitor drug in Alzheimer’s patients, which did not meet its primary endpoints in a subsequent human trial.

Across the cohorts above, the habits that moved the needle were unglamorous and consistent with basic dental guidance: brushing twice or more a day with fluoride toothpaste, cleaning between the teeth daily, and seeing a dentist or hygienist every 6 to 12 months. The Korean cohort specifically found people who moved up to brushing 3 times a day developed less dementia over follow-up than those who did not, and professional cleaning tracked with lower heart failure risk independent of brushing [4]. Mouthwash has not been shown to replace any of this.