Association between dentition defects and Alzheimer's disease risk: a systematic review and meta-analysis

Alzheimer's Disease (AD) is the most common neurodegenerative disorder among the elderly, with a steadily rising prevalence that poses a significant global public health challenge. Recently, dentition defects (DD), such as tooth loss, have gained attention as potential risk factors influencing neurocognitive health. However, the relationship between DD and AD remains inconclusive, necessitating a systematic analysis to clarify this association.

This systematic review and meta-analysis was conducted in accordance with PRISMA guidelines. We searched PubMed, Embase, Web of Science, and Cochrane Library databases to identify relevant studies published between 1996 and 2022. Eligible studies assessing the relationship between DD and AD were included. A random-effects model was applied to estimate the pooled odds ratios (ORs) with 95% confidence intervals (CIs). Heterogeneity and publication bias were also assessed.

Fourteen studies were included, with sample sizes ranging from 52 to 156,450 participants. The meta-analysis revealed a significant association between DD and an increased risk of AD (OR=1.38, 95% CI: 1.09-1.74, P < 0.05). Heterogeneity among the studies was substantial (I² = 97%), reflecting considerable variability in study designs, populations, and exposure definitions. Sensitivity analysis and publication bias assessments indicated the reliability of the results despite high heterogeneity. Mechanistic analyses suggested that DD may elevate AD risk through pathways such as chronic inflammation, nutritional deficiencies, alterations in the oral microbiome, and reduced cognitive reserve.

DD are significantly associated with an increased risk of AD. Improving oral health may represent a modifiable factor warranting. However, further high-quality prospective studies are needed to validate these findings and explore the underlying mechanisms.