Tooth Loss as a Modifiable Risk Factor for Mild Cognitive Impairment: A Systematic Review of Mechanisms and Evidence

The relationship between cognitive defects and missing teeth has drawn increasing research attention in recent years. However, little research has specifically demonstrated the correlation between mild cognitive impairment (MCI) and missing teeth, and existing findings remain inconsistent. Thus, we conducted a systematic review synthesizing current evidence on tooth loss and MCI, aiming to address this gap.

The reviewers searched Embase, Scopus, and PubMed for relevant studies published up to May 2025. An updated search was conducted in December 2025. Dual-independent literature reviewing was performed at all stages, with conflicts resolved by consensus.

From an initial pool of 2,709 articles, 113 underwent full-text reading, and 10 met the inclusion criteria. Our findings suggest that missing teeth, including the number of teeth lost, the number of functional teeth remaining, categorized tooth loss, and the rate of tooth loss, are significantly associated with MCI. Potential mechanisms may involve periodontal inflammation triggering neuroinflammation, reduced chewing-related neural stimulation, impaired nutrient intake, and social isolation.

Although limited evidence suggests an association between tooth loss and MCI, offering potential avenues for MCI prevention through oral health interventions, the overall quality of the research remains low. Further high-quality studies will be needed to validate these findings.