New research from Iran has identified a significant connection between poor oral health and mild cognitive impairment (MCI) in older adults, raising fresh concerns over the overlooked impact of dental health on brain function. The findings were published in the journal Clinical Epidemiology and Global Health.
The study, which examined 3,368 participants aged 60 and above from the Ardakan Cohort Study on Ageing, found that over one in five were living with MCI. Among those affected, a large proportion were edentulous, had missing teeth, wore full dentures, and showed poor dental hygiene behaviours. After controlling for a range of variables including age, sex, education, smoking, and chronic diseases, key dental indicators such as the number of missing teeth and the use of complete dentures remained significantly linked to cognitive decline.
Vahid Rashedi, PhD, assistant professor at University of Social Welfare and Rehabilitation Sciences in Iran, said: “The study was motivated by the growing global concern about cognitive decline in aging populations, particularly Mild Cognitive Impairment (MCI), which affects approximately 15% of older adults. Iran, as a developing country, is experiencing rapid population aging, raising concerns about age-related conditions like MCI.”
Participants with higher scores on the decayed, missing, and filled teeth (DMFT) index were more likely to show signs of MCI. Notably, each additional missing tooth slightly increased the odds of cognitive decline, while a greater number of filled teeth was associated with a lower risk. This suggests that receiving restorative dental care may help preserve mental acuity in older age.
Providing additional context on the findings, Rashedi noted: “Higher DMFT scores and missing teeth increased MCI risk, while filled teeth were protective. Complete denture use also raised MCI odds, possibly due to chewing difficulties. These results highlight the importance of oral health in cognitive aging, suggesting that better dental care could help mitigate cognitive decline.”
The findings challenge assumptions that tooth loss is a mere cosmetic or functional issue in later life. Instead, they indicate that poor oral health could be a warning sign or even a contributing factor in age-related cognitive decline. Researchers point to several potential explanations, including the impact of tooth loss on nutrition, chronic inflammation from gum disease, and reduced neural stimulation from impaired chewing.
Denture use also emerged as a marker of concern. Individuals wearing complete dentures on both jaws were significantly more likely to have MCI than those with partial or no dentures. While dentures can restore appearance and basic function, they may not fully compensate for the loss of natural teeth in terms of chewing ability, which some scientists believe plays a role in maintaining brain activity.
Rashedi pointed out: “Given Iran’s unique healthcare challenges, including limited access to dental care and cultural norms favouring tooth extraction over preservation, this study aimed to investigate the association between oral health and MCI while controlling for key confounders.” He added: “The researchers emphasised the importance of oral health as a modifiable risk factor, noting its potential impact on physical, cognitive, and overall well-being in older adults.”
The study also highlighted low levels of oral hygiene among the MCI group. Those with cognitive impairment were less likely to brush regularly or use floss, and fewer cleaned their dentures properly. These habits may contribute to a worsening cycle of dental decay and cognitive deterioration.
This is one of the first large-scale investigations in Iran to explore this association in a community-based setting, offering valuable insight in a context where healthcare access and dental care standards differ significantly from Western countries. It underlines the importance of public health strategies that integrate oral health into broader ageing and dementia prevention programmes.
Looking ahead, Rashedi stressed the importance of further study: “The cross-sectional design limits causal conclusions, so longitudinal studies with clinical and biomarker data are needed. Future research should assess denture quality, nutrition, and inflammation pathways. Interventions like community dental programs could test whether improving oral health slows cognitive decline, offering actionable strategies for healthy ageing.”
