Oral Health and Healthy Ageing: A Systematic Review of Longitudinal Studies.

: The global rise in life expectancy and the resulting shift toward ageing populations pose significant public health and socioeconomic challenges. As healthy ageing becomes a priority, understanding the factors that support well-being in older age is essential. Oral health is increasingly recognised as a critical determinant of overall health and has been linked to chronic conditions. : To conduct a systematic review of longitudinal studies examining the relationship between oral health and healthy ageing. : Two independent reviewers conducted searches in three databases (MEDLINE, EMBASE, and LILACS) up to April 2025, following a defined search strategy. Grey literature was explored using Open Grey and Google Scholar. The quality and the risk of bias of the included studies were evaluated using the Newcastle Ottawa Quality Assessment Scale (NOS) for longitudinal studies. The review protocol was registered with the International Prospective Register of Systematic Reviews (CRD420251029090). : Four longitudinal studies reporting the association between oral health and healthy ageing were recognised and included. All selected studies were considered of good quality according to the NOS. The studies varied in defining and measuring healthy ageing, the follow-up period, the sample size, and the measure of oral health; therefore, it was not possible to perform a meta-analysis. The studies included in the review demonstrated a positive relationship between the number of natural teeth and healthy ageing. : Despite variations in the definition of healthy ageing and the application of different oral health indicators, the review identified significant associations between the number of natural teeth and trajectories of healthy ageing. : This review recognised significant longitudinal associations between oral health measures (number of teeth) and trajectories of healthy ageing. The findings emphasise the need to incorporate oral health into research and policy related to healthy ageing.