Objective To systematically review longitudinal studies on the association between oral health and frailty indicated by any validated scale or index. Background Frailty and poor oral health are common among ageing populations; however, evidence from longitudinal studies is scarce. Methods Three databases (MEDLINE, EMBASE and LILACS) were searched for published literature up to July 2018 using prespecified search strategy. Grey literature was searched using OpenGrey and Google Scholar. Quality of included studies was checked using the Newcastle‐Ottawa Quality Assessment Scale (NOS) for longitudinal studies. Results Five longitudinal studies from three countries (Mexico, Japan, and UK) that examined the association between oral health and frailty were identified. All studies used Fried's frailty phenotype criteria for measuring frailty. Oral health indicators were number of teeth, periodontal disease, oral functions (functional dentition with occluding pairs and maximum bite force), use of removable dentures, accumulation of oral health problems and dry mouth symptoms. The studies showed significant association of number of teeth (two studies), oral functions (two studies), accumulation of oral health problems and number of dry mouth symptoms with frailty incidence, whereas periodontal disease showed inconsistent associations. Conclusion This systematic review identified significant longitudinal associations between oral health indicators and frailty that highlight the importance of oral health as a predictor of frailty in older age. There is a need for further research exploring the role of nutrition as a mediator of the relationship between oral health and frailty.

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Frailty is an important implication of ageing. Frailty is a state characterised by higher vulnerability to adverse health outcomes for older adults. 1 Frailty is prevalent among community-dwelling older adults and the ageing populations. 2 The evidence indicates that frailty is associated with mortality, chronic diseases, depression, dependence and reduced quality of life. 3 The underlying mechanism of frailty is related to impairments to the neuro-immuno-endocrine system, physical activity and nutritional status that modulate the process of ageing. 4 The most two prevailing models of frailty are the phenotypic model which defines frailty based on the presence of three of five physical criteria, 5 and the multiple deficit model which rates frailty based on the number of deficits across multiple domains. 6 Oral health is associated with nutritional status and nutritional intake among older adults. 7,8 Furthermore, the evidence indicates that oral health could be one of the predictors and markers of frailty. 9 Most of the previous studies that assessed the relationship between oral health and frailty used clinical and objective measure like, number of teeth, periodontal disease and oral function