Objective: Oral diseases and conditions are prevalent among older people with dementia and cognitive impairment. While many interventions have been advocated for use in this population, evidence for their effectiveness is unclear. Our objective was to review systematically the content and effectiveness of interventions and implementation strategies used to improve or maintain the oral health of people with dementia or cognitive impairment. Methods: Original studies published in English at any time until January 2015 were identified through electronic searches of the Medline, Embase, CINAHL, Scopus and Cochrane databases and hand searches of eligible studies and relevant reviews. Two investigators independently abstracted study characteristics and assessed the methodological quality of eligible studies. Results were presented as a narrative review because significant heterogeneity among included studies precluded a meta-analysis. Results: The 18 included studies varied considerably in terms of size, scope and focus. Only two studies were identified that had been designed specifically for and examined exclusively in people with dementia or cognitive impairment. All studies were in residential care; none was population-based. While several studies reported positive effects, a number of methodological weaknesses were identified and the overall quality of included studies was poor. The specific outcomes targeted varied across studies but most studies focused almost exclusively on proximal clinical oral health outcomes such as levels of dental or denture plaque. Attempts to measure intervention integrity were limited and there was usually little or no effort to evaluate intervention effects over a sustained period. Conclusion: There is a lack of high quality evidence to support the effectiveness of oral health interventions and implementation strategies for older people with dementia or cognitive impairment. More rigorous, large scale research is needed in this area. Recommendations are provided to improve the overall quality of evaluation in this area. Emphasis must be placed on developing evidence-based, achievable and sustainable oral health strategies if the needs of people with dementia and cognitive impairment are to be met into the future.