This is the first of two articles that provide a guide for the clinical management for people with dementia who present with periodontal disease in dental practice. Conditions that cause dementia and their increasing prevalence are described. Advice is given to aid the dental team in recognising patients with dementia. The impact that dementia and the medications used in its medical management have on the oral environment are also covered. The complexities of completing an accurate periodontal assessment for those with dementia are discussed and indications for best practice provided. Although both articles (Part 1 and Part 2) centre on periodontal care, much of the content is equally applicable to wider general dental care for the dementia patient.