Abstract : This thesis focuses on the 5 important oral health-related issues in care home residents, namely periodontal disease, xerostomia, hyposalivation, saliva acidity, and oral hygiene level. It consists of chapters addressing the following topics: (i) the association of vitamin B complex, ascorbic acid, vitamin D, calcium, and magnesium deficiencies with periodontal disease in older people; (ii) the diagnostic suitability of a xerostomia questionnaire and the association between xerostomia, hyposalivation and medication use in a group of nursing home residents; (iii) the validity and the properties of the Summated Xerostomia Inventory-Dutch version (SXI-D) in samples of older populations from Australia, Netherlands, Japan, and New Zealand; (iv) saliva secretion rate and acidity in a group of physically disabled older care home residents; (v) a oral health care guideline for older people in (residential) care homes; (vi) supervised vs. non-supervised implementation of an oral health care guideline in (residential) care homes: a cluster randomized controlled clinical trial; and (vii) the effectiveness of a supervised implementation of an oral health care guideline in care homes (single-blinded cluster randomized controlled trial). This thesis also includes a general discussion of the main findings, relevant aspects, and considerations of the 5 studies (one systematic literature review, 2 clinical cross-sectional studies, one reliability study, and one cluster randomized controlled clinical trial) presented in this thesis. Recommendations for health care providers, and directions for future research are also discussed.