Oral health can impact general health and systemic disease. Changes in dental plaque, oral microbial flora, and local oral immunity may be important in the development or exacerbation of disease in critically ill patients, trauma patients, adults with chronic obstructive pulmonary disease, and frail elderly. Inasmuch as oral health potentially can be influenced by nursing interventions, nursing research in this area can contribute greatly to improved patient outcomes in these diverse populations. The authors' research teams have conducted several federally funded projects focused on oral health and have developed synergy in research methods. A unifying theme for these research projects is the measurement of oral health. Standardized measures of components of oral health are available and applicable across populations, and their uses and relationship to nursing research and patient outcomes will be discussed.