The principles for SDA were develop by a Dutch research-group, who publish a high number of publications in the late eighties and early nineties. SDA became a very recognized treatment concept especially in gerontology and the global south. WHO based accordingly several guidelines on the concept- Thus, in 1992 as well on 2013 WHO in Oral Health Surveys stated that a functional and aesthetic dentition requires no less than 20 well distributed teeth. The concept challenged the former principle of the need for 28 teeth for sufficient oral function. More recent publications have, however, shown that the replacement of teeth in dentitions with 20 teeth an especially in dentitions with intermediate tooth spaces increase the oral health related quality of life by most citizens. It has also been shown that by increasing the number of functional units, the chewing efficiency will increase, and the risk of tooth migration, loss of vertical dimension and bite collapse will decrease. However, for specific groups in society e.g., dentistry for elderly, special cares dentistry the SDA concept is still a very useful treatment principle. In many cases patients will benefits when dentist is using the SDA principle instead of using very complex and time-consuming treatments. The lecture will try to focus on when and how sufficient functional and aesthetic dentitions can be established in special care dentistry.