The shortened dental arch: prevalence and normative treatment needs in a sample of older Canadian adults.

The concept of the shortened dental arch (SDA) was used to classify the dentition status and normative treatment needs of older adults. From 1982 to 1992, a descriptive survey was conducted in North York, Canada, of 1531 dentate adults aged 65 and over; 69% were nursing home residents. Based on the SDA concept, a "good" guadrant was defined as one which contained all premolar and anterior teeth. A "good" arch was defined as one which had two "good" quadrants. Only 6.3% of nursing home subjects and 7.5% of independently living subjects were classified as having "good" upper and lower arches; these subjects were considered to have a "functional dentition" by the criteria of the SDA concept. For subjects of both residence types, a higher percentage had a "good" lower arch (20%, 30%) as compared with a "good" upper arch (9%, 13%), and a higher proportion of non-denture wearers had "good" arches and quadrants compared with denture wearers. The most common reason for failure to meet SDA criteria was due to the loss of one or more upper premolar teeth; loss of lower canines was least frequently the reason. For subjects of both residence types, normative need for tooth extraction and prosthetic care was significantly associated with having no "good" arches. This was found for both denture wearers and non-denture wearers. Among non-denture wearers of both residence types, the need for urgent care was significantly associated with having no "good" arches.