Social and functional impact of reduced posterior dental units in older adults.

The number of teeth needed to maintain adequate dental function in older adults is unknown. The purpose of this study was to examine the relationship between oral function and the number of opposing pairs of posterior teeth. We identified 338 subjects with complete anterior dentitions from an interview and examination survey of Ontario adults aged 50 and over; 261 had no partial denture and 77 had removable partial dentures (RPD). Oral function was measured using questions assessing chewing ability, mandibular function and socio-psychological impact. Subjects with no partial dentures were further allocated to five groups, based on their dental status: complete dental arch (n = 69); 5-7 functional units-pairs of opposing posterior teeth (n = 109); 3 or 4 functional units (n = 48) and 0-2 functional units (n = 35). Oral function problems increased with decreasing functional units being markedly more prevalent among the groups with 0-2 functional units. 34% of subjects in the 0-2 group reported one or more problems with chewing ability compared to 6-17% in the other groups (chi 2 P = 0.001 d.f. = 3). The 77 subjects who wore removable partial dentures, reported social and dental function at levels comparable to those with no dentures. From these results, there appears to be little socio-functional need to replace lost posterior teeth with a partial denture unit the person has fewer than, 3 posterior functional units. The low number of partial denture wearers limited our ability to detect a lasting benefit from RPD treatment.