Caries experience of 35-year-old Oslo residents and changes over a 20-year period.

The dental health of 35-year-old Oslo citizens was investigated in cross-sectional studies applying similar methods in 1973, 1984 and 1993. In the 1993 investigation, a clinical and radiographic examination of dental caries was performed on 121 randomly selected individuals (response rate 68 per cent). DMFT/S scores were used for recording caries experience. Carious surfaces (DS) were related to independent variables organised under the four main categories of health field concept; environment, behaviour, biology and health care. Mean DMFS based on 28 teeth was 40.9 in 1993, compared to 66.5 in 1984 and 68.2 in 1973. DS, MS, FS and DMF values were significantly lower in 1993 compared with those from the previous 1973 and 1984 studies, while only minor differences were detected from 1973 to 1984. High numbers of decayed surfaces (DS) were significantly associated with poor oral hygiene, unsatisfactory economic status and irregular dental visiting habits. The most influential independent variables explained 35 per cent of the variance in carious surfaces (DS).