Radiographic interpretation and treatment decisions among dental therapists and dentists in Western Australia.

All dentists and dental therapists employed in the Community Dental Services in Western Australia were invited to participate in a questionnaire study to find out about their use of radiographs and opinions and knowledge about the diagnosis of approximal caries. Replies were received from 45 dentists (95.1%) and 207 dental therapists (84.0%). Most dentists would not restore a lesion before it appeared on radiograph to have reached the dentine, while therapists were more likely to consider a restoration for a lesion just in enamel. Sixty percent of all respondents thought that a cavity was present when the radiographic lesion was confined to enamel. Fifty-seven percent of dentists thought that an average lesion took at least 12 months to progress from outer enamel to dentine, while a majority of dental therapists thought this would take less than 12 months. Radiographs were not frequently taken by the participants. Operators' opinions about cavity formation were the most important predictor of choice of treatment. In general, these participant's responses were similar to those provided by Norwegian and Dutch respondents in similar surveys conducted 5-6 yr ago, but the present participants worked in an optimally fluoridated area and might therefore have been expected to have adopted more cautious criteria for restorative treatment. Differences between dentists and dental therapists were generally not great. The results suggest that calibration of the operators in the service would offer benefits.