Evaluation of dental radiographic identification: an experimental study

The object of this study was to assess the value of dental radiographs for the purposes of personal identification in the absence of tooth restorations. 198 periapical and bitewing radio graphs were taken of teeth contained in 22 dry skulls obtained from the skull collection of the Royal College of Surgeons of Edinburgh. Each selected view was taken three times: by a scientist, a dentist and a dental radiographer. Each operator independently positioned the films, selected the exposure times and positioned the cone of the X-ray machine. Three groups comprising forensic odontologists, dental vocational trainees and dental trainee hygienists attempted to match the randomly mixed radiographs into sets of three. Success rates for matching radio graphs ranged from 63.6 to 100%. The average for forensic odontologists was 93.3%, vocational trainees 85.2% and hygienists 89.7%. Where forensic odontologists had both formal training and experience, or extensive experience without formal training, the success rate was 100%. Where there was formal training but little experience the success rate was lower. Participants believed that root morphology and alignment had been the greatest aid to matching and not crown morphology. The depth of knowledge of the viewer correlated poorly with the number of correct results, although the forensic odontologists achieved the highest success rate. Formal training, although highly desirable, is no substitute for practical experience. Root morphology and alignment were cited most frequently as facilitating matching.