A method to reduce interproximal overlapping and improve reproducibility of bitewing radiographs for use in clinical trials.

To improve the quality of bitewing radiographs a Bite Registration Technique (BRT) was developed by modifying a commercially available Rinn XCP Instrument. The modification involved using a rubber impression material to register the subject's bite so that the subsequent replacement of the instrument in the mouth was guided by the registration indentations. A total of 240 radiographs were analysed to determine the frequency and severity of the overlapping and the degree of deviation in the horizontal angulation between the subsequent films. Approximately half the films were taken with BRT and the other half were taken with the unaltered Rinn SCP Instrument (without BRT). Two radiographs were taken of each side of the mouth. Only 11.6% of the proximal surfaces had more than half the enamel overlapped 'with BRT' compared with 33% 'without BRT'. In addition, when using the BRT, the initial and the subsequent radiographs of each child were more alike than 'without BRT'. Ninety percent were virtually identical; the mean difference in width of the largest overlap between the two films was 0.11 mm. To check the validity of these findings, 100 radiographs from a previously published clinical trial which used similar aged children and also used a Rinn SCP Instrument (modified), were analysed used the same criteria. The results obtained were similar to the 'without BRT' results; 30% of the proximal surfaces had more than half the enamel overlapped. Improved accuracy allowed a narrower X-ray beam to be used, thus reducing patient irradiation. The use of the Bite Registration Technique is recommended when a high degree of diagnostic accuracy is desired in clinical trials involving primary dentitions.