Contrast Imaging Paste for Enhanced Caries Diagnosis of Dental X-rays

Objectives: This proof-of-concept study investigated the use of a contrast imaging paste used as an adjunct to conventional bitewing radiography for identifying cavitated interproximal carious lesions. Methods: A contrast paste with optimal radiographic and clinical handling properties was developed using a base of polyethylene glycol of molecular weight 200 and glycerol with 63% barium sulphate radiopaque filler. A total of 30 extracted teeth with a variety of approximal natural carious cavitated lesions, approximal white spot lesions and sound approximal surfaces were mounted in correct anatomical position in sets of 3 in plaster. Bitewing radiographs were taken of the teeth with and without paste. Various paste application methods were trialled. In addition, artificial approximal cavities of various shapes were created in 24 sound teeth. These teeth were mounted and radiographed with and without paste. Results: Results for the 30 natural teeth were calculated in terms of sensitivity, specificity, positive predictive value and negative predictive value. Two of the three examiners recorded an increased sensitivity and specificity when using the paste as an adjunctive diagnostic tool compared to conventional bitewing radiographs. The third examiner did not record an improvement in sensitivity or specificity with the paste. The paste reliably detected artificial cavitations with a volume of 1µl and larger. Conclusions: These results provide some support for the concept that a radiopaque paste could improve the detection of cavitated approximal carious lesions when used as an adjunct to conventional bitewing radiographs. Further research is required using larger sample sizes as well as clinical trials to establish the value of this contrast paste to help determine if restorative treatment is required, or if preventive strategies would be suitable.