The validity of proximal caries detection using magnifying visual aids

The purpose of this study was to determine the validity of proximal caries detection supported by a prism loupe and a surgical microscope used by examiners having different professional experience. One hundred and sixty extracted premolars and molars with varying degrees of proximal caries or sound surfaces were embedded in 10 pairs of models with proximal tooth contacts and a simulated gingiva mask. The proximal surfaces were visually evaluated by 14 observers (7 students, 7 dentists) according to a 5-point caries rating scale using a head-worn prism loupe (x4.5), a surgical microscope (x 14) and without any magnifying device (control). The validity of observations was expressed as ROC curves calculated for two gold standard thresholds: (a) the presence of caries and (b) macroscopic cavitation. Repeated measures analysis of variance was used to determine the effects of 'observer group' and 'diagnostic modality'. An influence of the observer group could not be demonstrated (p > 0.72), whereas significant differences were revealed between the diagnostic modalities (p < 0.002). ROC areas of caries detection with magnifying aids were smaller compared to the control group. It was concluded that the use of a prism loupe or a surgical microscope does not improve the validity of proximal caries detection if the operators, irrespective of being dental students or clinical instructors, are inexperienced in its utilisation. In general only moderate validity was achieved with visual inspection of proximal sites.