In the skeletal remains of earlier populations, the presence and severity of dental caries preserves evidence about general health and diet. The quality of the data collected on dental caries is highly dependent on the diagnostic skills of the examining osteologist. A major barrier to more detailed data is reliance on visual inspection only. The present study compared quantification of carious lesions by osteologists, using both visual and radiographic inspection. Four osteologists with varying experience of caries diagnosis registered the presence and extent of dental caries on the crown and root surfaces of 61 teeth sourced from three different samples: Archaeological, Anthropological and Modern. The teeth were subsequently sectioned to provide a control or standard reference. The interobserver differences were calculated as sensitivity (observer correctness in identifying teeth with caries disease). The two observers with more experience of dental paleopathology showed higher agreement with the standard reference than the other two observers, i.e. they correctly diagnosed more carious lesions. The most pronounced interobserver difference was for radiographic inspection of root surfaces. The recordings by the two experienced observers conformed much more closely with the standard reference than those of the less experienced observers. The results confirm that experience has a major influence on practical observations in dental paleopathology. The quality of collected data on dental caries could be enhanced by improving osteologists’ knowledge of the disease process and the application of uniform, unambiguous criteria for registration of carious lesions.