The aim of this study was to compare the root canal systems of maxillary and mandibular premolars that had a single root using radiographs and clearing samples. 142 single rooted premolars were selected and mesio-distal and bucco-lingual views were radiographed using intra-oral dental standard films. Four equally trained examiners classify the root canal types from the developed radiographs. After opening the tooth for access, it was stored in 5% NaOCl to dissolve the pulp tissue. Indian ink was then injected into the pulp cavity to stain the pulp tissue. It was cleared in methyl salicylate after being decalcified with 5% nitric acid for 48 hours, and the root canal type was evaluated at a magnification of × 20 using a stereomicroscope.

The results are as follows;

There were statistically significant differences between the radiographs and clearing samples of the root canal types among examiners (p < 0.05). There might be differences in the root canal types among examiners when the same radiograph is used. Therefore, considering the difficulty in estimating the root canal types, clinicians need to be careful when interpreting radiographs before root canal therapy.