Nascimento EHL, et al. - Researchers examined how endodontic technical errors are related to the root canal configuration (RCC) of human premolars, as well as determined their relationship with periapical lesions using cone-beam computed tomography (CBCT) images. Analysis of CBCT scans belonging to 136 patients, totaling 152 root filled premolars (185 roots) revealed type I (71%) being the most common RCC, followed by type IV (15%), type II (8%), type V (3%), type VI (1%) and type III (1%). Observations revealed that the prevalence of endodontic technical errors has increased in addition to an increase in the presence of periapical lesions as the anatomical complexity of the root canals increased. The most frequent endodontic technical errors were underfilled and non-filled canal.