Aim

To study with cone-beam computed tomography (CBCT) the periradicular lesions of maxillary first molars with endodontical treatment; to evaluate its localization and, in those with a mesiobuccal root (MB) injury, assess the frequency of the MB2 root canal.

Materials and methods

From a sample of 179 tomographies (CBCT) that included maxillary first molars, those in which they had received previous endodontic treatment, presented periradicular lesions and had a coronary restoration were selected and analyzed. The analyzed variables were: localization of radiolucent areas compatible with periradicular lesions of endodontic origin and the correlation between different localizations and quality of the performed treatment (adequate, defective, or untreated). Data were analyzed by the chi-square test and the Spearman test.

Results

Of the 179 CBCT that included maxillary first molars, 90 met the required conditions. The frequency of periradicular lesions was significantly higher in the MB root when compared with distobuccal and palatal roots (P<0,05). The MB1 canal presented an adequate treatment in all cases. The MB2 canal received adequate treatment in 4 cases (4.44%), a defective one in 4 cases (4.44%) and was untreated in 82 cases (91.1%). The differences among these frequencies were statistically significant (P<0.05).

Conclusions

In the analyzed sample, the localization of periradicular lesions after endodontic treatment in maxillary first molars was associated more frequently with the mesiobuccal root in which in the majority of cases the MB2 canal was untreated or presented a defective treatment.