A retrospective study of initial root canal treatment failure in maxillary premolars via using cone-beam computed...

This case-series study examined canal morphology and common factors for endodontic failure in maxillary first and second premolars that were referred for retreatment owing to clinical symptoms or radiographic signs.

Records were retrospectively searched using Current Dental Terminology codes to identify maxillary first and second premolars with endodontic failure. Periapical and cone-beam computed tomographic images were examined to determine Vertucci classifications and suspected factors related to treatment failure.

A total of 235 teeth from 213 patients were included for evaluation. The following Vertucci classification of canal configurations were observed for maxillary first and second premolars: type I (1-1) (4.6% and 32.0%, respectively), type II (2-1) (15.9% and 27.9%, respectively), type III (2-2) (76.1% and 36.1%, respectively), type IV (1-2) (0% and 2%, respectively), and type V (3) (3.4% and 2%, respectively). More treatment failures were noticed in maxillary second premolars than first premolars and in females than in males. The 4 most common factors related to failure were inadequate filling, restorative failure, vertical root fracture, and missed canals. Missed canals were more frequently identified in maxillary second premolars (21.8%) than first premolars (11.4%) (P = .044).

Multiple factors are associated with primary root canal treatment failures in maxillary premolars. Variations in canal morphology appear to be underappreciated in maxillary second premolars.

Maxillary second premolars have more complicated canal configurations than first premolars. Besides adequate filling, clinicians should give extra attention to anatomic variability in second premolars owing to higher failure incidence.