[Influence of root canal working length on the clinical effect evaluated by periapical radiography and cone-beam computed tomography].

PURPOSE: The verification of the best length of root canal instrumentation and obturation is still controversial in endodontics. The purpose of this study was to determine the influence of root canal working length on the clinical effect evaluated by periapical radiography and cone-beam computed tomography (CBCT). METHODS: A total of 503 root canal obturations were evaluated by using periapical radiography and CBCT. Distances from the radiographic apex to the tip of filling material were measured and classified as 1-2 mm, less than 1 mm, beyond apex, and at the apex. Odds ratio, confidence intervals, and Chi-square test were used for statistical analyses with SPSS 13.0 software package. RESULTS: Periapical radiographs showed that root canal obturations were 1-2 mm short of the apex in 88%, 89.3%, and 95% of the anterior teeth, premolars, and molars, respectively. CBCT images showed obturations had the same length in 70%, 73.7%, and 79% of anterior teeth, premolars, and molars, respectively. The frequency of AP was significantly greater in molars than in the other tooth, regardless of diagnostic tools. AP was detected more frequently when CBCT was used. CONCLUSIONS: AP is detected at all lengths of root canal obturation. The analysis of diagnostic methods show that AP is detected more frequently using CBCT.