Comparison of electronic apex locator and simultaneous working length detection methods with radiological method in terms of postoperative pain.

Background: Precise knowledge of the apical construction, which determines the end of the area for canal preparation and filling, is essential for the success of root canal treatment and the management of postoperative pain. For this purpose, devices based on various methods that determine the working length (WL) are used. However, it is still controversial which method provides the most accurate measurements.

Aim: To investigate the compatibility of the electronic apex locator (EWL) and simultaneous working length determination (SWL) methods in single-root teeth in comparison with the radiographic working length determination (RWL) method and to determine which one produced more effective results in terms of postoperative pain.

Materials & methods: One hundred patients scheduled for root canal treatment (RCT) were randomly assigned to one of the three groups according to the working length measurement method (EWL, SWL or RWL). After WL determination with assigned method, root canals were prepared and then obturated. Age, gender, simplified oral hygiene index (OHI-S), oral and dental examinations and Visual Analogue Scale (VAS) results of all participants were recorded. The incidence and intensity of postoperative pain were rated on a Visual Analogue Scale (VAS) by patients 6, 12, 24, 48 h and 7 days after RCT. The number of analgesic tablets (400 mg Ibuprofen) taken by patients was also recorded. Data were analyzed using the chi-square, One- way ANOVA and Kruskal-Wallis tests. Bland-Altman and Passing-Bablock regression analysis were used as method comparison techniques.

Results: It was determined that the number of patients receiving analgesia and the total number of analgesia doses were higher in EWL and RWL groups compared to SWL group (p < 0.0001). When the WL values at which the treatment was applied were compared in the patient groups; WL values of EWL group were statistically lower than SWL group (p < 0.01). While there was no difference between the preoperative VAS scores of the groups (p = 0.7590), the postoperative 6th and 12th hour VAS scores of SWL group were lower than those of EWL and RWL groups (p = 0.005 and p = 0.0002, respectively). Again, the VAS scores of SWL group at the 24th and 48th postoperative hours were lower than those of RWL group (p < 0.05). According to the Bland-Altman and Passing-Bablock regression analysis results, although there was no statistically significant difference between the EWL and SWL methods (p = 0.471), the bias value of -0.1190 was well below the acceptable total error (0.1648). Additionally, a strong relationship was found between EWL and SWL methods (r = 0.9698, r² = 0.9406, p < 0.001). Therefore, statistically these two methods were considered compatible with each other. It was determined that there was a statistically significant bias (0.340, p < 0.0001) between the RWL and SWL methods, exceeding the total error.

Conclusions: As a result, it was determined that the SWL method, which is used to determine working length for the success of endodontic treatment, can be used as an alternative to the EWL method thus producing more effective results in the management of postoperative pain. However, in addition to the method used, the technology of the device developed for this method should not be ignored.

Clinical relevance: Precise knowledge of the apical construction, which determines the end of the area for canal preparation and filling, is essential for the success of root canal treatment and the management of postoperative pain. For this purpose, devices based on various methods that determine the working length are used. However, it is still controversial which method provides the most accurate measurements. This study found that the simultaneous working length determination method can be used as an alternative to the electronic working length determination method and produces more effective results in the management of postoperative pain. Another important outcome of this study is that the Total Allowable Error (TEa) for the electronic apex locator method, which is accepted as the reference, has been calculated for the first time. Other methods have been evaluated according to this reference method. This is a first in literature.