Effect of EDDY and Manual Dynamic Activation Techniques on Postoperative Pain in Retreatment: a Randomized Controlled Trial

The sample size was based on pilot study data that indicated that 38 patients would be sufficient for each group (type I alpha error = 5%, effect size = 0.7, power = 80%). To compensate for possible dropouts during the treatment and/or follow-up periods, 45 patients were assigned to each group.The study protocol was approved by the Ankara Yıldırım Beyazıt University Ethical Board of Clinical Trials and Non-interventional Research (2019-549).The inclusion criteria were as follows:

1. Healthy individuals aged 18 to 40 years.
2. Devital mandibular premolar teeth with asymptomatic periapical lesions.
3. Teeth with initial root canals filled 2-4 mm short of the apex.
4. Premolar teeth with periapical radiolucency (PAI 3-4) [12] detected by radiographic examination.
5. Coronal restoration.
6. Teeth on which root canal treatment had been performed in the researcher's hospital at least 4 years prior to the study.

The exclusion criteria were as follows:

1. The use of drugs, such as analgesics, anti-inflammatories, and antibiotics, for pain and infection control in the previous 12 hours.
2. A history of susceptibility or adverse reactions to any drugs or materials used in the study.
3. Teeth with open apexes and resorption.
4. Teeth with post-core restoration.
5. Vertical root fractures and teeth on which surgery had been performed.
6. Pregnancy and breastfeeding. A participant voluntary consent form was obtained from each patient. Ninety patients were numerically coded in computer environment by someone who was not included in the study for randomization (www.random.org)A single clinician performed retreatment on each of the 90 teeth during a single visit. A 27-gauge dental injector (Set Inject; Set Medical Instruments, Istanbul, Turkey) was used to anesthetize the patients with a solution of 40 mg Articain and 0.006 mg/mL epinephrine (Ultracain DS Forte; Aventis, Istanbul, Turkey). Old restorations and caries were removed, and on the basis of the straight-line principle, round diamond burs were used to create access cavities under rubber dam isolation. All subsequent treatment procedures were performed under rubber dam isolation, and 3.5× (Zumax Sle Loupe) magnification was used. When necessary, the cervical margin was elevated with composite resin to ensure the continuity of the isolation.

The gutta-percha and sealer were removed with hand files and ProTaper retreatment (Dentsply Maillefer) files. No solvent was used. The working length was calculated with a ProPex Pixi apex locater (Dentsply Maillefer). Periapical radiography allowed for the calculation of the working length and confirmation of the removal of the previous canal filling. Root canals were enlarged to be ProTaper Universal F3 (30/0.9). A lubricant (Glyde File Prep, Dentsply DeTrey, GmbH, Konstanz, Germany) was used between each file to prevent the rotary files from getting stuck in the root canal. A total of 20 mL 2.5% sodium hypochlorite (NaOCl) irrigation solution (Werax, Izmir, Turkey) was used for each treatment. For all teeth, the final irrigation was performed with 5 mL 17% ethylenediaminetetraacetic acid (EDTA) solution (Werax, Izmir, Turkey) for 1 minute. After the retreatment procedure, the patients were divided into two groups on the basis of the additional irrigation activation procedures with 6 mL 2.5% NaOCl (n = 45). Information on which irrigation activation methods to use was not given to the patient.