Success Rate of 4 Injection Protocols for Mandibular First Molars With Symptomatic Irreversible Pulpitis: A CONSORT Randomized Triple-blind Clinical Trial

Trial design This study was a prospective, randomized, parallel, triple blinded, clinical trial. The present trial design methodology conforms to the CONSORT guidelines for reporting randomized clinical trials.Participants A sample size calculation was performed based on the study by (Kanaa M, Whitworth JM, Meechan JG. A Prospective Randomized Trial of Different Supplementary Local Anesthetic Techniques after Failure of Inferior Alveolar Nerve Block in Patients with Irreversible Pulpitis in Mandibular Teeth. J Endod 2012;38:421-425). This research was based on a type I error of 0.05 and a power of 0.8 and indicated that ideally a sample size of 36 in each group would be required to detect a 20% difference in the success rate of the test groups. To increase the validity of the study, 40 subjects in each group were considered.Ethical considerations This trial was conducted with the approval of the institutional review of board (IRB) of the ethics committee at the Faculty of Dentistry, Ain Shams University, Cairo, Egypt (FDASU-REC 772019). Patients signed a printed informed consent form after explanation of the treatment procedure and associated possible adverse effects of the proposed interventions such as discomfort, pain, anesthetic failure and systemic side effects at this stage. Randomization To ensure random selection, participants were allocated randomly into four groups with1:1 allocation ratio by using computer generated randomization (www.randome.org). The sequence was therefore generated.

Allocation concealment mechanism: The sequentially generated numbers were placed in opaque envelopes until the intervention was conducted, and each participant was asked to select an envelope that determines which group of intervention was assumed.

Implementation: Co-researcher used computer generated randomization for participants who achieve eligibility criteria and accordingly participants were enrolled in either of the groups under study.

Blinding Both the participants, the operator who initiated endodontic treatment and monitored the pain, and the statistician were blinded to the anesthetic techniques used.

Intervention Diagnosis was confirmed through history reporting spontaneous pain, a moderate to severe painful response that persists after thermal stimulation, a prolonged response to cold testing with Endo-Ice (1,1,1,2 tetrafluoroethane; Hygenic Corp, Akron, OH), absence of percussion sensitivity and the periapical aspect of the tooth in the bidimensional periapical radiograph was normal. Matching vital contralateral teeth were also tested to ensure an accurate diagnosis and to serve as controls. To prevent bias, this diagnostic step was performed by one investigator (AH), while another investigator (DK) was responsible for administration of all anesthetic injections (DK), and a third investigator (SS) was responsible for root canal treatment procedures and pain recording. All investigators have a minimum of 12 years of clinical experience in endodontics.