Abstract
Objective: We evaluated, in a randomized controlled trial, the antibacterial efficacy of commonly used root canal irrigation solutions—5.25% sodium hypochlorite (NaOCl), 2% chlorhexidine gluconate (CHX), 1.0% NaOCl with a 17% ethylenediaminetetraacetic acid (EDTA) final rinse, and 0.9% normal saline—on intracanal bacterial elimination and their impact on early post-treatment infections (flare-ups) in permanent teeth requiring primary endodontic therapy at a tertiary-care hospital in Pakistan.
Methods: Adults presenting with asymptomatic or symptomatic apical periodontitis in single-rooted teeth were enrolled after informed consent. Participants were randomized (1:1:1:1) using computer-generated, permuted blocks stratified by preoperative diagnosis. All cases were treated under rubber dam isolation with standardized chemo-mechanical preparation (crown-down NiTi instrumentation) and sterile sampling at three time points: baseline (S1), after instrumentation with assigned irrigant (S2), and after final rinse (S3). Primary outcome was complete bacterial elimination at S3 (negative culture and 16S rRNA qPCR below detection). Secondary outcomes included quantitative bacterial load reduction from S1→S3, incidence of postoperative pain (VAS at 24/48 h), and flare-ups within 7 days. Analyses followed intention-to-treat; between-arm differences were estimated with risk ratios (RRs) and mean differences with 95% CIs.
Results: Of 244 randomized participants (mean age 36.8 ± 10.9 years; 52% female), 238 completed primary outcome assessment. Complete bacterial elimination at S3 occurred in 86.8% (NaOCl+EDTA), 79.7% (5.25% NaOCl), 61.5% (2% CHX), and 18.6% (saline). Compared with saline, NaOCl+EDTA achieved an RR of 4.66 (95% CI, 3.06–7.09); 5.25% NaOCl, RR 4.29 (2.80–6.58); and CHX, RR 3.30 (2.12–5.14). Mean log10 bacterial load reduction (qPCR) from S1→S3 was greatest with NaOCl+EDTA (−4.2, SD 1.1), followed by 5.25% NaOCl (−3.7, 1.2), CHX (−2.8, 1.3), and saline (−1.0, 0.9). Seven-day flare-ups occurred in 2.0% (NaOCl+EDTA), 3.4% (NaOCl), 6.6% (CHX), and 10.2% (saline).
Conclusion: In this pragmatic, single-center RCT, 5.25% NaOCl with a 17% EDTA final rinse achieved the highest rate of intracanal bacterial elimination and the lowest short-term flare-up risk. High-concentration NaOCl alone also performed well, while 2% CHX was less effective but superior to saline. These findings support NaOCl-based irrigation protocols with smear-layer removal to optimize antimicrobial outcomes in primary root canal therapy.
Keywords: Root canal irrigation; sodium hypochlorite; chlorhexidine; EDTA; bacterial elimination; qPCR; randomized controlled trial; Pakistan; endodontic infection; smear layer; postoperative pain; flare-up.