The use of 0.5% or 3% NaOCl for irrigation during root canal treatment results in similar clinical outcome: A 6-year follow-up of a quasi-randomized clinical trial.

AIM: To evaluate the 6-year outcome of root canal treatment irrigated with 0.5% or 3% sodium hypochlorite (NaOCl).

METHODOLOGY: The baseline trial was designed as a quasi-randomized clinical trial. Patients referred for root canal treatment to an endodontic specialist clinic were recruited to the study (n = 298). The concentration of NaOCl was allocated quasi-randomized to 271 subjects (0.5% [n = 139], 3% [n = 132]). Bacterial sampling was performed immediately before root canal filling. Samples were cultured and evaluated as growth or no growth. Patients were invited to a clinical and radiological follow-up >5 years postoperatively. The clinical outcome measurements were tooth survival, cumulative incidence of endodontic retreatments, patients' assessment of pain, clinical findings and radiological signs of apical periodontitis (AP).

RESULTS

Tooth survival was 85.6% in the 0.5% NaOCl group and 81.1% in the 3% NaOCl group (p = .45). There was no record of retreatment in 94.4% in the 0.5% NaOCl group and in 92.2% in the 3% NaOCl group (p = .76). The percentage of asymptomatic cases were 87.8% in the 0.5% group and 85.3% in the 3% NaOCl group (p = .81). Absence of clinical signs of AP was seen in 86.6% in the 0.5% NaOCl group and in 83.6% in the 3% NaOCl group (p = .80). Absence of radiological signs of AP was seen in 74.0% in the 0.5% NaOCl group and 64.1% in the 3% NaOCl group (p = .20). Subjects with positive culture before root filling reported subjective pain with a significantly higher frequency as compared to negative-culture subjects (p = .014).

CONCLUSIONS

The use of 0.5% or 3% NaOCl for irrigation during root canal treatment resulted in similar clinical outcomes 5-7 years postoperatively. Persisting bacteria immediately before root filling may predict future episodes of subjective pain.