Evaluation of Time-Dependent Chemical Alterations in Sodium Hypochlorite Solution Kept on the Unit Tray During an Average Root Canal Treatment Period

Bastug Guven E., Genç Şen Ö.

Medical science monitor : international medical journal of experimental and clinical research, cilt.32, 2026 (SCI-Expanded, Scopus)

Özet

BACKGROUND Sodium hypochlorite (NaOCl) is the most commonly used irrigant in root canal treatment because of its antimicrobial activity and tissue-dissolving capacity. Since these properties are related to its physicochemical characteristics, changes during chairside handling may be clinically relevant. This study aimed to evaluate time-dependent changes in pH, active chlorine content, and surface tension of NaOCl kept in transparent, open-lid containers during a typical chairside root canal treatment period. MATERIAL AND METHODS A commercially available 5% NaOCl solution was tested under 3 conditions: fresh (T₀), after 1 hour (T₁), and after 2 hours (T₂) of exposure in standardized transparent, open-lid containers under ambient clinic conditions (≈22°C). For each outcome (pH, active chlorine content, and surface tension), 3 groups were evaluated (n=10 per group), yielding 90 measurements in total (3 outcomes×3 groups×n=10). Data were analyzed using one-way analysis of variance followed by Duncan's multiple-comparison test (P<0.05). RESULTS pH decreased significantly after 1 hour and further decreased after 2 hours, compared with fresh NaOCl (P<0.05). Surface tension did not differ significantly among groups (P>0.05). Active chlorine values did not differ between T₀ and T₁ (P>0.05), whereas T₂ showed significantly higher measured active chlorine than both T0 and T1 (P<0.05). CONCLUSIONS In this in vitro study, leaving NaOCl in transparent, open-lid containers for up to 2 hours was associated with decreased pH and increased measured active chlorine values, while surface tension remained unchanged. Further studies are needed to determine the clinical relevance of these physicochemical changes.