The Effect of Surfactants on the Stability of Sodium Hypochlorite Preparations

• No previous investigation has looked into the effect of surfactants on the stability of NaOCl preparations.
• Dental NaOCl products from the same supplier showed more rapid degradation in free available chlorine for the products containing a surfactant.
• Free available chlorine and surface tension decreased with the passage of time for all NaOCl products tested.
• Viscosity and pH were stable over time.

IntroductionThe purpose of the present study was to assess the effect of the presence of surfactants over time on free available chlorine (FAC), pH, viscosity, and surface tension of sodium hypochlorite (NaOCl) preparations.MethodsThree preparations containing surfactant (Chlor-XTRA 6% [Vista Dental Products, Racine, WI], Hypocelle 4% Forte [Dentalife, Ringwood, Australia], and White King Lemon [Pental, Shepparton, Australia]) and 2 without, Vista 6% (Vista Dental Products) and Hypocelle 4% Forte plain (Dentalife), were tested. The solutions were stored in closed plastic bottles and protected from light at a constant 20°C for 213 days. FAC was measured using iodometric titration, whereas pH, surface tension, and viscosity were measured using a pH meter, pendant drop method, and rheometer, respectively. The influence of the type of solution and the presence of surfactant over time on FAC was compared with the aid of linear regression models. Two-way analysis of variance was used to evaluate the effect of passage of time and the type of solution on surface tension and the effect of the presence or absence of surfactant on the solutions. The Bonferroni test was used for multiple comparisons (post hoc) and to evaluate the effect of the presence of surfactant between solutions from the same manufacturer (α = 0.05).ResultsDegradation of available chlorine was faster in the presence of surfactant when comparing solutions from the same manufacturer [Chlor-XTRA versus Vista (P < .001) and for Hypocelle 4% Forte versus Hypocelle 4% Forte plain (P = .024)]. There was a gradual decline in pH over time, but viscosity remained stable. The surface tension of all products decreased over time (P = .025, F).ConclusionsThe presence of surfactant hastened the degradation of FAC in all affected NaOCl solutions. The observed changes in pH and viscosity were minor, whereas their surface tension showed a significant decrease.