The Effect of Surfactants on the Stability of Sodium Hypochlorite Preparations.

INTRODUCTION: The 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. METHODS: Three 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). RESULTS: Degradation 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). CONCLUSIONS: The 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.

Horizontal palatal root fracture in a vital upper first premolar.

Root fractures in non-root-filled teeth occur mostly in maxillary incisors because of trauma. Horizontal root fractures in posterior teeth are rare. This case report describes a horizontal fracture of the palatal root of an upper first premolar in which the pulp was vital. The patient had no symptoms and had no initial recollection of trauma. The dentition showed signs of bruxing and occlusal erosion. Cone-beam computed tomographic imaging identified the affected root. The literature revealed only 2 previous examples of horizontal root fractures in posterior teeth in which pulps remained vital. The possible roles of trauma and bruxing in the etiology are evaluated. A tooth with a fractured root may remain vital and symptomless. The etiology of the fracture can be difficult to establish in posterior teeth. Cone-beam computed tomographic imaging can be invaluable in identifying the fractured root. Pulp sensibility testing is critical before intervention.

The effect of surfactant on the dissolution of porcine pulpal tissue by sodium hypochlorite solutions.

INTRODUCTION: A previous study of the relative dental pulp-dissolving abilities of Milton brand of sodium hypochlorite (NaOCl) and other surfactant-containing NaOCl solutions produced specifically for endodontic treatment showed a markedly better performance of the surfactant-containing product that was not explained by differences in active chlorine content. This study investigated whether the presence of surfactant in the NaOCl solutions was responsible for the difference in dissolution times seen in the previous study. METHODS: Circular samples 2.5 mm in diameter were punched out of the pulps of mandibular incisor teeth from young pigs. The 4 NaOCl solutions tested were Hypochlor 1% and Hypochlor 4% forte, which contained surfactant, and 2 identical solutions without surfactant. Twenty pulp specimens were immersed in 20 individual 25-mL aliquots of each of the 4 NaOCl solutions and observed while stirring until dissolution was complete. The time to dissolution of each sample was determined by stopwatch. Dissolution times for each solution were averaged and compared statistically in R (version 2.12.0) by using multiple regression with nominal active chlorine content as a covariate. RESULTS: No statistical difference was detected between the dissolution times for either of the Hypochlor solutions with and without surfactant. CONCLUSIONS: The addition of surfactant alone does not appear to improve the abilities of NaOCl to dissolve dental pulp tissue.

Influence of ethylenediaminetetraacetic acid on the active chlorine content of sodium hypochlorite solutions when mixed in various proportions.

INTRODUCTION: This study documented the time-related effect on active chlorine content of NaOCl solutions of different concentrations after dilution with ethylenediaminetetraacetic acid (EDTA) in various proportions. METHODS: Five NaOCl solutions (Milton, Black and Gold domestic bleach, and the surfactant containing products, White King and Hypochlor 1% and 4% forte) were mixed with EDTA in the following proportions: 90:10, 75:25, and 50:50. Changes in active chlorine content were determined at intervals between 5 and 18 minutes. RESULTS: Results were analyzed statistically by using general linear statistical models in SPSS. With the exception of White King solutions, EDTA substantially and rapidly reduced available chlorine even in small proportions, with loss being extreme at first and then more gradual. The reaction was exothermic. Results showed that White King mixed 90:10 lost on average only 8% of its active chlorine at its first measurement (approximately 5 minutes) but lost 36% of its active chlorine when mixed 75:25. The Hypochlor products at 90:10 dilution lost on average 27%-31% active chlorine during this time period. Mixing EDTA with NaOCl caused a dramatic loss of active chlorine for all solutions mixed 50:50. NaOCl solutions containing surfactant had less active chlorine loss for the 75:25 and 90:10 admixtures. CONCLUSIONS: NaOCl and EDTA should not be present in the root canal at the same time if the therapeutic benefits of NaOCl are to be realized, but the order in which they should be used for endodontic irrigation remains a matter of debate.