Roger M. Clarkson

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.

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.

Free Active Chlorine in Sodium Hypochlorite Solutions Admixed with Octenidine, SmearOFF, Chlorhexidine, and EDTA

Introduction The therapeutic effects of sodium hypochlorite (NaOCl) solutions are dependent on the levels of free available chlorine (FAC). Mixing these solutions with irrigants can result in significant reductions in FAC. Although the effect of some irrigants on FAC is known, the effect of other commonly used irrigants is not. Thus, the therapeutic ramifications of the concurrent use of these on the efficiency of NaOCl solutions is not known. Methods Aliquots of 5.2% (w/v) NaOCl solutions were admixed in proportions of 90:10, 80:20, and 50:50 with the following irrigants: octenidine dihydrochloride (OCT); SmearOFF (Vista Dental Products, Racine, WI), 17% EDTA; and 0.2%, 2%, and 5% chlorhexidine (CHX) solutions. Changes in FAC were measured by iodometric titration. Statistical differences between means were determined using a post hoc Tukey analysis test after an analysis of variance. Results OCT appeared not to affect FAC and was significantly different than all other irrigants, except for 90:10 and 80:20 mixtures of low concentration (0.2%) CHX. CHX solutions showed a marked concentration‐ and mixture proportion–dependent detrimental effect on FAC. The reduction of FAC between different concentrations of CHX was statistically significant in 80:20 and 50:50 proportions, with 50:50 mixtures of 5% CHX having the greatest influence. Mixtures containing even small proportions of SmearOFF or EDTA exhibited significant losses in FAC. Conclusions OCT has little effect on FAC and can be used concurrently with NaOCl solutions. Higher concentrations of CHX significantly affect FAC. Their combined use with NaOCl solutions should be avoided. EDTA and SmearOFF should not be mixed with NaOCl solutions. HighlightsMixing irrigants with NaOCl solutions can affect FAC levels.A reduction in FAC reduces the therapeutic effect of NaOCl solutions.Octenidine has a minimal effect on FAC and can be used with sodium hypochlorite solutions.Chlorhexidine showed a marked concentration‐dependent reduction of FAC.Even small amounts of SmearOFF or EDTA cause a significant loss of FAC.

Assessment of residual active chlorine in sodium hypochlorite solutions after dissolution of porcine incisor pulpal tissue

BACKGROUND In previous studies, surfactant-containing Hypochlor brands of sodium hypochlorite showed better tissue solubilizing abilities than Milton; differences not explained by original active chlorine content or presence of surfactant. It was postulated that exhaustion of active chlorine content could explain differences. This study aimed to assess whether Miltons poorer performance was due to exhaustion of active chlorine. Parallel experiments assessed the influence of titration methods, and the presence of chlorates, on active chlorine measurements. METHODS Time required to dissolve one or groups of 10 samples of porcine incisor pulp samples in Milton was determined. Residual active chlorine was assessed by thermometric titration. Iodometric and thermometric titration was carried out on samples of Milton. Chlorate content was also measured. RESULTS Dissolution of single and 10 pulp samples caused a mean loss of 1% and 3% respectively of active chlorine, not being proportional to tissue dissolved. Thermometric ammonium ion titration resulted in 10% lower values than iodometric titration. Chlorate accounted for much of this difference. CONCLUSIONS Depletion of active chlorine is not the reason for differences in tissue dissolving capabilities of Milton. Thermometric ammonium ion titration gives more accurate measurement of active chlorine content than iodometric titration.

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.