Spectrophotometric Determination of Irrigant Extrusion Using Passive Ultrasonic Irrigation,EndoActivator, or Syringe Irrigation

Introduction

Sodium hypochlorite (NaOCl) irrigation is critical to endodontic success, and several new methods have been developed to improve irrigation efficacy (eg, passive ultrasonic irrigation [PUI] and EndoActivator [EA]). Using a novel spectrophotometric method, this study evaluated NaOCl irrigant extrusion during canal irrigation.

Methods

One hundred fourteen single-rooted extracted teeth were decoronated to leave 15 mm of the root length for each tooth. Cleaning and shaping of the teeth were completed using standardized hand and rotary instrumentation to an apical file size #40/0.04 taper. Roots were sealed (not apex), and 54 straight roots (n = 18/group) and 60 curved roots (>20° curvature, n = 20/group) were included. Teeth were irrigated with 5.25% NaOCl by 1 of 3 methods: passive irrigation with needle, PUI, or EA irrigation. Extrusion of NaOCl was evaluated using a pH indicator and a spectrophotometer. Standard curves were prepared with known amounts of irrigant to quantify amounts in unknown samples.

Results

Irrigant extrusion was minimal with all methods, with most teeth showing no NaOCl extrusion in straight or curved roots. Minor NaOCl extrusion (1–3 μL) in straight roots or curved roots occurred in 10%–11% of teeth in all 3 irrigant methods. Two teeth in both the syringe irrigation and the EA group extruded 3–10 μL of NaOCl.

Conclusions

The spectrophotometric method used in this study proved to be very sensitive while providing quantification of the irrigant levels extruded. Using the PUI or EA tip to within 1 mm of the working length appears to be fairly safe, but apical anatomy can vary in teeth to allow extrusion of irrigant.     

Tissue Dissolution by a Novel Multisonic Ultracleaning System and Sodium Hypochlorite

Introduction

This study aimed to evaluate the effectiveness of a novel Multisonic Ultracleaning System (Sonendo Inc, Laguna Hills, CA) in tissue dissolution in comparison with conventional irrigation devices.

Methods

Pieces of bovine muscle tissue (68 ± 2 mg) were placed in 0.7-mL test tubes (height: 23.60 mm, inner diameter: 6.00 mm, outer diameter: 7.75 mm) and exposed to 5 minutes of irrigation by different devices. Endodontic devices included the Multisonic Ultracleaning System, the Piezon Master 700 (EMS, Dallas, TX) ultrasonic system with agitation, the EndoVac negative-pressure irrigation system (SybronEndo, Orange, CA), and a conventional positive-pressure 27-G irrigation needle at a flow rate of 10 mL/min. The systems were tested with 0.5%, 3%, and 6% sodium hypochlorite (NaOCl) at room temperature (21°C) as well as 40°C. Irrigation with sterile water was used as a control. The mass of tissue specimens was measured and recorded before and after the use of each device, and if the specimen was completely dissolved visually within 5 minutes, the dissolution time was recorded. The rate of tissue dissolution (%/s) was then calculated.

Results

The Multisonic Ultracleaning System had the fastest rate of tissue dissolution (P < .05), at 1.0% ± 0.1% per second using 0.5% NaOCl, 2.3% ± 0.9% per second using 3% NaOCl, and 2.9% ± 0.7% per second using 6% NaOCl. This tissue dissolution rate was more than 8 times greater than the second fastest device tested (P < .01), the Piezon Master 700 ultrasonic system, which resulted in a tissue dissolution rate of 0.328% ± 0.002% per second using 6% NaOCl at 40°C. For all irrigation devices tested, the rate of tissue dissolution increased with a higher concentration and temperature of the NaOCl solution.

Conclusions

The novel Multisonic Ultracleaning System achieved a significantly faster tissue dissolution rate when compared with the other systems examined in vitro.     

Cyclic Fatigue Resistance of Nickel-Titanium Instruments after Immersion in Irrigant Solutions with or without Surfactants

Introduction

The aim of the study was to assess cyclic fatigue resistance of reciprocating (Reciproc and WaveOne) and continuous rotating (ProTaper) nickel-titanium files after immersion in different irrigation solutions with or without surfactants during several short time periods.

Methods

A total of 270 new Reciproc R25, WaveOne Primary, and ProTaper F2 files were tested. Instruments of each brand were divided into 1 control group (n = 10) formed by new files and 4 test groups (n = 20) formed by instruments dynamically immersed at 37°C for 16 mm in 5.25% sodium hypochlorite (NaOCl), Hypoclean (5.25% NaOCl with surfactant), 17% EDTA, or EDTA Plus (17% EDTA with surfactant). Each test group was subdivided into 2 subgroups (n = 10) on the basis of the time of dynamic immersion in the endodontic irrigant solution (45 seconds or 3 minutes). Resistance to cyclic fatigue was determined by recording time to fracture in a stainless steel artificial canal with a 60° angle of curvature and 5-mm radius of curvature. The fracture surface was examined by using scanning electron microscopy.

Results

Immersion in NaOCl did not reduce the cyclic fatigue of reciprocating or continuous nickel-titanium files. The 17% EDTA reduced the fatigue resistance of all instruments after 3 minutes. The immersion in irrigants with surfactants did not influence the cyclic fatigue of instruments except for Reciproc immersed in Hypoclean solution.

Conclusions

EDTA immersion reduced the cyclic fatigue resistance of all instruments after 3 minutes. Addition of surfactants did not influence the cyclic fatigue of files except when added to NaOCl when it contacts Reciproc instruments.     

An Evaluation of the Accuracy of Labeling of Percent Sodium Hypochlorite on Various Commercial and Professional Sources: Is Sodium Hypochlorite from These Sources Equally Suitable for Endodontic Irrigation?

Introduction

The shelf life of sodium hypochlorite (NaOCl) is limited, and a previous article showed that there can be a discrepancy between the expected concentration of free available chlorine (FAC) and the actual FAC concentration in NaOCl solutions intended for endodontic irrigation. The current study investigates the FAC content of domestic and professional NaOCls and evaluates the influences of dilution and storage on FAC concentration.

Methods

First, domestic and professional NaOCls not obtained from manufacturers were iodometrically titrated. Then, NaOCls were diluted with demineralized water or tap water and stored at 4°C or 18°C and analyzed at baseline and 2 and 22 weeks. Statistical analyses included paired samples, independent samples t tests and repeated multivariate analysis of variance. Correlations were calculated with the Pearson or Spearman rank correlation test. A P < .05 was considered significant.

Results

Label specifications of domestic NaOCl were very imprecise (ie, <5% NaOCl). Domestic NaOCl contained 1.8%–3.5% NaOCl (w/v). Professional NaOCl varied from 14.3% relative less FAC than specified on the label to 23.5% relative more FAC than specified. After 22 weeks, the relative average loss of FAC in all conditions was 5.4% FAC (P = .002). Dilution, diluents, or storage temperature had no effect on the decline of FAC caused by aging.

Conclusions

There is a great variation in NaOCl concentrations, with domestic NaOCl being the least accurate. NaOCl can be stored up to 5 months. The FAC concentration of domestic NaOCl is unpredictable, and, therefore, it appears less suitable for clinical application as root canal irrigant.     

Effect of Long-term Exposure to Endodontic Disinfecting Solutions on Young and Old Enterococcus faecalis Biofilms in Dentin Canals

Introduction

The purpose of this study was to evaluate the antimicrobial activity on Enterococcus faecalis biofilms in dentin canals of short-term and long-term exposure to different endodontic disinfecting solutions by using a dentin infection model and confocal laser scanning microscopy.

Methods

Dentinal tubules in semi-cylindrical dentin blocks were filled with E. faecalis by centrifugation and incubated to form 1-day-old and 3-week-old biofilms. The young and mature biofilms in dentin were subjected to sterile water, 2% chlorhexidine, 2% sodium hypochlorite (NaOCl), and 6% NaOCl for 3, 10, and 30 minutes. After treatments, the proportion of bacteria killed by the disinfectants was analyzed by confocal laser scanning microscopy by using LIVE/DEAD bacterial viability stain.

Results

The proportion of killed bacteria was lower after 3 minutes than after 10 and 30 minutes of exposure to the disinfecting agents (P < .05). The killing of bacteria in the E. faecalis biofilms was fastest during the first 3 minutes and slowed down greatly after 10 minutes. Six percent NaOCl was the most effective antibacterial solution against both the 1-day-old and 3-week-old biofilms (P < .05). No significant difference in bacterial killing was detected between 2% chlorhexidine and 2% NaOCl (P > .05). Significantly more cells were killed in young biofilms than in old biofilms in all groups (P < .05).

Conclusions

The killing of bacteria in infected dentin by disinfecting solutions is time-dependent. However, little additional killing is obtained after the first 10 minutes of exposure.     

Effect of EDTA,Sodium Hypochlorite,and Chlorhexidine Gluconate with or without Surface Modifiers on Dentin Microhardness

Introduction

This study aimed to evaluate the effects of root canal irrigants on the microhardness of root canal dentin in the presence and absence of surface-modifying agents.

Methods

Forty-eight root halves were prepared by longitudinal splitting of the distal roots of 24 freshly extracted mandibular human third molars and embedded in autopolymerizing acrylic resin, leaving the dentin surface exposed. After polishing, the microhardness values of the untreated dentin surfaces were recorded by using Vickers tester at the mid-root level. The root halves were randomly assigned to 6 groups composed of 8 samples each and treated for 5 minutes with one of the following irrigants: 17% EDTA, REDTA, 2% chlorhexidine gluconate (CHX), 2% CHX with surface modifiers (CHX-Plus), 6% NaOCl, or 6% NaOCl with surface modifiers (Chlor-XTRA). After surface treatment, dentin microhardness values were recorded at close proximity to the initial indentation areas. Experimental data were statistically analyzed by using the t test and one-way analysis of variance, followed by Tukey honestly significant difference test at α = 0.05.

Results

EDTA, REDTA, NaOCl, and Chlor-XTRA significantly decreased the microhardness of root dentin compared with intact controls (P < .05).

Conclusions

The addition of surface modifiers to the irrigants did not affect the microhardness of the samples.     

Osmolarity and root canal antiseptics

Antiseptics used in endodontics for disinfection purposes include root canal dressings and irrigants. Osmotic shock is known to cause the alteration of microbial cell viability and might have a role in the mechanism of action of root canal antiseptics. The aim of this review was to determine the role of osmolarity on the performance of antiseptics in root canal treatment. A literature search using the Medline electronic database was conducted up to 30 May 2013 using the following search terms and combinations: ‘osmolarity AND root canal or endodontic or antiseptic or irrigation or irrigant or medication or dressing or biofilm; osmolality AND root canal or endodontic or antiseptic or irrigation or irrigant or medication or dressing or biofilm; osmotic AND root canal or endodontic or antiseptic or irrigation or irrigant or medication or dressing or biofilm; osmosis AND root canal or endodontic or antiseptic or irrigation or irrigant or medication or dressing or biofilm; sodium chloride AND root canal or endodontic or antiseptic or irrigation or irrigant or medication or dressing or biofilm’. Publications were included if the effects of osmolarity on the clinical performance of antiseptics in root canal treatment were stated, if preparations with different osmolarities values were compared and if they were published in English. A hand search of articles published online, ‘in press’ and ‘early view’, and in the reference list of the included papers was carried out following the same criteria. A total of 3274 publications were identified using the database, and three were included in the review. The evidence available in endodontics suggests a possible role for hyperosmotic root canal medicaments as disinfectants, and that there is no influence of osmolarity on the tissue dissolution capacity of sodium hypochlorite. There are insufficient data to obtain a sound conclusion regarding the role of hypo‐osmosis in root canal disinfection, or osmosis in any further desirable ability.     

Clinical comparison between the bleaching efficacy of light‐emitting diode and diode laser with sodium perborate

The aim of this clinical study was to test the efficacy of a light‐emitting diode (LED) light and a diode laser, when bleaching with sodium perborate. Thirty volunteers were selected to participate in the study. The patients were randomly divided into two groups. The initial colour of each tooth to be bleached was quantified with a spectrophotometer. In group A, sodium perborate and distilled water were mixed and placed into the pulp chamber, and the LED light was source applied. In group B, the same mixture was used, and the 810 nm diode laser was applied. The final colour of each tooth was quantified with the same spectrophotometer. Initial and final spectrophotometer values were recorded. Mann–Whitney U‐test and Wicoxon tests were used to test differences between both groups. Both devices successfully whitened the teeth. No statistical difference was found between the efficacy of the LED light and the diode laser.     

Focus on Fluorides: Update on the Use of Fluoride for the Prevention of Dental Caries

Improving the efficacy of fluoride therapies reduces dental caries and lowers fluoride exposure.BackgroundFluoride is delivered to the teeth systemically or topically to aid in the prevention of dental caries. Systemic fluoride from ingested sources is in blood serum and can be deposited only in teeth that are forming in children. Topical fluoride is from sources such as community water, processed foods, beverages, toothpastes, mouthrinses, gels, foams, and varnishes. The United States Centers for Disease Control and Prevention (CDC) and the American Dental Association (ADA) have proposed changes in their long standing recommendations for the amount of fluoride in community drinking water in response to concerns about an increasing incidence of dental fluorosis in children. Current research is focused on the development of strategies to improve fluoride efficacy. The purpose of this update is to inform the reader about new research and policies related to the use of fluoride for the prevention of dental caries.MethodsReviews of the current research and recent evidence based systematic reviews on the topics of fluoride are presented. Topics discussed include: updates on community water fluoridation research and policies; available fluoride in dentifrices; fluoride varnish compositions, use, and recommendations; and other fluoride containing dental products. This update provides insights into current research and discusses proposed policy changes for the use of fluoride for the prevention of dental caries.ConclusionsThe dental profession is adjusting their recommendations for fluoride use based on current observations of the halo effect and subsequent outcomes. The research community is focused on improving the efficacy of fluoride therapies thus reducing dental caries and lowering the amount of fluoride required for efficacy.