Comparison of the antimicrobial activity of six irrigants on primary endodontic pathogens

Assessment of the Influence of Various Concentrations of Sodium Hypochlorite on Stem Cell Derived From Human Exfoliated Deciduous Teeth (SHED) Proliferation and Differentiation

Objectives  Previous research has established that sodium hypochlorite (NaOCl) has a detrimental effect on dental stem cell viability and maturation. However, a review of the literature revealed no study evaluating the response of NaOCl to the survival of stem cells derived from human exfoliated deciduous teeth (SHEDs). Hence, the aim of the present trial was to assess the influence of various dilutions of NaOCl on SHED proliferation and differentiation. Materials and Methods The 5.25% NaOCl solutions at concentrations of 0.5, 0.1, 0.025, 0.0125, and 0.005 mg/ml were used to assess the response to SHED proliferation and differentiation through methyl tetrazolium (MTT) assay, alkaline phosphatase (ALP) assay, and reverse transcription polymerase chain reaction gene expression analysis at various time point intervals. Results  MTT assay showed that the viability of SHEDs decreased with an increase in the concentration of NaOCl and an increase in incubation time. The ALP activity decreased with an increase in the concentration of NaOCl up to 14 days of incubation. However, the ALP activity of all the test specimens further decreased after 14 days of incubation. The gene expression levels of osteocalcin, dentin sialophosphoprotein, and STRO-1 were statistically significant when compared to the control after one, three, and seven days of incubation. Conclusion  Different doses of NaOCl other than 0.5 mg/ml revealed encouraging outcomes in terms of proliferation, long-term ALP functioning, and odontogenic differentiation potential when cultivated in SHEDs.

Antibacterial efficacy of peracetic acid in comparison with sodium hypochlorite or chlorhexidine against Enterococcus faecalis and Parvimonas micra

Background

The main goal of an endodontic treatment is a complete debridement of the root canal system; however, currently mechanical shaping and chemical cleaning procedures for this purpose have deemed non-satisfactory.

Methods

The efficacy of peracetic acid (PAA; 0.5, 1.0, 2.0%), as a root canal irrigation solution, against Enterococcus faecalis (DSM 20478) and Parvimonas micra (DSM 20468) when compared with the one of sodium hypochlorite (NaOCI; 1.0, 3.0, 5.0%), chlorhexidine digluconate (CHX; 0.12, 0.2, 2.0%) and 0.9% NaCI (as a control solution) was in vitro investigated with the agar diffusion and direct contact methods. The inhibition zone diameters observed with the agar diffusion test were determined. The viable bacterial counts (CFU/ml) were calculated with the direct method.

Results

The agar diffusion test showed that all three root canal irrigation solutions had an efficacy against E. faecalis at all concentrations. The largest inhibition zone diameters against E. faecalis were observed with 5.0% NaOCI. At all three concentrations of PAA, NaOCI, and CHX, the inhibition zone diameter increased with increase in concentration. For P. micra, PAA had a similar inhibition zone diameter despite a concentration increase. In contrast, for NaOCI and CHX, the inhibition zone diameter increased with increasing concentration. 2.0% CHX produced the largest inhibition zone diameter against P. micra. For E. faecalis, only the comparison between 2.0% PAA and 5.0% NaOCI showed statistical significance (p = 0.004). For P. micra the efficacy comparison between the lowest, middle, and highest concentrations of each solution, a statistical significance (p < 0.05) was found for all three solutions. After direct contact with PAA, NaOCI and CHX, no viable bacteria could be determined for either P. micra or E. faecalis.

Conclusions

PAA had a similar antibacterial efficacy as the one of NaOCl and CHX when in direct contact with E. faecalis and P. micra. In the agar diffusion test, PAA showed a similar antibacterial efficacy as the one of CHX and a lower one as the one of NaOCl for E. faecalis.

Efficacy of ozone to eliminate endopathogenic microorganism in rootcanal biofilm

Objective:

Materials and Methods:

Conclusions:

Assessment of Antimicrobial Efficacy of Nano Chitosan, Chlorhexidine, Chlorhexidine/Nano Chitosan Combination versus Sodium Hypochlorite Irrigation in Patients with Necrotic Mandibular Premolars: A Randomized Clinical Trial

AIM: The study was done to assess the antimicrobial effectiveness of Chitosan Nanoparticles (CNPs), Chlorhexidine (CHX), and their combination (CHX/CNPs) versus that of Sodium hypochlorite (NaOCl) in patients with mandibular necrotic premolars and to evaluate their effects on post-operative pain after single-visit endodontic treatment. MATERIALS AND METHODS: Sixty patients with necrotic mandibular premolars were divided randomly to four groups (n = 15) according to the used irrigating solution. Instrumentation was done using rotary ProTaper files. During instrumentation, irrigation was done using 2.5% NaOCl; afterward, canals were flushed with sterile saline. A final flush with the study irrigants was done as follows: 3% CNPs for Group A, 2% CHX for Group B, CHX/CNPs for Group C, and 5.25% NaOCl for Group D. Samples were collected from root canals before and after canal preparation then cultured to assess the number of colony-forming units/ml. All patients were instructed to record their pre- and post-operative pain levels on a numerical rating scale. RESULTS: CNPs and CHX/CNPs were significantly more effective than either CHX or NaOCl; however, there was no significant difference between them against anaerobic bacteria. All tested irrigants were similarly effective against aerobic bacteria. CNPs and CHX/CNPs were associated with significantly lower post-operative pain levels in the first 24 h after treatment. CONCLUSIONS: CNPs and its combination with CHX are significantly more effective than both CHX and NaOCl against anaerobic bacteria isolated from necrotic mandibular premolars. Post-operative pain intensity was significantly lower with CNPs and CNPs/CHX combination than with either NaOCl or CHX.

Antibacterial effect of silver diamine fluoride and potassium iodide against E. faecalis, A. naeslundii and P. micra

Background

The aim of this study was to determine in vitro the bactericidal potential of 38% silver diamine fluoride (SDF) alone, potassium iodide (PI) alone, and the two in combination (SDF + PI) against three bacterial species commonly found in root canal samples (Enterococcus faecalis, Actinomyces naeslundii and Parvimonas micra).

Methods

The potential bactericidal rates for SDF, PI and SDF + PI against E. faecalis, A. naeslundii and P. micra were calculated as reduction of bacteria colony forming units.

Results

The bactericidal potential of SDF was at 99.97–100% against E. faecalis and 100% against A. naeslundii and P. micra. SDF + PI showed a 100% bactericidal effect against P. micra, 99.89–99.98% against E. faecalis and 99.98–100% against A. naeslundii. The bactericidal effect of PI was 99.51–99.98% against E. faecalis, 99.27–99.95% against A. naeslundii and 99.93–100% against P. micra. The differences between controls and bacteria exposed to the antibacterial agents were statistically significant (p < 0.05).

Conclusions

SDF had an effective bactericidal effect against the examined bacteria. However, the limitations of this in vitro study do not allow a recommendation of the employment of these solutions as root canal irrigants. Additional investigations are necessary to assess their endodontic clinical applicability.

Antimicrobial efficacy of medium chain fatty acids as root canal irrigants: An in vitro study

BACKGROUND

Enterococcus faecalis and Candida albicans are the microbes that are most resistant to elimination by disinfecting agents and are the causative agents for reinfection of the root canal treated teeth. Medium chain fatty acids (MCFAs), which are the main components of coconut oil, are proven antimicrobial agents. Thus, the aim of this study was to evaluate their antimicrobial efficacy against E. faecalis and C. albicans.

METHODOLOGY

Ninety extracted single-rooted mandibular premolar teeth were decoronated, biomechanically prepared, autoclaved, and divided into three groups (n = 30): Group A (inoculated with E. faecalis), Group B (inoculated with C. albicans), and Group C (control group). Each group was again subdivided into three groups (n = 10) and irrigated with lauric acid (LA), decanoic acid (DA), and octanoic acid, respectively, for 5 min. Paper point samples were taken from canal walls and transferred into Brain Heart Infusion broth and potato dextrose broth and placed in an incubator at 37°C. The appearance of tubidity was checked at 24, 48, 72, and 96 h using direct contact test. The data were then statistically analyzed using the analysis of variance and Tukey honestly significant difference post hoc tests.

RESULTS

Among the three MCFAs, LA showed the maximum inhibitory against E. faecalis at 24 h and the inhibitory activity decreased considerably at 48, 72, and 96 h. DA was the most effective against C. albicans with a maximum inhibition at 48 h. DA also showed significant substantivity at 72 and 96 h.

CONCLUSION

Within the limitations of this study, it can be concluded that MCFAs show promising antimicrobial efficacy against E. faecalis and C. albicans.

Accuracy and consistency of electronic root canal length determination with electrically isolating rubber stoppers

The aim of this study was to investigate the influence of an isolating silicone stopper on the measuring accuracy and display consistency of three electrometric apex locators. The length of the canal to the major foramen was determined electrometrically using an ISO size 10 file in 20 extracted teeth each with natural crowns (Group I), amalgam fillings (Group II) or base-metal crowns (Group III), The measurements were performed with isolating or conventional silicone stoppers using three different apex locators with a four-level scale consistency rating. The use of isolating stoppers resulted in a more consistent display than with conventional stoppers, independent of the presence or type of coronal restoration (P = 0.017). Across all coronal restorations, the position of the major foramen could be determined to within ± 0.5 mm without significant differences (P = 0.79) using conventional and isolating stoppers. The use of modified isolating stoppers provides a significant increase in display consistency.

Antimicrobial Activity of Sodium Hypochlorite-Based Irrigating Solutions

Purpose

The objective of the present study was the in vitro evaluation of the antimicrobial activity of three different NaOCl-based endodontic irrigating solutions: a 5.25% conventional sodium hypochlorite solution; and two new irrigating solutions, a 5.25% sodium hypochlorite solution with the addition of a proteolytic enzyme and a surfactant; and a 5.25% sodium hypochlorite gel with inorganic silicate.

Methods

Enterococcus faecalis, Staphylococcus aureus and Streptococcus mutans strains were selected to evaluate the antimicrobial activity of the endodontic irrigating solutions by the agar disc diffusion test. Paper disks were saturated with each one of the tested solutions (at room temperature and pre-warmed at 45°C) and placed onto culture agar-plates pre-adsorbed with bacterial cells and further incubated for 24 h at 37°C. The growth inhibition zones around each irrigating solution were recorded and compared for each bacterial strain.

Results

The results were significantly different among the tested irrigating solutions: 5.25% sodium hypochlorite solution produced the highest inhibition areas; 5.25% sodium hypochlorite solution with a proteolytic enzyme and a surfactant, and 5.25% sodium hypochlorite gel with inorganic silicate showed the lowest zones of inhibition.

Conclusions

Even if all tested irrigating solution possessed antibacterial activity versus all tested bacterial strains, 5.25% sodium hypochlorite solution with a proteolytic enzyme and a surfactant, and 5.25% sodium hypochlorite gel with inorganic silicate showed lower in vitro efficacy than 5.25% conventional sodium hypochlorite solution.

Smear layer removal evaluation of different protocol of Bio Race file and XP- endo Finisher file in corporation with EDTA 17% and NaOCl

Background

The aim of the present study was to compare the amount of the smear layer remaining in prepared root canals with different protocols of Bio RaCe files and XP-endo Finisher file (XPF) in association with 17% EDTA and sodium hypochlorite solution.

Material and Methods

A total of 68 extracted single-rooted teeth were randomly divided into 4 experimental groups (n=14) and two control groups (n=6). The root canals were prepared with Bio RaCe files (FKG Dentaire, Switzerland) using the crown-down technique based on manufacturer’s instructions and irrigated according to the following irrigation techniques: Group 1: XPF with 2 mL of 2.5% NaOCl for 1 minute. Group 2:, XPF with 1 mL of 17% EDTA for one minute. Group 3: XPF was used for 1 minute in association with normal saline solution. Group 4: XP-endo Finisher file for 30 seconds in association with 2.5% NaOCl and 17% EDTA for 30 seconds. The negative control group: NaOCl (2.5%) was used during root canal preparation, followed by irrigation with 17% EDTA at the end of root canal preparation. The positive control group: Normal saline solution was used for irrigation during root canal preparation. In all the groups, during preparation of the root canals with Bio RaCe file, 20 mL of 2.5% NaOCl was used for root canal irrigation and at the end of the procedural steps 20 mL of normal saline solution was used as a final irrigant. The samples were analyzed under SEM at ×1000‒2000 magnification and evaluated using Torabinejad scoring system. Data were analyzed with non-parametric Kruskal-Wallis test and post hoc Mann-Whitney U test, using SPSS. Statistical significant was defined at P<0.05.

Results

The results of the study showed the least amount of the smear layer at coronal, middle and apical thirds of the root canals in groups 2, which was not significantly different from the negative control group (P<0.5).

Conclusions

Under the limitations of the present study, use of a combination of NaOCl and EDTA in association with XPF exhibited the best efficacy for the removal of the smear layer.

Key words:Smear layer, XP-endo Finisher file, EDTA, Sodium hypochlorite.

Evaluation of Antimicrobial Efficacy of Nanosilver Solution, Sodium Hypochlorite and Normal Saline in Root Canal Irrigation of Primary Teeth

Background:

Bacteria are the main etiological factors in the development of dentinal caries and its progression to pulpal and periapical disease. Enterococcus faecalis is the bacterial species most frequently recovered from the root-filled teeth.

Aim:

This study aimed to evaluate the antimicrobial effectiveness of nanosilver (NS) solution as an endodontic irrigation solution of primary teeth against E. faecalis.

Settings and Design:

Thirty-six canals of primary teeth were selected for this ex vivo study.

Methods and Materials:

Thirty-six canals of primary teeth were prepared up to the file #35 and all of the specimens were sterilized. Then, root canals were inoculated with a suspension containing E. faecalis bacteria. The teeth were then randomly divided into three groups. Antimicrobial effectiveness was evaluated immediately after dividing into groups by counting colony-forming units on brain heart infusion broth plates.

Statistical Analysis:

Data were analyzed using Kolmogorov–Smirnov, Welch, and Dunnett's T3 tests.

Results:

Sodium hypochlorite showed the highest antimicrobial effectiveness against E. faecalis and showed significant differences compared with normal saline and NS solution (P < 0.001).

Conclusion:

Based on the results of this study, solution of NS particles can be used as an alternative to other root canal irrigating solutions.

Comparison of Three Final Irrigation Activation Techniques: Effects on Canal Cleanness, Smear Layer Removal, and Dentinal Tubule Penetration of Two Root Canal Sealers

OBJECTIVE

The aim of this study was to compare three final irrigation activation techniques with respect to their effects on debridement efficacy, smear layer removal, and dentinal tubule penetration of two different root canal sealers.

BACKGROUND DATA

Different applications to improve the delivery of irrigating solutions within the root canal system are currently being investigated, as not all of the mechanisms and effects of these techniques have been clearly identified.

MATERIALS AND METHODS

One hundred forty-two single-rooted teeth were randomly divided into a control group and three experimental groups based on the irrigant activation technique used: EndoVac (EV) system, photon-induced photoacoustic streaming (PIPS), and conventional syringe irrigation (CSI). Thirteen specimens from each experimental group were evaluated for debris and smear layer removal using scanning electron microscopy. The remaining 30 specimens per group were divided into two subgroups according to the root canal sealer used: AH Plus and TotalFill BC. The maximum depth and total percentage of sealer penetration were measured using confocal laser scanning microscopy.

RESULTS

PIPS resulted in significantly less debris in the middle third of the root canal compared with CSI (p < 0.01). There were no significant differences among CSI, EV, and PIPS concerning debris removal at coronal and apical levels or smear layer removal at all levels (p > 0.05). TotalFill BC use after final irrigation with EV and CSI at 2 mm or PIPS at 5 mm exhibited a significantly higher percentage of sealer penetration than that with AH Plus (p < 0.05). When AH Plus was used, PIPS allowed deeper sealer penetration than CSI at 2 mm (p < 0.05).

CONCLUSIONS

The effects of EV, PIPS, and CSI on debridement efficacy, smear layer removal, and dentinal tubule penetration were almost comparable. TotalFill BC showed superior tubular penetration than AH Plus.

Root Canal Irrigation: Chemical Agents and Plant Extracts Against Enterococcus faecalis

BACKGROUND

There are various microorganisms related to intra and extra-radicular infections and many of these are involved in persistent infections. Bacterial elimination from the root canal is achieved by means of the mechanical action of instruments and irrigation as well as the antibacterial effects of the irrigating solutions. Enterococcus faecalis can frequently be isolated from root canals in cases of failed root canal treatments. Antimicrobial agents have often been developed and optimized for their activity against endodontic bacteria. An ideal root canal irrigant should be biocompatible, because of its close contact with the periodontal tissues during endodontic treatment. Sodium hypoclorite (NaOCl) is one of the most widely recommended and used endodontic irrigants but it is highly toxic to periapical tissues.

OBJECTIVES

To analyze the literature on the chemotherapeutic agent and plant extracts studied as root canal irrigants. In particularly, the study is focused on their effect on Enterococcus faecalis.

METHOD

Literature search was performed electronically in PubMed (PubMed Central, MEDLINE) for articles published in English from 1982 to April 2015. The searched keywords were "endodontic irrigants" and "Enterococcus faecalis" and "essential oil" and "plant extracts".

RESULTS

Many of the studied chemotherapeutic agents and plant extracts have shown promising results in vitro.

CONCLUSION

Some of the considered phytotherapic substances, could be a potential alternative to NaOCl for the biomechanical treatment of the endodontic space.

Effectiveness of XP-endo Finisher, EndoActivator, and File agitation on debris and smear layer removal in curved root canals: a comparative study

The purpose of this study was to assess the efficacy of the XP-endo Finisher (FKG Dentaire SA, La Chaux-de-Fonds, Switzerland) file on debris and smear layer removal in curved root canals in comparison to different irrigation regimens. Seventy-five freshly extracted human mandibular molar teeth with mesial root curved more than 20° were used in this study. The mesial root canals were mechanically prepared using the BT-Race rotary system (FKG Dentaire) and divided into five groups (n = 15) according to the following irrigation techniques: positive control, non-agitated, File agitation, XP-endo Finisher, and EndoActivator (Dentsply Tulsa Dental Specialities, Tulsa, OK, USA). Root canals were split longitudinally and evaluated by scanning electron microscopy. Five-grade scoring system was used to assess the presence of debris and smear layer at the coronal, middle, and apical regions. The XP-endo Finisher and EndoActivator groups revealed significantly lower debris and smear layer scores than the other groups at the coronal, middle, and apical regions (P < 0.05). There was no significant difference between XP-endo Finisher and EndoActivator groups (P > 0.05). The apical region had higher debris and smear layer scores compared with the coronal regions in all groups (P < 0.05), except for the positive control group; there was no significant difference between the three regions of the root canal (P > 0.05). Irrigation of curved root canals using XP-endo Finisher and EndoActivator methods appears to be more effective on debris and smear layer removal than the other tested groups.

Comparative antimicrobial efficacy of herbal alternatives (Emblica officinalis, Psidium guajava), MTAD, and 2.5% sodium hypochlorite against Enterococcus faecalis: An in vitro study

AIM

The objective of this study was to evaluate the antimicrobial efficacy of herbal alternatives (Emblica officinalis, Psidium guajava), BioPure MTAD, and 2.5% sodium hypochlorite against Enterococcus faecalis.

MATERIALS AND METHOD

The testing of the antimicrobial efficacy of selected medicaments against E. faecalis was done by the agar disk-diffusion method. Whatman paper discs of 6 mm diameter were prepared and soaked with the test solution. These discs were then placed onto the previously seeded agar Petri plates. Later, these plates were incubated for 48 h at 37 °C under the appropriate gaseous conditions in a CO2 incubator. A zone of inhibition was recorded in millimeter for each plate and the results were analyzed statistically.

RESULT

MTAD was found to be superior in its antibacterial abilities against E. faecalis compared with the other irrigants used. All the other tested irrigants showed significant zone of inhibition.

CONCLUSIONS

BioPure MTAD offers better antibacterial efficacy than NaOCl. E. officinalis and P. guajava are effective antibacterial agents against E. faecalis and can be used to reduce root canal microflora and root canal failures.

Comparative antibacterial efficacies of hydrodynamic and ultrasonic irrigation systems in vitro

INTRODUCTION

To ensure root canal treatment success, endodontic microbiota should be efficiently reduced. The in vitro bactericidal effects of a hydrodynamic system and a passive ultrasonic irrigation system were compared.

METHODS

Single-rooted extracted teeth (n = 250) were contaminated with suspensions of Enterococcus faecalis ATCC 29212, mixed aerobic cultures, or mixed anaerobic cultures. First, the antibacterial effects of the hydrodynamic system (RinsEndo), a passive ultrasonic irrigation system (Piezo smart), and manual rinsing with 0.9% NaCl (the control) were compared. Colony-forming units were counted. Second, the 2 systems were used with 1.5% sodium hypochlorite (NaOCl) alone or NaOCl + 0.2% chlorhexidine (CHX). The colony-forming units in the treated and untreated roots were determined during a period of 5 days.

RESULTS

Both irrigation systems reduced bacterial numbers more effectively than manual rinsing (P < .001). With NaCl, ultrasonic activated irrigation reduced bacterial counts significantly better than hydrodynamic irrigation (P = .042). The NaOCl + CHX combination was more effective than NaOCl alone for both systems (P < .001), but hydrodynamic irrigation was more effective with NaOCl + CHX than the passive ultrasonic irrigation system.

CONCLUSIONS

Both irrigation systems, when combined with NaOCl + CHX, removed bacteria from root canals.

Comparative evaluation of antimicrobial substantivity of different concentrations of chlorhexidine as a root canal irrigant: An in vitro study

INTRODUCTION

The aim of this in vitro study was to evaluate and compare the antimicrobial substantivity of different concentrations of chlorohexidine as root canal irrigant by microbiological assay using mitis salivarius bacitracin streptomycin, MSBS agar plate.

METHODS

Extracted single rooted permanent human teeth were selected as samples and randomly divided into four groups (three experimental, one control). The samples of the three experimental groups used different concentration of chlorhexidine, CHX (0.1%, 1% and 2%), deionized water used as an irrigant served as control. In each group the apices of teeth were sealed with composite and mounted on plaster blocks. Root canals were prepared using step back technique and enlarged upto no 80. With each change in the file size the corresponding irrigant was used and final irrigation was done with deionized water. Samples were taken with paper points at 12 h, 1 day, 2 days and 3 days respectively and stored in sterile phials which were then arranged on MSBS agar plates for microbiological assay.

RESULTS AND CONCLUSION

Results were analysed by ANOVA and Tukey's HSD test showed that antibacterial substantivity of 2% CHX was best followed by 1% CHX and 0.1% CHX in decreasing order respectively.

Antimicrobial effect of ozonated water, sodium hypochlorite and chlorhexidine gluconate in primary molar root canals

OBJECTIVE

The aim was to determine the antimicrobial effect of ozonated water, ozonated water with ultrasonication, sodium hypochloride and chlorhexidine (CHX) in human primary root canals contaminated by Enterococcus faecalis (E. faecalis).

MATERIALS AND METHODS

Fifty-eight extracted human primary molar teeth were used. Crowns were cut off using a diamond saw under water-cooling. One hundred roots were obtained and mechanically prepared. The roots were then sterilized by autoclaving in water for 15 min at 121°C. All samples were contaminated with E. faecalis for 24 h and the root canals were randomly divided into five groups (n = 20). Group I: 25 mg/L of Ozonated water (O3aq), Group II: 25 mg/L of O3aq with ultrasonication, Group III: 2.5% Sodium hypochloride (NaOCl), Group IV: 2% CHX and Group V: Positive control. The canal of each specimen was irrigated for 4 min and positive control was untreated. All root canals were agitated with sterile saline solution. The saline solution was collected from canals with sterile paper points. For each specimen, the paper points were transposed to eppendorf vials containing 2 ml of brain heart infusion. According to bacterial proliferation, the mean values of optical density were achieved by ELİSA (Biotek EL ×800, Absorbance Microplate Reader, ABD) and the data were analyzed.

RESULTS

NaOCI, CHX and two types of O3aq were found statistically different than positive control group. NaOCI irrigation was found significantly most effective.

CONCLUSIONS

NaOCl, CHX and O3aq applications provide antibacterial effect in vitro conditions in primary root canals.

The Effect of Root Canal Irrigation with Combination of Sodium Hypo-chlorite and Chlorhexidine Gluconate on the Sealing Ability of Obturation Materials

Objectives:

The aim of this study was to evaluate the effect of the precipitate that was formed by combining Sodium Hypochlorite (NaOCl) and Chlorhexidine Gluconate (CHX) on the sealing ability of root canal obturation materials.

Materials and Methods:

The fluid filtration method was conducted on a total of 100 roots. Samples were randomly divided into two control (n=5) and three experimental groups (n=30). The samples in group 1 were irrigated with 1.5 mL of 2.5% NaOCl, and then the smear layers of the teeth were removed by 17% EDTA, while the specimens of group 2 were irrigated by 1.5 mL of 2.5% NaOCl and 1.5 mL of 2% CHX; after the smear layer removal, a final flush with 1.5 mL of 2.5% NaOCl was performed. The samples of group 3 were irrigated the same as group 1 but after the smear layer removal canals were irrigated again with 1.5 mL of 2.5% NaOCl and then a final flush with 1.5 mL of 2% CHX was performed. Teeth were obturated with gutta-percha and AH26 sealer and after seven days, microleakage was evaluated by the fluid filtration technique. The results were analyzed by the ANOVA and Tukey's test.

Results:

The samples in group 3 had significantly greater microleakage compared to teeth in group 1, 2 (p<0.05), and the specimens in group 1 showed significantly less amount of microleakage than samples in group 2, 3 (p<0.05).

Conclusion:

The presence of the precipitate that is formed due to interaction between NaOCl and CHX has negative effect on the sealing ability of gutta-percha and AH26 sealer.

Immediate endodontic access cavity sealing: fundamentals of a new restorative technique

Endodontic access cavity sealing is conventionally performed after endodontic irrigation, referred to as delayed endodontic sealing (DES). Evidence shows that endodontic irrigation with NaOCl decreases dentinal bond quality and could cause coronal leakage. Access cavity sealing before endodontic irrigation is a new restorative approach, referred to as immediate endodontic sealing (IES). The primary aim of this in vitro study was to investigate whether IES improved internal adaptation. The secondary aim was to investigate the influence of the viscosity of the composite used to seal the dentine, on the internal adaptation in both IES and DES groups. Third molars (n= 40) with fully developed apices were used. The teeth were prepared into standard Class II MO cavities, and divided in 4 groups according to the approach, and composite viscosity was used for sealing. Group 1: IES + low viscosity composite; group 2: IES + high viscosity composite; group 3: DES + low viscosity composite; and group 4: DES + high viscosity composite. Samples were then sectioned axially for observation using scanning electron microscopy. Outcome was evaluated by determining the internal adaptation of the samples, which was judged based on the percentage of a continuous margin at the tooth-composite interface. The results were analyzed using a two-way analysis of variance and Mann-Whitney test. IES groups exhibited significantly greater internal adaptation (p = 0.000) as compared with DES groups. Composite viscosity did not significantly affect internal adaptation in either IES or DES groups (p > 0.005).

An in vitro evaluation of the cytotoxicity of varying concentrations of sodium hypochlorite on human mesenchymal stem cells

AIM

To evaluate and compare the cytotoxicity of various concentrations of sodium hypochlorite on immortalized human bone marrow mesenchymal stem cells (MSCs).

MATERIALS AND METHODS

The 5.25 percent sodium hypochlo-rite (NaOCl) at concentrations of 0.5, 0.1, 0.025, 0.0125, and 0.005 mg/ml were used to assess the cytotoxic effect on MSCs. Immortalized human bone marrow mesenchymal stem cells (hTERT-MSCs) were exposed to NaOCl at 5 different concentrations. Cell viability was assessed by 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and alamarBlue assays. The cell morphology changes were assessed with scanning electron microscopy (SEM) after exposure to 2, 4, and 24 hour incubation. The ethidium bromide/acridine orange (EB/ AO) fuorescent stain was applied to the cells in the 8-chamber slides after they were incubated with the testing agents for 2 and 4 hours to detect live and dead cells. The observations were quantitatively and qualitatively analyzed.

RESULTS

The cell viability study using MTT assay and AB assay showed significant reduction with varying concentration at 2 and 4 hours incubation period. The cell viability decreased with the higher percentage of NaOCl. The exposure time also revealed an inverse relation to the cell viability. The SEM analysis showed reduction in the number of cells and morphological alterations with 0.5 mg/ml at 2 and 4 hours compared to 0.025 mg/ml NaOCl. Destruction of the cells with structural alterations and lysis was evident under fuorescence microscope when the cells were exposed to 0.5 mg/ml NaOCl.

CONCLUSION

Within the limitations of this in vitro study it can be concluded that NaOCl is toxic to the human bone marrow MSCs. The cell lysis was evident with higher concentration of sodium hypochlorite. From the observations, it can be concluded that a lower concentration of NaOCl may be used as endodontic irrigant due to its cytotoxic properties. Further studies are mandatory to evolve a consensus on the optimal concentration of sodium hypochlorite to be used as endodontic irrigant.

Cytotoxic effect of endodontic irrigants in vitro

Background

Cytotoxicity of root canal irrigants is important due to their close contact with host tissues. The aim of this study was to assess the cytotoxic effect of NaOCl 3%, Chx 2%, and MTAD on rat periodontal ligament fibroblasts, at 0.1 and 100 μl/mL, using WST-1 colorimetric method.

Material/Method

Rat ligamental fibroblasts were exposed to the irrigants and their viability was assessed after 1, 24, 48, and 72 h. The measurements were determined using WST-1 assay, using a micro ELISA reader.

Results

At 100 ml/L all 3 irrigants were strongly cytotoxic, although CHX was less so than NaOCl and MTAD. At the 0.1 ml/L concentration, NaOCl and MTAD were only moderately cytotoxic, whereas Chx was highly deleterious to cell viability at all time points. There was a significant influence of the dilution rate of the substance, because the odds ratio for cell viability being over 50% was increased 51 times between the 100 ml/L and 0.1 ml/L dilutions.

Conclusions

It seems that irrigating solutions should be used at lower concentrations to enhance cell viability.

A comparative antimicrobial analysis of various root canal irrigating solutions on endodontic pathogens: an in vitro study

BACKGROUND AND OBJECTIVES

Evolution in understanding the poly-microbial environment of both endodontic infections and that of failed root canal treatments has been debatable over the years. The present study was designed to compare and analyze the effect of various root canal irrigation solutions on certain endodontic pathogens in vitro.

MATERIALS AND METHODS

To analyze in vitro the zone of inhibition of the micro-organisms the following irrigating solutions were employed: a. Sodium hypochlorite (NaOCl) 5% b. Sodium hypochlorite (NaOCl) 3% c. Chlorhexidine 2% d. Chlorhexidine (CHX) 0.12% e. Doxycycline 0.01% f. Doxycycline 0.005% g. MTAD. An agar culture plate inoculated with four endodontic pathogens was used namely 1. Enterococcus faecalis (MTCC-439) 2. Candida albicans (MTCC-183) 3. Fusobacterium nucleatum (ATCC-25586) 4. Peptostreptococcus anaerobius (ATCC-27337) The inoculums were streaked out on the trypticase soy agar plate for discrete colonies with a wire loop using standard method. The inoculated plates carrying the antibiotic disks were incubated in an anaerobic jar in the following way-Anaerobic incubation-the following procedure was used to provide anaerobiosis with an increased concentration of carbon dioxide. By this method the zone of inhibition obtained by different irrigating solutions against different pathogens could be compared.

RESULTS

MTAD showed maximum antibacterial activity. In case of C. albicans MTAD was less effective than 5% NaOCl, 3% NaOCl and 2% CHX, 0.12% CHX. However, it was more effective against E. faecalis, F. nuleatum and P. anaerobicus. In any case, antimicrobial activity is not the only prerequisite for an endodontic irrigant. E. faecalis strain used in this study showed resistance to doxycycline; also doxycycline was ineffective against C. albicans at 0.01% and 0.005% concentrations.

CONCLUSION

It was found that MTAD was more antimicrobial than 5% NaOCl for some of the test micro-organisms; however the ability of MTAD to dissolve pulp tissue is not comparable to 5% NaOCl. In addition, 5 and 3% NaOCl showed signifcant antimicrobial activity against all test micro-organisms. The best option for a primary endodontic irrigant therefore is 5% NaOCl.

An in vitro study to compare the effectiveness of F-fle with ultrasonically activated K-fle to remove smear layer by using a scanning electron microscope

AIM

The aim of this study was to compare the effectiveness of the F-fle with an ultrasonically activated #15 K-fle in removing the smear layer after biomechanical instrumentation along with irrigation of Saline, NaOCl and with or without a fush of EDTA.

MATERIALS AND METHODS

Sixty decoronated human premolar teeth with a single canal were instrumented with ProTaper using S1, S2 and F1 series to produce the smear layer and randomly divided into two groups. Group A used Ultrasonics and group B used F-fle for activation of irrigants respectively. Each group was further divided in to three subgroups consisting of 10 teeth in each as I, II, III consisting of saline, NaOCl, NaOCl and EDTA as irrigants respectively. SEM micrographs were taken and amount of smear layer removal was analyzed by using Chi-square statistics tests.

RESULTS

Most effective smear layer removal was seen only when EDTA was used. There was no statistically signifcant difference between the groups A and B in removal of smear layer.

CONCLUSION

There was no increase in smear layer between use of F-fle when compared with the Ultrasonically activated K-fle. CLINICAL SIGNIFCANCE: The F-fle although does not have a superior effcacy than the ultrasonics in removal of smear layer from root canals but when used along with EDTA, can be an effective alternative for the dentists who are unable to bear the initial setup cost of ultrasonics.

Comparative antimicrobial efficacy of Metapex, Metronidazole, BioPure MTAD, Aztreonam on Bacteroides fragilis and Propionibacterium acne

Aim:

The purpose of this study was to evaluate the comparative antibacterial efficacy of Biopure MTAD, Metapex, Metronidazole, and Aztreonam against two obligate anerobic bacteria.

Materials and Methods:

Antimicrobial efficacy of selected medicaments against two obligate anaerobic bacteria Bacteroides fragilis and Propionibacterium acnes was done by Agar disc-diffusion method. Pre-sterilized Whatman paper discs, 6 mm in diameter and soaked with the test solution, were prepared and placed onto the previously seeded agar Petri plates. Each plate was incubated in anaerobic jar for anerobic environment at 37°C for 48 hours. A zone of inhibition was recorded for each plate and the results were analysed statistically. Saline and ethanol used as control group in this study.

Results:

Biopure MTAD, Metapex and Metronidazole were effective against all the selected microorganisms. Aztreonam was effective against Bacteroides fragilis. Saline and ethanol used as control were ineffective.

Conclusions:

Metronidazole showed the superior antibacterial property amongst the tested medicaments.

Effect of Er:YAG laser-activated irrigation solution on Enterococcus Faecalis biofilm in an ex-vivo root canal model

Abstract Objective: The purpose of this study was to evaluate mineral content and surface morphology of root canals coated with Enterococcus faecalis biofilm after treatment with several endodontic irrigation solutions, with and without Er:YAG laser-activated irrigation (LAI).

BACKGROUND DATA

LAI has been introduced as a powerful method for root canal irrigation resulting in smear-layer removal from the root canal wall.

METHODS

Distal and palatal roots from 60 freshly extracted human molars were used in this study. The coronal of each tooth was removed. Roots were split longitudinally and placed in an ultrasonic bath to remove the smear layer, creating conditions for the formation of E. faecalis biofilm. After incubation, the two halves were reassembled in impression material to simulate clinical conditions. Specimens were divided into two main groups: roots rinsed with irrigation solutions and roots subjected to laser irradiation combined with irrigation solutions. Solutions tested were 2% chlorhexidine and 17% ethylenediaminetetraacetic acid (EDTA) and saline.

RESULTS

Surface morphology: 17% EDTA irrigant solution combined with Er:YAG laser showed the best results for removing bacteria from the root canal walls. Chemical analysis: all samples treated with combined laser irradiation and irrigation solution had low surface levels of Ca compared with samples treated with irrigation alone. The Ca/P ratio was highest in the laser-EDTA group. Overall, mineral changes caused by laser with irrigation solutions were minimal, and statistically nonsignificant.

CONCLUSIONS

In vitro irrigation solutions, combined with Er:YAG laser irradiation, were effective in removing E. faecalis biofilm from root canal walls. Irrigation solutions without laser irradiation were less effective, leaving a layer of biofilm on the dentin surface.

The antibacterial activity of sodium hypochlorite and chlorhexidine against Enterococcus faecalis: A review on agar diffusion and direct contact methods

Complete debridement and disinfection of the root canal system are fundamental requirements for successful endodontic treatment. Despite the morphological challenges of the internal root anatomy, root canal irrigants play an important role in the optimization of the root canal preparation, which is essentially a chemo-mechanical procedure. Enterococcus faecalis is one of the most resistant microorganisms that dominants the microbial ecosystem of persistent periradicular lesions in retreatment cases. For that reason, many in vitro and in vivo studies evaluated and compared the antibacterial activity of sodium hypochlorite and chlorhexidine at varying concentrations using different experimental models against this microorganism. However, many controversies with regard to the ideal irrigant and concentration do in fact exist. Hence, this review aims to discuss the antibacterial activity of these two main root canal irrigants against Enterococcus faecalis using the agar diffusion and direct contact methods and the possible modulating factors responsible for inconsistent findings among different studies. In addition, the disinfection potential of both chemical agents on gutta percha and Resilon cones are also discussed. The source of this review was conducted through an electronic literature search using PubMed database from December 1997 until December 2011, which analyze the related laboratory investigations of both irrigants, published in major endodontic journals.

Comprehensive analysis of secondary dental root canal infections: a combination of culture and culture-independent approaches reveals new insights

Persistence of microorganisms or reinfections are the main reasons for failure of root canal therapy. Very few studies to date have included culture-independent methods to assess the microbiota, including non-cultivable microorganisms. The aim of this study was to combine culture methods with culture-independent cloning methods to analyze the microbial flora of root-filled teeth with periradicular lesions. Twenty-one samples from previously root-filled teeth were collected from patients with periradicular lesions. Microorganisms were cultivated, isolated and biochemically identified. In addition, ribosomal DNA of bacteria, fungi and archaea derived from the same samples was amplified and the PCR products were used to construct clone libraries. DNA of selected clones was sequenced and microbial species were identified, comparing the sequences with public databases. Microorganisms were found in 12 samples with culture-dependent and -independent methods combined. The number of bacterial species ranged from 1 to 12 in one sample. The majority of the 26 taxa belonged to the phylum Firmicutes (14 taxa), followed by Actinobacteria, Proteobacteria and Bacteroidetes. One sample was positive for fungi, and archaea could not be detected. The results obtained with both methods differed. The cloning technique detected several as-yet-uncultivated taxa. Using a combination of both methods 13 taxa were detected that had not been found in root-filled teeth so far. Enterococcus faecalis was only detected in two samples using culture methods. Combining the culture-dependent and –independent approaches revealed new candidate endodontic pathogens and a high diversity of the microbial flora in root-filled teeth with periradicular lesions. Both methods yielded differing results, emphasizing the benefit of combined methods for the detection of the actual microbial diversity in apical periodontitis.

Efficacy of Er,Cr:YSGG laser with endodontical radial firing tips on the outcome of endodontic treatment: blind randomized controlled clinical trial with six-month evaluation

Clinical reports stating the efficacy of novel root canal disinfection protocols are an important focus in endodontic research. This blind randomized clinical trial assessed the clinical efficacy of the erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser radial firing tips (RFT) versus the concomitant use of 3 % sodium hypochlorite and interim calcium hydroxide paste in necrotic teeth with chronic apical periodontitis. We hypothesized to find similar or improved bone healing in the laser-assisted endodontic treatment. Thirty-six anterior and premolar teeth were randomly assigned. In group 1, teeth were prepared with 3 % sodium hypochlorite for irrigation and calcium hydroxide as inter-appointment dressing; in group 2, teeth were prepared with saline solution and irradiated with Er,Cr:YSGG laser using RFT2 (140 μs, 37.5 mJ, 20 Hz) and RFT3 (140 μs, 62.5 mJ, 20 Hz) in the first and second appointment, respectively, four times each, moving at 2 mm s(-1) from apical to coronal. The primary outcome measure was changed in apical bone density at 6 months, using the periapical index (PAI) for blind radiographic evaluation. Twenty-nine patients were examined and subjected to statistical analysis, 12 in group 1 and 17 in group 2. There was one treatment failure in group 1. Both groups gave similar outcomes exhibiting statistically significant decreases in PAI scores.

Complications following an accidental sodium hypochlorite extrusion: A report of two cases

Sodium hypochlorite (NaOCl) is the most commonly used solution in root canal treatments, as it is a low-cost method that displays a very effective antimicrobial activity against microbiota of infected root canals. However, this solution can cause complications especially due to its cytotoxic features. When this solution is injected into the adjacent tissues, the patient usually experiences intense pain, and an urgent treatment should be implemented in order to prevent a long-term sequelae. This paper describes the clinical features of two patients that experienced an accidental extrusion of NaOCl after endodontic treatment of varying severity and with different treatments. Furthermore, it shows the long-term neurologic injuries that this type of accidents may cause and a treatment protocol for these situations will be suggested.

Key words:Nerve damage, root canal irrigation, root canal treatment, sodium hypochlorite.

Newer root canal irrigants in horizon: a review

Sodium hypochloride is the most commonly used endodontic irrigant, despite limitations. None of the presently available root canal irrigants satisfy the requirements of ideal root canal irrigant. Newer root canal irrigants are studied for potential replacement of sodium hypochloride. This article reviews the potential irrigants with their advantages and limitations with their future in endodontic irrigation.

In vitro antibacterial activity of different endodontic irrigants

AIM

The objective of this study was to compare in vitro the antibacterial activity of Tetraclean (mixture of doxycycline, citric acid and polypropylene glycol), Niclor 5 (5.25% sodium hypochlorite solution), Cloreximid (0.2% chlorhexidine and 0.2% cetrimide solution) and hydrogen peroxide 12 volumes on three endodontic pathogens associated with primary endodontic infections. Enterococcus faecalis, Streptococcus mutans and Staphylococcus aureus strains were selected to evaluate the antibacterial activity of endodontic irrigants by the agar disc-diffusion test.

MATERIAL AND METHODS

Paper discs were saturated with each one of the test solutions (at room temperature and preheating at 50°C) and placed onto culture agar-plates preadsorbed with bacterial cells and further incubated for 24 h at 37°C. The growth inhibition zones around each irrigant were recorded and compared for each bacterial strain. Kruskal-Wallis and Mann-Whitney tests were applied to compare the various groups.

RESULTS

At room temperature, Tetraclean showed significantly higher inhibition of bacteria growth than all other irrigants tested. Preheating at 50°C significantly increased growth inhibition for all the groups tested. At 50°C, hydrogen peroxide 12 volumes and Tetraclean showed significantly higher efficacy than all other irrigants tested.

CONCLUSIONS

50°C-preheated hydrogen peroxide 12 volumes and Tetraclean showed highest inhibition of the bacterial growth.

Comparison of different irrigants on calcium hydroxide medication removal: microscopic cleanliness evaluation

Calcium hydroxide dressing residuals can compromise endodontic sealing. This study evaluated the cleaning efficacy of different endodontic irrigants in removing calcium hydroxide by SEM image analysis. Fifty-four single-rooted mandibular premolars were instrumented to a master apical file #60 and dressed with calcium hydroxide. After 36 hours, the teeth were reopened and Ca(OH)(2) medication was removed by 5 different experimental groups: 0.5% NaOCl (G1), EDTA-C (G2), citric acid (G3), EDTA-T (G4), and re-instrumentation with MAF using NaOCl and lubrificant, followed by EDTA-T (G5). The roots were split in the buccal-lingual direction and prepared for SEM analysis in cervical, middle, and apical thirds (9, 6, and 3mm from the apex). Five blinded examiners evaluated the wall cleanliness using a scale from 1 to 5. Statistical analysis was performed using Kruskal-Wallis at 5% level of significance. Group G5 had the best results in all thirds, with significant statistical differences compared to all other groups in the middle and coronal third, and to G1 in the apical third. On the other hand, G1, only flushed with NaOCl, had the worst results, with statistical differences in all thirds compared to the other groups. The best cleanliness was achieved by G4 and G5 groups. The recapitulation of MAF in combination with irrigants improved the removal of calcium hydroxide medication better than an irrigant flush alone.

Inorganic chemistry of defensive peroxidases in the human oral cavity

The innate host response system is comprised of various mechanisms for orchestrating host response to microbial infection of the oral cavity. The heterogeneity of the oral cavity and the associated microenvironments that are produced give rise to different chemistries that affect the innate defense system. One focus of this review is on how these spatial differences influence the two major defensive peroxidases of the oral cavity, salivary peroxidase (SPO) and myeloperoxidase (MPO). With hydrogen peroxide (H(2)O(2)) as an oxidant, the defensive peroxidases use inorganic ions to produce antimicrobials that are generally more effective than H(2)O(2) itself. The concentrations of the inorganic substrates are different in saliva vs. gingival crevicular fluid (GCF). Thus, in the supragingival regime, SPO and MPO work in unison for the exclusive production of hypothiocyanite (OSCN(-), a reactive inorganic species), which constantly bathes nascent plaques. In contrast, MPO is introduced to the GCF during inflammatory response, and in that environment it is capable of producing hypochlorite (OCl(-)), a chemically more powerful oxidant that is implicated in host tissue damage. A second focus of this review is on inter-person variation that may contribute to different peroxidase function. Many of these differences are attributed to dietary or smoking practices that alter the concentrations of relevant inorganic species in the oral cavity (e.g.: fluoride, F(-); cyanide, CN(-); cyanate, OCN(-); thiocyanate, SCN(-); and nitrate, NO(3)(-)). Because of the complexity of the host and microflora biology and the associated chemistry, it is difficult to establish the significance of the human peroxidase systems during the pathogenesis of oral diseases. The problem is particularly complex with respect to the gingival sulcus and periodontal pockets (where the very different defensive stratagems of GCF and saliva co-mingle). Despite this complexity, intriguing in vitro and in vivo studies are reviewed here that reveal the interplay between peroxidase function and associated inorganic chemistry.

In vitro bactericidal activity of recombinant human beta-defensin-3 against pathogenic bacterial strains in human tooth root canal

Human beta-defensin-3 (HBD3), an endogenous antimicrobial peptide, has strong broad-spectrum antimicrobial activity. This study aimed to obtain recombinant HBD3 (rHBD3) and to test the hypothesis that the antimicrobial characteristics of HBD3 may offer an advantage over conventional medicine in reducing intracanal bacteria. Genetic engineering was used to obtain active rHBD3 and analysis revealed that it exhibited a broad spectrum of antibacterial activity at low micromolar concentrations against not only Staphylococcus aureus and Escherichia coli but also against some critical pathogenic microbes in infected root canals, including Fusobacterium nucleatum, Prevotella melaninogenica, Peptostreptococcus anaerobius, Streptococcus mutans, Actinomyces naeslundii, Enterococcus faecalis and Candida albicans. In an in vitro antibacterial experiment, rHBD3 significantly eliminated pathogenic bacteria in root canals. The ratio of bacterial death was up to 98%. We conclude that HBD3 has the potential to eliminate bacteria effectively and rapidly in the local microenvironment of the root canal system and that it may contribute to successful endodontic treatment.

Bactericidal activity of phosphoric acid, citric acid, and EDTA solutions against Enterococcus faecalis

OBJECTIVES

The objectives of this study were to evaluate the minimal bactericidal concentration (MBC) for Enterococcus faecalis of phosphoric acid, citric acid, and ethylenediaminetetraacetic acid (EDTA) solutions, and to determine the contact time required for 2.5% and 5% phosphoric acid, 10% and 25% citric acid, and 17% EDTA to exert bactericidal activity.

STUDY DESIGN

Bactericidal activity was tested by means of the dilution neutralization method in accordance with BS-EN-1040:2005 norm, using contact times of 0.5 to 60 minutes.

RESULTS

The MBCs of citric and phosphoric acid were 20% and 2.5%, respectively. EDTA solution lacks bactericidal activity, even after 60 minutes of contact. The 2.5% and 5% phosphoric acid solutions required 5- and 3-minute contact times, and the 10% and 25% citric acid solutions required 10- and 3-minute contact times, respectively.

CONCLUSIONS

Phosphoric acid revealed bactericidal activity against E. faecalis and required less time than citric acid to exert its activity.

The antimicrobial and antifungal activity of a root canal core material

BACKGROUND

The authors conducted an in vitro study to determine the antimicrobial and antifungal activity of a recently introduced thermoplastic, synthetic, polymer-based polyester root canal core material (Resilon, Resilon Research, Madison, Conn.) against five different microorganisms by means of the agar diffusion test over different periods.

METHODS

The microorganisms tested were Enterococcus faecalis, Pseudomonas aeruginosa, Staphylococcus aureus, Porphyromonas endodontalis and Candida albicans. A microbiologist transferred Resilon cones and gutta-percha cones to the inoculated agar and incubated them at 37 C, either aerobically or anaerobically, as required for optimal growth.

RESULTS

The Resilon cones exhibited no antimicrobial effect against any of the bacteria tested, except for S. aureus. It showed antimicrobial efficacy against S. aureus during the first 24-hour period (P < .05). However, after 48 and 72 hours, Resilon cones no longer inhibited the growth of S. aureus. In addition, the material demonstrated no antifungal activity during any of the three testing periods.

CONCLUSION

The results of this study indicate that the antibacterial and antifungal efficacy of the Resilon cone is not superior to that of conventional gutta-percha.

CLINICAL IMPLICATIONS

Clinicians should not use the new root canal core material for its antimicrobial or antifungal efficacy.

Effect of CHX on the Decalcifying Effect of 10% Citric Acid, 20% Citric Acid, or 17% EDTA

The objective of this study was to measure the demineralization capacity of 10% and 20% citric acid and 17% EDTA after three time periods and to determine whether it was modified by the addition of 1% of commercial chlorhexidine (CHX). Three slices of 2-mm thickness were cut from the cervical third of the root of ten bovine incisors and sectioned into two equal parts, obtaining six specimens per tooth. Specimens were assigned to one of six groups (n = 10) for immersion in 25 ml of the above mentioned solutions or 25 ml of these same solutions plus 1% CHX (Hibimax). At 3, 10, and 15 min of immersion, the concentration of Ca2+ was measured by atomic absorption spectrophometry. The demineralization effect of all solutions was time-dependent (F = 158,448; p < 0.001), without significant differences among them (p = 0.783). Addition of 1% CHX did not modify the demineralizing capacity of these solutions. In the first three minutes, significantly more [Ca2+] was obtained when 17% EDTA was used in comparison with the other solutions.

In Vitro Assessment of a Gel Base Containing 2% Chlorhexidine as a Sodium Perborate’s Vehicle for Intracoronal Bleaching of Discolored Teeth

The purpose of this study was to assess a gel base containing 2% chlorhexidine (CHX) as a vehicle to be mixed with sodium perborate for intracoronal bleaching of discolored teeth, comparing its bleaching efficacy to sodium perborate mixed with other vehicles; 37% carbamide peroxide and 30% hydrogen peroxide. There were 110 fresh bovine incisors artificially stained using whole blood. The samples were divided into 11 groups and the intracoronal bleaching was performed using the "walking bleach technique". The bleaching agents were replaced three times at 7-day intervals. Using digital photos and a shade guide created for bovine teeth, the samples were evaluated at day 0, 7, 14, 21, and 28. On evaluation day, the photos were examined by three endodontists giving scores from 1 to 5 based on the shade guide created. Data were analyzed statistically by Kruskall-Wallis test. After 28 days, all evaluated teeth received scores that were statistically similar. Groups that used sodium perborate and a liquid vehicle bleached faster than those that used a gel based vehicle. The CHX gel allowed dissociation for the bleaching agent. The 2% CHX gel exhibited a good potential for use as a vehicle for sodium perborate or as a complement for carbamide peroxide.