Microbial susceptibility to calcium hydroxide pastes and their vehicles

Antimicrobial effect of Pentaclethra Macroloba plant extract against Enterococcus Faecalis

This study evaluated the antimicrobial efficacy of a new intracanal drug based on Pentaclethra macroloba extract, a plant of Amazonian origin, against Enterococcus faecalis using macrodilution test and intratubular evaluation with Confocal Laser Scanning Microscopy (CLSM). The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of the pure extract of Pentaclethra macroloba andits association with calcium hydroxide and ultracall were determined. Then, thirty-three dentin cylinders were prepared and inoculated with E. faecalis, to evaluate the antimicrobial effect of the medications on the dentinal tubules with CLSM. The data was analyzed using the Kruskal-Wallis and Dunn tests. The extract in association with calcium hydroxide showed a lower CBM, and in the intratubular test all tested medications were effective against E. faecalis (P >0.05). The new intracanal drug based on P. macroloba extract has an antimicrobial effect against E. faecalis and further studies are needed for its clinical use.

Fast self-curing α-tricalcium phosphate/β-dicalcium silicate composites beneficial for root canal sealing treatment

Objectives

α-tricalcium phosphate (α-TCP) and β-dicalcium silicate (β-C2S) have attracted much attention since these two types of self-curing Ca-phosphate and Ca-silicate are valuable biomaterials for bone defect or endodontic therapy. However, the injectable paste of their individual with high liquid/solid ratio is junior for root canal sealing due to very long self-setting time, low pH value and/or much volume shrinkage during paste-to-cement transformation.

Methods

Our studies evaluated the effect of biphasic ratio, liquid/solid ratio and pH condition of aqueous medium on setting time and mechanical strength of this biphasic composite cement, and also the hydroxyapatite re-mineralization potential and anti-microleakage level of the cements with different α-TCP/β-C2S ratio were explored in vitro. A control group free of paste filler was included in the extracted teeth model. Dentine re-mineralization and microleakage degree were observed by scanning electron microscopy and microCT reconstruction analysis.

Results

It indicated that the weak acidic solution with pH value of 6.0 may produce a significantly shorter initial setting time (from 90 min to less 20 min) and expected final setting time (<150 min) for the biphasic composite (2:1 or 1:2) in comparison with the pure β-C2S. Notably, the phasic composites exhibited limited microleakage and induced hydroxyapatite mineralization in the dentine tubules. These hydraulic pastes also produced strong alkaline feature and appreciable compressive resistance (12–18 MPa) after setting for a very short time stage. Moreover, a link between the addition of α-TCP leading to fast re-mineralization reaction was established.

Significance

Our findings suggest that the appreciable self-setting and physicochemical properties adaption to root canal sealability make α-TCP/β-C2S composites as preferential candidates for endodontic treatments.

Activity of Two Antimicrobial Peptides against Enterococcus faecalis in a Model of Biofilm-Mediated Endodontic Infection

Enterococcus faecalis is a common cause of biofilm-associated opportunistic infections, which are often difficult to treat. The formation of E. faecalis biofilms on the dentinal walls of the root canal is frequently the cause of endodontic treatment failure and secondary apical periodontitis. In a preliminary work, two recognized antifungal peptides, KP and L18R, showed antibacterial activity against planktonic E. faecalis cells at micromolar concentrations. Moreover, L18R proved to reduce the biomass in the early stage of E. faecalis biofilm development on polystyrene plates, while a qualitative biofilm inhibition was demonstrated on hydroxyapatite disks by confocal laser scanning microscopy (CLSM). The aim of this study was to better characterize the effect of both peptides on E. faecalis biofilm. A reduction in metabolic activity after peptide treatment was detected by Alamar Blue assay, while a remarkable impairment in the architecture of E. faecalis biofilms on hydroxyapatite disks, along with a significant reduction in viable bacteria, was caused mostly by L18R, as assessed by CLSM and scanning electron microscopy. The lack of cytotoxicity of the investigated peptides against L929 murine fibroblasts was also determined. Obtained results suggest L18R as a promising candidate for the development of new strategies for endodontic infection control.

Antimicrobial Activity of an Implantable Wireless Blue Light-Emitting Diode Against Root Canal Biofilm In Vitro

Objective: We developed an implantable wireless blue micro light-emitting diode (micro-LED) device and evaluated the utility of continuous antimicrobial blue light (aBL) irradiation emitted from this micro-LED for root canal disinfection. Methods: An implantable wireless blue micro-LED device (peak wavelength: 410 nm, maximum power: 15 mW) was developed to be placed in the root canal. Optical transmission of the device in human dentin tissue was simulated using Monte Carlo ray-tracing method. The bactericidal effect of low-level aBL on planktonic root canal infection-related bacteria [Enterococcus faecalis, methicillin-resistant Streptococcus aureus (MRSA), and Prevotella intermedia] was evaluated by colony counting. The biocompatibility of continuous low-level aBL exposure was evaluated by infrared thermal imaging and cell viability tests. Thirty extracted intact human single-rooted teeth were prepared and the root canals were infected with E. faecalis for 14 days to form biofilm. The infected root canals were randomly divided into three groups (n = 10), and treated with normal saline (group NS), calcium hydroxide (group CH), and micro-LED device (group aBL) for 3 and 7 days. The bactericidal effect of each group was evaluated by confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). Results: Monte Carlo simulation showed that blue light irradiation of the micro-LED device decreased exponentially with the light transmission distance through human dentin tissue. Planktonic E. faecalis, MRSA, and P. intermedia were significantly eliminated after irradiation with 432, 36, and 1.35 J/cm² aBL, respectively (p < 0.05). Infrared thermal imaging and cell viability tests showed that continuous aBL exposure is biocompatible in vitro. CLSM and SEM analyses revealed that the micro-LED device had a greater antimicrobial effect than CH on E. faecalis biofilm in the root canal. Conclusions: The wireless blue micro-LED device is a promising and user-friendly approach for root canal disinfection that will facilitate infection control in the root canal using aBL.

Effect of a calcium hydroxide-based intracanal medicament containing N-2-methyl pyrrolidone as a vehicle against Enterococcus faecalis biofilm

This study investigated the effect of a calcium hydroxide (CH) paste (CleaniCal^®) containing N-2-methyl pyrrolidone (NMP) as a vehicle on Enterococcus faecalis (E. faecalis) biofilms compared with other products containing saline (Calasept Plus™) or propylene glycol (PG) (Calcipex II^®).

Chronic orofacial pain animal models - progress and challenges

INTRODUCTION

Chronic orofacial pain is one of the most common pain conditions experienced by adults. Animal models are often selected as the most useful scientific methodology to explore the pathophysiology of the disorders that cause this disabling pain to facilitate the development of new treatments. The creation of new models or the improvement of existing ones is essential for finding new ways to approach the complex neurobiology of this type of pain. Areas covered: The authors describe and discuss a variety of animal models used in chronic orofacial pain (COFP). Furthermore, they examine in detail the mechanisms of action involved in orofacial neuropathic pain and orofacial inflammatory pain. Expert opinion: The use of animal models has several advantages in chronic orofacial pain drug discovery. Choosing an animal model that most closely represents the human disease helps to increase the chances of finding effective new therapies and is key to the successful translation of preclinical research to clinical practice. Models using genetically modified animals seem promising but have not yet been fully developed for use in chronic orofacial pain research. Although animal models have provided significant advances in the pharmacological treatment of orofacial pain, several barriers still need to be overcome for better treatment options.

Antimicrobial activity of Psidium cattleianum associated with calcium hydroxide against Enterococcus faecalis and Candida albicans: an in vitro study

OBJECTIVE

Evaluate, in vitro, the antimicrobial activity of Psidium cattleianum leaf extracts combined with calcium hydroxide against Enterococcus faecalis and Candida albicans biofilm.

MATERIALS AND METHODS

Dentin specimens obtained from extracted bovine incisors were infected during 14 days with E. faecalis ATCC 29212 and C. albicans ATCC 10231. The specimens were filled with calcium hydroxide pastes prepared with the following vehicles: Psidium cattleianum ethanolic, Psidium cattleianum propylene glycolic, distilled water, and saline as control. After 24 h, 3, 7, and 14 days, the canals were irrigated with sterile saline and dried. Dentin samples were collected from the canals with burs of increasing diameters. To determine the number of colony-forming units (CFU), samples were inoculated onto BHI agar supplemented with yeast extract (0.5%), at 37 °C, for 48 h, in CO₂ enriched atmosphere. Comparisons among the groups for the variation factors were performed by ANOVA and Tukey's test.

RESULTS

Ethanolic and propylene glycolic extracts showed significantly higher antimicrobial activity against E. faecalis (p < 0.01) when compared with distilled water. The ethanolic extract exhibited in 24 h the same antibacterial activity that propylene glycolic extract and distilled water after 7 and 14 days. For C. albicans, all were effective in reducing the number of CFU at all periods.

CONCLUSION

The P. cattleianum ethanolic extract presented the fastest and highest antimicrobial activity against E. faecalis, significantly reducing the microbial load in 24 h. All medications were effective against C. albicans.

CLINICAL RELEVANCE

The antibacterial potential of P. cattleianum and its biological compatibility associated with calcium hydroxide indicate promising applications in the field of dentistry.

Removal efficacy and cytotoxicity of a calcium hydroxide paste using N-2-methyl-pyrrolidone as a vehicle

Objectives

This study investigated the removal efficacy and cytotoxicity of a newly developed calcium hydroxide paste (cleaniCal, Maruchi) using N-2-methyl-pyrrolidone (NMP) as a vehicle in comparison with ApexCal (Ivoclar Vivadent) and Calcipex II (Nishika), which use different vehicles such as polyethylene glycol and propylene glycol, respectively.

Materials and Methods

Thirty maxillary premolars with oval-shaped canals were divided into 3 groups and the teeth were filled with one of the pastes. After removal of the paste, micro-computed tomographic (μ-CT) imaging was obtained to assess the volume of residual paste in the root canal of each tooth. The teeth were then split longitudinally and the area of the paste-coated surface was evaluated by stereomicroscopy. The cytotoxicity of each product was assessed using an agar overlay assay. The effect of each vehicle on cell viability was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The data were analyzed using one-way analysis of variance and Tukey's tests to detect any significance (p < 0.05).

Results

In the μ-CT and stereomicroscopic analysis, cleaniCal exhibited less remnants of medicament than ApexCal and Calcipex. cleaniCal showed a higher cytotoxicity than the other pastes in the agar overlay assay. Furthermore, NMP exhibited lower cell viability compared to the other vehicles.

Conclusions

cleaniCal showed better removal efficacy compared to the other products. However, clinicians should be aware of the higher cytotoxicity of the NMP-based material and consider its possible adverse effects on periradicular tissue when it is overfilled.

Effect of Trauma to Primary Tooth on Permanent Maxillary Incisors: A Clinical Case Report

Trauma to primary tooth leads to abnormal variations in crown and root canals of permanent teeth that presents a challenge in diagnosis and clinical management to the practitioner. This article presents a detailed case report of the endodontic treatment of a three canalled maxillary central incisor and maxillary lateral incisor having single canal with open apex linked with periodontal defect. Root canals were prepared with hand files and canals were irrigated with 2.5% sodium hypochlorite solution. Calcium hydroxide was placed as an intracanal medicament. As the expected healing did not occur even after one month of calcium hydroxide therapy, so periapical endodontic surgery was performed using Platelet Rich Plasma (PRP). Satisfactory clinical and radiographic results were obtained at 12 months. Detailed knowledge of the anatomical variations in the root canal and awareness of their configuration is essential for the success of such cases.

Intratubular disinfection with tri-antibiotic and calcium hydroxide pastes

OBJECTIVE

The aim of this study was to compare the in vitro intradentinal antimicrobial ability of the calcium hydroxide and tri-antibiotic pastes.

MATERIALS AND METHODS

Standard bovine dentin tubes were sterilized and then infected with Enterococcus faecalis by a new contamination protocol of great depths of dentin. The specimens were filled with the medications, divided into two test-groups: calcium hydroxide (Group 1) and tri-antibiotic (Group 2) pastes. After 15 days, the teeth were evaluated by microbiological culture and confocal laser scanning microscopy (CLSM) with viability dye assay LIVE/DEAD inside dentinal tubules. In experiment of culture, the bacterial collection of the dentin fragments was done for counting the colony-forming units.

RESULTS

The tri-antibiotic paste had a slightly greater antimicrobial effect; however, there was no statistical difference between the groups.

CONCLUSIONS

It was concluded that the tri-antibiotic paste and the calcium hydroxide paste exercise the same effect on intra-tubular decontamination against E. faecalis. So, due the multiples advantages, the calcium hydroxide paste can be the choice for dentinal decontamination in regenerative procedures.

Measurement of pH and calcium ions release from different calcium hydroxide pastes at different intervals of time: Atomic spectrophotometric analysis

AIM

To evaluate the effect of different vehicles on pH and release of calcium ions from calcium hydroxide (CH) paste from apical third of root canals.

METHODS

40 single rooted extracted human mandibular premolars were instrumented with RevoS files (MicroMega) up to ISO size 40. The teeth were divided into 4 groups on the basis of vehicle as follows: Group I - calcium hydroxide mixed with 2% chlorhexidine; Group II - calcium hydroxide mixed with propylene glycol; Group III - calcium hydroxide mixed with glycerine; and Control - calcium hydroxide mixed with double distilled water. Each group had two subgroups (n = 5) on the basis of the calcium hydroxide delivery. Subgroup A - calcium hydroxide paste placed with spiral filler (Lentulospiral) subgroup B - calcium hydroxide paste placed with flat wire filler (Paste Inject). pH and calcium ion release was evaluated at 24 h, 48 h, 7th day, 15th day and 30th day using a pH meter and atomic absorption spectrophotometer respectively.

RESULTS

The calcium release from various groups was highest for CH+glycerine (Group III) followed by CH+chlorhexidine (Group I), CH+propylene glycol (Group II) and CH+double distilled water (control). At all the intervals the differences in calcium ion release among the groups were statistically significant (p < 0.05), except on day 7. Delivery technique did not have a significant effect on calcium ion release. Highest pH values were recorded from CH+glycerine group at day 30 for both the delivery systems, however rise in pH from day 1 to day 30 were non-significant in all groups with both delivery systems.

CONCLUSION

Demonstrable changes in calcium ion release occurred from the calcium hydroxide mixed with various vehicles and CH+glycerine group showed the maximum calcium ion release at all intervals and highest pH day 30.

Tumor Necrosis Factor Receptor-associated Factor 6 Plays a Role in the Inflammatory Responses of Human Periodontal Ligament Fibroblasts to Enterococcus faecalis

INTRODUCTION

Enterococcus faecalis is a frequently isolated microorganism in persistent periapical lesion or secondary infection. However, no evidence has demonstrated that E. faecalis induced inflammation directly in the apical area. This study aimed to explore the mechanism of the inflammatory responses of human periodontal ligament fibroblasts (PDLs) to E. faecalis.

METHODS

PDLs were stimulated with heat-killed E. faecalis (HKEF) or lipoteichoic acid from E. faecalis (LTA) with or without silencing of tumor necrosis factor receptor-associated factor 6 (TRAF6). The expressions of toll-like receptor 2/4, nucleotide-binding oligomerization domain 1/2, and TRAF6 were detected by using quantitative real-time polymerase chain reaction and Western blot. The secretions of proinflammatory cytokines, including interleukin-1β, interleukin-6, interleukin-8, and tumor necrosis factor-α, were determined in the cell supernatants with enzyme-linked immunosorbent assay.

RESULTS

Both HKEF and LTA stimulated the expression of toll-like receptor 2 and TRAF6 in a time-dependent manner. The secretions of proinflammatory cytokines were also increased. After silencing TRAF6, the upregulations of proinflammatory cytokines induced by HKEF or LTA were attenuated.

CONCLUSIONS

TRAF6 plays a pivotal role in inflammation induced by E. faecalis or its LTA in PDLs.

Antimicrobial and cytotoxic effects of phosphoric acid solution compared to other root canal irrigants

Phosphoric acid has been suggested as an irrigant due to its effectiveness in removing the smear layer.

Antibacterial effect of calcium hydroxide combined with chlorhexidine on Enterococcus faecalis: a systematic review and meta-analysis

Objective

Enterococcus faecalis (E. faecalis) is the most frequently isolated strain in failed endodontic therapy cases since it is resistant to calcium hydroxide (CH). Whether a combination of CH and chlorhexidine (CHX) is more effective than CH alone against E. faecalis is a matter of controversy. Thus, the aim of this study was to conduct a systematic review and meta-analysis of the literature.

Material and Methods

A comprehensive search in PubMed, EMbase, EBSCOhost, The Cochrane Library, SciELO, and BBO databases, Clinical trials registers, Open Grey, and conference proceedings from the earliest available date to February 1, 2013 was carried out and the relevant articles were identified by two independent reviewers. Backward and forward search was performed and then inclusion and exclusion criteria were applied. The included studies were divided into "comparisons" according to the depth of sampling and dressing period of each medicament. Meta-analysis was performed using Stata software 10.0. The level of significance was set at 0.05.

Results

Eighty-five studies were retrieved from databases and backward/forward searches. Fortyfive studies were considered as relevant (5 in vivo, 18 in vitro, 18 ex vivo, and 4 review articles). Nine studies were included for meta-analysis. Inter-observer agreement (Cohen kappa) was 0.93. The included studies were divided into 21 comparisons for meta-analysis. Chi-square test showed the comparisons were heterogeneous (p<0.001). Random effect model demonstrated no significant difference between CH/CHX mixture and CH alone in their effect on E. faecalis (p=0.115).

Conclusions

According to the evidence available now, mixing CH with CHX does not significantly increase the antimicrobial activity of CH against E. faecalis. It appears that mixing CH with CHX does not improve its ex vivo antibacterial property as an intracanal medicament against E. faecalis. Further in vivo studies are necessary to confirm and correlate the findings of this study with the clinical outcomes.

Antimicrobial effect and transdentinal diffusion of new intracanal formulations containing nitrofurantoin or doxycycline

The aim of this study was to investigate in vitro the antimicrobial effect and diffusion against E. faecalis of new intracanal medications on the external root surface. The medications tested were a placebo gel (PC); the new formulations with either 3% nitrofurantoin (NIT) or 3% doxycycline hydrochloride (DX) and 2% chlorhexidine (CHX) gel as positive control. The new formulations were tested using the traditional agar diffusion test (ADT) and an adapted agar diffusion method (AADM), where the teeth were filled with the medications and left to diffuse on agar surface seeded with E. faecalis. In the ADT, the larger zones of microbial growth inhibition were seen in DX, followed by CHX and NIT. In the AADM test only DX and CHX showed antimicrobial effect. Statistically significant differences between groups were observed by the Kruskal-Wallis test (2=47.126; p<0.001). The new intracanal formulations with DX and NIT have demonstrated antimicrobial effect against E. faecalis, but only DX was able to diffuse through the dentinal tubules and exert antimicrobial effect outside the roots.

Antimicrobial effect of calcium hydroxide as an intracanal medicament in root canal treatment: a literature review - Part I. In vitro studies

The goal of endodontic treatment is the prevention and control of pulpal and periradicular infections. Calcium hydroxide (Ca(OH)2) has been widely used in endodontics as an intracanal medicament to eliminate the remaining microorganisms after chemomechanical preparation. The purpose of this article is to review the antimicrobial properties of Ca(OH)2 as an intracanal medicament in root canal treatment. The first part of this review details the characteristics of Ca(OH)2 and summarizes the results of in vitro studies related to its antimicrobial effect. The antimicrobial effect of Ca(OH)2 results from the release of hydroxyl ions when it comes into contact with aqueous fluids. Ca(OH)2 has a wide range of antimicrobial effects against common endodontic pathogens, but is less effective against Enterococcus faecalis and Candida albicans. The addition of vehicles or other agents might contribute to the antimicrobial effect of Ca(OH)2.

Enterococcus faecalis activates caspase-1 leading to increased interleukin-1 beta secretion in macrophages

INTRODUCTION

Recent studies of inflammasome activation have focused on the pathogenesis of diverse inflammatory and autoimmune diseases. Inflammasome activation results in caspase-1 activation, which is required for processing of prointerleukin (IL)-1 beta to its secreted form as well as a proinflammatory cell death (ie, pyroptosis). The purpose of this study was to analyze whether Enterococcus faecalis associated with endodontic infection induces inflammasome activation.

METHODS

THP-1 macrophages were treated with E. faecalis in the presence or absence of caspase-1 inhibitors. Caspase-1 activation, pro-IL-1 beta expression, and IL-1 beta secretion were detected by immunoblotting, real-time reverse-transcription polymerase chain reaction, and enzyme-linked immunosorbent assay, respectively. Cell death was measured by lactate dehydrogenase release and propidium iodide staining. Adenosine triphosphate (ATP) release was measured by an ATP bioluminescence assay kit.

RESULTS

E. faecalis induced caspase-1 activation and pro-IL-1 beta expression, which resulted in IL-1 beta secretion in macrophages. E. faecalis significantly induced ATP release, which is a mechanism of Nod-like receptor family protein 3 (NLRP3) inflammasome activation, whereas oxATP treatment inhibited E. faecalis-induced caspase-1 activation. E. faecalis significantly increased lactate dehydrogenase release and propidium iodide uptake, which are characteristics of pyroptosis.

CONCLUSIONS

Our results show that E. faecalis may contribute to the progression of pulpal inflammation by stimulating excessive secretion of IL-1 beta and cell death.

Efficacy of ethylene-diamine-tetra-acetic acid associated with chlorhexidine on intracanal medication removal: a scanning electron microscopy study

The aim of this study was to evaluate the effectiveness of 17% ethylene-diamine-tetra-acetic acid (EDTA) used alone or associated with 2% chlorhexidine gel (CHX) on intracanal medications (ICM) removal. Sixty single-rooted human teeth with fully formed apex were selected. The cervical and middle thirds of each canal were prepared with Gates Glidden drills and rotary files. The apical third was shaped with hand files. The specimens were randomly divided into two groups depending on the ICM used after instrumentation: calcium hydroxide Ca(OH)(2) +CHX or Ca(OH)(2) +sterile saline (SS). After seven days, each group was divided into subgroups according to the protocol used for ICM removal: instrumentation and irrigation either with EDTA, CHX+EDTA, or SS (control groups). All specimens were sectioned and processed for observation of the apical thirds by using scanning electron microscopy. Two calibrated evaluators attributed scores to each specimen. The differences between the protocols for ICM removal were analyzed with Kruskal-Wallis and Mann-Whitney U tests. Friedman and Wilcoxon signed rank tests were used for comparison between the score of debris obtained in each root canal third. Remains of Ca(OH)(2) were found in all specimens independently of the protocol and ICM used (P > 0.05). Seventeen percent EDTA showed the best results in removing ICM when used alone (P < 0.05), particularly in those associated with CHX. It was concluded that the chelating agent 17% EDTA significantly improved the removal of ICM when used alone. Furthermore, the type of the vehicle associated with Ca(OH)(2) also plays a role in the ICM removal.

Evaluation of cytotoxicity, antimicrobial activity and physicochemical properties of a calcium aluminate-based endodontic material

A calcium aluminate-based endodontic material, EndoBinder, has been developed in order to reduce MTA negative characteristics, preserving its biological properties and clinical applications.

OBJECTIVES

The aim of this study was to evaluate the cytotoxicity, antimicrobial activity, pH, solubility and water sorption of EndoBinder and to compare them with those of white MTA (WMTA).

MATERIAL AND METHODS

Cytotoxicity was assessed through a multiparametric analysis employing 3T3 cells. Antimicrobial activity against Enterococcus faecalis (ATCC 29212), Staphylococcus aureus. (ATCC 25923) and Candida albicans (ATCC 10556) was determined by the agar diffusion method. pH was measured at periods of 3, 24, 72 and 168 hours. Solubility and water sorption evaluation were performed following ISO requirements. Data were statistically analyzed by ANOVA and Tukey`s test with a significance level of 5%.

RESULTS

EndoBinder and WMTA were non-cytotoxic in all tested periods and with the different cell viability parameters. There was no statistical differences between both materials (P>.05). All tested materials were inhibitory by direct contact against all microbial strains tested. EndoBinder and WMTA presented alkaline pH in all tested times with higher values of pH for WMTA (P<.05). Both materials showed values complying with the solubility minimum requirements. However, EndoBinder showed lower solubility than WMTA (P<.05). No statistical differences were observed regarding water sorption (P>.05).

CONCLUSION

Under these experimental conditions, we concluded that the calcium aluminate-based endodontic material EndoBinder demonstrated suitable biological and physicochemical properties, so it can be suggested as a material of choice in root resorption, perforations and root-end filling.

Nonsurgical management of large periapical lesion in mature and immature teeth using different calcium hydroxide formulations: case series

This case series evaluates the effectiveness of different calcium hydroxide formulations with various vehicles in management of large periapical lesion in mature and immature teeth. This will help clinicians to make informed judgments about which formulations of calcium hydroxide should be used for specific endodontic procedures.

In Vitro Alkaline pH Resistance of Enterococcus faecalis

Enterococcus faecalis is a bacterial species often found in root canals with failed endodontic treatment. Alkaline pastes are widely used in Endodontics because of their biocompatibility and antimicrobial activity, but this microorganism can resist alkalinity. The purpose of this study was to evaluate in vitro the alkaline pH resistance of E. faecalis for different periods up to 14 days. Samples were obtained from the oral cavity of 150 patients from the Endodontic clinic. The pH of the experimental tubes (n=84) was first adjusted with 6M NaOH to pH values of 9.5, 10.5, 11.5 and 12.5 (21 tubes per pH). Twenty clinical isolates and the ATCC 29212 strain were tested. The 5 positive controls and experimental tubes of each pH were inoculated with 10 µL of bacterial suspension and incubated at 36 °C for 24, 48 and 72 h, 7 and 14 days. For each period, the turbidity of the medium was visually compared with a 0.5 McFarland standard. The presence of the microorganism was confirmed by seeding on M-Enterococcus agar. Four tubes containing BHI broth adjusted to the tested pHs were incubated for 14 days to verify if pH changes occurred. The pH of inoculated BHI broth was also measured on day 14 to determine if the microorganism acidified the medium. The growth of all E. faecalis strains occurred at pH 9.5 to 11.5 in all periods. Although turbidity was not observed at pH 12.5, there was growth of 13 and 2 strains at 24 and 48 h, respectively, on M-Enterococcus agar. No tube showed growth at pH 12.5 after 72 h. It was concluded that E. faecalis can survive in highly alkaline pH, and some clinical isolates require 72 h at pH 12.5 to be killed.

Antibacterial action of calcium hydroxide vehicles and calcium hydroxide pastes

AIM

To evaluate the in vitro action of vehicles alone and with calcium hydroxide against different bacterial species.

METHODS

Agar plates were inoculated with the microbial suspensions, and wells were made and filled with the calcium hydroxide pastes and the vehicles used to prepare the pastes. The zones of inhibited bacterial growth were recorded, and the resulting measurements were statistically analyzed.

RESULTS

Enterococcus faecalis was the most resistant microorganism to all medicaments. Calcium hydroxide + p-monochlorophenol; calcium hydroxide + p-monochlorophenol-propylene glycol pastes; and p-monochlorophenol, p-monochlorophenol-propylene glycol, and chlorhexidine gluconate gel alone showed the largest zones of inhibition against all the tested microorganisms.

CONCLUSIONS

The vehicle used to prepare the calcium hydroxide paste might contribute to its antibacterial action. Chlorhexidine gluconate gel used alone, and camphorated p-monochlorophenol and camphorated p-monochlorophenol-propylene glycol as vehicles of calcium hydroxide, could be recommended, in an antimicrobial sense.

Evaluation of antimicrobial efficacy of calcium hydroxide paste, chlorhexidine gel, and a combination of both as intracanal medicament: An in vivo comparative study

Aim:

To compare the antimicrobial efficacy of calcium hydroxide (CH), 2% chlorhexidine gel (CHX) and a combination of both, on obligate anaerobes, facultative anaerobes and Candida spp .

Materials and Methods:

90 single rooted permanent teeth were included in the study. After complete disinfection and access opening, the first microbiological pre-treatment sample (S1) was collected. After completion of instrumentation, a post-instumentation sample (S2) was taken and the teeth were divided into three groups: Group I: CH, Group II: 2% CHX, Group III: 2% CHX with CH. After 1 week, a post-medication sample (S3) was collected.

Results:

All three medicaments were effective in the elimination of obligate anaerobes. CHX and combination showed higher antimicrobial effect against facultative anaerobes and Candida spp. in comparison with CH. But there was no statistical significant difference between Group II and Group III.

Conclusion:

CHX with or without CH was more effective than CH alone against all the tested micro-organisms.

Characterization of virulence factors and clonal diversity of Enterococcus faecalis isolates from treated dental root canals

The high prevalence of Enterococcus faecalis in root canal treated teeth with post-treatment disease, as evidenced by both molecular and traditional culturing methods, suggests that this species may be a key player in endodontic treatment failure. This study aimed to detect virulence factors by phenotypic and western blotting tests, and virulence genes by PCR from 20 clinical strains of E. faecalis isolated from treated root canals of teeth with (10) or without (10) apical periodontitis. Moreover, genomic diversity of these strains was assessed by pulsed-field gel electrophoresis (PFGE) and rep-PCR. All 20 strains presented the gelE gene (gelatinase), but 10 of them did not hydrolyze gelatin. Seven of the 10 gelatinase-producing isolates were recovered from root canals with lesions, which suggests a role for this virulence factor in the pathogenesis of post-treatment disease. The esp gene was expressed only in cases where gelatinase production was negative. The other virulence genes were found in 90% (efaA and ace genes), 45% (agg gene) and 95% (cpd gene) of the E. faecalis isolates. As for PFGE and rep-PCR, no specific clonal type of E. faecalis was found in association with teeth with or without disease, revealing the interindividual clonal diversity of endodontic infections.

JF. Influence of serum and necrotic soft tissue on the antimicrobial effects of intracanal medicaments

The purpose of this study was to investigate the influence of serum and necrotic soft tissue on the antimicrobial activity of intracanal medicaments. The medicaments tested were: calcium hydroxyde/glycerin paste, calcium hydroxide/chlorhexidine paste, calcium hydroxide/camphorated paramonochlorophenol/glycerin paste, and chlorhexidine/zinc oxide paste. Survival of Enterococcus faecalis and Candida albicans exposed to the medicaments tested in the presence or absence of serum or necrotic tissue was monitored in three in vitro experiments where samples for culturing were taken at different time periods. The overall results demonstrated that the antimicrobial activity of all intracanal medicaments tested was slowed down in the presence of necrotic tissue. Calcium hydroxide pastes in glycerin or chlorhexidine were significantly affected by serum. Of the medicaments tested in this study, the least affected was the calcium hydroxide/camphorated paramonochlorophenol/glycerin paste.

Bacterial leakage in root canals filled with calcium hydroxide paste associated with different vehicles

This in vitro study evaluated, using a bacterial leakage model, whether intracanal medication with calcium hydroxide [Ca(OH)2]-based pastes prepared with different vehicles, has inhibitory effect on corono-apical leakage of bacteria. Forty instrumented human canines were dressed with Ca(OH)2 p.a. associated with: G1 = distilled water; G2 = polyethylene glycol (PG); G3 = PG + CMCP; and G4 = glycerin. Five teeth with intact crowns served as negative controls and 5 instrumented teeth without temporary dressing served as positive controls. All teeth were mounted in a 2-chamber apparatus and then exposed to human saliva for 63 days. Leakage was recorded when turbidity was observed in the lower chamber. Fifty percent of the samples of G1 and G2, 10% of G3 and 80% of G4 were fully contaminated after 9 weeks. Statistically significant differences were observed with paired comparisons G3 and G4 (p=0.0069), with G3 achieving better seal against bacterial leakage than G4.

Dentinal tubule invasion and adherence by Enterococcus faecalis

AIM

To investigate dentinal tubule invasion and the predilection of Enterococcus faecalis for dentinal tubule walls.

METHODOLOGY

The invasion of dentinal tubules in extracted human teeth by E. faecalis was measured ex vivo after 8 weeks of incubation. The canal walls of 16 root sections were either intact or instrumented with or without smear layer present. Extent and maximum depth of tubule invasion were assessed histologically and compared between groups. In the adherence study, 44 vertically split root samples were prepared to expose longitudinally aligned dentinal tubules and fractured orthodentine (OD). Surfaces were exposed to E. faecalis (erythromycin resistant strain, JH2-2 carrying plasmid pGh9:ISS1) and incubated aerobically for 2 h. Samples were processed for analysis using scanning electron microscopy. Bacterial adhesion to tubule walls versus fractured OD was calculated as number of cells per 100 microm(2).

RESULTS

The strain of E. faecalis used in this study showed moderate to heavy tubule invasion after 8 weeks. In the adhesion studies, significantly more bacteria adhered to fractured OD than to dentinal tubule walls (ANOVA, P < 0.001). With respect to the tubule wall, adherence was greater in inner versus outer dentine (P = 0.02) and greater when bacterial adhesion was tested in chemically defined medium than in phosphate-buffered saline (ANOVA, P < 0.001).

CONCLUSIONS

Although E. faecalis readily invaded tubules, it did not adhere preferentially to tubule walls. Initial colonization of dentinal tubules by E. faecalis may depend primarily on other factors.

Antimicrobial activity of calcium hydroxide pastes on Enterococcus faecalis cultivated in Root Canal Systems

The effectiveness of calcium hydroxide pastes: Calen™ and PMCC-Calen™ associated to chemo-mechanical preparation was assessed on Enterococcus faecalis grown within root canals. Seventy incisors were inserted into TSB medium, sterilized and contaminated with E. faecalis. Culture medium was replaced each 24 h and incubated at 37oC for 72 h. After chemo-mechanical preparation, root canals were filled with Calen™ or PMCC-Calen™ (7 or 14 days). Pastes were removed and teeth were inserted into test tubes containing Enterococcosel broth. Calen™ paste (maintained for 7 and 14 days) induced 70% elimination of enterococci and PMCC-Calen™ 100% elimination only after maintenance for 14 days. These medications were significantly more effective (p<0.001) than chemo-mechanical protocol alone and PMCC-Calen™ maintained for 7 days, both incapable to eliminate the viability of enterococci. Calcium hydroxide pastes demonstrated important adjuvant effects in the elimination of enterococci during chemo-mechanical preparation of root canal systems. When associated with PMCC, calcium hydroxide pastes should be maintained for at least 14 days.

In vitro evaluation of the effectiveness of the chemomechanical preparation against Enterococcus faecalis after single- or multiple-visit root canal treatment

The purpose was to assess the elimination of Enterococcus faecalis in vitro in human mandibular premolars after chemomechanical preparation with or without the use of a calcium hydroxide dressing. After 60 days of contamination with E. faecalis, the root canals were prepared using the Crown-Down technique combined with 2% chlorhexidine gel irrigation. Then, the specimens were divided into two experimental groups, treated in a single visit or in multiple visits, and two control groups. The multiple-visit group received a dressing with calcium hydroxide for 14 days (Calen) and the single-visit group did not receive any medication. In the two control groups, the canals were filled with BHI after chemomechanical preparation with 2% chlorhexidine gel or distilled water. Microbial samples were taken from the root canals for colony forming unit count for each phase of the treatment using sterile paper points inside the root canal lumen. Data were ranked and analyzed by the Kruskal-Wallis statistical test. The residual microbial colonies were then assessed. The results showed that chemomechanical preparation using 2% chlorhexidine gel with no intra-canal dressing reduced by 100% the E. faecalis contamination of the root canal lumen. The calcium-hydroxide group that received the 14-day intra-canal dressing allowed a small number of bacteria to grow between visits, but without statistical differences between groups.

Antimicrobial effect of propolis and other substances against selected endodontic pathogens

OBJECTIVE

The aim of this study was to determine the antimicrobial effect of ethanol extract of propolis (EEP) and intracanal medicaments calcium hydroxide, camphorated paramonochlorophenol, and formocresol by means of the macrodilution method using the reinforced clostridial medium (RCM) and brucella and brain heart infusion media.

STUDY DESIGN

The antimicrobial agents were sequentially diluted and tested against anaerobic bacteria Prevotella nigrescens, Fusobacterium nucleatum, Actinomyces israelii, and Clostridium perfringens and against Enterococcus faecalis, with the 5 x 10(5) CFU/mL standardized inocula. The tubes were anaerobically incubated and the minimum inhibitory concentration was detected. Blood agar RCM subcultures were performed to provide minimum bactericidal concentration. The results were analyzed by analysis of variance test.

RESULTS

All drugs were effective against all tested strains, without statistical differences. E. faecalis was the less susceptible strain, and RCM broth promoted faster bacterial growth, but there were no significant differences in these results. Ethanol did not influence the antimicrobial effect of EEP.

Duration-dependent susceptibility of endodontic pathogens to calcium hydroxide and chlorhexidene gel used as intracanal medicament: an in vitro evaluation

The aim of this study was to evaluate the effective duration of antimicrobial activity of a calcium hydroxide-based medicament (Apex Cal) and 2% chlorhexidene gluconate gel against selected endodontic pathogens (Enterococcus faecalis, Candida albicans, Porphyromonas gingivalis, and Prevotella intermedia). The agar diffusion test was used to determine the antimicrobial activity. Chlorhexidene gluconate gel showed the largest inhibitory zones. The antimicrobial action of both medicaments decreased significantly with time, with calcium hydroxide showing no antimicrobial action after 72 hours. In conclusion, 2% chlorhexidene gel showed better antimicrobial activity than calcium hydroxide, and the effective antimicrobial action of both medicaments decreased after 48 hours.

Bacterial reduction in infected root canals treated with 2.5% NaOCl as an irrigant and calcium hydroxide/camphorated paramonochlorophenol paste as an intracanal dressing

This clinical study investigated the bacterial reduction after instrumentation using 2.5% sodium hypochlorite (NaOCl) as an irrigant and further interappointment dressing with a calcium hydroxide (Ca(OH)(2))/camphorated paramonochlorophenol (CPMC) paste. Eleven teeth with primary intraradicular infections and chronic apical periodontitis selected according to stringent inclusion/exclusion criteria followed in the study. Bacterial samples were taken before treatment (S1), after chemomechanical preparation using hand NiTi files and 2.5% NaOCl (S2), and following a 7-day medication with a Ca(OH)(2) paste in CPMC (S3). Cultivable bacteria recovered from infected root canals at the three stages were counted and identified by means of 16S rRNA gene sequencing analysis. At S1, all cases harbored bacteria, with a mean number of 2.8 taxa per canal (range, 1-6). At S2, 6 of 11 (54.5%) of the cases yielded positive cultures, with one to three species per canal. At S3, only one case (9.1%) was positive for the presence of bacteria, with Propionibacterium acnes as the only taxon isolated. A significantly high reduction in bacterial counts was observed between S1 and S2, and S1 and S3. Significant differences were also observed for comparisons involving S2 and S3 samples with regard to both quantitative bacterial reduction (p = 0.029) and number of culture-negative cases (p = 0.03). It was concluded that chemomechanical preparation with 2.5% NaOCl as an irrigant significantly reduced the number of bacteria in the canal but failed to render the canal free of cultivable bacteria in more than one-half of the cases. A 7-day intracanal dressing with Ca(OH)(2)/CPMC paste further significantly increased the number of culture-negative cases.

Residual antibacterial activity of chlorhexidine digluconate and camphorated p-monochlorophenol in calcium hydroxide-based root canal dressings

The purpose of this study was to evaluate the residual antibacterial activity of several calcium hydroxide [Ca(OH)2]-based pastes, placed in root canals of dogs' teeth with induced chronic periapical lesions. Root canals were instrumented with the ProFile rotary system and filled with 4 pastes: G1 (n=16): Ca(OH)2 paste + anesthetic solution; G2 (n=20): Calen® paste + camphorated p-monochlorophenol (CMCP); G3 (n=18): Calen®; and G4 (n=18): Ca(OH)2 paste + 2% chlorhexidine digluconate. After 21 days, the pastes were removed with size 60 K-files and placed on Petri plates with agar inoculated with Micrococcus luteus ATCC 9341. Pastes that were not placed into root canals served as control. After pre-diffusion, incubation and optimization, the inhibition zones of bacterial growth were measured and analyzed by Mann-Whitney U test at 5% significance level. All pastes showed residual antibacterial activity. The control samples had larger halos (p<0.05). The mean residual antibacterial activity halos in G1, G2, G3 and G4 were 7.6; 10.4; 17.7 and 21.4 mm, respectively. The zones of bacterial growth of G4 were significantly larger than those of G1 and G2 (p<0.05). In conclusion, regardless of the vehicle and antiseptic, all Ca(OH)2-based pastes showed different degrees of measurable residual antibacterial activity. Furthermore, unlike CMCP, chlorhexidine increased significantly the antibacterial activity of Ca(OH)2.

In vitro evaluation of the antimicrobial activity of calcium hydroxide combined with chlorhexidine gel used as intracanal medicament

The aim of this study was to investigate the antimicrobial activity of calcium hydroxide (Ca(OH)2) combined with 2% chlorhexidine gluconate (CHX) gel against endodontic pathogens and to compare the results with the ones achieved by Ca(OH)2 mixed with sterile water and by CHX gel alone. Two methods were used: the agar diffusion test and the direct contact test. Ca(OH)2 + 2% CHX gel produced inhibitory zones ranging from 2.84 to 6.5 mm, and required from 30 seconds to 6 hours to eliminate all tested microorganisms. However, 2% CHX gel showed the largest microbial growth zones from 4.33 to 21.67 mm, and required 1 minute or less to inhibit all tested microorganisms. A paste of Ca(OH)2 plus sterile water inhibited only the microorganisms with which it was in direct contact and required from 30 seconds to 24 hours to kill all tested microorganisms. In conclusion, 2% CHX gel + Ca(OH)2 showed better antimicrobial activity than Ca(OH)2 manipulated with sterile water.

Recovery of Enterococcus faecalis after single- or multiple-visit root canal treatments carried out in infected teeth ex vivo

AIM

To assess the presence of Enterococcus faecalis after root canal treatment in single or multiple visits in an ex vivo model.

METHODOLOGY

Forty-five premolar teeth were infected ex vivo with E. faecalis for 60 days. The canals were then prepared using a crowndown technique with System GT and Gates-Glidden burs and irrigated with 2% chlorhexidine gel. The specimens were divided into five groups (G1, G2, G3, G4 and G5) according to the time elapsed between chemical-mechanical preparation and root canal filling, the irrigant solution used and the use or nonuse of a calcium hydroxide intra-canal medicament. The teeth were then root-filled and incubated for 60 days at 37 degrees C. Dentine chips were removed from the canal walls with sequential sterile round burs at low speed. The samples obtained with each bur were immediately collected in separate test tubes containing Brain-Heart Infusion broth. These samples were placed onto agar plates and colony forming units were counted after 24 h at 37 degrees C. Data were ranked and analysed using the Kruskal-Wallis statistical test.

RESULTS

Enterococcus faecalis was recovered from 20% (three of 15 specimens) of G1 (chlorhexidine irrigation and immediate root filling in a single visit), 25% (four of 15 specimens) of G2 (chlorhexidine irrigation and filling after 14 days use of a calcium hydroxide dressing in multiple visits), 40% (two of five specimens) of G3 (chlorhexidine irrigation and filling after 7 days), 60% (three of five specimens) of G4 (saline irrigation and filling after 7 days) and from 100% (five of five specimens) of G5 (saline irrigation and immediate filling without sealer).

CONCLUSIONS

Neither single- nor multiple-visit root canal treatment ex vivo, eliminated E. faecalis completely from dentinal tubules. Up to 60 days after root filling, E. faecalis remained viable inside dentinal tubules. When no sealer was used, E. faecalis presented a higher growth rate.

Histologic evaluation of periradicular tissues in dogs treated with calcium hydroxide in combination with HCT20 and camphorated P-chlorophenol

OBJECTIVE

The aim of this study was to evaluate the biocompatibility of calcium hydroxide suspended in HTC20 or calcium hydroxide plus CMCP and their effects on the healing of periapical lesions in dogs.

STUDY DESIGN

Experimental apical periodontitis was induced by opening the pulp chamber of 36 mandibular premolars in 6 3-year old dogs. The teeth were left opened for 1 week and then closed with IRM for 60 days in order to induce periapical lesions. The teeth were divided into 1 control and 2 experimental groups. Both experimental groups received intracanal dressings with a calcium hydroxide slurry. In the first experimental group calcium hydroxide was mixed with a detergent vehicle and in the second group with camphorated parachlorophenol. The medications were kept in the root canal for 2 periods of 30 days each. Afterwards, the dogs were killed and the periapical areas were studied histologically.

RESULTS

Based on biocompatibility and tissue remodeling in the periapical area, the best results were observed when calcium hydroxide was mixed with the detergent. The difference was statistically significant (P < .05).

CONCLUSION

Calcium hydroxide plus CMCP intracanal dressing was the most irritating to the periapical region, and the group of calcium hydroxide plus HCT 20 showed the best results whenever biocompatibility and the capacity of new bone formation was considered.

Apical Diffusion of Calcium Hydroxide in an in vitro Model

An in vitro agar model was developed to study the effect of intracanal medicaments on periapical tissues and was used to study the diffusion of three calcium hydroxide (Ca(OH)2) medicaments of varying viscosity through simulated root canals with various sizes of apical foramina. Experimental medicaments were added to pipette tips used to represent tooth roots, which were fixed in syringes containing brain heart infusion agar and calcium-reactive dye. OH and Ca concentrations were measured in the agar at 30 minutes and 24 hours. Ca concentration and pH increased with larger aperture sizes, and higher pH and Ca diffusion was produced by a 10% Ca(OH)2 solution than was produced by Pulpdent or a Ca(OH)2 paste. The results suggest that the properties of the Ca(OH)2-containing vehicle could affect the action of the medicament in the periapical tissues.

Antibacterial Efficacy of Calcium Hydroxide and Chlorhexidine Gluconate Irrigants at 37°C and 46°C

This study investigated the ability of two endodontic irrigants to eliminate Enterococcus faecalis from dentinal tubules, and whether their antimicrobial action was enhanced by heat. The lumens of disks prepared from extracted bovine roots were infected with E. faecalis and incubated for 72 h. Specimens were then filled with saline, 10% calcium hydroxide (Ca(OH)2), or 0.12% chlorhexidine gluconate (CHX) at 24 degrees C or 46 degrees C and incubated at 37 degrees C or 46 degrees C. The samples were then pulverized and plated to quantify residual bacteria. No statistical difference (p > 0.05) in bacterial growth was seen between the two saline groups, or between the two medication groups at a given temperature. CHX and Ca(OH)2 at either temperature produced significantly less growth than either saline group, and CHX or Ca(OH)2 at 46 degrees C produced significantly less growth than either group at 37 degrees C. Heat enhanced the antibacterial action of both experimental irrigants against E. faecalis, but heating saline produced no increase in bactericidal effect.