A green hydrophobic deep eutectic solvent for extraction of phenol from aqueous phase.

Deep eutectic solvents (DESs), have been recognized as effective materials for the extraction of different compounds. In this study, the performance of a novel hydrophobic DES was evaluated for the extraction of phenol from aqueous solutions. Octanoic and dodecanoic fatty acid precursors with a definite molar ratio of 3:1, respectively, were used for the DES having a low melting point of 8.3 °C. The purity and stability of the product were confirmed via characterizing by FTIR, 1H and 13C NMR methods. The liquid-liquid equilibrium of the water + phenol + DES ternary system at different temperatures of 293.2, 298.2 and 308.2 K was accordingly studied through cloud point titration method and refractive index measurement. Interestingly, the important parameters of the solute distribution coefficient and the separation factor were, respectively, within the high levels of (6.8321-9.7787) and (895.76-2770.17), indicating the amazing capability of the DES. Reasonably, both of these parameters decreased with temperature. The NRTL and UNIQUAC thermodynamic models were employed to reproduce the obtained tie-lines and to determine the interaction parameters at each temperature. The low level root mean square deviations for the mentioned models were, respectively, within (0.0014-0.0027) and (0.0045-0.0063); confirming satisfactorily agreement with the experimental data.

Mass transfer intensification for carbon quantum dot nanofluid drops under pulsed electric fields.

Simultaneous use of carbon quantum dot (CQD) nanofluids and pulsed electric fields exhibits amazing mass transfer intensification in liquid-liquid extraction of circulating drops. Here, the chemical system of kerosene-acetic acid-water with mass transfer resistance in the organic phase was used in which organic nanofluid drops contained CQD or modified CQD-Fe. These products with extremely small sizes of 7.2 and 13.4 nm were synthesized and characterized by DLS, Zeta potential, XRD, EDS and SEM techniques. To find optimum conditions, CQD concentrations within (0.0005-0.003) wt%, electric field frequencies within (50-550) Hz and electric field strengths to 16 V/cm were examined. From hydrodynamic point of view, the flow pattern of drops was in circulating mode, and that terminal velocity of drops correctly followed the Grace model. The substantial effect of pulsed electric field on the CQD and CQD-Fe nanofluids, brought about mass transfer enhancements to 263.5 and 291.6%. This can be attributed to the electro-induced motion of global CQDs with pulsed electric fields. For the aim of modelling, the adapted Kumar and Hartland equation with a developed correlation of the enhancement factor versus involved dimensionless variables were satisfactory to reproduce the mass transfer coefficient data.

Integrated ozone-sono-Fenton for the enhanced degradation of acid orange 7: process optimization and kinetic evaluation.

The performance of novel hybrid advanced oxidation, ozone-sono-Fenton process in degradation of acid orange 7 (AO7), as a model of azo dyes was modelled and optimized using response surface methodology (RSM) based on central composite design (CCD). Utilizing a bubbling reactor equipped with an ultrasound probe and in the presence of Fenton reagents, a promising hybrid homogeneous AOP, ozone-sono-Fenton, was investigated. According to the experimental results, the variation trend of degradation efficiency (DE%) with pH, reaction time and Fe2+/H2O2 molar ratio was modelled with the reduced quadratic model. Additionally, the suitability of the model was indicated with close to unity regression coefficient [Formula: see text]. Furthermore, the comparative study of degradation efficiency and COD removal for the individual methods including ozonation, sonication and Fenton reagents as well as their hybrid processes reveals that the novel proposed technique, ozone-sono-Fenton process, is able to rapid and complete degradation of acid orange 7 with initial concentration of 300 mg L-1, 100% in only 12 min. The complete degradation was obtained under optimum conditions such as pH = 6, reaction time = 12 min and Fe2+/H2O2 molar ratio = 0.0040. The kinetics evaluation of the acid orange 7 concentration during the processing implied the first-order reaction. Considering the synergetic effect and cost-effectiveness of the hybrid method, the promising ozone-sono-Fenton method could effectively degrade using a wide range of organic contaminants.

Effect of Incorporating Hydroxyapatite and Zinc Oxide Nanoparticles on the Compressive Strength of White Mineral Trioxide Aggregate.

STATEMENT OF THE PROBLEM: Many efforts have been made to improve the properties of mineral trioxide aggregate (MTA), including the incorporation of nanoparticles. PURPOSE: The aim of this study was to investigate the incorporation of zinc oxide and hydroxyapatite nanoparticles on the compressive strength of white MTA (WMTA). MATERIALS AND METHOD: In this in vitro study, the following materials were evaluated: MTA, MTA+5% zinc oxide (ZnO) nanoparticles, MTA+10% zinc oxide nanoparticles, MTA+5% hydroxyapatite (HA) nanoparticles, MTA+10% zinc oxide nanoparticles. The compressive strength of the groups under investigation was measured on days 4 and 21 after mixing the MTA using a universal testing machine. Two-way ANOVA test was used to compare the groups and determine the significance of the effect of time and material on the compressive strength (p<0.05). RESULTS: The highest and lowest compressive strength values were respectively measured for the second group, MTA/21 days, and the fourth group, MTA+Nano ZnO/4 days. Two-way ANOVA indicated that incorporation of zinc oxide and hydroxyapatite nanoparticles into MTA did not have a significant effect on compressive strength (p= 0.05). Compressive strength in all the groups increased over time from day 4 to day 21. However, this increase was not statistically significant (p= 0.06) except for the MTA group, which exhibited significant increase in compressive strength over time from day 4 to day 21 (p=0.007). CONCLUSION: Incorporation of HA and ZnO nanoparticles into MTA had no detrimental effects on its strength and these nanoparticles can be used to improve the other properties of MTA.

The Effect of Submucosal Injection of Corticosteroids on Pain Perception and Quality of Life after Root Canal Treatment of Teeth with Irreversible Pulpitis: A Randomized Clinical Trial.

INTRODUCTION: The aim of the present investigation was to study the effect of local infiltration of corticosteroids on postoperative pain and quality of life (QOL) in teeth with irreversible pulpitis after 1-visit endodontic treatment. METHODS: In this double-blind randomized clinical trial, 242 healthy patients with irreversible pulpitis undergoing 1-visit endodontic treatment were included. Forty-five patients were lost during the follow-up, and the remaining 197 patients were followed for 7 days (67 patients in the placebo group, 66 in the long-acting betamethasone group, and 64 in the dexamethasone group). The patients marked their level of pain and QOL before treatment and at 6-, 12-, 24-, 48-, and 72-hour and 7-day postoperative intervals using a questionnaire. Freidman and Kruskal-Wallis tests were used for statistical analysis. P ≤ .05 was considered significant. RESULTS: The pain was more severe in the placebo group compared with the other groups at all time intervals. A significant increase was observed in pain severity after 12 hours in all 3 groups. In general, the pain was less severe in the dexamethasone group compared with the betamethasone group at 6-, 12-, and 24-hour intervals. The pain severity was similar in both groups at 48 hours, and it was less severe in the long-acting betamethasone group compared with the dexamethasone group after 72 hours and 7 days. There were no significant differences in the betamethasone and dexamethasone groups in pain intensity between males and females. Moreover, overall pain perception was higher in the mandible than in the maxilla. There was an inverse and significant relationship between pain severity and QOL. CONCLUSIONS: Infiltration of long-acting betamethasone and dexamethasone resulted in decreased postoperative pain experience. Dexamethasone was more effective in alleviating pain within the first 24-hour period after treatment. Infiltration of long-acting betamethasone and dexamethasone exhibited the same efficacy in 48 hours. The efficacy of long-acting betamethasone in pain relief lasted for 7 days. The QOL in the 2 groups receiving corticosteroids was higher than that in the placebo group.

Effect of acidic and alkali shocks on expression of efaA gene in Enterococcus faecalis, isolated from root canal infection.

Enterococcus faecalis is an important opportunistic infectious agent involving the oral cavity and endodontics. The aim of this study was to evaluate the expression ratio of efaA gene in biofilm producer E. faecalis before and after receiving acidic and alkali shocks. One hundred E. faecalis isolates were gathered from 170 infectious root canals. After analysis of biofilm formation by the Microtiterplate method, the presence of efaA gene was examined by PCR and its expression was evaluated by Real-time PCR, one before applying any stressed to isolates and another by applying acidic and alkali shock. Chi-square method was used for statistical analysis. Eighty-two percent of samples had efaA gene. Evaluation of biofilm formation, 49% of the isolates were strong biofilm producer, 42% moderate and 10 % of them had no biofilm. 59% overexpression of efaA gene was observed in biofilm producer isolates, while there were no significant changes in samples with acidic stress and decreased expression after alkali shock. Findings of the present study, indicates importance of efaA gene in biofilm formation and pathogenesis of E. faecalis. Acid had no effect of expression of this gene but alkali reduced expression of this gene in a significant level. These results indicate the importance of efaA and acidic conditions in biofilm production by E. faecalis.

Anatomic Features of C-shaped Mandibular Second Molars in a Selected Iranian Population Using CBCT.

INTRODUCTION: The aim of this retrospective study was to analyze the frequency of C-shaped root canal configuration and characterize mandibular root canal morphology using cone-beam computed tomography (CBCT) with 3D images in an Iranian population. METHODS AND MATERIALS: This study consisted of retrospective evaluation of CBCT images from 231 adult patients (153 with bilateral second mandibular molars). Two endodontists examined 384 mandibular second molars of a population in Tabriz, Iran to determine the presence of C-shaped canals and their anatomical characteristics. Root canal configurations were categorized at three different levels. Bilateral or unilateral occurrence of C-shaped canals and their relationship to gender, age and tooth position were examined and statistically analyzed using chi squared test and Fisher's exact test in SPSS 17. The significance level was set at 0.05. RESULTS: Of 384 mandibular second molars examined, 82 (21.4%) molars from 58 patients had a C-shaped root canal configuration. The prevalence of bilateral C-shaped canals was 15.6% amongst 153 patients with bilateral mandibular second molars. There were no significant differences in the distribution of C-shaped canals with respect to gender or age (P=0.06 and P=0.86, respectively). Only 4 teeth (4.9%) had the same root canal configuration from the orifice to the apex. In the remainder of the teeth, the cross-sectional root canal configuration changed at different levels of the root. CONCLUSION: There were significant variations in the number of roots and canal morphology in mandibular second molars, which should be considered during debridement and obturation of the root canal system.

Genotoxicity, Bioactivity and Clinical Properties of Calcium Silicate Based Sealers: A Literature Review.

An ideal endodontic sealer should have many properties such as excellent seal after setting, dimensional stability, slow setting time to ensure sufficient working time, insolubility to tissue fluids, adequate adhesion with canal walls and biocompatibility. Genotoxicity is one of the important factors that influence biocompatibility of an endodontic sealer. This literature review was conducted to survey the genotoxicity, bioactivity and clinical perspectives of calcium silicate based sealers. We searched PubMed using appropriate MeSH keywords. Also a hand search was conducted in the related journals. Sixty eight articles were assessed finally. Genotoxicity and acute inflammation were high in calcium silicate based sealers. Both resin-based and calcium silicate based sealers caused perceptible tooth discoloration. There were controversies regarding the fracture resistance, apical patency and retreatability of different sealers. Clinical properties of calcium silicate-based sealers are also outlined.

Composition and physicochemical properties of calcium silicate based sealers: A review article.

BACKGROUND: Recently a new generation of endodontic sealers has been developed based on calcium silicate as MTA Fillapex, Endoseal MTA, Total Fill BC Sealer, EndoSequence BC Sealer, iRoot SP, Endo CPM sealer, MTA-Angelus and ProRoot Endo Sealer. A review of literature was conducted to discuss the composition, physicochemical properties, and clinical perspectives of calcium silicate based sealers. MATERIAL AND METHODS: A literature search was conducted in PubMed and web of knowledge databases with appropriate MeSh terms and keywords. A total of 71 studies were reviewed for data extraction. RESULTS AND CONCLUSIONS: Calcium silicate based sealers showed suitable physical properties to be used as an endodontic sealer. However, its high solubility remains an important issue. They show good performance regarding calcium ion release, film thickness, and fowability. More researches are required about features of calcium silicate based sealers before recommending them for clinical applications. Key words:Calcium silicate, root canal filling materials, composition, physical properties.

Effect of different mixing methods on the bacterial microleakage of white Portland cement and white Mineral Trioxide Aggregate.

Background. of this study was to investigate the effect of different mixing methods (ultrasonic, amalgamator, and conventional) on the bacterial microleakage of white Portland cement (WPC) and white MTA (Tooth-colored Formula, Dentsply, Tulsa Dental, Tulsa, OK). Methods. A hundred human single-rooted permanent teeth were decoronated to obtain 14 mm of root length in all the samples. The root canals were cleaned, shaped and obturated. Three millimeters of each root apex were cut off and randomly divided into 6 groups of 15 each (3 groups for WMTA and 3 groups for WPC, each with 3 different mixing methods) and 2 positive and negative control groups (each containing 5 samples). Brain-heart infusion agar (BHI) suspension containing the bacterial species Enterococcus faecalis (ATCC 29212) was used for leakage assessment. Statistical analysis was carried out using descriptive statistics and Kaplan Mayer survival analysis with censored data and log rank test using SPSS 18. Statistical significance was set at P<0.05. Results. The survival means in PC for conventional method, amalgamator, and ultrasonic were 80.2±13.64, 78.5±13.46 and 84.667±11.42 days, with 49.13±12.96, 66±13.32 and 69.07±11.5 days for MTA, respectively. The log rank test showed no significant differences between the three methods in each material (P>0.05). Conclusion. Bacterial microleakage in the studied samples was not significantly different in terms of the type of the mixing method.

Importance and methodologies of endodontic microleakage studies: A systematic review.

INTRODUCTION: It is very important to obtain a tight seal in obturated root canal, making it necessary to conduct clinical or laboratory studies on the sealability of endodontic materials. Different methodologies have been historically used to assess microleakage of different endodontic materials. The aim of the present study was to comprehensively review different material testing methods used in microleakage studies, their interpretation and importance in endodontic literature. MATERIAL AND METHODS: A systematic search was conducted in Medline, Cochrane, and Web of Science databases. In addition, the reference lists of review articles on the topic were searched. No language restriction was applied. Two independent reviewers screened the article. RESULTS: Microleakage is considered the single most important risk factor responsible for apical periodontitis. Dye penetration, dye diffusion, bacterial and endototoxin infiltration, fluid filtration, glucose, caffeine and protein infiltration, radioisotope penetration, animal studies, and electrochemical or 3D evaluation are different methodologies used to assess dental leakage. 91 out of 177 articles in the primary search were included in the study. These methods are very divergent in their viewpoints; that is why their results cannot be easily compared. It is necessary to standardize microleakage detection methods in order to more correctly evaluate the phenomena that are found between the root canal wall and the root canal filling materials. CONCLUSIONS: All the methods are useful if studies are performed strictly with large sample sizes and proper control groups and if the technique can be standardized. Furthermore, more evaluations of the reliability of the methods are strongly recommended. Key words:Dental leakage, review, root canal, material testing methods, data interpretation.

Endodontic microleakage studies: correlation among different methods, clinical relevance, and potential laboratory errors.

INTRODUCTION: Creation of a tight seal in endodontically treated root canals is of utmost importance. Clinical and laboratory studies have a great role in the assessment of the sealing ability of endodontic materials. The present review was undertaken to evaluate correlation between different techniques used in microleakage studies in endodontics and the potential laboratory errors. EVIDENCE ACQUISITION: A systematic search was run using Medline, Biosis, Cochrane Database, Embase, Google Scholar, and Web of Science databases. Furthermore, the reference lists of the articles published on the subject were thoroughly searched. There was no language restriction in the search. Two reviewers separately evaluated the titles and abstracts. EVIDENCE SYNTHESIS: All the methods used might have proved useful if the study could have been carried out with a larger sample size, with carefully designed control groups. Furthermore, extra evaluations are recommended on the reliability of the method used. Examinations like glucose reactivity test, assessment of antimicrobial activity of the tested materials and in situ FISH examination for the reliability of bacterial leakage model have been recommended. It has been recommended that two or more methods be considered for each material in the same study. On the other hand, long-term animal studies can be useful with histological and radiographic evaluations for meticulous assessment of leakage. Furthermore, long-term clinical trials on humans might be helpful on the condition that confounding factors are controlled. CONCLUSIONS: Studies on microleakage should be focused on animal studies, clinical trials or laboratory tests. On the basis of available evidence, it appears that despite potential errors on microleakage studies they are very valuable.

In vitro Cytotoxicity Comparison of MTA Fillapex, AH-26 and Apatite Root Canal Sealer at Different Setting Times.

INTRODUCTION: This study aimed to compare the cytotoxicity of MTA Fillapex, AH-26 and Apatite root canal sealers at different times after mixing. METHODS AND MATERIALS: In this in vitro study, MTA Fillapex, AH-26 and Apatite root canal sealer were spilled uniformly by 40 µm mesh in a 96-well plate. Then, human fetal foreskin fibroblast cell line (HFFF2) were added to each sealer cell culture medium. Cytotoxicity was measured using MTT assay after 24, 48 and 72 h and seven days. Multiple comparisons were done using analysis of variances (ANOVA) and Scheffe's post hoc test. RESULTS: All studied sealers exhibited severe cytotoxicity (more than 70%) except for Apatite sealer (95%) at 48 h after mixing. Cytotoxicity of MTA Fillapex and AH-26 were similar (P>0.05) at 24, 48 and 72 h and 7 days after mixing of sealers. Cytotoxicity of MTA Fillapex and Apatite root canal sealer, at 24 and 48 h, were significantly different (P=0.003 and P=0.000, respectively); MTA Fillapex was more cytotoxic. However in 72 h and 7 days after mixing, the difference was not significant (P>0.05). At 24 and 48 h after mixing, AH-26 was more cytotoxic (P=0.002 and P=0.000, respectively). Same as above at 72 h and 7 days after mixing, their cytotoxicity were similar (P>0.05). CONCLUSION: Overall cytotoxicity of all studied materials were severe. However, it was observed that the cytotoxicity of MTA Fillapex, AH-26 and Apatite root canal sealer decreased over time. Apatite root canal sealer exhibited the least cytotoxicity. Cytotoxicity of MTA Fillapex and AH-26 were similar at different time intervals.

Evaluation of Antibacterial Efficacy of Photodynamic Therapy vs. 2.5% NaOCl against E. faecalis-infected Root Canals Using Real-time PCR Technique.

BACKGROUND: Bacteria like E. faecalis can produce intra- and extra-radicular biofilms. Theoretically, the adjustable penetration ability of lasers enables better access to root canal system. Therefore the aim of the present study was to compare the ability of photoactivated laser and 2.5% NaOCl irrigation solution to eliminate E. faecalis from the root canals by real-time PCR technique. MATERIAL AND METHODS: Sixty extracted human upper central incisors were selected and sterilized in an autoclave. The root canals were infected with E. faecalis (PTCC 1237, Persian Type Culture Collection, Iran) and then incubated for 24 hours. The samples were randomly divided into 3 groups. No intervention was made in the control group (group 1). In group 2, laser therapy was performed with a power of 100 mW by diode laser for 120 seconds. In group 3, the canals were irrigated with 5 mL of 2.5% NaOCl; then all the samples were sonicated in 15 mL of normal saline in test tubes in order to isolate the bacteria. DNA extraction was performed followed by real-time PCR technique for all the samples. RESULTS: Inhibition of bacterial growth in all the experimental samples was significantly more than that in the control group. There was a significant difference between photodynamic therapy and 2.5% NaOCl. The effect of NaOCl in all the samples was better than photodynamic therapy. The results of the mean CT (cyclic threshold) were 40, 30.2 and 15.35 for 2.5% NaOCl, photodynamic therapy and control group, respectively. CONCLUSIONS: Based on the results of this experimental study, 2.5% NaOCl eliminated E. faecalis from infected root canals more effectively compared to photodynamic therapy. Key words:Photoactivated laser, Enterococcus faecalis, antibacterial agents, sodium hypochlorite.

Antifungal Activity of Two Root Canal Sealers against Different Strains of Candida.

INTRODUCTION: Microorganisms and microbial products are the main etiologic factors in pulp and periapical diseases. The present study aimed to compare the antifungal activity of two different sealers, AH-26 and MTA Fillapex against three strains of Candida, 24, 48, 72 h and 7 days after mixing. METHODS AND MATERIALS: The microorganisms used in this study were Candidia albicans (ATCC 10231), Candidia glabrata (ATCC 90030) and Candidia krusei (DSM 70079). This test was based on growth of microorganisms and turbidity measurement technique using a spectrophotometer. The direct contact test was conducted by direct and indirect methods. Multiple comparisons were carried out using analysis of variances (ANOVA) with repeated measures followed by Tukey's tests. RESULTS: The antifungal activity of both sealers was similar in the indirect method. The antifungal activity of both sealers in the direct method was similar against Candida albicans and higher for AH-26 sealer against Candida krusei and Candida glabrata. CONCLUSION: The total antifungal effect of MTA Fillapex sealer was significantly less than AH-26 sealer in direct method. The antifungal effect of both sealers was similar in indirect method.

Effect of different mixing methods on the physical properties of Portland cement.

BACKGROUND: The Portland cement is hydrophilic cement; as a result, the powder-to-liquid ratio affects the properties of the final mix. In addition, the mixing technique affects hydration. The aim of this study was to evaluate the effect of different mixing techniques (conventional, amalgamator and ultrasonic) on some selective physical properties of Portland cement. MATERIAL AND METHODS: The physical properties to be evaluated were determined using the ISO 6786:2001 specification. One hundred sixty two samples of Portland cement were prepared for three mixing techniques for each physical property (each 6 samples). Data were analyzed using descriptive statistics, one-way ANOVA and post hoc Tukey tests. Statistical significance was set at P<0.05. RESULTS: The mixing technique had no significant effect on the compressive strength, film thickness and flow of Portland cement (P>0.05). Dimensional changes (shrinkage), solubility and pH increased significantly by amalgamator and ultrasonic mixing techniques (P<0.05). The ultrasonic technique significantly decreased working time, and the amalgamator and ultrasonic techniques significantly decreased the setting time (P<0.05). CONCLUSIONS: The mixing technique exerted no significant effect on the flow, film thickness and compressive strength of Portland cement samples. Key words:Physical properties, Portland cement, mixing methods.

In vitro evaluation of the sealing ability of three newly developed root canal sealers: A bacterial microleakage study.

BACKGROUND: The purpose of this study was to compare the sealing ability of MTA Fillapex, Apatite Root Canal Sealer and AH26 sealers. MATERIAL AND METHODS: The present in vitro study was carried out on 142 extracted single-rooted human mature teeth. The teeth were randomly divided into three experimental groups (n=44) and two control groups (n=5). Three root canal sealers were MTA Fillapex, Apatite Root Canal Sealer and AH26. The teeth in the control groups were either filled with no sealer or made completely impermeable. The root canals were prepared and obturated with gutta-percha and one of the sealers. The teeth were sterilized with ethylene oxide gas prior to the bacterial leakage assessment using Enterococcus faecalis. Leakage was evaluated every 24 hours for 90 days. Data were analyzed with descriptive statistical methods and chi-squared test. If the data were significant, a proper post hoc test was used. Statistical significance was set at P<0.05. RESULTS: The positive control specimens exhibited total bacterial penetration whilst the negative control specimens showed no evidence of bacterial penetration. At the end of the study, the analysis of microleakage with chi-squared test showed no significant differences between the experimental groups (P<0.05). The results of chi-squared test analyzing the pair-wise differences between the groups considering the numerical values for leakage day indicated the lowest leakage with AH26 and the highest with Apatite root sealer. CONCLUSIONS: According to the results of the present study, sealing ability of AH26 was significantly higher than that of MTA Fillapex and Apatite Root Canal Sealer. Key words:Mineral Trioxide aggregate, root canal obturation, dental seal.

Effect of different mixing methods on the bacterial microleakage of calcium-enriched mixture cement.

BACKGROUND: Calcium-enriched mixture (CEM) cement is used in the field of endodontics. It is similar to mineral trioxide aggregate in its main ingredients. The present study investigated the effect of different mixing methods on the bacterial microleakage of CEM cement. METHODS: A total of 55 human single-rooted human permanent teeth were decoronated so that 14-mm-long samples were obtained and obturated with AH26 sealer and gutta-percha using lateral condensation technique. Three millimeters of the root end were cut off and randomly divided into 3 groups of 15 each (3 mixing methods of amalgamator, ultrasonic and conventional) and 2 negative and positive control groups (each containing 5 samples). BHI (brain-heart infusion agar) suspension containing Enterococcus faecalis was used for bacterial leakage assessment. Statistical analysis was carried out using descriptive statistics, Kaplan-Meier survival analysis with censored data and log rank test. Statistical significance was set at P<0.05. RESULTS: The survival means for conventional, amalgamator and ultrasonic methods were 62.13±12.44, 68.87±12.79 and 77.53±12.52 days, respectively. The log rank test showed no significant differences between the groups. CONCLUSIONS: Based on the results of the present study it can be concluded that different mixing methods had no significant effect on the bacterial microleakage of CEM cement.

Antibacterial Activity of MTA Fillapex and AH 26 Root Canal Sealers at Different Time Intervals.

INTRODUCTION: The main goal of endodontic treatment is elimination of bacteria and their by-products from infected root canals. This study compared the antibacterial effect of two different sealers, AH 26 and MTA Fillapex, on 4 microorganisms 24, 48 and 72 h and 7 days after mixing. METHODS AND MATERIALS: The microorganisms used in this study consisted of Lactobacillus acidophilus (ATCC 4356), Lactobacillus casei (ATCC 39392), Staphylococcus aureus (ATCC 25923) and Enterococcus faecalis (ATCC 29212). This test is based on the growth of bacteria and turbidity measurement technique using a spectrophotometer, and direct contact was conducted. Multiple comparisons were carried out using repeated-measures ANOVA followed by Tukey's test and student's t-test. The level of significance was set at 0.05. RESULTS: The antibacterial activity in the indirect technique was more than the technique with both sealers. In the direct technique the antibacterial activity on all microorganisms were lower for MTA Fillapex sealer. In the indirect technique, both sealers exhibited similar antibacterial properties. CONCLUSION: The antibacterial effect of MTA Fillapex sealer was significantly less than that of AH 26 sealer in the direct technique. The antibacterial effects of both sealers were similar in the indirect technique.

Effect of different mixing methods on the bacterial microleakage of calcium-enriched mixture cement.

BACKGROUND: Calcium-Enriched Mixture Cement is used in the field of endodontics. It is similar to Mineral Trioxide Aggregate in its main ingredients.The present study investigated the effect of different mixing methods on the bacterial microleakage of CEM cement. METHODS: A total of 55 human single-rooted human permanent teeth were decoronated so that 14- mm-long samples were obtained and obturated with AH26 sealer and gutta-percha using lateral condensation technique. Three millimeters of the root end were cut off and randomly divided into 3 groups of 15 each (3 mixing methods of amalgamator, ultrasonic and conventional) and 2 negative and positive control groups (each containing 5 samples). BHI (Brain-Heart Infusion Agar) suspension containing Enterococcus faecalis was used for bacterial leakage assessment. Statistical analysis was carried out using descriptive statistics, Kaplan‒Meier survival analysis with censored data and log rank test. Statistical significance was set at P<0.05. RESULTS: The survival means for conventional, amalgamator and ultrasonic methods were 62.13±12.44, 68.87±12.79 and 77.53±12.52 days, respectively. The log rank test showed no significant differences between the groups. CONCLUSIONS: Based on the results of the present study it can be concluded that different mixing methods had no significant effect on the bacterial microleakage of CEM cement.