Antimicrobial effect of six endodontic sealers: an in vitro evaluation

Evaluation of the Antibacterial Activity of Triclosan-incorporated Root Canal Filling Materials for Primary Teeth against Enterococcus faecalis

Aim and objective

To compare the antibacterial activity of root canal filling materials namely zinc oxide eugenol and Endoflas FS with or without the incorporation of Triclosan.

Materials and methods

The study consisted of four groups, with 15 samples in each group: group I (zinc oxide eugenol paste), group Ia (zinc oxide eugenol paste + 2.5% Triclosan), group II (Endoflas FS), and group IIa (Endoflas FS + 2.5% Triclosan). A double layer agar well diffusion test was used to evaluate the antibacterial activity against Enterococcus faecalis. The zones of microbial inhibition were measured at the end of 24 hours, 6th day, and 29th day.

Results

On intergroup comparison, the difference in the antibacterial activity was found to be highly significant (p < 0.001). Among the various groups evaluated, group IIa showed the highest antibacterial activity against E. faecalis followed by group II, group Ia, and the least activity being shown by group I throughout the experimental periods. On intragroup comparison at different time intervals, a maximum zone of inhibition was seen at 24 hours with a p value < 0.05 in all the tested groups.

Conclusion

Incorporation of 2.5% triclosan into zinc oxide eugenol and Endoflas FS enhanced the antimicrobial activity of both the root canal filling materials with lasting antimicrobial activity even at the end of the 29th day.

Clinical significance

The antimicrobial efficacy of a root canal filling material is an ideal requirement, which will help in combating the residual microflora present in the root canal system following chemomechanical preparation. The addition of an antimicrobial agent such as triclosan to the root canal filling materials, enhances their antimicrobial efficacy significantly and thus, rendering the pulpectomy-treated tooth with a better prognosis.

How to cite this article

Deepak BM, Prabhakar AR, Karuna YM, et al. Evaluation of the Antibacterial Activity of Triclosan-incorporated Root Canal Filling Materials for Primary Teeth against Enterococcus faecalis. Int J Clin Pediatr Dent 2021;14(3):393–397.

Adding Two Antimicrobial Glasses to an Endodontic Sealer to Prevent Bacterial Root Canal Reinfection: An In Vivo Pilot Study in Dogs

Current endodontic procedures continue to be unsuccessful for completely removing pathogens present inside the root canal system, which can lead to recurrent infections. In this study, we aimed to assess the antimicrobial capacity and tissue response of two inorganic bactericidal additives incorporated into a paste root canal sealer on contaminated root dentin in vivo. An experimental study was performed in 30 teeth of five Beagle dogs. After inducing microbiological contamination, root canal systems were treated by randomly incorporating one of two antimicrobial additives into a commercial epoxy-amine resin sealer (AH Plus), i.e., G3T glass-ceramic (n = 10) and ZnO-enriched glass (n = 10); 10 samples were randomized as a control group. After having sacrificed the animals, microbiological, radiological, and histological analyses were performed, which were complemented with an in vitro bactericidal test and characterization by field emission scanning electron microscopy. The tested groups demonstrated a non-significant microbiological reduction in the postmortem periapical index values between the control group and the bactericidal glass-ceramic group (p = 0.885), and between the control group and the ZnO-enriched glass group (p = 0.169). The histological results showed low values of inflammatory infiltrate, and a healing pattern characterized by fibrosis in 44.4% of the G3T glass-ceramic and 60.0% of ZnO-enriched glass. Bactericidal glassy additives incorporated in this root canal sealer are safe and effective in bacterial reduction.

Evaluation of the Antimicrobial Efficacy of Herbal Extracts Added to Root Canal Sealers of Different Bases: An In Vitro Study

Aim

This study aimed to evaluate and compare the antimicrobial efficacy of root canal sealers of different bases when mixed with herbal extracts.

Materials and methods

An evaluation of three sealers (Endomethasone, AH plus, Apexit plus) mixed with three herbal extracts [Emblica officinalis (Amla), Myristica fragrans (Nutmeg) and Salvadora persica (Miswak)] was done against nine strains of bacteria at various time intervals using the agar diffusion test. Moreover, measurement of the mean zones of inhibition was done.

Results

The largest zones of bacterial growth inhibition were observed with Endomethasone mixed with Myristica fragrans (Nutmeg) followed in the descending order by AH plus mixed with Salvadora persica (Miswak) and Apexit plus mixed with Salvadora persica (Miswak) respectively. The differences between zones of inhibition among different groups were found to be statistically significant.

Conclusion

Zinc-oxide-eugenol-based sealer (Endomethasone) mixed with herbal extracts produced the largest inhibitory zones followed in the descending order by resin-based sealer (AH plus) and calcium-hydroxide-based sealer (Apexit plus), respectively.

Clinical significance

Herbal plants such as [Emblica officinalis (Amla), Myristica fragrans (Nutmeg) and Salvadora persica (Miswak)] are rich sources of bioactive compounds that possess antimicrobial properties. Mixing their extracts with endodontic sealers can produce additive antimicrobial effect against microbes found in inflamed pulp.

How to cite this article

Devi MT, Saha S, Tripathi AM, et al. Evaluation of the Antimicrobial Efficacy of Herbal Extracts Added to Root Canal Sealers of Different Bases: An In Vitro Study. Int J Clin Pediatr Dent 2019;12(5):398–404.

Physical and biological properties of a novel root canal sealer modified by polyhexamethylene guanidine

The key of the root canal therapy is to eliminate the micro-organism infection, fill the root canal tightly and reduce the stimulation to the periapical tissues. However, it is quite difficult to meet all the conditions due to the defect of the material. Here we develop a novel root canal sealer (MZOE), in which zinc oxide eugenol (ZOE) were fabricated with polyhexamethylene guanidine (PHMG), and the PHMG's concentration is 0.8, 1.0, 1.2 and 1.4%. Our investigation tested its physical properties, antibacterial effect to E. faecalis, C. albicans, E. coli, S. aureus and cytotoxicity to human periodontal ligament fibroblasts (HPDLFs). The physical properties of the MZOE conformed to the ISO 6876:2001, and its antibacterial effect was stronger than ZOE (p<0.05), the RGR of HPDLFs was tested between 1 to 24%, belonging to moderate cytotoxicity. It was suggested that MZOE had good physical properties, high antibacterial effect, and moderate cytotoxicity.

Evaluation of the actual chlorine concentration and the required time for pulp dissolution using different sodium hypochlorite irrigating solutions

Introduction:

The goal of root canal treatment is to shape and clean the endodontic space, reducing the bacterial load and removing the pulp tissue. Obviously, the action of the endodontic instruments is limited to the main canals, regardless of the complexity of the endodontic space. Consequently, finding the best possible cleaning technique, which can be obtained chemically using irrigation solutions, is a fundamental aid in endodontic therapy. One of the most commonly used root canal irrigants is sodium hypochlorite (NaOCl), available in various commercial formulations. The effectiveness of NaOCl is undeniable. However, the action of dissolution of the pulp tissue is merely dependent on the concentration and the characteristics of the irrigant itself.

Aim:

The aim of this study is to evaluate the effective concentration of different commercial formulas of NaOCl, by evaluating the percentage of total chlorine in each product. The dissolution capacity of the pulp tissue of each of the tested products was then analyzed by measuring the required time.

Materials and Methods:

Three commercial types of NaOCl were selected for this study: 5% NaOCl (ACE, Procter and Gamble), 5% NaOCl (N5, Simit Dental), and 6% NaOCl (CanalPro, Coltene). For each product, 10 packages were used, from which samples of the product were taken and 30 ml × 5 ml tubes were filled. All samples were divided into three groups and were analyzed using the DIN EN ISO 7393-2 method and the percentage of total chlorine (expressed as a percentage) was calculated. Forty samples of vital pulp were obtained from teeth freshly extracted for periodontal reasons and stored in physiological solution. In order to unify the size and weight of the samples (0.0001 mg), a microtome and a precision balance (Pro Explorer Ohaus) were used. Each sample, carefully examined by stereomicroscope (×40), was placed in artificial plastic containers and submerged in 0.1 ml of irrigating solution at room temperature (26°C). A fourth control group used saline solution as irrigant. Simultaneously with the insertion of the irrigating solution, a digital stopwatch was activated and the time necessary for the complete dissolution of the pulp sample was measured. The data obtained was subjected to statistical analysis.

Results:

The average percentages of chlorine detected for each group were: 4.26% (ACE), 5.16% (N5), and 5.97% (CanalPro). The Kruskal–Wallis test showed statistically significant differences between the different commercial formulations of hypochlorite (P < 0.05). CanalPro showed the lowest values, whereas ACE showed the highest values of dissolution time of the pulp.

Discussion:

The analysis of the total chlorine percentage found that the actual concentration of the NaOCl in the samples is close to the values declared by the manufacturers both in the case of N5 and CanalPro. On the contrary, the concentration detected in the samples of common bench bleach (ACE) is significantly lower, which has average values <5%. This explains the longer time taken for the complete dissolution of the pulp tissue. The average dissolution time of the pulp samples was in fact inversely proportional to the concentration detected in the tested irrigants and hence that a lower time corresponds to a higher concentration.

Triple antibiotic paste: momentous roles and applications in endodontics: a review

This study investigated the latest findings and notions regarding ‘triple antibiotic paste’ (TAP) and its applications in dentistry, particularly endodontics. TAP is a combination of 3 antibiotics, ciprofloxacin, metronidazole, and minocycline. Despite the problems and pitfalls research pertaining to this paste has unveiled, it has been vastly used in endodontic treatments. The paste's applications vary, from vital pulp therapy to the recently introduced regeneration and revascularisation protocol. Studies have shown that the paste can eliminate the root canal microorganisms and prepare an appropriate matrix for further treatments. This combination is able to remove diverse groups of obligate and facultative gram-positive and gram-negative bacteria, providing an environment for healing. In regeneration protocol cases, this allows the development, disinfection, and possible sterilization of the root canal system, so that new tissue can infiltrate and grow into the radicular area. Moreover, TAP is capable of creating a discipline in which other wanted and needed treatments can be successfully performed. In conclusion, TAP, as an antibacterial intracanal medication, has diverse uses. Nevertheless, despite its positive effects, the paste has shown drawbacks. Further research concerning the combined paste and other intracanal medications to control microbiota is a must.

SEM Evaluation of the Root Canal Walls after Treatment with Tetraclean

Purpose

In this ex vivo study, the surface cleanliness of root canal walls after shaping with Ni-Ti instruments and irrigating with different endodontic solutions was evaluated by SEM.

Methods

50 single-rooted teeth were divided into 5 groups. All root canals were shaped with Revo-S™ (MICRO-MEGA®, Besancon, France) rotary Ni-Ti instruments and irrigated with NaOCl, varying the final rinse: NaOCl, Tetraclean, 17% EDTA, Cloreximid, Tetraclean liquid not mixed with powder. Specimens were fractured longitudinally and prepared for SEM analysis in order to evaluate the presence/absence of smear layer and the presence/absence of open tubules at the coronal, middle, and apical third of each canal, using a 3-step scale for scores. Numeric data were analyzed using Kruskall-Wallis test and Mann-Whitney U test and significance was predetermined at p<0.05.

Results

This study showed significant differences between the various groups. The 5.25% NaOCl + Tetraclean and 5.25% NaOCl + 17% E.D.T.A. groups had significantly lower scores than other groups (p<0.001), with no significant difference between them.

Conclusions

Final rinse with Tetraclean is effective in removing the smear layer, leaving a high number of opened dentin tubules.

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.

Intracanal heating of sodium hypochlorite: Scanning electron microscope evaluation of root canal walls

Introduction:

The aim of this study is to evaluate the surface of root canals dentine using scanning electron microscope (SEM) after instrumentation with rotary Nickel-Titanium systems and two different protocols of activation of sodium hypochlorite (NaOCl) (extracanal heating at 50°C and intracanal heating at 180°C), to assess the presence/absence of smear layer and also the presence/absence of open dentinal tubules along the walls at the coronal, middle, and apical third of each sample.

Materials and Methods:

Thirty-six single-rooted teeth were selected, divided into three groups and shaped with ProTaper Universal instruments following irrigation protocols with 5.25% NaOCl. At the end of the preparation, three different protocols of activation were used: nonheated NaOCl in Group A, extra-canal heated NaOCl at 50°C for Group B and intracanal heated NaOCl at 180°C for Group C. Specimens were cut longitudinally and analyzed by SEM at standard magnification of ×1000. The presence/absence of the smear layer as well as the presence/absence of open tubules at the coronal, middle, and apical third of each canal were estimated using a five-step scale for scores. Numeric data were analyzed using Kruskal–Wallis and Mann–Whitney U statistical tests and significance was predetermined at P < 0.05.

Results:

Kruskal–Wallis analysis of variance (ANOVA) for debris score showed significant differences among the Ni-Ti systems (P < 0.05). Mann–Whitney test confirmed that Group A presented significantly higher score values than other Ni-Ti systems. The same results were assessed considering the smear layer scores. ANOVA confirmed that the apical third of the canal maintained a higher quantity of debris and smear layer after preparation of all the samples.

Discussion and Conclusions:

Intra-canal heating of NaOCl at 180°C proved to be more effective in obtaining clean canal walls. On the other hand, extra-canal heating at 50°C of NaOCl left a higher quantity of debris and the smear layer was widely represented.

Evaluation of dental adhesive systems incorporating an antibacterial monomer eugenyl methacrylate (EgMA) for endodontic restorations

OBJECTIVE

The purpose of this study was to incorporate EgMA, an antibacterial monomer into two commercial dental adhesive systems for their application in endodontic restoration with the aim to disinfect the root canal space before curing and to inhibit bacterial growth on their surfaces after being cured.

METHODS

EgMA monomer was added at 20%wt. into the formulation of the single-component self-etch, Clearfil Universal Bond™ (CUB) and into the catalyst and the adhesive components of the total-etch Adper Scotchbond-multipurpose™ (SBMP) adhesive systems. The degree of conversion (DC) was calculated from FTIR spectra, glass transition temperature (Tg) determined by DSC, water sorption and solubility were measured gravimetrically, and surface free energy (SFE) via contact angle measurements. The bonding performance to coronal and middle root canal dentin was assessed through push-out bond strength after filling the canals with a composite core material and the surface integrity was observed using SEM and confocal laser scanning microscopy (CLSM). The standard agar diffusion test (ADT) was used to identify the sensitivity of three endodontically pathogenic bacteria, Enterococcus faecalis, Streptococcus mutans and Propionibacterium acnes to uncured EgMA modified adhesives. Multispecies biofilm model from these strains was grown on the disc surface of cured adhesives and investigated using quantitative microbial culture and CLSM with live/dead staining. MTT assay was also used to determine the cytotoxicity of these adhesives.

RESULTS

The incorporation of EgMA lowered polymerization exotherm and enhanced the hydrophobic character of these adhesives, without changing the DC and Tg in comparison to the controls (without EgMA). The total push-out bond strengths of the EgMA-containing adhesives were not significantly different from those of the controls (p>0.05). The modification of self-etch adhesive system enhanced the bond strength in the middle region of the roots canal. SEM of debonded specimens and CLSM examination showed the integrity of the resin-dentin interfaces. For all three bacteria tested, the sizes of the inhibition zones produced by uncured EgMA modified adhesives were significantly greater (p<0.05) than those of the controls. The results of biofilm inhibition tests showed less CFU for total bacteria on bonding agents with EgMA compared to the control materials (p<0.05). The modification at 20% monomer concentration had no adverse effects on cytocompatibility of both adhesives tested.

SIGNIFICANCE

The inclusion of EgMA endows dental adhesives with effective antibacterial effects without influencing their curing properties, bonding ability to root canal dentin, and cytotoxicity against human gingival fibroblasts, indicating the usefulness of their application in endodontic restorations.

Debris Evaluation after Root Canal Shaping with Rotating and Reciprocating Single-File Systems

This study evaluated the root canal dentine surface by scanning electron microscope (SEM) after shaping with two reciprocating single-file NiTi systems and two rotating single-file NiTi systems, in order to verify the presence/absence of the smear layer and the presence/absence of open tubules along the walls of each sample; Forty-eight single-rooted teeth were divided into four groups and shaped with OneShape (OS), F6 SkyTaper (F6), WaveOne (WO) and Reciproc and irrigated using 5.25% NaOCl and 17% EDTA. Root canal walls were analyzed by SEM at a standard magnification of 2500×. The presence/absence of the smear layer and the presence/absence of open tubules at the coronal, middle, and apical third of each canal were estimated using a five-step scale for scores. Numeric data were analyzed using Kruskal-Wallis and Mann-Whitney U statistical tests and significance was predetermined at P < 0.05; The Kruskal-Wallis ANOVA for debris score showed significant differences among the NiTi systems (P < 0.05). The Mann-Whitney test confirmed that reciprocating systems presented significantly higher score values than rotating files. The same results were assessed considering the smear layer scores. ANOVA confirmed that the apical third of the canal maintained a higher quantity of debris and smear layer after preparation of all the samples; Single-use NiTi systems used in continuous rotation appeared to be more effective than reciprocating instruments in leaving clean walls. The reciprocating systems produced more debris and smear layer than rotating instruments.

F360 and F6 Skytaper: SEM evaluation of cleaning efficiency

AIM

Root canal preparation may produce a large quantity of smear layer that covers canal walls. Single-file systems have recently appeared, with the aim of reducing the number of steps and files to reach a correct endodontic treatment. The purpose of this study was to evaluate by SEM the root canal walls after instrumentation with F360 (Komet, Brasseler GmbH & Co., Lemgo, Germany) and F6 Skytaper (Komet, Brasseler GmbH & Co., Lemgo, Germany), in order to evaluate the presence/absence of smear layer and the presence/absence of open tubules on the root canal walls at coronal, middle, and apical third of each sample.

METHODS

Twenty single-rooted freshly extracted teeth were selected and divided into 2 groups. For each group root canals were shaped with F360 (Komet, Brasseler GmbH & Co., Lemgo, Germany) and F6 Skytaper (Komet, Brasseler GmbH & Co., Lemgo, Germany) instruments under irrigation with 5,25% NaOCl and 17% EDTA. Specimens were fractured longitudinally and analyzed by SEM at standard magnification of 5000x. The presence/absence of smear layer and the presence/absence of open tubules at the coronal, middle, and apical third of each canal were evaluated using a 5-step scale for scores. Numeric data were analyzed using Kruskall-Wallis and Mann-Whitney U statistical tests and significance was predetermined at P <0.05.

RESULTS

This study did not reveal differences among two groups at the coronal and apical third. The apical third showed the highest values of scores for all Ni-Ti systems used. Significant differences in smear layer scores were recorded among the Ni-Ti systems at middle canal level (P < 0.05), where F6 Skytaper showed significantly lower scores than F360.

CONCLUSIONS

Within the limitation of this study, F360 and F6 Skytaper rotary instruments seem to be effective in shaping root canals with good debridement from canal walls, without significant differences between the two systems as it regards the coronal third and the apical third, the area where more debris is still visible. Instead, in the middle third F6 Skytaper seems to be more effective than F360, with statistically significative differences between the two systems.

Cleaning Effectiveness of Three NiTi Rotary Instruments: A Focus on Biomaterial Properties

Nickel-titanium (NiTi) instruments are commonly used for shaping the root canal system in endodontic practice. They are more flexible and have better cutting efficiency than conventional stainless steel files. The superelasticity of NiTi rotary files allows the clinicians to produce the desirable tapered root canal form with a reduced tendency to canal transportation and instrument fracture. HyFlex CM instruments are new NiTi rotary instruments with shape memory produced by an innovative methodology (patent pending) that uses a complex heating and cooling treatment that controls the material’s memory. The aim of the present study was to compare the cleaning efficacy of two conventional (Mtwo, Revo-S) Ni-Ti rotary instruments with HyFlex CM. 30 single-rooted freshly extracted teeth were divided into three groups. Root canals were shaped with three NiTi instruments (Mtwo, Revo-S and HyFlex CM) using 5.25% NaOCl and 17% EDTA solutions. Specimens were fractured longitudinally and prepared for SEM analysis at standard magnification of 1000×. The presence/absence of debris smear layer and the presence/absence of smear layer at coronal, middle, and apical third of each canal were evaluated using a 5-step scale for scores. Numeric data were analyzed using Kruskall-Wallis and Mann-Whitney U statistical tests and significance was predetermined at P < 0.05. This study revealed significant differences among the various groups. Despite some minor differences, all instruments removed smear layer and debris produced during instrumentation. HyFlex CM seem to be not so effective in promoting cleanliness of root canal walls and in removing smear layer from dentine if compared to Mtwo and Revo-S.

Effects of NiTi rotary and reciprocating instruments on debris and smear layer scores: an SEM evaluation

PURPOSE

The purpose of the present study was to investigate the cleaning efficacy of 2 different nickel-titanium (NiTi) rotary systems: a new single system Reciproc compared with the rotary full sequence Mtwo. The amount of debris and the morphology of smear layer were the parameters for the evaluation of the cleanliness of root canals. The null hypothesis of the study was that there would be no significant difference in debris scores and smear layer scores between the 2 systems. 


METHODS

Forty single-rooted freshly extracted teeth were selected and divided into 2 groups. For each group, all root canals were shaped with 2 different NiTi instruments (Mtwo and Reciproc) and irrigated with 5.25% NaOCl and 17% ethylenediaminetetraacetic acid (EDTA) solutions by 3 trained operators. Specimens were fractured longitudinally and prepared for scanning electron microscopy (SEM) analysis at a standard magnification of ×5,000. The presence/absence of smear layer and the presence/absence of debris at the coronal, middle and apical third of each canal were evaluated using two 5-step scales for scores. Numeric data were analyzed using the Kruskal-Wallis and Mann-Whitney U statistical tests, and significance was set at a P value <0.05. 


RESULTS

This study revealed significant differences among the various groups. The Mtwo group presented significantly lower smear layer scores than the Reciproc group (P<0.01) in the middle and apical third of the canal. 


CONCLUSIONS

Conventional continuous rotary NiTi instruments associated with 5.25% NaOCl and 17% EDTA solutions seem to be better for obtaining clean dentinal canal walls. Reciprocating instruments leave a higher quantity of smear layer which covers dentinal walls and dentinal tubules.

In Vitro Evaluation of the Antimicrobial Efficacy of Four Endodontic Biomaterials against Enterococcus faecalis, Candida albicans, and Staphylococcus aureus

Root canal sealers that possess good antimicrobial property can prevent residual and recurrent infection and contribute to successful endodontic therapy. This study evaluated the antimicrobial activity of four endodontic sealers, AH Plus, Tubliseal EWT, EndoRez, and iRoot SP, against three different microorganisms, E. faecalis, C. albicans, and S. aureus, by direct contact test. 10 μL microbial suspensions were allowed to directly contact the four endodontic sealers for 1 hr at 37°C. Subsequently microbial growth was measured spectrophotometrically every 30 min for 18 hours. The microbial suspensions were simultaneously tested to determine the antimicrobial effect of components which are capable of diffusing into the medium. The results revealed that AH Plus and iRootSP had significantly higher antimicrobial activity against E. faecalis. AH Plus and Tubliseal EWT showed significantly higher antimicrobial activity against C. albicans and S. aureus compared to iRoot SP and EndoRez. EndoRez showed the least antimicrobial activity against all the three microorganisms. Inhibition of microbial growth is related to the direct contact of microorganisms with the sealers. In conclusion AH Plus had significantly higher antimicrobial activity against E. faecalis, C. albicans, and S. aureus.

Ultrastructural analysis of the root canal walls after preparation with two rotary nickel-titanium endodontic instruments

Background:

Root canal preparation may produce a large quantity of smear layer that covers canal walls.

Aims:

The aim of this study was to evaluate by Scanning Electron Microscope (SEM) the root canal dentine after instrumentation with nickel-titanium rotary files, in order to evaluate the presence/absence of smear layer and the presence/absence of open tubules on the root canal walls at the coronal, middle, and apical third of each sample.

Materials and Methods:

A total of 20 single-rooted freshly extracted teeth were selected and divided into two groups. For each group, root canals were shaped with Mtwo and Revo-S instruments under irrigation with Sodium hypochlorite and 17% ethylenediaminetetraacetic acid. Specimens were fractured longitudinally and SEM analyzed at standard magnification of ×1000 and ×5000. The presence/absence of smear layer and the presence/absence of open tubules at the coronal, middle, and apical third of each canal were evaluated using a three-step scale for scores.

Statistical Analysis Used:

Numeric data were analyzed using the Kruskall-Wallis and Mann-Whitney U-Statistical tests and significance was pre-determined at P < 0.05.

Results and Conclusions:

This study did not reveal differences among the two groups. Mtwo and Revo-S showed no significant difference between them and both presented very low smear layer scores and open tubules scores, with no significant difference among coronal, middle, and apical third. Mtwo and Revo-S rotary instruments seem to be effective in removing smear layer from canal walls.

Antibacterial Efficacy of Conventional and Single-use Ni-Ti Endodontic Instruments: An in vitro Microbiological Evaluation

Purpose

The purpose of this in vitro study was to investigate the capability of different Ni-Ti instruments in disinfecting root canals previously infected with E. faecalis.

Methods

60 single-rooted, freshly extracted teeth were selected, sterilized and inoculated with cells of E. faecalis strain. All root canals were shaped with different Ni-Ti instruments (MTwo, Revo-S, Reciproc, and OneShape) under irrigation with NaOCl and 17% EDTA solutions by the same trained operator. The number of Colony Forming Units (CFU)/ml of E. faecalis was evaluated for each group. Numeric data were submitted to statistical analysis.

Results

MTwo, REVO-S, Reciproc and OneShape reported significantly lower CFU/ml values and showed no significant differences among them (p>0.05). All groups showed significantly higher CFU/ml values than not treated samples (negative control).

Conclusions

All the Ni-Ti instrumentation efficiently reduced E. faecalis counts and no significant differences were found among them. Single-use files can offer antibacterial results comparable with traditional instruments.

An Assessment of Antibacterial Activity of Four Endodontic Sealers on Enterococcus faecalis by a Direct Contact Test: An In Vitro Study

Aim. To evaluate the antibacterial activity of four endodontic sealers on Enterococcus faecalis by a direct contact test. Material and Methods. Enterococcus faecalis was used as a test organism. Direct contact test which is based on measuring the effect of close contact between test bacteria and tested material on the kinetics of bacterial growth was performed to overcome the disadvantages of agar diffusion test. The sealers tested were zinc oxide eugenol-based sealer, glass-ionomer-based sealer, polydimethyl-siloxane-based sealer, and urethane dimethacrylate resin-based sealer. Data was collected by recording the optical density with the help of a spectrophotometer. Results. The sealers exhibited different inhibitory effects. The results obtained were subjected to statistical analysis by Kruskal Wallis analysis of variance and Dunn's multiple comparison test. Group comparison showed very highly significant difference between the groups. Conclusion. Zinc oxide eugenol-based sealer was the most effective and urethane dimethacrylate resin-based sealer was the least effective against Enterococcus faecalis, whereas glass-ionomer-based and polydimethyl-siloxane-based sealers were effective only for a short period. Inhibition of the bacterial growth is related to the direct contact of the microorganism with the sealer.

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.

Antibacterial effect of silver-zeolite containing root-canal filling material

The aim of this study was to determine the in vitro antibacterial effect of two experimental glass ionomer cements (GICs) on Streptococcus milleri, Staphylococcus aureus, and Enterococcus faecalis after 24 and 48 h incubation by using the agar diffusion inhibitory test. Silver zeolite (SZ) was added at 0.2 and 2% mass fraction concentration to GIC (Endion). The control group was Endion with no SZ. Each of them were prepared to uniform size using a custom-made Teflon mold, and the GIC materials were prepared to form disks (n = 5 per group). The effect of these materials on the growth of three bacteria associated with endodontic infections was determined using the agar diffusion inhibitory test. The amounts of silver ion release from these materials were measured with atomic absorption spectrophotometry at 10 min, 24- and 48-h periods. The pH of samples was measured with a pH-meter at 10 min, 24- and 48-h periods. After the incubation period, the agar plates were evaluated and the degrees of bacterial inhibition were measured in millimeters. A comparison of the mean of the test materials was statistically different in each group of specimens (p < 0.05). Between the two tested materials 2% SZ containing GIC showed the largest zone of inhibition on the agar plates of all the tested strains (p < 0.05). The most inhibition in bacterial growth occurred in E. faecalis. Adding 2% SZ to GIC resulted in a significant increase in the silver release into deionized water. This study demonstrated that GIC had an inhibitory affect on Streptococcus milleri, Staphylococcus aureus, and Enterococcus faecalis and that adding SZ increases that affect proportional to its concentration.

Calcium hydroxide-based root canal sealers: a review

The aim of this review was to consider laboratory experiments and clinical studies of calcium hydroxide-based root canal sealers. An extensive search of the endodontic literature was made to identify publications related to calcium hydroxide-based root canal sealers. The articles were assessed for the outcome of laboratory and clinical studies on their biological properties and physical characteristics. Comparative studies with other sealers were also considered. Several studies were evaluated covering different properties of calcium hydroxide-based sealers including physical properties, biocompatibility, leakage, adhesion, solubility, antibacterial properties, and periapical healing effect. Calcium hydroxide-based root canal sealers have a variety of physical and biological properties. Comparative studies reveal their mild cytotoxicity, but their antibacterial effects are variable. Further research is required to establish the tissue healing properties of calcium hydroxide in root canal sealers.

Intrinsically antibacterial materials based on polymeric derivatives of eugenol for biomedical applications

Infections are the most common cause of biomaterial implant failure representing a constant challenge to the more widespread application of medical implants. This study reports on the preparation and characterization of novel hydrophilic copolymeric systems provided with antibacterial properties coming from eugenol residues anchored to the macromolecular chains. Thus, high conversion copolymers were prepared from the hydrophilic monomer 2-hydroxyethyl methacrylate (HEMA) and different eugenol monomeric derivatives, eugenyl methacrylate (EgMA) and ethoxyeugenyl methacrylate (EEgMA), by bulk polymerization reaction. Thermal evaluation revealed glass transition temperature values in the range 95-58 degrees C following the order HEMA-co-EgMA > PHEMA > HEMA-co-EEgMA and a clear increase in thermal stability with the presence of any eugenyl monomer in the system. In vitro wettability studies showed a reduction of water sorption capacity and surface free energy values with increasing the content of eugenol residues in the copolymer. The antimicrobial activity of copolymeric discs was evaluated by determining their capacity to reduce or inhibit colony formation by different bacterial species. All eugenyl containing materials showed bacteria growth inhibition, this one being higher for the EEgMA derivative copolymers.

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.

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.

In vitro activity of zinc oxide-eugenol and glass ionomer cements on Candida albicans

The aim of this study was to evaluate in vitro the antimicrobial activity of glass ionomer (GIC) and zinc oxide-eugenol (ZOE) cements against Candida albicans. Standardized GIC and ZOE specimens were maintained in contact with C. albicans suspension (1 x 10(6) cells/ml) at 37 degrees C for 24 h, 48 h or 7 days. A control group without any testing cement was included. After the incubation period, aliquots of 0.1 ml were plated on Sabouraud's agar, and then the number of colonies was counted. The results were expressed as values of logarithms of colony-forming units per milliliter (log CFU/mL) and were analyzed statistically by Kruskal-Wallis ANOVA. After 48 h of incubation, the ZOE group presented no growth of C. albicans. GIC and control groups presented similar mean values at all tested periods. According to the results obtained, it could be concluded that, under the experimental conditions, ZOE cement was more effective in vitro against C. albicans than GIC.

Conservative endodontic management of teeth associated with extensive periapical pathology: report of two cases

Traditionally, long-term calcium hydroxide dressings have been recommended for the conservative management of large periapical lesions. However, calcium hydroxide therapy has some disadvantages such as variability of treatment time, difficulties with patient follow-up and prolonged treatment periods that increase the risk of root canal contamination via microleakage and crown fractures. This paper reports the healing of large periapical lesions following conservative non-surgical treatment with calcium hydroxide dressings.

Survival ofEnterococcus faecalisin infected dentinal tubules after root canal filling with different root canal sealersin vitro

AIM

To investigate the ability of different endodontic sealers and calcium hydroxide to kill bacteria in experimentally infected dentinal tubules.

METHODOLOGY

Fifty-six human root segments were enlarged to size 2 (ISO size 090) Largo Peeso Reamer. After treatment with 17% EDTA and 5% NaOCl for 4 min each, the specimens were infected with Enterococcus faecalis for 3 weeks. The roots were divided into eight groups and filled with gutta-percha and AH Plus (AH); Grossman's sealer (GS); Ketac-Endo (KE); Apexit (AP); RoekoSeal Automix (RSA); or RoekoSeal Automix with an experimental primer (RP), or calcium hydroxide (CH) only. One group of specimens was left unfilled for control (CT). Following storage in humid conditions at 37 degrees C for 7 days, the root canals were re-established with new sterile Largo size 2. Dentine samples from each canal were then collected using a sterile size 5 (ISO size 150) Largo Peeso Reamer. The number of colony-forming units (CFU) was determined for each sample.

RESULTS

The mean log10 CFU in all test groups was significantly lower (P < 0.05) than that in the CT group. Root filling with AH and GS killed bacteria (mean CFU = 0) in the dentinal tubules. The mean log10 CFU for the CH group (0.53) was lower than that of RSA, AP, RP and KE (1.36, 1.40, 1.46 and 1.94, respectively), but only the difference between the CH and the KE groups was statistically significant (P < 0.05).

CONCLUSION

Root fillings in vitro with gutta-percha and AH or GS were effective in killing E. faecalis in dentinal tubules. Other endodontic sealers, as well as CH, were less effective.

In Vitro Antibacterial Activities of Root-Canal Sealers By Using Two Different Methods

The purpose of this in vitro study was to evaluate the antibacterial activity of five different root-canal sealers (RoekoSeal, Ketac-Endo, AH Plus, Sealapex, Sultan). With the use of Enterococcus faecalis as a test organism, both the agar-diffusion test (ADT) and direct-contact test (DCT) were performed. For DCT, sealers were mixed and placed on the sidewall of microtiter plate wells. A 10-microl bacterial suspension was placed on the tested material samples. Bacteria were allowed to directly contact to the sealers for 1 h at 37 degrees C. Bacterial growth was then spectrophotometrically measured through every 30 min for 19 h by using an Anthos Labtec HT 2. For ADT, a 200-microl bacterial suspension was spread on brain-heart infusion agar plates. Freshly mixed sealers were poured into uniform wells punched in the agar. After periods of incubation at 37 degrees C for 24 h and 7 days in humid atmosphere, the zones of inhibition of bacterial growth on agar plates were observed and measured. Ketac-Endo, Sultan, and AH Plus had similar results for DCT. These sealers were more potent bacterial-growth inhibitors than Sealapex and RoekoSeal. According to ADT, RoekoSeal showed no antibacterial activity. There was no significant difference among AH Plus, Sealapex, and Sultan (p > 0.05). Ketac-Endo demonstrated lower antimicrobial activity than these sealers (p < 0.05). Time had no effect on the antibacterial activity of the tested sealers (p > 0.05). The antibacterial efficiency of the materials varied according to the tests used. It was concluded that the technique, time, and ingredients of the tested material can affect the results of the microbiological studies.

In vitro evaluation of the antimicrobial activity of five root canal sealers

The aim of the present study was to analyze the antimicrobial properties of five endodontic sealers: Endo Fill, Endomethasone, Endomethasone N, Sealer 26 and AH-Plus, against the following microorganisms: Candida albicans, Staphylococcus aureus, Enterococcus faecalis, Streptococcus sanguis and Actinomyces naeslundii. The sealers were tested immediately, 24 h, 48 h and 7 days after manipulation.The direct contact method through the observation of the microbial growth in liquid medium and the agar diffusion test were used to evaluate the antimicrobial properties of the sealers. The results, in both methodologies used, showed that immediately after manipulation, Endo-Fill and Endomethasone demonstrated the highest antimicrobial activity, with no statistically significant difference between them. Sealer 26 demonstrated the lowest antimicrobial activity. At all other times after manipulation, there were no statistically significant differences among all the sealers tested. In conclusion, none of the sealers totally inhibited the growth of the microorganisms. Furthermore, the antimicrobial activity of each sealer decreased with time and was dependent upon the microbial susceptibility to them.

Effects of oral environment stabilization procedures on counts of Candida spp. in children

The effects of oral environment stabilization procedures on counts of Candida spp. have rarely been discussed, and no conclusive results are found in the literature. The aim of this study was thus to ascertain the effects of oral environment stabilization procedures with glass ionomer and zinc oxide-eugenol cements on counts of Candida spp. in the oral cavity of children. For this purpose, oral rinses of sterile phosphate-buffered saline were initially collected from 30 boys and 30 girls, positive for Candida in the saliva and aged from 4 to 10 years. Data on the initial quantity of CFU/ml of Candida were obtained. Then, the children were randomly divided into two groups and oral environment stabilization procedures were performed using zinc oxide-eugenol cement or glass ionomer cement. One week after the procedures were performed, oral rinses were collected again and final Candida counts were obtained. An expressive reduction in Candida counts was observed in both groups. The zinc oxide-eugenol and glass ionomer cements were efficient in the reduction of Candida counts and statistically significant differences were observed between initial and final counts in both groups. Considering the percentage of reduction, the zinc oxide-eugenol cement presented more favorable results, with a reduction of 70%. A reduction of 46% was observed with the use of the glass ionomer cement. According to the obtained results, we concluded that oral environment stabilization procedures were efficient in reducing Candida spp. counts, especially when the zinc oxide-eugenol cement was employed.

Development of bacterial resistance to several biocides and effects on antibiotic susceptibility

The aims of this study were to investigate the development of bacterial resistance to eugenol, thymol, trichlorocarbanalide (TCC), didecyldimethylammonium chloride (DDDMAC) and C10-16-alkyldimethyl, N-oxides (ADMAO) and subsequent effects on antibiotic susceptibility. An agar minimum inhibitory concentration (MIC) method was used to assess the activity of the biocides against standard bacterial strains and laboratory mutants. A range of techniques including disk diffusion and gradient plate experiments were used to attempt to develop bacterial 'resistance' or tolerance to the biocides. The mutants produced were examined for cross-resistance to the other biocides and to antibiotics via disk diffusion and gradient plate MIC methods. Outer membrane proteins of the mutants were extracted and examined using sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Escherichia coli triclosan-resistant mutants were not cross-resistant to eugenol, thymol, TCC, DDDMAC and ADMAO. Mutants with elevated MICs to DDDMAC (E. coli and Pseudomonas aeruginosa), thymol (E. coli) and eugenol (E. coli) were isolated, but all remained sensitive to higher concentrations of the agents. Bacteria with elevated MICs to TCC and ADMAO were not obtained. Some low-level cross-resistance between DDDMAC, eugenol and thymol was observed with the E. coli gradient plate mutants, as well as reduced susceptibility to antibiotics, most notably chloramphenicol. The lack of cross-resistance of the triclosan mutants suggested that the mode of action of triclosan is not shared with the other biocides studied. SDS-PAGE results indicated that the DDDMAC P. aeruginosa mutant had a reduced amount (or absence) of one outer membrane protein in comparison with the standard strain. In conclusion, under laboratory conditions, bacterial exposure to thymol, eugenol and DDDMAC can lead to reduced susceptibility between selected biocidal agents and antibiotics, more specifically, chloramphenicol. However, further studies are required to determine if this is of clinical significance.

Antimicrobial effects of glass ionomer cements containing bioactive glass (S53P4) on oral micro-organisms in vitro

The antimicrobial effects of two glass-ionomer cements (GICs), GC Fuji II and Fuji II LC, mixed with different amounts (0 wt%, 10 wt% and 30 wt% of the total powder weight) of bioactive glass (BAG), S53P4, on Streptococcus mutans and Candida albicans were studied in vitro. The growth inhibition was tested using agar diffusion. The materials were also studied in a liquid media. The effect of the material extracts on acid production was studied using cell suspensions. The antimicrobial activity of the materials was examined by incubating the cell suspensions with the material powder. In the agar diffusion test, only the GICs containing 30 wt% BAG inhibited the growth of S. mutans. When the materials were tested in culture medium, no inhibitory effects on S. mutans were detected. The only materials to inhibit acid production of S. mutans were the GIC extracts without added BAG. Furthermore, they also had antibacterial activity against S. mutans when tested as powders. We found very few effects of the tested materials on C. albicans. The only material with an antimicrobial effect on C. albicans was BAG when incubated in a suspension with C. albicans. This is the first time that this effect has been demonstrated for C. albicans. By adding BAG to GICs the structure of the material becomes more brittle than the structure of GICs without BAG. Thus, in addition to the composition of the tested materials, their structure may also have influenced the results. In summary, commercially available GICs and GIC disks containing 30 wt% of BAG exerted antibacterial effects on S. mutans. BAG exerted antimicrobial effects on both S. mutans and C. albicans.

Antimicrobial activity of endodontic sealers on Enterococcus faecalis

Enterococcus faecalis has been shown to be highly resistant once established in the root canal system and may play an important role in endodontic failures. The purpose of this study was to evaluate the antimicrobial activity of four root canal sealers on E. faecalis. Seventeen blood-agar plates were inoculated with E. faecalis using the Lawn technique. Five discs were placed on each plate, four with sealers--Sealapex, Roth 811, Kerr EWT, and AH-Plus--and an ampicillin disc as the control. The plates were incubated at 37 degrees C. The zones of inhibition were measured at 24 and 48 h. Analysis using a one-way ANOVA and Tukey test showed a statistically significance difference (p < 0.05) between all four groups of sealers. Roth 811 showed the largest zone of inhibition (1.1 mm), followed by Sealapex (0.8 mm) and Kerr EWT (0.5 mm), whereas AH-Plus had no antimicrobial activity. There was no difference in the zones of inhibition between the 24- and 48-h time periods.

Activity and mechanisms of action of selected biocidal agents on Gram-positive and -negative bacteria

AIMS

This study investigates the antimicrobial activity and mode of action of two natural products, eugenol and thymol, a commonly utilized biostatic agent, triclocarban (TCC), and two surfactants, didecyldimethylammonium chloride (DDDMAC) and C10-C16 alkyldimethyl amine N-oxides (ADMAO).

METHODS AND RESULTS

Methods used included: determination of minimum inhibitory concentrations (MICs), lethal effect studies with suspension tests and the investigation of sub-MIC concentrations on growth of E. coli, Staph. aureus and Ps. aeruginosa using a Bioscreen microbiological analyser. Leakage of intracellular constituents and the effects of potentiating agents were also investigated. Only DDDMAC was bactericidal against all of the organisms tested. Eugenol, thymol and ADMAO showed bacteriostatic and bactericidal activity, but not against Ps. aeruginosa. TCC was only bacteristatic against Staph. aureus, but like the other agents, it did affect the growth of the other organisms in the Bioscreen experiments. All of the antimicrobial agents tested were potentiated by the permeabilizers to some extent and leakage of potassium was seen with all of the agents except TCC.

CONCLUSIONS

DDDMAC was bactericidal against all organisms tested and all compounds had some bacteriostatic action. Low level static effects on bacterial growth were seen with sub-MIC concentrations. Membrane damage may account for at least part of the mode of action of thymol, eugenol, DDDMAC and ADMAO.

SIGNIFICANCE AND IMPACT OF THE STUDY

The ingredients evaluated demonstrated a range of bactericidal and bacteriostatic properties against the Gram-negative and -positive organisms evaluated and the membrane (leakage of intracellular components) was implicated in the mode of action for most (except TCC). Sub-MIC levels of all ingredients did induce subtle effects on the organisms which impacted bacterial growth, even for those which had no true inhibitory effects.

Influence of calcium hydroxide root-canal sealer on microbial growth in vitro

The calcium hydroxide-based filling material Apexit, which is often used in endodontic practice, was evaluated for its antibacterial and antifungal effects against microorganisms isolated from oral cavity (Serratia marcescens, Pseudomonas putida, Staphylococcus aureus, Candida albicans). Two different quantitative techniques were employed--the direct-contact test was used to examine the efficacy of freshly mixed material while the broth-survival test was employed to check the antimicrobial properties of 5-d-old material. Apexit inhibited Gram-negative bacteria more effectively than Gram-positive ones but had none or a very weak inhibitory effect on C. albicans.

Periapical healing of endodontically treated teeth in one and two visits obturated in the presence or absence of detectable microorganisms

AIM

The purpose of the present study is to evaluate the healing of periapical lesions of teeth with positive and negative canal cultures at the time of obturation, and to evaluate the periapical healing of teeth treated in one visit (without) or in two visits with an interappointment dressing of calcium hydroxide.

METHODOLOGY

Thirty-nine patients received root-canal treatment. In the first visit, teeth were instrumented, and 18 of these teeth were filled (after microbiological sampling) with calcium hydroxide in sterile saline. The other 21 teeth were obturated with gutta-percha and AH-26 sealer after microbiological sampling. Four weeks later, the teeth with calcium hydroxide were accessed again and after microbiological sampling they were obturated with gutta-percha and AH-26 sealer. Healing of periapical radiolucency was recorded over a period up to 4.5 years.

RESULTS

In both the treatment groups, the size of the periapical lesions reduced significantly during the follow-up period. Complete radiographic healing was observed in 81% of the cases in the one-visit group, and in 71% of the cases in the two-visit group. The probability of success increased continuously over time for both treatment groups. Seven out of eight cases (87.5%) that showed a positive root-canal culture at the time of obturation healed. The number of colony forming units (CFU) in six out of eight positive canals was <10(2) CFU mL(-1).

CONCLUSIONS

Within the limitations of this study, no significant differences in healing of periapical radiolucency was observed between teeth that were treated in one visit (without) and two visits with inclusion of calcium hydroxide for 4 weeks. The presence of a positive bacterial culture (CFU<10(2)) at the time of filling did not influence the outcome of treatment.

Microbial flora of root canal-treated teeth associated with asymptomatic periapical radiolucent lesions

This study aimed to investigate the composition of microflora in endodontically treated teeth associated with asymptomatic periapical lesions in southern Chinese patients. Twenty-four teeth which had received nonsurgical root canal treatment more than 4 years previously, and which presents an acceptable coronal restoration with a periapical radiolucent area, were re-treated nonsurgically. Bacteriological samples were obtained after removal of the old root canal filling. The samples were inoculated on enriched trypticase soy agar and four selective media for incubation at 37 degrees C in both a carbon dioxide-enriched atmosphere and anaerobically. Eighteen teeth that had received gutta-percha root canal fillings were grouped for analysis, 12 (66.7%) of which contained cultivable microorganisms. The total colony forming units per ml of transport medium ranged from 0 to 2.3 x 10(5). The number of bacterial genera recovered ranged between 0 and 6, with facultative gram-positive cocci being the most prevalent group of bacteria isolated. Facultative anaerobic bacteria were present in all, whereas strict anaerobic bacteria were found in 3 out of the 12 teeth with positive growth. The size of the periapical rarefaction did not show any relationship with the quantity of microorganisms recovered. Coagulase-negative staphylococci, streptococci and Pseudomonas aeruginosa were most frequently isolated in this group of patients. The possible origin of these organisms is discussed.

Bacterial coronal leakage after obturation with three root canal sealers

The purpose of this study was to compare the bacterial leakage of root canals obturated with three root canal sealers, using Endodontalis faecalis as a microbial tracer to determine the length of time for bacteria to penetrate through the obturated root canal to the root apex. Seventy-five, single-rooted teeth with straight root canals had the crown cut off at the cementoenamel junction. Root canals were instrumented by a step-back technique. The prepared teeth were randomly divided into 3 groups of 19 teeth each and another 2 groups as positive and negative controls (9 teeth each). The experimental groups were dependent on the sealer used: AH-Plus, Apexit, and Ketac-Endo. The root canals were obturated using a lateral condensation technique. After 24 h the teeth were attached to microcentrifuge tubes with 2 mm of the root apex submerged in Brain Heart Infusion broth in glass test tubes. The coronal portions of the root canal filling materials were placed in contact with E. faecalis. The teeth were observed for bacterial leakage daily for 30 and 60 days. With the chi2 test for comparing pairs of groups at the 0.05 level (p < 0.05), there was no statistical difference between Ketac-Endo and AH-Plus (p > 0.06), but Apexit had significantly higher leakage (p < 0.05) at 30 days. After 60 days there was no statistical difference between Ketac-Endo and Apexit (p > 0.05), but Apexit leaked more than AH-Plus. The conclusion drawn from this experiment was that epoxy resin root canal sealer was found to be more adaptable to the root canal wall and filling material than a calcium hydroxide sealer when bacterial coronal leakage was studied.

Lactate dehydrogenase leakage of hepatocytes with AH26 and AH Plus sealer treatments

Numerous root canals filling materials are available in the field of dentistry, based on various formulas that contain a variety of different and partly mutagenic components, such as epoxy resin sealers, Ca(OH)2-based materials, and zinc oxide-eugenol cements. AH Plus root canal sealer will not release formaldehyde according to the manufacturer, although AH26 does. The purpose of this study was to analyze the leakage of lactate dehydrogenase (LDH) from rat hepatocytes after treatment with AH26 and AH Plus root canal sealers in vitro. Hepatocytes from male Sprague-Dawley rats were used to test the cytotoxicity of AH26 and AH Plus. The root canal sealers were mixed and then dissolved in the dimethyl sulfoxide to final concentrations of 0.01%, 0.04%, and 0.1% (wt/vol), with a dimethyl sulfoxide concentration of < 0.05%. Dosage-dependent and time-dependent lactate dehydrogenase leakage values were measured and tested by one-way ANOVA. The results showed that both AH26 and AH Plus are toxic to rat hepatocytes. At a low concentration, AH26 had a higher toxicity than AH Plus to rat hepatocytes.