The antibacterial activity of mineral trioxide aggregate containing calcium fluoride

Evaluating the antimicrobial effectiveness of endodontic sealers against oral pathogens associated with failed root canal treatments

Overview

Residual pathogens lead to treatment failure. Microbes like Enterococcus faecalis, Candida albicans, and Actinomyces israelii are often isolated after failed root canal therapy. Therefore, the antimicrobial efficacy of sealers is critical for treatment outcomes.

Aim

To evaluate the antimicrobial efficacy of endodontic sealers against E. faecalis and C. albicans.

Methodology

The agar diffusion test was used to evaluate the antibacterial efficacy of four sealers: MTA Fillapex, Bio-C-Sealer, Sealapex, and Seal-Pex. Each microorganism's bacterial suspension was added to agar plates separately. The sterile discs were then placed on the plates; later, a freshly mixed sealer was coated on the sterile discs. After 24 h of incubation, inhibition zones were measured.

Results

The Kruskal-Wallis test was used to analyze the data, and the Mann-Whitney U-test was used for post hoc pairwise comparison. The results demonstrated that Seal-Pex has potent antibacterial activity against E. faecalis (P < 0.05). Against C. albicans, both MTA Fillapex and Seal-Pex were effective, with MTA Fillapex showing a statistically significant difference compared to Bio-C Sealer and Sealapex.

Conclusion

Seal-Pex, an epoxy resin-based sealer, exhibited a significant antimicrobial efficacy against E. faecalis. Conversely, MTA Fillapex demonstrated notable antifungal activity against C. albicans, surpassing other tested sealers. These findings highlight the differential antimicrobial and antifungal properties of the sealers.

Evaluation of the pH and Antibacterial Efficacy of Mineral Trioxide Aggregate With and Without the Incorporation of Titanium Tetrafluoride

Introduction Microorganisms play an important role in causing inflammation in the pulp and periapical regions. Even after undergoing chemo-mechanical procedures during root canal treatment, bacteria may persist within dentinal tubules, posing a risk of disease recurrence. Mineral trioxide aggregate (MTA), introduced as a dental material, has been investigated as a potential antibacterial agent since its early use. Calcium and phosphorus are the primary ions in MTA, and their antibacterial characteristics are attributed to the release of calcium hydroxide through surface hydrolysis of calcium silicate components. Previous studies have shown that MTA has limited antimicrobial properties. Several alterations have been made to enhance the biological properties of MTA, such as incorporating nanoparticles made from silver, zinc, gold, and titanium. Therefore, in this study, titanium tetrafluoride (TiF4) was added to MTA in an effort to enhance its antimicrobial properties. Aim To compare and evaluate the antibacterial efficacy of MTA after the incorporation of TiF4. Materials and methods A total of 56 samples were made by mixing MTA with different weight proportions of TiF4 (1 wt%, 2 wt%, and 3 wt%). Out of these, 28 samples were taken to test each of the following properties: antibacterial efficacy and pH. The specimens were prepared using stainless steel molds of recommended dimensions for testing the pH. The pH was evaluated using a pH meter, and the antibacterial efficacy was assessed using the direct contact test. Data regarding the antibacterial efficacy and pH of MTA with various proportions of TiF4 were investigated for normality using the Kolmogorov-Smirnov test and assessed for normal distribution. The antibacterial properties among the four groups were analyzed using one-way analysis of variance (ANOVA), followed by pairwise multiple comparisons using Tukey's Honest Significant Difference test. The level of statistical significance was determined at p ≤ 0.05. MTA, when incorporated with TiF4, showed enhanced antibacterial properties. Results On day 1, the group treated with MTA containing 3% TiF4 demonstrated the strongest antibacterial effectiveness, with a mean of 4.67 ± 0.04 colony-forming units (CFU)/mL × 10^8. However, the group treated with plain MTA had the lowest mean values, at 5.67 ± 0.25 CFU/mL × 10^8. On day 1, the MTA group with 3% TiF4 also had the highest mean pH values (11.90 ± 0.05), while the plain MTA group had the lowest mean pH values (11.64 ± 0.78). On day 7, the MTA group with 3% TiF4 had the highest pH value (12.85 ± 0.08), whereas the plain MTA group had the lowest pH value (11.92 ± 0.09). Conclusion The inclusion of TiF4 resulted in an augmentation of the antibacterial efficacy of MTA against Enterococcus faecalis (E. faecalis). Hence, the integration of TiF4 into MTA can be considered a promising development against E. faecalis during endodontic procedures.

Histologic Assessment of a Fast-Set Mineral Trioxide Aggregate (MTA) and Two Novel Antibacterial-Enhanced Fast-Set MTAs for Apexification and Periapical Healing of Teeth With Incomplete Root Formation in a Rat Model: An In Vivo Animal Study

Background Pulp necrosis in incomplete root formation halts dentine development, resulting in larger canals with fragile walls and an open apex, complicating canal instrumentation and apical stop formation. Bioactive endodontic cements such as mineral trioxide aggregate (MTA) are crucial for creating artificial apical barriers or inducing apical foramen closure, but challenges remain regarding their antimicrobial efficacy and cytotoxicity. Modifications to MTA formulations aim to address these concerns. Methods This in vivo animal study involved 80 Wistar albino rats, with incomplete root formation induced by pulp exposure. Rats were divided into four groups receiving different MTA formulations for apexification: conventional MTA, modified MTA, and MTA enhanced with metronidazole or doxycycline. Histopathological evaluations were conducted at seven and 28 days post-treatment to assess calcific barrier formation, inflammatory reactions, and antimicrobial efficacy. Results By day 7, modified MTA formulations exhibited enhanced antibacterial activity compared to conventional MTA (p = 0.000), with fewer inflammatory reactions and microorganisms. By day 28, modified formulations showed superior calcific barrier formation, particularly in the metronidazole- and doxycycline-enhanced groups compared to conventional MTA (p = 0.000). These outcomes suggest that modifications to MTA formulations improve antimicrobial efficacy and calcific barrier formation in vivo. Conclusion Novel modified MTA formulations, particularly those enhanced with metronidazole or doxycycline, exhibit superior antibacterial efficacy and calcific barrier formation compared to conventional MTA. Further long-term studies are warranted to validate these findings for potential clinical translation.

Low concentration zinc oxide nanoparticles enrichment enhances bacterial and pro-inflammatory resistance of calcium silicate-based cements

Calcium silicate-based cement (CSC) is a commonly used material in endodontic treatment. However, it has limited antibacterial activity, especially for cases involving primary infections. Zinc oxide nanoparticles (ZnO-NPs) are recognized for their potential in biomedical applications due to their antibacterial properties and ability to reduce inflammation. This study aims to optimize CSC by incorporating ZnO-NPs to maintain its physical properties, enhance its antibacterial activity, and reduce the production of pro-inflammatory cytokines. ZnO-NPs were integrated into a commercial CSC (Endocem MTA) at 1 wt% (CSZ1) or 3 wt% (CSZ3). Setting time, compressive strength, and X-ray diffraction were then measured. In addition, pH, calcium ion release, and zinc ion release were measured for 7 days. Antibacterial activity against Enterococcus faecalis and viability of murine macrophages (RAW264.7) were determined using colorimetric assays. Gene expression levels of pro-inflammatory cytokines in lipopolysaccharide induced RAW264.7 were evaluated using quantitative polymerase chain reaction. Results were compared to an unmodified CSC group. In the CSZ3 group, there was a significant increase of approximately 12% in setting time and a reduction of about 36.4% in compressive strength compared to the control and CSZ1 groups. The presence of ZnO-NPs was detected in both CSZ1 and CSZ3. Both CSC and CSZ1 groups maintained an alkaline pH and released calcium ions, while zinc ions were significantly released in the CSZ1 group. Additionally, CSZ1 showed a 1.8-fold reduction of bacterial activity and exhibited around 85% reduction in colony-forming units compared to the CSC group. Furthermore, the CSZ1 group showed a more than 39% reduction in pro-inflammatory cytokine levels compared to the CSC group. Thus, enriching CSC with 1 wt% ZnO-NPs can enhance its antibacterial activity and reduce pro-inflammatory cytokines without showing any tangible adverse effects on its physical properties.

Comparative Evaluation of Push-Out Bond Strength of Conventional Mineral Trioxide Aggregate, Biodentine, a Modified Mineral Trioxide Aggregate, and Two Novel Antibacterial-Enhanced Mineral Trioxide Aggregates

Background The challenges associated with incorporating antimicrobial agents, such as the potential diminishment of the cement's physical properties, highlight the need for comprehensive evaluations. Balancing antimicrobial efficacy with the maintenance of structural integrity is a crucial aspect of material development. The acknowledgment of cytotoxic properties associated with tricalcium aluminate, a major constituent in conventional mineral trioxide aggregate (MTA), is critical in terms of long-term evaluation of treatment procedures. The primary focus of the push-out test is to evaluate the resistance of the tested material to dislodgement. Greater push-out strength implies stronger adhesion between the tested material and the tooth surface. Aim This study aims to evaluate the push-out bond strength of two antibacterial-enhanced MTAs with conventional MTA and Biodentine. Material and methods A total of five materials were tested: a) modified MTA, b) doxycycline-enhanced MTA, c) metronidazole-enhanced MTA, d) conventional MTA, and e) Biodentine. All the materials were mixed based on a predetermined powder:liquid ratio and then carried using a plastic instrument to the desired experimental design. Single-rooted permanent teeth, preferably incisors, were used in the present study. Teeth were embedded vertically in a rubber mold, and sectioning of the tooth was performed. A single operator instrumented the canal space in each slice using Gates-Glidden burs, and the mixed cements were placed in the respective groups and stored for 72 hours. A push-out test was carried out using a universal testing machine. Following the bond failure, the slices were examined under a stereomicroscope to determine the nature of the bond failure. The collected data was subjected to a one-way analysis of variance test, post hoc test, and chi-square test for statistical analysis. Results The mean push-out bond strength was found to be the highest for Biodentine (43.25 ± 0.62 megapascals (MPa)), followed by doxycycline- and metronidazole-enhanced MTAs (39.54 ± 0.65 MPa and 39.29 ± 0.16 MPa, respectively), modified MTA formulation (37.75 ± 0.73 MPa), and the lowest for conventional MTA (25.93 ± 0.7 MPa). Conventional MTA samples had an adhesive failure (89.4%), while Biodentine samples had a cohesive failure (80.3%). Mixed failures were noticed with the samples containing modified MTA formulation (71.3%), doxycycline-enhanced MTA (76.6%), and metronidazole-enhanced MTA (78.0%). Conclusion Despite not surpassing Biodentine in bond strength, antibacterial-enhanced MTAs are considered potential alternatives to conventional MTA in day-to-day clinical practice.

Comparative Evaluation of Push-out Bond Strength of Conventional Mineral Trioxide Aggregate, Biodentine, and Two Novel Antibacterial-enhanced Mineral Trioxide Aggregates

AIM

To evaluate the push-out bond strength of two newly modified mineral trioxide aggregates (MTAs) with conventional MTA and biodentine.

MATERIALS AND METHODS

Material preparation: Two commercially available bioactive bioceramics: Group I: Mineral trioxide aggregate; Group II: Biodentine; and two newly formulated modified MTAs: Group III: Doxycycline incorporated MTA formulation; Group IV: Metronidazole incorporated MTA formulation was used in the present study. All the test materials were then carried using a plastic instrument to the desired experimental design. Teeth sample preparation: A total of 120 teeth samples were collected and divided into four groups of test materials with 30 teeth samples per group. Single-rooted permanent teeth, that is, incisors were collected and stored in saline until the study was performed. Sectioning of the teeth into 2.0 ± 0.05-mm thick slices was performed perpendicular to the long axis of the tooth. The canal space was instrumented using Gates Glidden burs to achieve a diameter of 1.5 mm. All four prepared materials were mixed and placed in the lumen of the slices and placed in an incubator at 37°C for 72 hours. Push-out test and bond failure pattern evaluation: The push-out test was performed using a universal testing machine. The slices were examined under a scanning electron microscope (SEM) at 40× magnification to determine the nature of bond failure. All the collected data were recorded and statistically analyzed.

RESULTS

The mean push-out bond strength was found to be the highest for group II (37.38 ± 1.94 MPa) followed by group III (28.04 ± 2.22 MPa) and group IV (27.83 ± 1.34 MPa). The lowest mean push-out bond strength was noticed with group I (22.89 ± 2.49 MPa). This difference was found to be statistically significant (p = 0.000). Group I samples had the predominantly adhesive type of failure (86.4%), while group II samples showed the cohesive type of failure (94.2%). Both the modified MTAs (groups III and IV) primarily showed mixed types of failures.

CONCLUSION

Both the antibacterial-enhanced MTAs had better pushout bond strength compared to conventional MTA but did not outperform biodentine. Hence, it could serve as a substitute for conventional MTA due to its augmented physical properties.

CLINICAL SIGNIFICANCE

Carious pulp exposure and nonvital open apices pose a critical challenge to pediatric dental practitioners. In such circumstances, maintaining the vitality of pulp and faster healing would help in a better prognosis. Novel MTAs without any cytotoxic components, and enhanced antibacterial contents with augmented physical properties can help in treating such clinical conditions. How to cite this article: Merlin ARS, Ravindran V, Jeevanandan G, et al. Comparative Evaluation of Push-out Bond Strength of Conventional Mineral Trioxide Aggregate, Biodentine, and Two Novel Antibacterial-enhanced Mineral Trioxide Aggregates. J Contemp Dent Pract 2024;25(2):168-173.

Comparative Evaluation of the Antimicrobial Activity of NeoPutty MTA and Modified NeoPutty MTA: An In Vitro Study

AIM

Mineral trioxide aggregate (MTA) is a relatively new versatile dental material. MTA has many advantages as well as disadvantages. To reduce most of the drawbacks of MTA, a premixed bioceramic MTA, NeoPutty MTA, was introduced in 2020. In this study, we assessed the antimicrobial activity of the newer MTA, NeoPutty MTA. We modified NeoPutty MTA and compared both against Enterococcus faecalis, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli.

MATERIALS AND METHODS

Using the agar diffusion method, NeoPutty MTA was tested for antibacterial activity against the above-mentioned microorganisms. A base layer of Petri plates was done using Muller-Hinton agar for S. aureus, E. coli, and P. aeruginosa and brain heart infusion agar for E. faecalis. A total of 32 plates were employed; the plates were divided randomly into four test groups having eight plates each, so microorganisms were tested eight times. Three cavities were made in agar and filled with freshly mixed materials after 24 h. A pour plate seeded the microorganisms. The plates were pre-incubated for 2 h at room temperature and incubated at 37°C for 24 h. An independent observer measured the inhibition zone diameters.

RESULTS

NeoPutty MTA, when tested alone, did not show much antibacterial activity against E. faecalis, S. aureus, and E. coli but had significant antimicrobial activity against P. aeruginosa when used at different concentrations. Modified NeoPutty (NeoPutty with antibiotics added individually) showed significant antibacterial activity against these microorganisms, as seen by the zone of inhibition of these bacteria.

CONCLUSION

Modified NeoPutty with antibiotics has a better antimicrobial effect than NeoPutty MTA.

The Cytotoxic Assessment of Antibacterial-Enhanced Mineral Trioxide Aggregate Compared to Commercially Available Bioceramic Cements by Using Methyl-Thiazoldiphenyl-Tetrazolium (MTT) Assay on Human Dental Pulp Stem Cells: An In Vitro Study

Background and objective Preserving the vitality of the tooth is of prime significance during therapies such as direct pulp capping and pulpotomy that promote tertiary dentine formation and healing of pulp stumps. Procedures like apexogenesis and apexification also stimulate dentin and bone formation for root growth and closure. Conventional mineral trioxide aggregate (MTA) has good biocompatible and physical properties like longer setting time, presence of a cytotoxic component, i.e., tricalcium aluminate (TCA), moderate compressive strength, and moderate antimicrobial activity. Eliminating TCA and the addition of antibacterial components would improve the properties of the cement. In this study, we aimed to assess the cytotoxicity of MTA Angelus, Biodentine, and two antibacterial-enhanced MTAs by using methyl-thiazoldiphenyl-tetrazolium (MTT) assay. Materials and methods Human dental pulp was extirpated from extracted third molars, and human dental pulp stem cells (HDPSCs) were isolated and characterized by flow cytometry. HDPSCs were treated with MTA, Biodentine, or two antibacterial-enhanced MTAs depending on the study group. The control group constituted the untreated HDPSCs. The cell viability of HDPSCs was assessed using an MTT assay on days one, three, and seven. Results Varied levels of cytotoxicity were noticed at different time periods assessed using the tested materials, which was statistically significant (p=0.01). At all time periods assessed, the highest cell viability was noticed with Biodentine (88.7% on the first day, 80.4% on the third day, and 91.8% on the seventh day). Antibacterial-enhanced MTAs, either added with metronidazole or doxycycline, had more mean viable cells compared to conventional MTA on the third and seventh day (p=0.043 and 0.018 respectively). Conclusion Antibacterial-enhanced MTAs showed reduced cytotoxic properties when compared to conventional MTA. Biodentine was associated with the highest cell viability at all time periods.

Comparative Evaluation of the Physical and Antimicrobial Properties of Mineral Trioxide Aggregate, Biodentine, and a Modified Fast-Setting Mineral Trioxide Aggregate Without Tricalcium Aluminate: An In Vitro Study

Background Tricalcium aluminate, one of the major constituents of mineral trioxide aggregate (MTA), has been shown to have cytotoxic properties. Mineral trioxide aggregate has moderate to low antimicrobial activity against the most common endodontic pathogen, Enterococcus faecalis. Aim To assess the physical and antimicrobial properties of a newly modified formulation of mineral trioxide aggregate. Materials & methods The final setting time, compressive strength, and antimicrobial properties were tested for three groups of materials. The material used for Group 1 was mineral trioxide aggregate (white MTA, Angelus, Londrina, Brazil); the material for Group 2 was Biodentine (Septodont, Saint Maur des Fossés, France); and for Group 3, a modified MTA formulation was used. Results Group 1 had the longest setting time, and Group 2 had the shortest setting time. Group 3's material was set at 83.65 ± 0.28 minutes. This difference among the groups was statistically significant (p < 0.05). The highest mean compressive strength during all the time periods was seen in Group 2, followed by Group 3, and the least in Group 1. This difference in compressive strength was statistically significant (p=0.001). The largest zone of inhibition against Enterococcus faecalis, Candida albicans, and Streptococcus mutans was seen in Group 3, followed by Group 2 and Group 1. Conclusion Under the limitations of the present study, the newly modified MTA could serve as an alternative to the conventional MTA in terms of faster setting, higher strength, and better antimicrobial properties.

Feasibility of the crude extracts of Amorphophallus paeoniifolius and Colocasia esculenta as intracanal medicaments in endodontic therapy in comparison to the 940 nm diode laser: An in vitro antimicrobial study

Background/purpose

The elimination and debridement of intracanal bacteria are credited with long-term effectiveness in endodontic therapy. This study aimed to compare the antimicrobial efficacies of Amorphophallus paeoniifolius (Suran), Colocasia esculenta (Aravi) crude extracts as intracanal medicaments with calcium hydroxide (CH), 2% chlorhexidine (CHX) gel, and 940 nm diode laser.

Materials and methods

Fifty-eight intact, single-root, extracted human mandibular premolar teeth were prepared. The samples were sterilized, transferred into microcentrifuge tubes, and inoculated with E. faecalis. The samples were placed in an incubator for three weeks to allow the biofilm to grow. Then the samples were randomly divided into five experimental groups (n = 10), disinfected with Suran, Aravi crude extracts, CH, 2% CHX gel, and a 940 nm diode laser. The negative control group (n = 4) and the positive control group (n = 4). Then the samples were observed under light and scanning electron microscopy to monitor the E. faecalis biofilm. The sampling method was carried out in paper point (intracanal) and Peeso bur (intradentinal). Later the number of colony-forming units was counted and analyzed.

Results

Colony-forming units were significantly reduced in the 2% CHX gel in both sampling methods, while Suran showed lower colony-forming units compared to Aravi and CH. The differences between experimental groups were not statistically significant (P > 0.05) in both sampling methods.

Conclusion

This study showed that the application of Suran and Aravi crude extracts as intracanal medicaments leads to a significant reduction in the number of bacterial colonies compared to CH, 2% CHX gel, and 940 nm diode laser.