The antimicrobial properties, cytotoxicity, and differentiation potential of double antibiotic intracanal medicaments loaded into hydrogel system

Cytocompatibility and Antibiofilm Activity of Calcium Hydroxide Mixed with Cyperus articulatus Essential Oil and Bio-C Temp Bioceramic Intracanal Medicament

Calcium hydroxide represents the most commonly used intracanal dressing between sessions; however, it may not be effective against all types of microorganisms. Several compounds of plant origin have attracted increasing attention from researchers in recent years. The objective of this study was to evaluate the cytocompatibility and antimicrobial activity of calcium hydroxide associated with the essential oil of Cyperus articulatus and the new bioceramic intracanal medicament Bio-C Temp®. Five experimental groups were designed: group Ca-C. articulatus essential oil; group CHPG-calcium hydroxide associated with propylene glycol; group CHCa-essential oil of C. articulatus associated with calcium hydroxide; and group U-UltraCal® XS; group BCT-Bio-C Temp®. The control group was a culture medium. Cytocompatibility was assessed by the methyltetrazolium (MTT) assay after exposure of the Saos-2 human osteoblast-like cell line to dilutions of commercial products/associations for 24 h and 72 h. The antimicrobial activity against mature Enterococcus faecalis biofilm was evaluated by the crystal violet assay. All commercial products/associations showed a cell viability similar to or even higher than the control group (p > 0.05) for both periods evaluated. C. articulatus essential oil associated or not with calcium hydroxide showed better antibiofilm capacity. C. articulatus associated or not with calcium hydroxide showed superior cytocompatibility and antimicrobial capacity, representing a promissory intracanal medicament.

Comparative Analysis of the Cytotoxic Effects of Modified Triple Antibiotic Hydrogel: Insights From Experimental Models

INTRODUCTION

 The effectiveness of intracanal medicaments (ICMs) in root canal therapy is critical for successful dental treatments, yet their cytotoxic effects pose significant challenges. This research uses zebrafish embryos and dental pulp stem cells (DPSCs) to identify the optimal concentration that balances antibacterial efficacy with minimal toxicity.

AIM

 This study aims to address the need for effective ICMs in dentistry by formulating and assessing the embryotoxicity and cytocompatibility of a novel carrageenan-based modified triple antibiotic paste (MTAP) hydrogel at different concentrations (1, 5, and 10 mg/mL) using a zebrafish model and cell culture assay.

MATERIALS AND METHODS

 The hydrogel was formulated by combining antibiotic solutions (ciprofloxacin, metronidazole, and amoxicillin) with carrageenan and xanthan gum. Zebrafish embryos were exposed to varying concentrations of MTAP hydrogel, chlorhexidine (CHX), calcium hydroxide (CaOH2), and plain carrageenan to assess developmental toxicity, survival rate, heart rate, hatching rate, and macrophage migration. The cytotoxicity against DPSCs was examined within a timeframe of 6, 24, and 72 hours with the use of the 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide (MTT) assay.

RESULTS

 The analysis revealed developmental toxicity with malformations observed at higher concentrations of MTAP hydrogel, CaOH2, and CHX medicaments, indicating potential toxicity. Significant impacts on survival, heart rate, and hatching rate were noted in the CaOH2 and CHX groups, as well as at higher MTAP hydrogel concentrations, emphasizing the importance of dosage considerations. The neutral red assay confirmed toxicity, with macrophage migration observed in CaOH2, CHX, and higher MTAP hydrogel concentrations. Lower concentrations, particularly at 1 mg/mL, showed no adverse effects on zebrafish embryos and larvae. These findings align with cell viability investigations, which demonstrated that higher antibiotic concentrations resulted in decreased cell proliferation and viability over time. Conversely, at a lower concentration of 1 mg/mL, cell proliferation notably increased after 72 hours. Plain MTAP and CHX exhibited the highest toxicity levels in the MTT assay.

CONCLUSION

 The study concludes that while higher concentrations of MTAP hydrogel exhibit toxic effects, the hydrogel at 1 mg/mL demonstrates no adverse impact on zebrafish embryos, larvae, and DPSCs. These findings underscore the necessity of optimizing ICM concentrations to balance antibacterial efficacy and minimal cytotoxicity.

Effect of Boswellic Acid on Viability of Dental Pulp Stem Cells Compared to the Commonly Used Intracanal Medications: An In Vitro Study

AIM

This study was aimed at evaluating the effect of acetyl-11-keto-β-boswellic acid (AKBA) on dental pulp stem cells (DPSCs) viability and proliferation to be used as a potential root canal medicament.

MATERIALS AND METHODS

Dental pulp stem cells were isolated from human third molars. The phenotypic characterization of DPSCs was verified by flow cytometry analysis. The viability assay was performed using the methyl-thiazoltetrazolium (MTT) assay. Cells were treated with different concentration of triple antibiotic paste (TAP) and calcium hydroxide Ca(OH2) (5, 2.5, 1, 0.5, and 0.25 mg/mL), AKBA (10, 5, 1, 0.1, and 0.01 µM). All experiments were done in separate triplicate experiments. Results: Dental pulp stem cells were characterized by flow cytometry. Cells treated with Ca(OH)2 (1, 2.5, and 5 mg/mL) showed significantly reduced viability compared with the control cells (p < 0.05). Dental pulp stem cells treated with 1, 2.5, and 5 mg/mL TAP resulted in a significant decrease in viability (p < 0.05). Cells treated with AKBA in concentrations (1, 0.1, and 0.01 µM) demonstrated higher viability than the control group (p < 0.05), while AKBA in concentrations (5 and 10 µM) showed equal or decreased viability than the control group. (p > 0.05). Regarding cell density assay, AKBA showed significant increase in cell density after 5 and 7 days compared with cells medicated with TAP and Ca(OH)2 while TAP revealed marked reduction in cell density in all the tested intervals.

CONCLUSION

Acetyl-11-keto-β-boswellic acid in lower concentrations (0.01, 0.1, and 1 µM) demonstrated superior cell viability than TAP and Ca(OH)2, and it may possess the potential to be an intracanal medicament in regenerative endodontics.

CLINICAL SIGNIFICANCE

Studying the effect of different potential root canal medicaments and their capability to induce DPSCs proliferation might be of value. The influence of AKBA on the viability and proliferation of DPSCs tested in this study sheds light on its use as a potential intracanal medication especially in regenerative endodontics. How to cite this article: Amer NA, Badawi MF, Elbeltagi MG, et al. Effect of Boswellic Acid on Viability of Dental Pulp Stem Cells Compared to the Commonly Used Intracanal Medications: An In Vitro Study. J Contemp Dent Pract 2023;24(12):957-966.

A prospective case series in regenerative endodontics: The effective use of diluted antibiotic hydrogels in endodontic regeneration procedures

Objective

to investigate the effectiveness of diluted antibiotic hydrogels in endodontic regeneration procedures.

Materials and Methods

One conventional treatment (calcium hydroxide) and two experimental treatments containing 1 mg/mL antibiotic in gel (MC-TAP and MC-DAP) were prepared for this study. The effect of these medicaments on the proliferation and differentiation potential of dental pulp stem cells (DPSCs) was examined before their clinical use, using WST and ALP assays. Twenty-two teeth diagnosed with necrotic immature roots were treated with calcium hydroxide, MC-TAP or MC-DAP using the endodontic regeneration protocol as described by the American Association of Endodontists (AAE). Teeth were examined after application of the medicament, at the time of regeneration and after 12-24 months.

Results

All treated teeth showed resolution of signs and symptoms shortly after treatment with the different medicaments. However, signs and symptoms returned a few months after initial treatment in clinical cases treated with MC-DAP. All successfully treated teeth examined after 12-24 months were free of signs and symptoms, but vitality was not achieved.

Conclusion

Low concentration antibiotic gel containing triple antibiotic paste (MC-TAP) can be successfully used for endodontic regeneration procedures.

Advances in antimicrobial hydrogels for dental tissue engineering: regenerative strategies for endodontics and periodontics

Dental tissue infections have been affecting millions of patients globally leading to pain, severe tissue damage, or even tooth loss. Commercial sterilizers may not be adequate to prevent frequent dental infections. Antimicrobial hydrogels have been introduced as an effective therapeutic strategy for endodontics and periodontics since they have the capability of imitating the native extracellular matrix of soft tissues. Hydrogel networks are considered excellent drug delivery platforms due to their high-water retention capacity. In this regard, drugs or nanoparticles can be incorporated into the hydrogels to endow antimicrobial properties as well as to improve their regenerative potential, once biocompatibility criteria are met avoiding high dosages. Herein, novel antimicrobial hydrogel formulations were discussed for the first time in the scope of endodontics and periodontics. Such hydrogels seem outstanding candidates especially when designed not only as simple volume fillers but also as smart biomaterials with condition-specific adaptability within the dynamic microenvironment of the defect site. Multifunctional hydrogels play a pivotal role against infections, inflammation, oxidative stress, etc. along the way of dental regeneration. Modern techniques (e.g., 3D and 4D-printing) hold promise to develop the next generation of antimicrobial hydrogels together with their limitations such as infeasibility of implantation.

Efficacy of disinfection procedures performed prior to regenerative endodontic therapy: An integrative review

The aim of this integrative review was to identify whether the disinfection procedures performed prior to regenerative endodontic treatment were effective on biofilm removal from the root canals. The research was based on PubMed, Latin American and Caribbean Health Sciences Literature (Lilacs) and Scientific Electronic Library Online (SciELO) databases. Four articles were selected; one of the studies was in vivo and the others ex vivo. Different disinfection procedures were studied, characterised mainly by the use of intracanal medication, highlighting the double antibiotic paste, triple antibiotic paste and calcium hydroxide paste. Disinfection ability was evaluated against Enterococcus faecalis and multispecies biofilms by using the fluorescence technique and colony forming unit counting, for 7 to 21 days. Double antibiotic paste and triple antibiotic paste demonstrated excellent antibiofilm activity, unlike CH paste that showed limited disinfection, even when associated with different antimicrobial agents. Triple antibiotic paste was the most effective medication against biofilm.

The antimicrobial efficacy of nanographene oxide and double antibiotic paste per se and in combination: part II

BACKGROUND

Finding strategies to overcome the rising trends of antimicrobial resistance against currently available antimicrobial agents has become increasingly relevant. Graphene oxide has recently emerged as a promising material due to its outstanding physicochemical and biological properties. This study aimed to validate previous data on the antibacterial activity of nanographene oxide (nGO), double antibiotic paste (DAP), and their combination (nGO-DAP).

METHODS

The antibacterial evaluation was performed against a wide range of microbial pathogens. Synthesis of nGO was achieved using a modified Hummers' method, and loading it with ciprofloxacin and metronidazole resulted in nGO-DAP. The microdilution method was utilized to assess the antimicrobial efficacy of nGO, DAP, and nGO-DAP against two gram-positive bacteria (S. aureus and E. faecalis), two gram-negative bacteria (E. coli, and S. typhi), and an opportunistic pathogenic yeast (C. albicans). Statistical analysis was conducted using one-sample t-test and one-way ANOVA (α = 0.05).

RESULTS

All three antimicrobial agents significantly increased the killing percent of microbial pathogens compared to the control group (P < 0.05). Furthermore, the synthesized nGO-DAP exhibited higher antimicrobial activity than nGO and DAP per se.

CONCLUSION

The novel synthesized nGO-DAP can be used as an effective antimicrobial nanomaterial for use in dental, biomedical, and pharmaceutical fields against a range of microbial pathogens, including gram-negative and gram-positive bacteria, as well as yeasts.

Regenerative endodontic therapy in mature teeth with necrotic pulp and apical periodontitis using two disinfection protocols

OBJECTIVE

This study compared the effect of diode laser (DL) 980 nm and double antibiotic paste (DAP) on response of mature teeth with necrotic pulp and apical periodontitis to regenerative endodontic therapy in a dog model.

METHODS

Pulp necrosis and periapical pathosis were induced in 40 mature double rooted premolars in four 2-year-old mongrel dogs. These teeth were randomly divided according to disinfection protocol into four equal groups (10 teeth each/20 roots), group I: DAP; group II: DL980 nm; group III: positive control (without treatment) and group IV: negative control (untouched teeth). These groups were further subdivided into 2 subgroups (5 teeth each/10 roots) according to evaluation period, subgroup (A): one month and subgroup (B): three months. Revascularization techniques were performed using bleeding induction and application of platelet rich fibrin (PRF). The coronal cavities were sealed with mineral trioxide aggregate (MTA) and glass ionomer cement. The inflammatory response, vital tissue in-growth, new hard tissue formation and bone resorption were assessed. Statistical analysis was done utilizing ANOVA, Tukey's post hoc and paired t tests.

RESULTS

In both subgroups, there were no significant differences between DAP and DL980 in terms of inflammatory cell count, vital tissue in-growth, new hard tissue formation and bone resorption (P ≤ 0.05).

CONCLUSION

Diode laser 980 nm can alternate DAP as a disinfection method of the root canal during RET for mature necrotic teeth, therefore it may accelerate regenerative endodontic therapy for both the patient and dentist and allows for RET in a single appointment.

Use of a Cellulase from Trichoderma reesei as an Adjuvant for Enterococcus faecalis Biofilm Disruption in Combination with Antibiotics as an Alternative Treatment in Secondary Endodontic Infection

Apical periodontitis is an inflammation leading to the injury and destruction of periradicular tissues. It is a sequence of events that starts from root canal infection, endodontic treatment, caries, or other dental interventions. Enterococcus faecalis is a ubiquitous oral pathogen that is challenging to eradicate because of biofilm formation during tooth infection. This study evaluated a hydrolase (CEL) from the fungus Trichoderma reesei combined with amoxicillin/clavulanic acid as a treatment against a clinical E. faecalis strain. Electron microscopy was used to visualize the structure modification of the extracellular polymeric substances. Biofilms were developed on human dental apices using standardized bioreactors to evaluate the antibiofilm activity of the treatment. Calcein and ethidium homodimer assays were used to evaluate the cytotoxic activity in human fibroblasts. In contrast, the human-derived monocytic cell line (THP-1) was used to evaluate the immunological response of CEL. In addition, the secretion of the pro-inflammatory cytokines IL-6 and TNF-α and the anti-inflammatory cytokine IL-10 were measured by ELISA. The results demonstrated that CEL did not induce the secretion of IL-6 and TNF-α when compared with lipopolysaccharide used as a positive control. Furthermore, the treatment combining CEL with amoxicillin/clavulanic acid showed excellent antibiofilm activity, with a 91.4% reduction in CFU on apical biofilms and a 97.6% reduction in the microcolonies. The results of this study could be used to develop a treatment to help eradicate persistent E. faecalis in apical periodontitis.

Antimicrobial potential of new diclofenac hydrogels for disinfection in regenerative endodontics: An in vitro and ex vivo study

AIM

There is a need to explore new alternatives for root canal disinfection in regenerative endodontics, since the current strategies are far from ideal. Currently, the potential use of diclofenac (DC) is being investigated for controlling root canal infections. The objective was to evaluate the antimicrobial efficacy of novel DC-based hydrogels (DCHs) against polymicrobial biofilms grown in radicular dentine and root canals and to compare results with triantibiotic (TAH) and diantibiotic (DAH) hydrogels, and calcium hydroxide (Ca[OH]₂ ).

METHODOLOGY

The in vitro antimicrobial activity of intracanal medicaments was evaluated against 3-week-old polymicrobial root canal biofilms grown on human radicular dentine. Dentine samples were obtained and randomly divided into the study groups (n = 4/group): (1) 1 mg/ml TAH; (2) 1 mg/ml DAH; (3) 5% diclofenac (DCH); (4) 2.5% DCH; (5) 1.25% DCH; (6) 1 mg/ml DAH + 5% DCH; (7) Ca(OH)₂ paste; (8) positive control. The microbial viability, in terms of percentage of intact cell membranes, was assessed after 7 days by confocal scanning laser microscopy (CSLM). The ex vivo efficacy of intracanal medications was evaluated in root canals infected with a polymicrobial suspension. Intracanal microbiological samples at baseline (S1) and 7 days post-treatment (S2) were taken; microbial quantification and cell viability were assessed by quantitative polymerase chain reaction (qPCR) and flow cytometry (FC). The mean Log₁₀ of bacterial DNA copies in root canal samples before (S1) and the Log₁₀ reduction of DNA copies S1-S2 in qPCR were recorded. The absolute value of total cells stained, and the percentage reduction of intact membrane cells after treatment (S1-S2), were analysed by FC. Global comparison was done using the Kruskal-Wallis test, whilst the Mann-Whitney U test was used for pair-by-pair comparison.

RESULTS

Confocal scanning laser microscopy analysis indicated that the greatest effectiveness was obtained with 5% DCH, showing significant differences with respect to the other groups (p < .001). In root canals, the highest Log₁₀ DNA reduction S1-S2 was obtained with 5% DCH and TAH, with no differences between them. The results of FC showed that only 5% DCH proved significantly superior to the other treatments.

CONCLUSIONS

Sodium DC hydrogels demonstrate antimicrobial efficacy against endodontic biofilms.

Antibacterial efficacy of antibiotic pastes versus calcium hydroxide intracanal dressing: A systematic review and meta-analysis of ex vivo studies

Background

Conflicting findings on the potency of antibiotic pastes versus calcium hydroxide (CH) have been evident in the literature.

Aims

To compare the antibacterial efficacy of single antibiotic paste (SAP), double antibiotic paste (DAP), triple antibiotic paste (TAP), and modified TAP (mTAP) with CH on bacterial biofilms.

Methods

PubMed, Scopus, and Embase were comprehensively searched until August 23, 2021. The study protocol was registered in the PROSPERO. Ex vivo studies performed on Enterococcus faecalis or polymicrobial biofilms incubated on human/bovine dentin were selected. The quality of the studies was assessed using a customized quality assessment tool. Standardized mean difference (SMD) with a 95% confidence interval (CI) was calculated for the meta-analysis. Meta-regression models were used to identify the sources of heterogeneity and to compare the efficacy of pastes.

Results

The qualitative and quantitative synthesis included 40 and 23 papers, respectively, out of 1421 search results. TAP (SMD = -3.82; CI, -5.44 to -2.21; P < 0.001) and SAPs (SMD = -2.38; CI, -2.81 to - 1.94; P < 0.001) had significantly higher antibacterial efficacy compared to the CH on E. faecalis biofilm. However, no significant difference was found between the efficacy of DAP (SMD = -2.74; CI, -5.56-0.07; P = 0.06) or mTAP (SMD = -0.28; CI, -0.82-0.26; P = 0.31) and CH. Meta-regression model on E. faecalis showed that SAPs have similar efficacy compared to TAP and significantly better efficacy than DAP. On dual-species (SMD = 0.15; CI, -1.00-1.29; P = 0.80) or multi-species (SMD = 0.23; CI, -0.08-0.55; P = 0.15) biofilms, DAP and CH had similar efficacy.

Conclusions

Ex vivo evidence showed that antibiotic pastes were either superior or equal to CH. The studied SAPs had considerably higher or similar antibacterial effectiveness compared to DAP, CH, and TAP. Hence, combined antibiotic therapy was not necessarily required for root canal disinfection ex vivo.

Novel trends, challenges and new perspectives for enamel repair and regeneration to treat dental defects

Dental enamel is the hardest tissue in the human body, providing external protection for the tooth against masticatory forces, temperature changes and chemical stimuli. Once enamel is damaged/altered by genetic defects, dental caries, trauma, and/or dental wear, it cannot repair itself due to the loss of enamel producing cells following the tooth eruption. The current restorative dental materials are unable to replicate physico-mechanical, esthetic features and crystal structures of the native enamel. Thus, development of alternative approaches to repair and regenerate enamel defects is much needed but remains challenging due to the structural and functional complexities involved. This review paper summarizes the clinical aspects to be taken into consideration for the development of optimal therapeutic approaches to tackle dental enamel defects. It also provides a comprehensive overview of the emerging acellular and cellular approaches proposed for enamel remineralization and regeneration. Acellular approaches aim to artificially synthesize or re-mineralize enamel, whereas cell-based strategies aim to mimic the natural process of enamel development given that epithelial cells can be stimulated to produce enamel postnatally during the adult life. The key issues and current challenges are also discussed here, along with new perspectives for future research to advance the field of regenerative dentistry.

Effect of Different Intracanal Medicaments on the Viability and Survival of Dental Pulp Stem Cells

Background: Stem cells play an important role in the success of regenerative endodontic procedures. They are affected by the presence of medicaments that are used before the induction of bleeding or the creation of a scaffold for endodontic regeneration. This study examines the effects of different intracanal medicaments on the viability and survival of dental pulp stem cells at different doses and over different exposure times. Methods: Dental pulp stem cells were cultured from healthy third molar teeth using the long-term explant culture method and characterized using flow cytometry and exposed to different concentrations of calcium hydroxide, doxycycline, potassium iodide, triamcinolone, and glutaraldehyde, each ranging from 0 (control) to 1000 µg/mL. Exposure times were 6, 24, and 48 h. Cell viability was measured using the MTT assay, and apoptosis was measured using the Annexin V-binding assay. Results: All medicaments significantly reduced cell viability at different concentrations over different exposure times. Calcium hydroxide and triamcinolone favored cell viability at higher concentrations during all exposure times compared to other medicaments. The apoptosis assay showed a significant increase in cell death on exposure to doxycycline, potassium iodide, and glutaraldehyde. Conclusion: The intracanal medicaments examined in our study affected the viability of dental pulp stem cells in a time and dose-dependent manner. They also adversely affected the survival of dental pulp stem cells. Further studies are needed to better understand the effect of prolonged exposure to medicaments according to clinical protocols and their effect on the stemness of dental pulp stem cells.

Regenerative Endodontics and Minimally Invasive Dentistry: Intertwining Paths Crossing Over Into Clinical Translation

Regenerative endodontic procedures have been described for over a decade as a paradigm shift in the treatment of immature necrotic permanent teeth, owing to their ability to allow root maturation with subsequent enhancement of the tooth’s fracture resistance in addition to the potential for regeneration of vital intracanal tissues. Concomitantly, minimally invasive endodontics is another rising concept with the main concern of preservation of tooth structure. Stemming from their potential to preserve the original tooth structure, both regenerative and minimally invasive endodontics could be considered as two revolutionary sciences with one common goal. Achieving this goal would entail not only employing the appropriate strategies to recreate the ideal regenerative niche but modifying existing concepts and protocols currently being implemented in regenerative endodontics to address two important challenges affecting the outcome of these procedures; conservation of tooth structure and achieving effective disinfection. Therefore, the search for new biomimetic cell-friendly disinfecting agents and strategies is crucial if such a novel integratory concept is to be foreseen in the future. This could be attainable by advocating a new merged concept of “minimally invasive regenerative endodontic procedures (MIREPs),” through modifying the clinical protocol of REPs by incorporating a minimally invasive access cavity design/preparation and biomimetic disinfection protocol, which could enhance clinical treatment outcomes and in the future; allow for personalized disinfection/regeneration protocols to further optimize the outcomes of MIREPs. In this review, we aim to introduce this new concept, its realization and challenges along with future perspectives for clinical implementation.

Antimicrobial and immunomodulatory in vitro profile of double antibiotic paste

AIM

To evaluate the antimicrobial and immunomodulatory activity of double antibiotic paste (DAP) in an in vitro infection model.

METHODOLOGY

The minimum inhibitory and bactericidal concentrations (MIC and MBC) and the antibiofilm activities (TTC assay) of DAP and its components (ciprofloxacin and metronidazole) were evaluated against Staphylococcus aureus and Enterococcus faecalis compared with triple antibiotic paste (TAP). The cellular viability of RAW 264.7 macrophages (24 and 72 h) and L929 fibroblasts (48 and 72 h) was evaluated by MTT. Furthermore, the production of TNF-α, IL-12, IL-6, IL-1α, IL-10 and NO (on RAW 264.7), besides IL-6, TGF-β and NO (on L929), stimulated with DAP in baseline and associated with heat-killed microbial-antigen conditions was measured by ELISA and Griess reaction. Data were analysed using the one-way ANOVA test with Bonferroni's corrections.

RESULTS

The MBC of pharmacopoeia DAP was similar to TAP for E. faecalis (0.25 μg.  mL^-1 ) and lower for S. aureus (DAP 1 μg. mL^-1 and TAP 2 μg. mL^-1 ; p < .001). Ciprofloxacin was the most effective antibiofilm drug from the pastes (35% of reduction for E. faecalis and S. aureus; p < .0001), and both pastes had a similar antibiofilm eradication against both biofilm species (29% and 35% for S. aureus and 76% and 85% for E. faecalis; p < .0001). DAP was cytotoxic against the tested cells. DAP significantly upregulated IL-1α (p < .001), IL-6 (p < .0001), TNF-α (p < .01) and IL-12 (p < .05; in the absence of antigens) and significantly reduced IL-6 (p < .0001; in the presence of HK-S. aureus) and IL-10 (p < .05; in the presence of both antigens) on macrophages. Furthermore, DAP upregulated IL-6 (p < .001) and NO (p < .05; in the absence of antigens), IL-6 (p < .001; in the presence of HK-S. aureus) and reduced NO (p < .001; in the presence of HK-S. aureus).

CONCLUSIONS

Double antibiotic paste and TAP had similar antimicrobial activity against S. aureus and E. faecalis. DAP upregulated pro-inflammatory cytokines mainly in the absence of antigens and had pro- and anti-inflammatory activity in RAW 264.7 macrophages and L929 fibroblasts in the presence of antigens involved in pulp infections.

Antibacterial activity, cytocompatibility and effect of Bio-C Temp bioceramic intracanal medicament on osteoblast biology

AIM

To analyse the antimicrobial and biological properties of a new bioceramic intracanal medicament (Bio-C Temp), and to compare it with two calcium hydroxide-based intracanal medicaments (Calen^® and UltraCal^® XS).

METHODOLOGY

The direct contact and the crystal violet tests were performed to assess the antimicrobial activity of intracanal medicaments against Enterococcus faecalis. The cytocompatibility and the effect of the medication on the biology of the human osteoblast-like cell line (Saos-2) were evaluated with methylthiazole tetrazolium (MTT), neutral red, alkaline phosphatase activity and mineralization (alizarin red) assays. The data were analysed using one-way anova and Tukey's tests, two-way anova and Bonferroni's tests, or Kruskal-Wallis and Dunn's tests (α = 0.05).

RESULTS

Bio-C Temp had significantly less antibacterial activity and biofilm biomass reduction than the other intracanal medicaments (P < 0.05). There was no difference in the viability of Saos-2 exposed to the various intracanal medicaments, except regarding the 1 : 2 dilution, when the Bio-C Temp group had significantly lower cell viability than the UltraCal^® XS and Calen^® groups (P < 0.05). Bio-C Temp induced significantly greater ALP activity than the other intracanal medicaments (P < 0.05) at day 1. Calen^® induced significantly greater deposition of mineralized nodules than the other intracanal medicaments (P < 0.05), and no difference was observed between Bio-C Temp and UltraCal^® XS (P > 0.05).

CONCLUSIONS

Bio-C Temp had similar cytocompatibility at higher dilutions, and higher or similar induction of ALP activity and deposition of mineralized nodules in comparison with Calen® and UltraCal® XS. However, it had significantly less antibacterial and antibiofilm activity than Calen® and UltraCal® XS.

Effect of Hydrogel-Based Antibiotic Intracanal Medicaments on Push-Out Bond Strength

OBJECTIVE

 This study aimed to evaluate the effects of typical clinical concentration (1,000 mg/mL), low concentration (1 mg/mL) triple antibiotic pastes (TAP), and double antibiotic pastes (DAP) on the bond strength between various root cements and radicular dentin.

MATERIALS AND METHODS

 Intact single-rooted human teeth (n = 144) were horizontally decoronated and canals instrumented. The roots were treated for 4 weeks with Ca(OH)₂, 1,000 mg/mL of TAP or DAP, and 1 mg/mL of TAP or DAP. Untreated roots served as a control. After treatment, the medicaments were irrigated and each group was divided into three subgroups receiving MTA, Biodentine, or Endosequence putty cement. After 2 weeks, coronal and middle root cylinders were obtained from each root. Push-out bond strength test and failure analysis were performed for all root cylinders.

STATISTICAL ANALYSIS

 Three-way ANOVA, pairwise comparisons and logistic regression were used for statistical analyses. A significance level of 5% was used.

RESULTS

 For MTA applied in the coronal part of the roots, 1 mg/mL DAP and TAP and Ca(OH)₂ demonstrated significantly higher bond strength compared with the typical clinical concentration and the control groups. For Biodentine applied coronally in the roots, 1 mg/mL of DAP resulted in significantly higher bond strength than all other groups. For Endosequence putty cement applied coronally in the roots, 1 mg/mL of DAP offered significantly higher bond strength than all groups except for Ca(OH)₂.

CONCLUSION

 The use of 1 mg/mL DAP resulted in significantly higher push-out bond strength compared with the typical clinical concentration of TAP and DAP regardless of the type of the root cement used.

Optimal antimicrobial concentration of mixed antibiotic pastes in eliminating Enterococcus faecalis from root dentin

This study aims to identify the optimal concentrations of triple antibiotic paste (TAP), modified triple antibiotic paste (mTAP) and double antibiotic paste (DAP) that could completely eradicate Enterococcus faecalis in dentinal tubules. One hundred and ninety extracted human premolars inoculated with E. faecalis were medicated with calcium hydroxide and mixed antibiotic pastes (TAP, mTAP and DAP at 0.1, 1.25, 5, 10 and 20 mg mL^-1 of each drug) for seven days before being frozen, pulverised and cultured. Specimens treated with the lowest concentration of the mixed antibiotics capable of eradicating E. faecalis were examined using scanning electron and confocal laser scanning microscopy to confirm the eradication of the microbial. TAP at 10 mg mL^-1 of each drug was able to completely eliminate bacteria inside dentinal tubules, whereas mTAP and DAP required 20 mg mL^-1 of each drug. Calcium hydroxide was not effective in eradicating E. faecalis inside dentinal tubules.

The Effects of Intracanal Irrigants and Medicaments on Dental-Derived Stem Cells Fate in Regenerative Endodontics: An update

Regenerative endodontics is a biologically based treatment designed for immature permanent teeth with necrotic pulp to replace dentin and root structures, as well as dental pulp cells. This procedure has become a part of novel modality in endodontics therapeutic manner, and it is considered as an alternative to apexification. In the last decade, numerous case reports, which describe this procedure, have been published. This therapeutic approach succeeded due to its lower financial cost and ease of performance. Although the clinical protocol of this procedure is not standardized and the effects of irrigants and medicaments on dental stem cells fate remain somewhat ambiguous, however when successful, it is an improvement of endodontics treatment protocols which leads to continued root development, increased dentinal wall thickness, and apical closure of immature teeth. To ensure a successful regenerative procedure, it is essential to investigate the appropriate disinfection protocols and the use of biocompatible molecules in order to control the release of growth factors and the differentiation of stem cells. This is the first review in the literature to summarize the present knowledge regarding the effect of intracanal irrigants and medicaments on the dental derived stem cells fate in regenerative endodontic procedures.

Effects of radiopaque double antibiotic pastes on the proliferation, alkaline phosphatase activity and mineral deposition of dental pulp stem cells

OBJECTIVE

The aim of this study was to investigate the effects of two radiopaque agents, barium sulfate (BaSO₄) or zirconium oxide (ZrO₂) in double antibiotic paste (DAP), on the proliferation and mineral deposition of human dental pulp stem cells (DPSC).

MATERIALS AND METHODS

Radiopaque antimicrobial medicaments composed of methylcellulose (MC) thickening polymer with BaSO₄ or ZrO₂ and either 1 or 5 mg/mL DAP (equal portions of metronidazole and ciprofloxacin) were used to investigate DPSC proliferation after 3 days, and alkaline phosphatase (ALP) activity and mineral deposition after 7 and 14 days. Radiopaque agents without DAP and Ca(OH)₂ were used as controls.

RESULTS

MC-BaSO₄ DAP and MC-ZrO₂ DAP at 1 or 5 mg/mL had no adverse effect on DPSC proliferation, compared to the media and MC controls. MC-ZrO₂ (DAP-free) greatly increased ALP activity after 7 days. DPSC mineral deposition was modestly reduced at 7 days by MC-BaSO₄ DAP and MC-ZrO₂ DAP, but not by DAP-free radiopaque agents, and was most reduced by 5 mg/mL DAP in the 14-day cultures.

CONCLUSIONS

MC-BaSO₄ or MC-ZrO₂ medicaments containing up to 5 mg/mL of DAP supported the proliferation and early osteogenic differentiation of DPSC. Low DAP concentrations and short culture times led to more favorable effects on ALP activity and mineral deposition by DPSC. The findings suggest that radiopaque agents added for the purpose of detecting whether medicaments occupy the full extent of the root canal may have clinical applications. Radiopaque antibiotic medicaments containing low DAP concentrations may be an alternative to Ca(OH)₂ for regenerative endodontic procedures.