The Effect of Glycyrrhizin on the Viability and Proliferation of Dental Pulp Stem Cells Compared to Intracanal Medicaments.

AIM: To study the effect of glycyrrhizin (GA) on the viability and proliferation of dental pulp stem cells (DPSCs) compared with intracanal medicaments. MATERIALS AND METHODS: Third molars of an adult donor were used to obtain the DPSCs. Flow cytometry was utilized to conduct phenotypic analysis for DPSCs. The methyl-thiazol tetrazolium (MTT) test was used to detect the cell viability. Cell proliferation assay was conducted at distinct time intervals: 3, 5, and 7 days. RESULTS: The flow cytometry analysis verified the positive expression of mesenchymal cell surface antigen molecules (CD73, CD90, and CD105) and the absence of hematological markers (CD14, CD34, and CD45) in the DPSCs. The cells that treated with concentrations more than 0.5 mg/mL of Ca(OH2) and triple antibiotic paste (TAP) gave significant decrease in viability in comparison to the untreated cells (p < 0.05). Also, the cells treated with concentrations 50 and 25 µM of GA showed no significant difference compared with the untreated cells (p > 0.05), while concentrations 12.5 and 6.25 µM expressed a significant increase in viability compared with the untreated cells (p < 0.05). At 7 days, cells treated with the three different concentrations of GA (12.5, 25, and 50 µM) demonstrated a significant increase in cell density compared with Ca(OH)2 and TAP-treated cells (p < 0.05). CONCLUSION: Based upon the potential of GA on DPSCs proliferation compared with Ca(OH)2 and TAP, It is conceivable to acknowledge that GA could be used as an intracanal medicaments for revascularization process of necrotic immature teeth. CLINICAL SIGNIFICANCE: This study emphasizes the significance of assessing alternative root canal medicaments and their impact on the proliferation and viability of DPSCs. The results regarding GA, specifically its impact on the viability and growth of DPSCs, provide essential understanding for its potential application as an intracanal medicine. This study adds to the continuous endeavors in identifying safer and more efficient intracanal therapies, which are essential for improving patient outcomes in endodontic operations. How to cite this article: Alrashidi MA, Badawi MF, Elbeltagy MG, et al. The Effect of Glycyrrhizin on the Viability and Proliferation of Dental Pulp Stem Cells Compared to Intracanal Medicaments. J Contemp Dent Pract 2024;25(3):267-275.

Antibacterial ability of different activated irrigation after root canal preparation: intratubular analyses.

This study assessed the intratubular antibacterial ability of different activated irrigations after chemical mechanical preparation. Seventy-two palatal root canals of upper molars were infected with Enterococcus faecalis for 4 weeks, and then initial bacterial collection from the main root canal was performed. The root canals were prepared by using a WaveOne Gold large (45/.05) and distributed into 6 groups according to the activation of the final irrigation: ultrasonic activation (UA), XP-Endo Finisher (25/.00), XP Clean (25/.02), EasyClean (25/.04) in reciprocating motion and continuous rotary motion (ECRot), and conventional irrigation. After final irrigation, another bacterial collection from the main root canal was performed, and the root was sectioned transversely in three-thirds and stained for analysis by confocal laser microscopy. Intratubular bacteria were collected through dentin powder and plated for bacterial viability analysis. Intergroup and intragroup comparisons were performed by using analysis of variance and repeated measures analysis of variance, respectively, both at 5% significance. ECRot had higher antibacterial ability than UA (p<0.05), and both were superior to the other groups (p<0.05) in both methodologies. It can be concluded that activation of final irrigation enhances the disinfection of the root canal system, and activators have different efficacies.

Antimicrobial action and cytotoxicity of hypochlorous acid obtained from an innovative electrolytic device - An in vitro study.

OBJECTIVE: This study evaluated the antimicrobial effect and cytotoxicity of hypochlorous acid(HClO) obtained from an innovative electrolytic device. DESIGN: The root canals of fifty extracted human teeth were inoculated with Enterococcus faecalis and divided into 5 groups (n = 10): DW (control); 2% chlorhexidine gel(CHX); 2.5% sodium hypochlorite(NaOCl); 250 ppm HClO and 500 ppm HClO. The counting of colony forming units evaluated the decontamination potential of each group. Cytotoxicity was evaluated after inoculation of tested protocols in fibroblastic cells for 3 min, calculating the cell viability. Specific statistical analysis was performed (α = 5%). RESULTS: The highest bacterial reduction was observed in experimental groups, with no statistical differences from each other (p > 0.05). The highest number of viable cells was observed in control group, followed by 250 ppm HClO and 500 ppm HClO groups, with statistical differences from each other (p < 0.05). CONCLUSIONS: It could be concluded that HClO presented high antimicrobial activity and low cytotoxicity at both tested concentrations.

Elimination of E. faecalis with NaOCl versus chlorhexidine gluconate from primary molar root canal systems: an ex vivo model study.

OBJECTIVES: This ex vivo human study aimed to evaluate the efficacy of NaOCl and chlorhexidine gluconate (CHG) irrigations in eliminating Enterococcus faecalis from the RCS of primary molars. MATERIALS AND METHODS: Disinfected extracted primary molars were inoculated with E. faecalis for 24 h. Then, the RCS samples were then irrigated with either 2.5% NaOCl, 0.2% and 2% CHG, or sham saline. The samples were collected immediately after irrigation; and 24 h later, the bacterial viability and counts were measured using blood agar and qRT-PCR, respectively. Histological sections were used to measure E. faecalis penetration and viability in dentin tubules using fluorescence microscopy. RESULTS: The recovery of viable E. faecalis after the irrigation of the primary molars showed more significant bactericidal effects of NaOCl and 0.2% and 2% CHG than of saline. Immediately after the irrigation, the NaOCl group showed the greatest reduction in E. faecalis; and 24 h later, all the groups had lower viable E. faecalis than the saline control. The bacterial penetration was also lowest in the NaOCl group, although there was no difference in bacterial viability in the tubules between the groups. CONCLUSION: In primary teeth, NaOCl and CHG showed similar degrees of bacterial elimination efficacy in terms of E.faecalis. CLINICAL RELEVANCE: Within the limitations of this study, NaOCl and CHG have the similar ability to perform endodontic irrigation of primary ex vivo teeth regarding the elimination of E.faecalis, but NaOCl penetrates dentin tubules better.

Photodynamic and nitric oxide therapy-based synergistic antimicrobial nanoplatform: an advanced root canal irrigation system for endodontic bacterial infections.

BACKGROUND: The main issues faced during the treatment of apical periodontitis are the management of bacterial infection and the facilitation of the repair of alveolar bone defects to shorten disease duration. Conventional root canal irrigants are limited in their efficacy and are associated with several side effects. This study introduces a synergistic therapy based on nitric oxide (NO) and antimicrobial photodynamic therapy (aPDT) for the treatment of apical periodontitis. RESULTS: This research developed a multifunctional nanoparticle, CGP, utilizing guanidinylated poly (ethylene glycol)-poly (ε-Caprolactone) polymer as a carrier, internally loaded with the photosensitizer chlorin e6. During root canal irrigation, the guanidino groups on the surface of CGP enabled effective biofilm penetration. These groups undergo oxidation by hydrogen peroxide in the aPDT process, triggering the release of NO without hindering the production of singlet oxygen. The generated NO significantly enhanced the antimicrobial capability and biofilm eradication efficacy of aPDT. Furthermore, CGP not only outperforms conventional aPDT in eradicating biofilms but also effectively promotes the repair of alveolar bone defects post-eradication. Importantly, our findings reveal that CGP exhibits significantly higher biosafety compared to sodium hypochlorite, alongside superior therapeutic efficacy in a rat model of apical periodontitis. CONCLUSIONS: This study demonstrates that CGP, an effective root irrigation system based on aPDT and NO, has a promising application in root canal therapy.

Antimicrobial action, cytotoxicity and erosive potential of hypochlorous acid obtained from an electrolytic device compared with sodium hypochlorite.

OBJECTIVES: This study aimed to compare the antimicrobial action, cytotoxicity, cleaning ability, and erosion of dentine of hypochlorous acid (HClO) obtained from an electrolytic device at two different concentrations (Dentaqua) and three concentrations of sodium hypochlorite (NaOCl). METHODS: Microbiological test-The root canals of sixty single-rooted extracted human teeth were inoculated with Enterococcus faecalis and divided into 6 groups (n = 10), according to decontamination protocol: DW (control); 1% NaOCl; 2.5% NaOCl; 5.25% NaOCl; 250 ppm HClO and 500 ppm HClO. The colony-forming units were counted to evaluate the decontamination potential of each group, calculating the reduction in bacterial percentage. Cytotoxicity test-Cytotoxicity was evaluated after inoculation of the same tested protocols in fibroblastic cells for 3 min, calculating the cell viability percentages. Specifical statistical analysis was performed (α = 5%). Cleaning ability and erosion-Fifty-six single-rooted bovine lower incisors were divided into seven groups of 8 roots each, being the test groups 1% NaOCl; 2.5% NaOCl; 5,25% NaOCl; 250 ppm HClO and 500 ppm HClO, and a negative and positive control. Negative control was not contaminated, and the other groups were inoculated with Enterococcus faecalis. SEM images were ranked as from the cleanest to the least clean. Erosion was also assessed, being ranked from the least to the most eroded dentine. RESULTS: The highest bacterial reduction was observed in experimental groups, with no statistical differences between them (p > 0.05). The highest number of viable cells was observed in control group, followed by 250 ppm HClO and 500 ppm HClO groups, with statistical differences between them (p < 0.05). 1% NaOCl; 2.5% NaOCl; 5.25% NaOCl and 500 ppm HClO displayed the cleanest areas. All sodium hypochlorite groups displayed erosion with higher ranks with greater concentration, while hypochlorous acid did not display any erosion regardless the concentration. CONCLUSIONS: It is possible to conclude that HClO obtained from an electrolytic device presented high antimicrobial activity and low cytotoxicity in both tested concentrations. 500 ppm HClO did not display erosion and showed great cleaning ability. CLINICAL RELEVANCE: The use of 500 ppm hypochlorous acid may reduce unfavorable behavior of sodium hypochlorite whilst maintaining its antimicrobial action.

Lipopeptide biosurfactant as a potential root canal irrigation agent: Antimicrobial and anti-biofilm evaluation.

OBJECTIVES: Lipopeptide Biosurfactant (LB) is a bacteria derived compound able to reduce surface tension between water and hydrophobic substances and exhibit antimicrobial and anti-biofilm properties. This study aimed to investigate the antimicrobial and anti-biofilm effect of a Lipopeptide Biosurfactant (LB) on Enterococcus faecalis, and its potential use in root canal treatment, either as a standalone irrigation solution or in conjunction with sodium hypochlorite (NaOCl). METHODS: LB was extracted from Bacillus clausii isolate and the dry extract was diluted in deionized water. The antimicrobial effect of LB against planktonic E. faecalis was evaluated by determining the Minimal Inhibitory Concentration (MIC50). The anti-biofilm effect was evaluated by Minimal Biofilm Inhibitory Concentration (MBIC50) and Minimal Biofilm Eradication Concentration (MBEC50) assays on biofilm grown on dentin specimen surface. To evaluate the effectiveness of LB as a single irrigation solution and as a pre-irrigation prior to NaOCl, live and dead bacterial cells were quantified using Confocal Laser Scanning Microscopy (CLSM), and cell biomass was assessed. RESULTS: LB exhibited an MIC50 and MBIC50 of 100 ppm, with an MBEC50 of 1000 ppm, resulting in 52.94 % biofilm inhibition and 60.95 % biofilm eradication on dentin specimens. The effectiveness was concentration-dependent, at 500 ppm, LB demonstrated comparable antimicrobial efficacy to 2.5 % NaOCl. Pre-irrigation with LB resulted in lower biofilm biomass compared to NaOCl alone. CONCLUSION: Pre-irrigation with LB enhanced the antimicrobial effect when followed by NaOCl irrigation. Consequently, LB shows promise as both a standalone root canal irrigation solution and as an adjunct to NaOCl in root canal treatment. CLINICAL SIGNIFICANCE: The study highlights the potential of Lipopeptide Biosurfactant (LB) as an environmentally friendly irrigation solution for root canal treatment, demonstrating potent antimicrobial and anti-biofilm properties against Enterococcus faecalis. LB exhibits concentration-dependent efficacy comparable to 2.5 % NaOCl and can be used as a standalone irrigation solution or in conjunction with NaOCl.

Effects of Sodium Hypochlorite Concentration and Application Time on Bacteria in an Ex Vivo Polymicrobial Biofilm Model.

INTRODUCTION: In endodontic treatment, it is important to remove or inactivate biofilms in the root canal system. We investigated the effects of different concentrations and application times of sodium hypochlorite (NaOCl) on the viability of bacteria in ex vivo polymicrobial biofilms of different maturation levels. METHODS: Polymicrobial biofilms were prepared from dental plaque samples and grown for 1, 2, and 3 weeks under anaerobic conditions on collagen-coated hydroxyapatite discs as an ex vivo biofilm model. The biofilms were then exposed to NaOCl at concentrations ranging from 0.1% to 2% for 1 or 3 minutes. The control group was exposed to sterile distilled water. Viability staining was performed and examined by confocal laser scanning microscopy to determine the percentage of biofilm bacteria killed by NaOCl. Scanning electron microscopy was also performed to visually examine the biofilms. RESULTS: Application of NaOCl at 0.5%-2% for both 1 and 3 min killed significantly more bacteria when compared to the controls (P < .05). Cell viability tended to be lower after the application of NaOCl for 3 minutes than that for 1 minute. CONCLUSIONS: Our experiments using an ex vivo model showed that within the range of 0.1%-2% of NaOCl, higher NaOCl concentrations and longer application times were more effective in killing biofilm bacteria, and that mature biofilms were more resistant to NaOCl than younger biofilms.

Comparation of the effectiveness of conventional needle irrigation and photon-induced photoacoustic streaming with sodium hypochorite in the treatment of teeth with apical periodontitis: a randomized clinical trial.

Photon-initiated photoacoustic streaming (PIPS) with an Er: YAG laser has been introduced in root canal treatment to improve irrigation and facilitate the removal of bacteria in the root canal system. This study aimed to compare the antibacterial effectiveness of two different root canal irrigation techniques, conventional needle irrigation (CNI) and PIPS, using 1% sodium hypochlorite (NaOCl), in the treatment of teeth with apical periodontitis. Sixty patients with a total of sixty teeth affected by apical periodontitis were included in this study. The teeth underwent root canal therapy, and after mechanical instrumentation, they were randomly assigned to two groups (n = 30) based on the final irrigation protocol: CNI or PIPS with 1% NaOCl. Bacterial suspensions in the root canals were evaluated using Adenosine 5'-triphosphate (ATP) assay kit after mechanical instrumentation and after final irrigation. Then, a follow-up was conducted after 7 days. The results revealed that final irrigation significantly reduced ATP values in both the CNI and PIPS groups (P < 0.001). The ATP values after final irrigation was greater in the CNI group compared to the PIPS group (P < 0.001). After a 7-day follow-up, percussion tenderness and fistula were significantly resolved in both groups (P < 0.05). A multivariate linear regression model was used to identify the factors that influence post irrigation ATP values. The analysis demonstrated that pre-operative percussion tenderness (P = 0.006), the presence of a fistula (P < 0.001) and the method used in the final irrigation (P < 0.001) had a significant impact on the ATP value after final irrigation. These results indicate that employing PIPS with 1% NaOCl as the final irrigation protocol exhibited superior antibacterial effectiveness and has the potential to enhance clinical outcomes in the treatment of teeth afflicted with apical periodontitis.

The Evaluation of Anti-Osteoclastic Activity of the Novel Calcium Hydroxide Biodegradable Nanoparticles as an Intracanal Medicament.

INTRODUCTION: The aim of this study was to evaluate the anti-osteoclastic activity of calcium hydroxide-loaded poly(lactic-co-glycolic acid) nanoparticles [Ca(OH)2-loaded PLGA NPs] in comparison to calcium hydroxide nanoparticles [Ca(OH)2 NPs]. METHODS: RAW 264.7 cell lines (third-fifth passage) were cultured and incubated with soluble receptor activator of nuclear factor kappa B ligand in triplicate. Subsequently, Ca(OH)2-loaded PLGA NPs and Ca(OH)2 NPs were added for 7 days to evaluate their effects on receptor activator of nuclear factor kappa B ligand-induced osteoclast differentiation of RAW 264.7 cells by tartrate-resistant acid phosphatase activity. Additionally, a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was conducted to confirm the cytotoxicity of treatments to cells. RESULTS: Tartrate-resistant acid phosphatase staining showed a significant reduction in the osteoclast number when treated with Ca(OH)2-loaded PLGA NPs compared with Ca(OH)2 NPs (P < .01). In comparison to the control, the number of osteoclasts significantly reduced upon treatment with Ca(OH)2-loaded PLGA NPs (P < .05), but there was no significant difference in Ca(OH)2 NPs. Furthermore, osteoclast morphology in both treatment groups exhibited smaller sizes than the control group. Neither Ca(OH)2-loaded PLGA NPs nor Ca(OH)2 NPs demonstrated cytotoxic effects on RAW264.7 cells. CONCLUSIONS: Both Ca(OH)2 NPs with and without poly(lactic-co-glycolic acid) have the ability to inhibit osteoclast differentiation. However, Ca(OH)2-loaded PLGA NPs exhibit greater potential than Ca(OH)2 NPs, making them a promising intracanal medicament for cases of root resorption.

Final irrigation with bioglass solution in regenerative endodontic procedure induces tissue formation inside the root canals, collagen maturation, proliferation cell and presence of osteocalcin.

AIM: To evaluate the influence of an experimental solution of cobalt-doped F18 bioactive glass (F18Co) on tissue repair following regenerative endodontic procedure (REP) in rat molars. METHODOLOGY: The F18Co solution was prepared at a ratio of 1:5 F18Co powder to distilled water. The right or left upper first molars of 12 Wistar rats were used, where the pulps were exposed, removed, and irrigated with 2.5% sodium hypochlorite (NaOCl), followed by 17% ethylenediaminetetraacetic acid (EDTA) (5 min each). Subsequently, the molars were divided into two groups (n = 6): REP-SS and REP-F18Co, where they received a final irrigation (5 min) with saline solution (SS) or F18Co solution, respectively. Then, intracanal bleeding was induced, and the tooth was sealed. Untreated molars were used as controls (n = 3). At 21 days, the rats were euthanized, and the specimens were processed for analysis of mineralized tissue and soft tissue formation inside the root canal using haematoxylin-eosin. The presence and maturation of collagen were evaluated by Masson's trichrome and picrosirius red staining. Immunolabelling analyses of proliferating cell nuclear antigen (PCNA) and osteocalcin (OCN) were performed. The data were submitted to the Mann-Whitney U-test (p < .05). RESULTS: There was a similar formation of mineralized tissue in thickness and length in REP-SS and REP-F18Co groups (p > .05). Regarding the presence of newly formed soft tissue, most specimens of the REP-F18Co had tissue formation up to the cervical third of the canal, whilst the REP-SS specimens showed formation up to the middle third (p < .05), and there was higher maturation of collagen in REP-F18Co (p < .05). The number of PCNA-positive cells found in the apical third of the root canal was significantly higher in the F18Co group, as well as the OCN immunolabelling, which was severe in most specimens of REP-F18Co, and low in most specimens of REP-SS. CONCLUSION: The final irrigation with F18Co bioactive glass solution in REP did not influence mineralized tissue formation but induced soft tissue formation inside the root canals, with higher collagen maturation, and an increase in PCNA-positive cells and OCN immunolabelling.

In vitro efficacy of Er:YAG laser-activated irrigation versus passive ultrasonic irrigation and sonic-powered irrigation for treating multispecies biofilms in artificial grooves and dentinal tubules: an SEM and CLSM study.

BACKGROUND: Multispecies biofilms located in the anatomical intricacies of the root canal system remain the greatest challenge in root canal disinfection. The efficacy of Er:YAG laser-activated irrigation techniques for treating multispecies biofilms in these hard-to-reach areas has not been proved. The objective of this laboratory study was to evaluate the effectiveness of two Er:YAG laser-activated irrigation techniques, namely, photon-induced photoacoustic streaming (PIPS) and shock wave-enhanced emission photoacoustic streaming (SWEEPS), in treating multispecies biofilms within apical artificial grooves and dentinal tubules, in comparison with conventional needle irrigation (CNI), passive ultrasonic irrigation (PUI), and sonic-powered irrigation (EDDY). Two types of multispecies root canal biofilm models were established in combination with two assessment methods using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) with the aim to obtain more meaningful results. METHODS: Ninety extracted human single-rooted premolars were chosen for two multispecies biofilm models. Each tooth was longitudinally split into two halves. In the first model, a deep narrow groove was created in the apical segment of the canal wall. After cultivating a mixed bacterial biofilm for 4 weeks, the split halves were reassembled and subjected to five irrigation techniques: CNI, PUI, EDD, PIPS, and SWEEPS. The residual biofilms inside and outside the groove in Model 1 were analyzed using SEM. For Model 2, the specimens were split longitudinally once more to evaluate the percentage of killed bacteria in the dentinal tubules across different canal sections (apical, middle, and coronal thirds) using CLSM. One-way analysis of variance and post hoc multiple comparisons were used to assess the antibiofilm efficacy of the 5 irrigation techniques. RESULTS: Robust biofilm growth was observed in all negative controls after 4 weeks. In Model 1, within each group, significantly fewer bacteria remained outside the groove than inside the groove (P < 0.05). SWEEPS, PIPS and EDDY had significantly greater biofilm removal efficacy than CNI and PUI, both from the outside and inside the groove (P < 0.05). Although SWEEPS was more effective than both PIPS and EDDY at removing biofilms inside the groove (P < 0.05), there were no significant differences among these methods outside the groove (P > 0.05). In Model 2, SWEEPS and EDDY exhibited superior bacterial killing efficacy within the dentinal tubules, followed by PIPS, PUI, and CNI (P < 0.05). CONCLUSION: Er:YAG laser-activated irrigation techniques, along with EDDY, demonstrated significant antibiofilm efficacy in apical artificial grooves and dentinal tubules, areas that are typically challenging to access.

Antibacterial biofilm efficacy of calcium hydroxide loaded on Gum Arabic nanocarrier: an in-vitro study.

BACKGROUND: An innovative intracanal medication formulation was introduced in the current study to improve the calcium hydroxide (Ca(OH)2) therapeutic capability against resistant Enterococcus faecalis (E. faecalis) biofilm. This in-vitro study aimed to prepare, characterize, and evaluate the antibacterial efficiency of Ca(OH)2 loaded on Gum Arabic (GA) nanocarrier (Ca(OH)2-GA NPs) and to compare this efficiency with conventional Ca(OH)2, Ca(OH)2 nanoparticles (NPs), GA, and GA NPs. MATERIALS AND METHODS: The prepared nanoparticle formulations for the tested medications were characterized using Transmission Electron Microscope (TEM) and Fourier-Transform Infrared Spectroscopy (FTIR). 141 human mandibular premolars were selected, and their root canals were prepared. Twenty-one roots were then sectioned into 42 tooth slices. All prepared root canals (n = 120) and teeth slices (n = 42) were divided into six groups according to the intracanal medication used. E. faecalis was inoculated in the samples for 21 days to form biofilms, and then the corresponding medications were applied for 7 days. After medication application, the residual E. faecalis bacteria were assessed using CFU, Q-PCR, and SEM. Additionally, the effect of Ca(OH)2-GA NPs on E. faecalis biofilm genes (agg, ace, and efaA) was investigated using RT-PCR. Data were statistically analyzed at a 0.05 level of significance. RESULTS: The synthesis of NPs was confirmed using TEM. The results of the FTIR proved that the Ca(OH)2 was successfully encapsulated in the GA NPs. Ca(OH)2-GA NPs caused a significant reduction in the E. faecalis biofilm gene expression when compared to the control (p < 0.001). There were significant differences in the E. faecalis CFU mean count and CT mean values between the tested groups (p < 0.001) except between the Ca(OH)2 and GA CFU mean count. Ca(OH)2-GA NPs showed the least statistical E. faecalis mean count among other groups. SEM observation showed that E. faecalis biofilm was diminished in all treatment groups, especially in the Ca(OH)2-GA NPS group when compared to the control group. CONCLUSIONS: Ca(OH)2 and GA nanoparticles demonstrate superior anti-E. faecalis activity when compared to their conventional counterparts. Ca(OH)2-GA NPs showed the best antibacterial efficacy in treating E. faecalis biofilm. The tested NP formulations could be considered as promising intracanal medications.

The efficacy of 2780 nm Er,Cr;YSGG and 940 nm Diode Laser in root canal disinfection: A randomized clinical trial.

OBJECTIVES: Effective disinfection of the root canals is the cornerstone of successful endodontic treatment. Diminishing the microbial load within the root canal system is crucial for healing in endodontically treated teeth. The aim of this study was to evaluate the effect of 2780 nm Er,Cr:YSGG and 940 nm diode lasers on the eradication of microorganisms from single-rooted teeth with asymptomatic apical periodontitis. MATERIALS AND METHODS: Thirty participants conforming to the inclusion criteria were randomly divided into 3 groups according to the disinfection protocol used; Conventional group: 2.5% Sodium Hypochlorite (NaOCl) and 17% EDTA solution NaOCl/EDTA, Dual laser group: 2780 nm Erbium, chromium: yttrium scandium-gallium-garnet (Er,Cr:YSGG) laser and 940 nm diode laser Er,CrYSGG/Diode, and Combined group: 17% EDTA and 940 nm diode laser EDTA/Diode. Bacterial samples were collected before and after intervention. The collected data were statistically analyzed using Friedman's test and Kruskal-Wallis test (P ≤ 0.05). RESULTS: The results of the study showed that both dual laser Er,CrYSGG/Diode and combined laser EDTA/Diode groups showed significantly less mean Log10 CFU/ml of aerobic and anaerobic bacterial counts than the conventional NaOCl/EDTA group. CONCLUSIONS: In this study we evaluated in vivo the bactericidal efficacy of three disinfection protocols for endodontic treatment of single-rooted teeth with apical periodontitis. The results indicated that both dual laser Er,CrYSGG/Diode and combined laser EDTA/Diode groups provide superior bactericidal effect compared to the conventional NaOCl/EDTA group. CLINICAL RELEVANCE: The integration of lasers into root canal disinfection protocols has demonstrated significant bacterial reduction which might promote healing and long-term success.

The dynamics of bacterial proliferation, viability, and extracellular polymeric substances in oral biofilm development.

OBJECTIVES: This study investigated the relationship between bacterial growth, viability, and extracellular polymeric substances (EPS) formation in biofilms, particularly regarding resistance development. It also examined the impact of chemical factors on the EPS matrix and bacterial proliferation in oral biofilms. METHODS: Three multi-species oral biofilms were incubated in anaerobic conditions. Three strains of Enterococcus faecalis were incubated in aerobic conditions. The incubation periods ranged from 0 h to 7 days for short-term biofilms, and from 3 to 90 days for long-term biofilms. Fluorescent labeling with carboxyfluorescein diacetate succinimidyl ester (CFSE) and flow cytometry were used to track EPS and bacterial growth. Confocal laser scanning microscopy (CLSM) assessed bacterial viability and EPS structure. Biofilms aged 7, 14, and 21 days were treated with 2 % chlorhexidine (CHX) and 1 % sodium hypochlorite (NaOCl) to evaluate their effects on EPS and bacterial proliferation. RESULTS: Short-term biofilms showed rapid bacterial proliferation and a gradual increase in EPS, maintaining stable viability. In the first two weeks, a significant rise in CFSE indicated growing maturity. From 14 to 90 days, EPS and CFSE levels stabilized. Following treatment, CHX significantly reduced bacterial proliferation, while NaOCl decreased EPS volume. CONCLUSIONS: Biofilm development involves a balance between bacterial proliferation and EPS production. The complexity of this process poses challenges in treating biofilm-associated infections, requiring strategies tailored to the biofilm's developmental stage. CLINICAL SIGNIFICANCE: For effective root canal treatment, it is imperative to focus on reducing bacterial proliferation during the early stages of oral infections. In contrast, strategies aimed at minimizing EPS production could be more beneficial for long-term management of these conditions.

Effect of sodium hypochlorite temperature and concentration on the fracture resistance of root dentin.

BACKGROUND: Sodium hypochlorite (NaOCl) is the most efficient root canal irrigant to date. The aim of this study was to compare the effect of NaOCl used at different temperatures and concentrations on the compressive strength of root dentin. MATERIALS AND METHODS: Seventy-two extracted human single-canaled straight roots of comparable size and length were selected and randomly divided into six groups (n = 12): Group (A) served as a control with unprepared canals. The other groups were instrumented with rotary ProTaper Universal files up to size F3. Group (B) was irrigated with 1% NaOCl at room temperature, Group (C) with 1% NaOCl heated to 70 °C, Group (D) with 5.25% NaOCl at room temperature, and Group (E) with 5.25% NaOCl heated to 70 °C. Saline was used in Group (F). The roots were sectioned into 2-mm-thick disks that underwent compression testing using a universal testing machine. Data were analyzed using one-way ANOVA and post hoc Tukey tests. The significance level was set at p ≤ 0.05. RESULTS: A total of 255 disks were tested. The control group showed the highest compressive strength (p = 0.0112). However, this did not differ significantly from that of heated (p = 0.259) or unheated (p = 0.548) 1% NaOCl. There were no statistically significant differences between the groups of instrumented teeth. CONCLUSION: Within the conditions of this study, irrigation with NaOCl at different concentrations and temperatures during root canal preparation did not affect the compressive strength of root dentin. CLINICAL RELEVANCE: This study demonstrates that the use of NaOCl as a root canal irrigant is not associated with a clinically relevant decrease in root compressive strength, especially when compared to saline.

Effect of final irrigation protocols with chitosan nanoparticle and genipin on dentine against collagenase degradation: An ex-vivo study.

AIM: Endodontic irrigants may affect the mechanical and chemical properties of dentine. This study evaluated the effects of various final irrigation protocols including the use of chitosan nanoparticle (CSnp) and cross-linking with genipin on the (1) mechanical and (2) chemical properties of dentine against enzymatic degradation. METHODOLOGY: CSnp was synthesized and characterized considering physiochemical parameters and stability. The root canals of 90 single-rooted teeth were prepared and irrigated with NaOCl. Dentine discs were obtained and divided into groups according to the following irrigation protocols: Group NaOCl+EDTA, Group NaOCl+CSnp, Group NaOCl+EDTA+CSnp, Group NaOCl+CSnp+Genipin, Group NaOCl+EDTA+CSnp+Genipin and Group distilled water. (1) Mechanical changes were determined by microhardness analysis using Vickers-tester. (2) Chemical changes were determined by evaluating molecular and elemental compositions of dentine using Fourier transform infrared spectroscopy (FTIR) analysis and scanning electron microscope (SEM)/energy dispersive X-ray spectroscopy (EDS) analysis, respectively. All analyses were repeated after the discs were kept in collagenase for 24 h. Data were analysed with repeated measures analysis of variance and Bonferroni correction for microhardness analysis, and Kruskal-Wallis and Wilcoxon tests for FTIR and SEM/EDS analyses (p = .05). RESULTS: (1) Collagenase application did not have a negative effect on microhardness only in Group NaOCl+EDTA+CSnp+Genipin when compared with the post-irrigation values (p > .05). Post-collagenase microhardness of Group NaOCl+EDTA+CSnp and Group NaOCl+CSnp+Genipin was similar to the initial microhardness (p > .05). (2) After collagenase, Amide III/ PO 4 3 - ratio presented no change in Group NaOCl+EDTA+CSnp, Group NaOCl+CSnp+Genipin and Group NaOCl+EDTA+CSnp+Genipin (p > .05), while decreased in other groups (p < .05). Collagenase did not affect CO 3 2 - / PO 4 3 - ratio in the groups (p > .05). There were no changes in the groups in terms of elemental level before and after collagenase application (p > .05). CONCLUSIONS: CSnp and genipin positively affected the microhardness and molecular composition of dentine. This effect was more pronounced when CSnp was used after EDTA.

Sonic-assisted antibacterial photodynamic therapy: a strategy for enhancing lateral canal disinfection.

BACKGROUND: Bacterial infections in lateral canals pose challenges for root canal treatment. This in vitro study aims to evaluate the antibacterial efficacy of sonic-assisted methylene blue mediated antimicrobial photodynamic therapy (MB-aPDT) against Enterococcus faecalis (E. faecalis) in infected lateral canals. METHODS: Sixty-five premolars infected with E. faecalis in lateral canals were randomly divided into five groups (n = 13) and treated with : (1) 5.25% NaOCl (positive control); (2) Saline (negative control); (3) Sonic-assisted MB-aPDT; (4) 3% NaOCl + MB-aPDT; (5) 3% NaOCl + sonic-assisted MB-aPDT, respectively. The antibacterial efficacy was evaluated by the colony- counting method (CCM) and scanning electronic microscope (SEM). RESULTS: Both 5.25% NaOCl and the 3% NaOCl + sonic-assisted MB-aPDT exhibited the most effective while comparable antibacterial effects without significant statistical difference (P > 0.05). Furthermore, the antibacterial effect of the 3% NaOCl + MB-aPDT group was significantly higher compared to that of the sonic-assisted MB-aPDT group (P < 0.05). The SEM results demonstrated notable morphological alterations in E. faecalis across all experimental groups, except for the negative control group. CONCLUSION: The concentration of NaOCl can be reduced to a safe level while preserving its antibacterial efficacy through the synergism with the sonic-assisted MB-aPDT in this study.

The Effect of Calcium Hydroxide Pastes on Isolated Vital Nerve Fibers.

INTRODUCTION: Calcium hydroxide pastes (CHPs), commonly used for disinfecting root canals during endodontic treatment, are generally considered safe. However, accidental extrusions result in minimal injuries and little to no discomfort, except when extruded pastes come into contact with nerve bundles, such as the inferior alveolar nerve. Currently, there is a lack of information about the possible role of specific paste vehicles on the extent of nerve injury. The purpose of this study was to compare the role that paste vehicles, such as water or methylcellulose, may play when nerve fibers are exposed to CHP. METHODS: Isolated sciatic nerves of Sprague-Dawley rats were exposed to either water-based or methylcellulose-based CHP for varying durations of time (30, 60, or 90 minutes). Histopathological changes, including axonal edema, myelin alterations, and loss of cellular outlines, were assessed, and the degrees of changes were compared using chi-square intraclass correlation coefficient tests. RESULTS: Both groups exposed to the pastes demonstrated varying degrees of histopathologic changes, including axonal edema, myelin changes, and loss of cellular outlines, at different exposure times. The water-based calcium hydroxide paste induced these changes more rapidly than the methylcellulose-based paste. Similar patterns were observed in the scanning electron microscopic findings. Exposure time emerged as an important difference in the effects of the 2 pastes. In each of these tests, all observations of water-based paste exposure were rated as moderate to severe, whereas the observed cellular changes (axonal, myelin, and intact cellular outline) were rated as mild to moderate after exposure to methylcellulose-based paste for the same exposure durations. The chi-square tests indicated a statistically significant association between the material and each of the outcomes (axonal changes: χ²15 = 81.0, P < .001; myelin changes: χ²15 = 81.0, P < .001; intact cellular outline, χ²15 = 81.0, P < .001). The intraclass correlation coefficient value was 0.93. CONCLUSIONS: The study demonstrates that axonal and myelin damage increase with longer exposure times, with water-based CHP causing more damage than methylcellulose-based CHP at each time point.

Iontophoresis use for increasing drug penetration into root canals and dentinal tubules: A proof-of-concept study.

INTRODUCTION: The success of endodontic treatment depends on the significant disinfection of the root canal system, its irregularities, and dentinal tubules. However, achieving complete disinfection remains challenging, with frequent failures and occurrence of secondary infections. Here, we propose using iontophoresis to increase the penetration and distribution of disinfecting agents into root canals, using methylene blue for proof-of-concept. METHODS: The marker was applied in bovine root canals, and the radial distribution of the dye in the dentinal tubules was evaluated by optical microscopy. Iontophoresis was applied at 0.5 and 1.5 mA for 5 and 15 min. RESULTS: A significant statistical difference (p < 0.05) was observed in the marker penetration between passive and iontophoretic applications. Both current density and application time had an important effect on methylene blue distribution, with a greater efficacy delivery to the apical region achieved after 1.5 mA for 5 min or 0.5 mA for 15 min, showing longer application time can compensate for lower application current. CONCLUSION: Iontophoresis increases the penetration and distribution of methylene blue into bovine root canals and dentinal tubules, including its innermost portions. CLINICAL SIGNIFICANCE: Iontophoresis has shown to be a promising technique for root canal and dentinal tubule disinfection.