Endodontic sealers after exposure to chlorhexidine digluconate: An assessment of physicochemical properties.

OBJECTIVES: Final root canal irrigation should ideally maintain the physicochemical stability of root canal sealers. We seek to assess the effect of contact with 2% chlorhexidine digluconate (CHX) on the physicochemical properties of AH Plus, BioRoot™ RCS, and Pulp Canal Sealer (PCS). METHODS: Mixed sealers were placed in cylindrical teflon molds and allowed to set for 1.5x the manufacturers' setting time. Half of the specimens had their free surface in contact with CHX for the first minute of their setting period. Solubility, radiopacity, surface roughness, microhardness and wettability of the sealers were assessed up to 28 days after setting. Elemental analysis of sealer surfaces and their leachates together with pH measurements were also performed. Appropriate parametric and non-parametric analysis with post hoc tests were performed (p < 0.05). RESULTS: Exposure to CHX had no effect on solubility and radiopacity of all sealers. CHX altered the surface roughness of PCS and BioRoot RCS (p < 0.05). Contact with CHX reduced the microhardness of AH Plus and PCS (p < 0.05). AH Plus was more hydrophilic after CHX contact, whereas PCS became more hydrophobic (p < 0.05). AH Plus and PCS surfaces appeared to adsorb CHX as exhibited by chlorine peaks after contact with CHX. Sealer leachates' alkalinity was not affected. CHX increased elution of silicon and zirconium for BioRoot and zinc for PCS leachates. SIGNIFICANCE: In our study, CHX affected sealers' physicochemical properties to various extents. Further studies are needed to confirm the obtained results by investigating various final irrigation strategies and correlating to biological properties.

Antibacterial Activity of Root Repair Cements in Contact with Dentin-An Ex Vivo Study.

This study assessed the antibacterial characteristics of the dentin/material interface and dentin surfaces exposed to experimental hydraulic calcium silicate cement (HCSC) with or without bioactive glass (BG) replacement (20% or 40%) or mixed with a silver nanoparticle (SNP) solution (1 or 2 mg/mL), and Biodentine, TotalFill BC RRM putty and Intermediate Restorative Material (IRM). Human root dentin segments with test materials were assessed at 1 or 28 days. In one series, the specimens were split to expose the dentin and material surfaces. A 24 h direct contact test was conducted against three-day established Enterococcus faecalis and Pseudomonas aeruginosa monospecies biofilms. In another series, the dentin/material interface of intact specimens was exposed to biofilm membranes for 3 days and the antibacterial activity was assessed via confocal microscopy. The interface was additionally characterised. All one-day material and dentin surfaces were antibacterial. Dentin surfaces exposed to HCSC with 40% BG-replacement, Biodentine and IRM had decreased antibacterial properties compared to those of the other cements. The HCSC mixed with a 2 mg/mL SNP solution had the highest antimicrobial effect in the confocal assay. The interfacial characteristics of HCSCs were similar. The test materials conferred antibacterial activity onto the adjacent dentin. The BG reduced the antibacterial effect of dentin exposed to HCSC; a 2 mg/mL SNP solution increased the antibacterial potential for longer interaction periods (three-day exposure).

Effect of exposure conditions on chemical properties of materials for surgical endodontic procedures.

This study investigated the role of aging and changes in environmental conditions on selected properties of a prototype radiopacified calcium silicate-based cement (TZ-base) with or without incorporation of silver nanoparticles or bioactive glass, and two commercial materials, Biodentine and intermediate restorative material. Materials were immersed in ultrapure water or fetal bovine serum for 28 days and were characterized with scanning electron microscopy and energy dispersive x-ray analysis. Immersion media were either replaced weekly or not replenished at all and were assessed for alkalinity and calcium release after 1, 7, 14, 21, and 28 days; antibacterial effect against 2-day monospecies biofilms; and cytotoxicity by the 3-(4,5 dimethylthiazolyl-2-yl)-2,5-diphenyl tetrazolium bromide assay after 1, 7, or 28 days. Alkalinity, calcium release, antibacterial activity, and cell cytotoxicity increased over time when the medium was not changed but decreased with medium replenishment. Immersion in fetal bovine serum resulted in lower alkalinity, less bactericidal properties, and lower cytotoxicity of prototype cements and Biodentine than did water immersion. Biodentine and 20% bioactive glass-containing cement had overall lower alkalinity, calcium release, and antibacterial activity than TZ-base, and Biodentine was less cytotoxic than TZ-base. In conclusion, exposure conditions and cement modifications significantly affected materials' leaching properties. Exposure conditions warrant consideration when evaluating cements' clinical properties.

Surface characteristics and bacterial adhesion of endodontic cements.

OBJECTIVES: To investigate the effect of inclusion of silver nano-particles (SNP) or bioactive glass (BG) on the surface characteristics and bacterial adhesion of prototype tricalcium silicate (TCS)-based cements alongside two commercial cements, under different aging periods and exposure conditions. MATERIALS AND METHODS: A basic formulation of radio-opacified TCS without (TZ-base) and with additions of SNP (0.5, 1, or 2 mg/ml) or BG (10 or 20%) was used. Biodentine and intermediate restorative material (IRM) served as reference materials. Material disks were immersed in ultrapure water or fetal bovine serum (FBS) for 1, 7, or 28 days. Surface roughness (n = 3), microhardness (n = 9), and wettability (n = 6) were analyzed by standard procedures. Adhesion of Enterococcus faecalis was assessed by fluorescence microscopy (n = 5). Data from these assays were evaluated for normality and comparisons among groups were conducted with statistical procedures (p < 0.05 for significance). RESULTS: The surface morphology of SNP- and BG-containing cements had higher roughness values than TZ-base after 28 days (p < 0.05). No differences in microhardness were observed among prototype cements (p > 0.05). Biodentine presented smooth surface characteristics and the highest hardness values (p < 0.05). The FBS-immersion resulted in surface reactions in prototype materials and Biodentine, depicted with scanning electron microscopy. All 1- and 7-day prototype cements showed negligible bacterial adhesion, while in Biodentine and IRM, noticeable E. faecalis adherence was observed from day 1 (p < 0.05). CONCLUSIONS: Incorporation of SNP or BG did not improve the antibacterial effect of the experimental cement; all 28-day aged materials failed to inhibit bacterial adherence. The measured physical parameters did not appear to be related to the degree of bacterial adhesion. Exposure of TCS-based cements in FBS resulted in surface reactions, which did not affect bacterial adhesion. CLINICAL RELEVANCE: Changes in the surface characteristics of prototype TCS-based cements by inclusion of SNP and BG or exposure to different environments did not affect bacterial adhesion. All experimental materials showed inferior physical properties and higher antibacterial effect than Biodentine.

On the biocompatibility of endodontic sealers.

Periapical tissue may be exposed to root canal filling materials in consequence of root canal therapy. There is scant scientific data about the biocompatibility of root canal filling materials of various chemistry on the periapical area. This study aimed to investigate the effects of different root canal sealers and their eluates on human alveolar osteoblasts in terms of cell proliferation, adhesion, morphology and gene expression in vitro. Five endodontic sealers (AH Plus®, Apexit®, Tubli-Seal®, Real Seal SE®, EndoRez®) and one gutta-percha obturation material (BeeFill®) were tested. Human alveolar osteoblasts derived from 3 different donors following incubation with sealer eluates after 24 h and 72 h were investigated by means of qPCR (gene expression). Morphological reactions of the alveolar osteoblasts were measured by culturing the cells for 3 d, and 7 d and 14 d, respectively, followed by scanning electron microscopy (morphology, adhesion) and fluorescence imaging of the actin cytoskeleton (morphology, proliferation). A repeated measures analysis was performed and p-values were adjusted by Tukey. While all sealers influenced the cell morphology and the expression of genes associated with apoptosis (Casp3), proliferation (histone H3), and inflammation (interleukin-6 and matrix metalloproteinases 1 and 3), mainly AH Plus® and Apexit® yielded a regular actin cytoskeleton and beneficial gene expression patterns. Regarding cell adhesion, only AH Plus® supported proper anchorage for alveolar osteoblasts. Our results provide evidence for the biocompatibility of epoxy resin-based endodontic sealers, i.e. AH Plus®, while other sealers proved cytotoxic for alveolar osteoblasts. Further studies are needed for understanding the bone cell reactions after endodontic treatment and the clinical decision-making regarding the sealer of choice for root canal fillings.

Effect of chlorhexidine digluconate on antimicrobial activity, cell viability and physicochemical properties of three endodontic sealers.

OBJECTIVE: Assess the biological and physicochemical properties of AH Plus, BioRoot RCS and Pulp Canal Sealer (PCS) leachates with and without chlorhexidine (CHX). METHODS: The sealers were studied in no contact and 1-minute contact with CHX. For biological properties (antibacterial activity and cytotoxicity), leachates were formed in saline of freshly mixed, 1-, 7- and 28 days set sealers. The antibacterial properties of sealer leachates were investigated for planktonic and biofilm growth of E. faecalis, S. mutans, S.epidermidis and S.aureus. The 3-(4,5 dimethylthiazolyl-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was used to evaluate murine fibroblast cell viability after exposure to the leachates. The physical properties (water uptake, sorption, solubility, porosity, surface characteristics) of sealers and the pH of the immersion liquid (saline or distilled water) were also assessed over a 28-days period. RESULTS: CHX improved the antibacterial properties of the sealer leachates and reduced cell viability for all sealer leachates, except for freshly mixed PCS. BioRoot RCS leachates presented the highest antibacterial properties and cell viability with and without CHX contact. PCS was the material most affected by CHX in terms of physical properties, whereas for AH Plus, solubility was increased. CHX did not affect the physical properties of BioRoot RCS, except for solubility that was decreased. CHX contact did not change sealers' alkalinity in distilled water whereas it increased it for AH Plus and BioRoot RCS in saline. SIGNIFICANCE: CHX improved the antibacterial efficacy of sealer leachates and either compromised or did not affect cell viability. CHX affected to various extent sealers' physicochemical properties.

The dentine-sealer interface: Modulation of antimicrobial effects by irrigation.

AIM: Assess whether sodium hypochlorite (NaOCl) or chlorhexidine (CHX) and two irrigation protocols may alter the antibacterial properties of dentine and three endodontic sealers using a novel ex vivo tooth model. METHODOLOGY: Prior to antibacterial testing, the tooth model was validated by means of scanning electron microscopy (SEM) to evaluate the separation between dentine and sealer surfaces. Root blocks prepared from extracted human roots were pre-treated with 17% EDTA + 0.9% saline and subsequently treated with 1% NaOCl (G1), 2% CHX (G2) or no irrigant (G3). Two irrigation protocols were further investigated, "1% NaOCl + 17% EDTA" (P1) and "1% NaOCl + 17% EDTA + 2% CHX" (P2). Following irrigation, the root blocks were either filled with AH Plus, BioRoot RCS and Pulp Canal Sealer (PCS), or left empty. All groups were incubated for 1, 7 and 28 days. Direct contact tests for planktonic E. faecalis and 48 h E. faecalis biofilms were performed at the level of dentine and sealer surfaces. Statistical analysis was performed on the bacterial survival between irrigants (G1, G2 and G3) and between irrigation protocols (P1 and P2); p < .05. RESULTS: The model was considered reproducible as SEM examination of dentine samples indicated consistent separation between dentine and sealer surfaces. Irrigation with CHX (G2) and irrigation protocol P2 enhanced the antibacterial properties of dentine without sealer application as well as dentine in contact with all three sealers tested, especially against planktonic E. faecalis. G2 and P2 also improved the antibacterial effect of AH Plus surfaces for all three incubation times. No irrigation groups (G1, G2) or irrigation protocols (P1, P2) altered the antibacterial properties of BioRoot RCS surfaces against planktonic bacteria or biofilms. Only BioRoot RCS surfaces eliminated the planktonic E. faecalis in all irrigation groups (G1, G2, G3) and protocols (P1, P2) investigated whilst PCS surfaces eliminate E. faecalis in biofilms in all groups up to 7 days. CONCLUSIONS: The tooth model was reproducible. CHX improved the antibacterial activity upon both sealer and dentine surfaces. Amongst sealers, BioRoot RCS was less affected by NaOCl and CHX, and exhibited high antibacterial properties regardless the irrigation applied.

Antimicrobial and physicochemical characterization of endodontic sealers after exposure to chlorhexidine digluconate.

OBJECTIVES: Assess the antibacterial, physical and chemical properties of AH Plus, BioRoot RCS and Pulp Canal Sealer (PCS) in contact with 2% chlorhexidine digluconate (CHX) used as final irrigant prior to root canal obturation. METHODS: The antimicrobial properties were investigated by direct contact tests for planktonic and biofilm growth of E. faecalis, S. mutans, S.epidermidis and S.aureus in vitro. The setting time, wettability, microhardness and surface roughness were also assessed. The sealers were studied in no contact, 1-minute (short-term) and continuous contact (long-term) with CHX. Chemical characterization of sealers was performed by scanning electron microscopy, X-ray diffraction analysis and Fourier-transform infrared spectroscopy after CHX or saline used as the last irrigant in an ex vivo tooth model and in endo training blocks. RESULTS: CHX increased the antibacterial activity of all the sealers investigated against planktonic bacteria and biofilms with PCS exerting the highest antimicrobial activity with and without the presence of CHX. The setting of AH Plus and BioRoot RCS was retarded, while for PCS accelerated in the presence of CHX. AH Plus and PCS were more hydrophilic after contact with CHX, whilst BioRoot RCS was hydrophobic in a time-dependent manner. The microhardness of sealers was compromised and the surface roughness increased after CHX exposure for AH Plus and BioRoot RCS, and decreased for PCS. CHX did not affect the sealers' chemistry, but PCS that exhibited two extra phases. SIGNIFICANCE: CHX improved the antibacterial efficacy of endodontic sealers but further evidence is needed to confirm its suitability as a final irrigant prior to root canal obturation.

Digital subtraction radiography in detection of vertical root fractures: accuracy evaluation for root canal filling, fracture orientation and width variables. An ex-vivo study.

OBJECTIVE: Ex-vivo evaluation of the detectability of vertical root fractures (VRFs) using digital subtraction radiography (DSR) and conventional digital periapical radiography (CDPR); investigation of the effect of root canal filling, x-ray angulation, and thickness of the VRF in the diagnostic accuracy. MATERIALS AND METHODS: Sixty root canals were mechanically prepared and radiographed either with a gutta-percha root canal filling or without, at 0o and ± 10o. VRFs were introduced with a universal testing machine. The width and angulation of the fracture line with the radiographic beam were calculated. DSR was performed comparing radiographs obtained prior to and after the VRF induction. Five examiners evaluated the resultant images and analysis was performed using receiver operator characteristic (ROC) statistics and binary logistic regression tests. RESULTS: No significant differences in sensitivity, specificity, and the areas under the ROC curves (AUC) between the CDPR and DSR were detected (p > 0.05), except for root canal filled teeth where the AUC for DSR was higher (p < 0.05). Using DSR, a VRF was 1.3 times more likely to be diagnosed [95% confidence intervals (CI): 1.045-1.59; p = 0.018]. A correct diagnosis was 2.399 times more likely to occur in non-filled teeth regardless of the radiographic technique (95% CI 1.940-2.965; p = 0). The regression coefficients were positive for width and negative for angle. CONCLUSIONS: DSR showed a better diagnostic accuracy of VRFs compared with CDPR, in single root canal filled teeth. The angulation, the width, and the presence of a root canal filling affected the diagnostic potential. CLINICAL RELEVANCE: DSR is a cost- and time-effective imaging technique that could contribute in early diagnosis of VRFs.

Diagnosis of vertical root fractures in endodontically treated teeth utilising Digital Subtraction Radiography: A case series report.

Vertical root fractures are commonly associated with root-filled teeth. Diagnosis is challenging because the clinical signs are not completely pathognomonic, and conventional periapical radiography is often unreliable. Digital subtraction radiography (DSR) is able to detect small radiographic changes between two successive radiographs by subtracting out consistent radiographic elements. Its use could possibly assist in the diagnostic procedure. Four cases are presented to demonstrate the potential use of DSR in the detection of vertical root fractures in endodontically treated teeth. After the digital subtractions had been carried out, a dark line in the body of the roots was distinguishable, raising the possibility of the presence of a vertical root fracture. The use of contrast enhancement and pseudocolouring techniques assisted with the diagnosis of vertical root fractures. DSR proved to be a useful diagnostic tool for the detection of vertical root fractures in these four clinical cases.

Antibacterial Activity of Endodontic Sealers against Planktonic Bacteria and Bacteria in Biofilms.

INTRODUCTION: The aim of this study was to investigate the antibacterial activity of 4 endodontic sealers against bacteria planktonic grown or in biofilms commonly detected from persistent and secondary endodontic infections. METHODS: The antibacterial activity of the sealers AH Plus, TotalFill BC sealer, RoekoSeal, and Guttaflow 2 was investigated for planktonic grown and 24-hour-old biofilms of Enterococcus faecalis, Staphylococcus epidermidis, Staphylococcus aureus, and Streptococcus mutans. RESULTS: AH Plus had high antibacterial activity toward all species investigated, both planktonic and in biofilms. However, the antibacterial activity was lost after 24 hours. TotalFill BC sealer showed marked antibacterial effect on planktonic bacteria up to 7 days after setting. TotalFill BC sealer had lower antibacterial activity against biofilms of S. aureus and E. faecalis compared with AH Plus when direct contact between the sealer and biofilm was investigated and for all species investigated when a membrane was used to separate the biofilm and sealer. Guttaflow 2 and RoekoSeal had no antibacterial activity against planktonic bacteria or bacteria in biofilms. CONCLUSIONS: Bacteria in biofilms showed higher susceptibility for AH Plus compared with TotalFill BC sealer during the first 24 hours after setting. Investigating the antibacterial activity of endodontic sealers and materials against bacteria in biofilms is highly important to evaluate the materials' ability to eradicate bacteria from the infected root canal.