Effect of intracanal dentine wettability on human dental pulp cell attachment

A critical analysis of research methods and experimental models to study irrigants and irrigation systems

Irrigation plays an essential role in root canal treatment. The purpose of this narrative review was to critically appraise the experimental methods and models used to study irrigants and irrigation systems and to provide directions for future research. Studies on the antimicrobial effect of irrigants should use mature multispecies biofilms grown on dentine or inside root canals and should combine at least two complementary evaluation methods. Dissolution of pulp tissue remnants should be examined in the presence of dentine and, preferably, inside human root canals. Micro-computed tomography is currently the method of choice for the assessment of accumulated dentine debris and their removal. A combination of experiments in transparent root canals and numerical modeling is needed to address irrigant penetration. Finally, models to evaluate irrigant extrusion through the apical foramen should simulate the periapical tissues and provide quantitative data on the amount of extruded irrigant. Mimicking the in vivo conditions as close as possible and standardization of the specimens and experimental protocols are universal requirements irrespective of the surrogate endpoint studied. Obsolete and unrealistic models must be abandoned in favour of more appropriate and valid ones that have more direct application and translation to clinical Endodontics.

Conductive Scaffolds for Bone Tissue Engineering: Current State and Future Outlook

Bone tissue engineering strategies attempt to regenerate bone tissue lost due to injury or disease. Three-dimensional (3D) scaffolds maintain structural integrity and provide support, while improving tissue regeneration through amplified cellular responses between implanted materials and native tissues. Through this, scaffolds that show great osteoinductive abilities as well as desirable mechanical properties have been studied. Recently, scaffolding for engineered bone-like tissues have evolved with the use of conductive materials for increased scaffold bioactivity. These materials make use of several characteristics that have been shown to be useful in tissue engineering applications and combine them in the hope of improved cellular responses through stimulation (i.e., mechanical or electrical). With the addition of conductive materials, these bioactive synthetic bone substitutes could result in improved regeneration outcomes by reducing current factors limiting the effectiveness of existing scaffolding materials. This review seeks to overview the challenges associated with the current state of bone tissue engineering, the need to produce new grafting substitutes, and the promising future that conductive materials present towards alleviating the issues associated with bone repair and regeneration.

Experimental Solution of Chitosan and Nanochitosan on Wettability in Root Dentine: In Vitro Model Prior Regenerative Endodontics

Aims

To compare the effect of CS and CSnp on the wettability in root dentine with other irrigation protocols with an experimental in vitro model prior regenerative endodontics. Methods and Material. An in vitro experimental study that included eighty hemisected human root distributed into 8 groups: G1- distilled water; G2- 1% NaOCl/17% EDTA; G3- hypochlorous acid 0.025% HOCl, G4- 1% NaOCl/0.025% HOCl/17% EDTA, G5- 0.2 g/100 mL CS, G6- 1% NaOCl/0.2 g/100 mL CS, G7- CSnp, and G8- 1% NaOCl/CSnp. The wettability analysis calculated the contact angle (θ) between a drop of a blood-like and root dentinal surface; topographic characterization with scanning electron microscopy (SEM) quantified the diameter and number of tubules per area; spectroscopy infrared analyses (IR-S) identified chemical changes in the inorganic (phosphate/carbonate) and organic phase (amide/methyl). Statistical analysis: a linear mixed model, Kruskal–Wallis, and Holm–Bonferroni correction (P < 0.05) were used.

Results

Significantly higher wettability for G2 (27.1 (P = 0.0001)) was found. A mean value of 67°±°for experimental groups (P = 0.07) was found, and we did not identify differences between them. The SEM identified greater tubular opening and erosion for G4 and greater dentinal permeability per area for NaOCl/CS. IR-S identified dentinal organic integrity with NaOCl-CS/CSnp compared to organic reduction promoted for NaOCl/EDTA.

Conclusions

This in vitro dentin determined an indirect association between the wettability and organic contents. The oxidative effect of NaOCl could be neutralized by CS-CSnp, and consequently, the wettability of the substrate decreases.

A comparative evaluation of Advanced Platelet-Rich Fibrin (A-PRF) and Platelet-Rich Fibrin (PRF) as a Scaffold in Regenerative Endodontic Treatment of Traumatized Immature Non-vital permanent anterior teeth: A Prospective clinical study

Background

Regenerative endodontic treatment (RET) is a promising treatment alternative for traumatized immature non-vital teeth. Advanced platelet-rich fibrin (A-PRF) contains significantly more growth factors than Platelet-rich fibrin (PRF) and has not been evaluated as a scaffold in RET. The aim of the present study was to evaluate and compare A-PRF and PRF as scaffolds in the RET concerning periapical healing, and root development of traumatized immature non-vital teeth.

Material and Methods

In the present study, RET was performed on 30 traumatized immature non-vital maxillary incisors in 28 patients aged between 8-27 years. Minimal mechanical debridement and irrigation with 1.5% sodium hypochlorite and 17% ethylenediaminetetraacetic acid was performed. Canals were disinfected using modified triple antibiotic paste consisting of ciprofloxacin, metronidazole and cefaclor. Based on the type of scaffold, teeth were randomly assigned into A-PRF (n=15) and PRF groups (n=15). Periapical healing, apical response and quantitative root dimensions (length and thickness) were analyzed radiographically after 12 months follow-up.

Results

Nineteen patients with 21 teeth (A-PRF n=11, PRF n=10) completed the follow-up and 9 patients were excluded. Clinically, patients in both the groups were asymptomatic. The survival rates for A-PRF and PRF were 78.5% and 77.5%, respectively. No statistically significant differences were detected between A-PRF and PRF regarding periapical healing and type of apical response (p& 0.05). The difference in the pre-operative and follow-up root thickness and root length in both A-PRF and PRF groups were statistically significant (p< 0.05).

Conclusions

Based on short-term results of 13 months, both A-PRF and PRF can be used as scaffold in regenerative endodontic treatment of traumatized immature non-vital teeth. A-PRF could be recommended in such cases since it yielded more root dentin thickness which is crucial for reinforcing immature teeth.

Key words:Regenerative endodontic treatment, dental trauma, Non-vital teeth, immature teeth, platelet-rich fibrin, advanced platelet-rich fibrin.

Properties of a modified quaternary ammonium silane formulation as a potential root canal irrigant in endodontics

OBJECTIVES

Evaluate a new modified quaternary ammonium silane irrigant solution for its antimicrobial, cytotoxic and mechanical properties of dentine substrate.

METHODS

Root canal preparation was performed using stainless steel K-files™ and F4 size protaper with irrigation protocols of 6% NaOCl + 2% CHX; 3.5% QIS; 2% QIS and sterile saline. Biofilms were prepared using E. faecalis adjusted and allowed to grow for 3 days, treated with irrigants, and allowed to grow for 7 days. AFM was performed and surface free energy calculated. MC3T3 cells were infected with endo irrigant treated E. faecalis biofilms. Raman spectroscopy of biofilms were performed after bacterial re-growth on root dentine and exposed to different irrigation protocols and collagen fibers analysed collagen fibers using TEM. Antimicrobial potency against E. faecalis biofilms and cytoxicity against 3T3 NIH cells were also. Resin penetration and MitoTracker green were also evaluated for sealer penetration and mitochondrial viability. Data were analysed using One-way ANOVA, principal component analysis and post-hoc Fisher's least-significant difference.

RESULTS

Elastic moduli were maintained amongst control (5.5 ± 0.9) and 3.5% QIS (4.4 ± 1.1) specimens with surface free energy higher in QIS specimens. MC3T3 cells showed reduced viability in 6%NaOCl+2%CHX specimens compared to QIS specimens. DNA/purine were expressed in increased intensities in control and 6% NaOCl + 2% CHX specimens with bands around 480-490 cm^-1 reduced in QIS specimens. 3.5% QIS specimens showed intact collagen fibrillar network and predominantly dead bacterial cells in confocal microscopy. 3.5% QIS irrigant formed a thin crust-type surface layer with cytoplasmic extensions of 3T3NIH spread over root dentine. Experiments confirmed MitoTracker accumulation in 3.5% treated cells.

SIGNIFICANCE

Novel QIS root canal irrigant achieved optimum antimicrobial protection inside the root canals facilitating a toxic effect against the Enterococcus faecalis biofilm. Root dentine substrates exhibited optimum mechanical properties and there was viability of fibroblastic mitochondria.

Effect of benzalkonium chloride addition to EDTA on attachment and proliferation of dental pulp stem cells on dentin and on transforming growth factor-β1 release

To investigate the effect of benzalkonium chloride (BAC) addition to ethylenediaminetetraacetic acid (EDTA) on transforming growth factor-β1 (TGF-β1) release, as well as attachment and proliferation of dental pulp stem cells (DPSCs) on dentin. A total of standard 268 human dentin disks were prepared and immersed in 1.5% sodium hypochlorite (NaOCl) for 5 min. The disks were rinsed with distilled water and randomly divided into seven groups. In control group, the disks received no further treatment. The remaining disks were immersed in following solutions: 17% EDTA or 17% EDTA + 0.008% BAC for 1, 5 or 10 min and rinsed with distilled water. DPSCs were seeded in part of the disks since the TGF-β1 release assay was performed with disks with and without cells. The attachment and proliferation of DPSCs on dentin disks were analyzed using lactate dehydrogenase activity and WST-1 assays, respectively. The cell morphology was observed by scanning electron microscopy. The release of TGF-β1 was quantified using ELISA. Data were analyzed using three- and two-way analysis of variance with Bonferroni corrections. Both EDTA solutions increased the attachment and proliferation of DPSCs (p < .05) while there was no significant difference between them (p > .05). The exposure time of both EDTA solutions had no influence on cell attachment, proliferation and TGF-β1 release (p > .05). There was no significant difference in TGF-β1 release between the control and experimental groups (p > .05). The amount of released TGF-β1 from dentin disks was similar whether or not they were seeded with cells (p > .05). Dentin treatment with either of the EDTA solutions had no effect on the amount of TGF-β1 release while both EDTA solutions improved cell attachment and proliferation on dentin surface regardless of exposure time.

Antimicrobial peptide GH12 as root canal irrigant inhibits biofilm and virulence of Enterococcus faecalis

AIM

The objectives of this laboratory-based study were to investigate the effects of GH12 on Enterococcus faecalis biofilm and virulence.

METHODOLOGY

Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of GH12 against E. faecalis were first determined. A time-kill assay was further conducted. The effects of GH12 on the expression of virulence and stress genes in E. faecalis were evaluated by RT-qPCR. Crystal violet stain was used to investigate the effects of GH12 on E. faecalis biofilm formation and 1-day-old biofilm. Finally, an ex vivo tooth model contaminated with E. faecalis was used to evaluate the antimicrobial activity of GH12 as an irrigant by CFU counting, SEM and CLSM. One-way anova and Tukey's multiple comparisons test were used to compare the differences amongst groups (α = 0.05).

RESULTS

The MICs and MBCs of GH12 against E. faecalis were 8.0 ± 0.0 and 16.0 ± 0.0 mg L^-1 , respectively, and GH12 at 32.0 mg L^-1 reduced the bacterial numbers by more than 99.9% within 1 min. Various virulence genes (efaA, esp and gelE) and stress genes (dnaK, groEL, ctsR and clpPBCEX) in E. faecalis were significantly downregulated by GH12 at sub-MIC levels (P < 0.05). Additionally, both E. faecalis biofilm formation and the biomass of 1-day-old E. faecalis biofilm were significantly reduced by GH12 (P < 0.05). Elimination of E. faecalis in biofilms from root canal walls was achieved through irrigation with 64.0 mg L^-1 GH12 for 30 min. CLSM analysis revealed that GH12 at 64.0 mg L^-1 was most effective in eliminating bacteria within dentinal tubules (P < 0.05).

CONCLUSION

In a laboratory setting, and when used as an irrigant, GH12 suppressed E. faecalis, downregulated specific virulence and stress-associated genes, eliminated intracanal E. faecalis protected by biofilms and killed bacteria in dentinal tubules. These results emphasize the need for preclinical and clinical studies to explore the potential of GH12 as an antimicrobial agent during root canal treatment.

Dynamic Irrigation Promotes Apical Papilla Cell Attachment in an Ex Vivo Immature Root Canal Model

INTRODUCTION

The use of dentin preconditioning techniques in regenerative endodontic procedures is currently promising. Several growth factors have been detected on dentin after ultrasonic irrigation with EDTA. This study aimed to evaluate the effects of dynamic irrigation with different solution regimens on apical papilla cell (APC) attachment in an ex vivo immature tooth model.

METHODS

Various dynamic irrigation techniques, needle irrigation (NI), NI with EndoActivator, and NI with passive ultrasonic irrigation, were used with different solution regimens, normal saline solution (NSS), EDTA, and chlorhexidine digluconate followed by EDTA, in enlarged root canal models where calcium hydroxide-medicated dentin slices were inserted. The initial number of attached fibronectin-positive APCs was counted. Dentin surface morphology was also inspected by using scanning electron microscopy.

RESULTS

The number of APCs was significantly greater in the dynamic irrigation groups than in the control group (P < .001). Greater APC numbers were observed in the groups in which NSS was used than in those in which EDTA or chlorhexidine digluconate/EDTA was used, when using the same techniques (P < .001). Cell numbers were similar at all levels of the root canals; however, in the ultrasonically supplemented group irrigated with NSS, the number of attached cells was significantly increased at the middle and apical levels (P < .05).

CONCLUSIONS

The use of dynamic irrigation techniques in an immature tooth model definitely promoted APC attachment to calcium hydroxide-medicated dentin. Furthermore, when NSS was used as a final irrigant, the number of attached cells was significantly increased.

EDTA Treatment for Sodium Hypochlorite-treated Dentin Recovers Disturbed Attachment and Induces Differentiation of Mouse Dental Papilla Cells

INTRODUCTION

The disturbance of cellular attachment to dentin by sodium hypochlorite (NaOCl) may hamper pulp tissue regeneration. The aims of this study were to examine the recovering effect of EDTA on the attachment/differentiation of stemlike cells and to address the mechanisms of EDTA-induced recovery under the hypothesis that attachment to the exposed dentin matrix and the subsequent activation of integrin/phosphatidylinositol 3-kinase (PI3K) signaling play a crucial role.

METHODS

Mouse dental papilla (MDP) cells were cultured on bovine dentin disks treated with NaOCl (0%, 1.5%, or 6%) followed by EDTA (0%, 3%, or 17%). Cell attachment was evaluated by cell density, viability, and scanning and transmission electron microscopy. Odonto-/osteoblastic gene expression in attached MDP cells was analyzed with or without a pan-PI3K inhibitor (LY294002) using real-time polymerase chain reaction.

RESULTS

NaOCl treatment (1.5%, 10 minutes) significantly diminished attached MDP cells (P < .00001), but EDTA treatment (3% and 17%, ≥10 minutes) of NaOCl-pretreated dentin induced a significant increase in attached cells (P < .05). Ultrastructurally, MDP cells on EDTA-treated dentin showed attachment to exposed collagen fibers. MDP cells cultured on EDTA-treated disks (with or without 1.5% NaOCl pretreatment) showed significant up-regulation of alkaline phosphatase, dentin matrix protein 1, and dentin sialophosphoprotein messenger RNAs (P < .05). Alkaline phosphatase expression was down-regulated by LY294002 (P < .05).

CONCLUSIONS

Under the present experimental conditions, 10 minutes of EDTA treatment was sufficient to recover attachment/differentiation of MDP cells on 1.5% NaOCl-pretreated dentin. EDTA-induced exposure of collagen fibers and subsequent activation of integrin/PI3K signaling may contribute, at least partly, to the recovery.

Dentin Conditioning with Bioactive Molecule Releasing Nanoparticle System Enhances Adherence, Viability, and Differentiation of Stem Cells from Apical Papilla

INTRODUCTION

Temporal-controlled bioactive molecule (BM) releasing systems allow the delivery of appropriate concentration of BM to enhance the interaction of stem cells to dentin matrix and subsequent odontogenic differentiation in regenerative endodontics.

OBJECTIVES

The goal of this study was to evaluate the effect of dentin conditioning with 2 variants of dexamethasone (Dex) releasing chitosan nanoparticles (CSnp), (1) Dex-CSnpI (slow releasing) and (2) Dex-CSnpII (rapid releasing), on adherence, viability, and differentiation of stem cells from apical papilla (SCAP) on root dentin exposed to endodontic irrigants.

METHODS

Slab-shaped dentin specimens were prepared parallel to the root canal and treated with 5.25% sodium hypochlorite (NaOCl) for 10 minutes and/or 17% EDTA for 2 minutes. Dentin was then conditioned accordingly by (1) no nanoparticle treatment, (2) CSnp, (3) Dex-CSnpI, and (4) Dex-CSnpII. The effect of nanoparticle conditioning on SCAP viability was determined by cell count and a circularity index. SCAP adherence and viability on dentin were assessed by fluorescence and scanning electron microscopy and odontogenic differentiation by immunofluorescence.

RESULTS

SCAP on dentin treated with NaOCl alone or NaOCl as the last irrigant showed the least adherence, minimal cytoplasmic extensions, and higher circularity. SCAP adherence and viability on Dex-CSnpI and Dex-CSnpII conditioned dentin were increased and had a well-developed cytoplasmic matrix and significantly lower circularity (P < .05). SCAP cultured in Dex-CSnpII group expressed higher levels for DSPP and DMP-1 than in CSnp or Dex-CSnpI groups.

CONCLUSIONS

Dex-CSnpI and Dex-CSnpII conditioning of dentin enhanced SCAP adherence and viability. Temporal-controlled release of Dex from Dex-CSnpII enhanced odontogenic differentiation of SCAP. This study highlighted the ability of dentin conditioning with temporal-controlled BM releasing nanoparticles to improve the local environment in regenerative endodontics.

Attachment Ability of Human Apical Papilla Cells to Root Dentin Surfaces Treated with Either 3Mix or Calcium Hydroxide

INTRODUCTION

Tissue regeneration and root continuation are the ultimate goals in regenerative endodontics. Apical papilla cells (APCs) have been hypothesized to play roles in those processes. Therefore, preservation of cell vitality and promoting initial cell attachment seem to be crucial steps. The purposes of this study were to investigate the attachment ability and morphology of viable human APCs by using fibronectin immunofluoresence, alamarBlue assay, and scanning electron microscopy, when APCs were grown on human root dentin surfaces treated with 3Mix or calcium hydroxide (Ca(OH)2) at different concentrations.

METHODS

Human root dentin slices were divided into 6 groups: (1) control, (2) 3Mix 0.39 μg/mL, (3) 3Mix 100 μg/mL, (4) 3Mix paste, (5) Ca(OH)2 1 mg/mL, and (6) Ca(OH)2 1000 mg/mL. All samples were separately treated for 7 days and final rinsed with 17% EDTA. Then primary human APCs were seeded. Fibronectin immunofluorescence was used to evaluate the attachment ability of APCs on treated dentin. A vitality assay by using alamarBlue was monitored at specific time intervals. The morphology of the cells on the dentin was observed under scanning electron microscopy.

RESULTS

The lowest number of fibronectin-positive cells was observed on root dentin treated with 3Mix paste (P < .05). The 3Mix at 0.39 and 100 μg/mL did not affect the amount of APC attachment, whereas the viability of APCs on the dentin surface was significantly lower in the 100-μg/mL 3Mix-treated group than in the negative control group (P < .05). Both concentrations of Ca(OH)2 induced APC attachment (P < .05). Moreover, only cells grown on the surfaces treated with Ca(OH)2 exhibited cytoplasmic processes.

CONCLUSIONS

Human root dentin treated with 3Mix paste had significantly lower APC attachment. The 3Mix at 0.39 μg/mL and 100 μg/mL had no significant negative effect on APC attachment on dentin. Higher numbers of cells attaching on dentin were observed in calcium hydroxide-treated groups.

The effects of radicular dentine treated with double antibiotic paste and ethylenediaminetetraacetic acid on the attachment and proliferation of dental pulp stem cells

AIM

This study explored the effects of dentine treated with two concentrations of double antibiotic paste (DAP) and ethylenediaminetetraacetic acid (EDTA) on the attachment and proliferation of dental pulp stem cells (DPSCs).

MATERIALS AND METHODS

Radicular dentine samples were prepared with identical dimensions and randomized into six groups (n = 4). Four groups were treated with double antibiotic paste (DAP) at concentrations of 500 mg ml(-1) or 1 mg ml(-1) with or without EDTA. The other two groups were treated with EDTA only or received no treatment. DPSCs were seeded on each dentine sample (10 000 cells per sample). Lactate dehydrogenase activity assays were used to calculate the attached DPSCs after 1 day of incubation. Water soluble tetrazolium assays were performed to investigate DPSCs proliferation on the treated dentine samples after three additional days of incubation. Two-way anova followed by Tukey-Kramer tests was used for statistical analyses (α = 0.05).

RESULTS

Dentine treated with 1 or 500 mg ml(-1) of DAP followed by EDTA caused significant increases in DPSCs attachment compared to the dentine treated with the DAP alone. The 500 mg ml(-1) of DAP with or without EDTA caused significant reductions in DPSCs proliferation. However, the treatment of dentine with 1 mg ml(-1) of DAP did not have significant negative effects on DPSCs proliferation regardless of the use of EDTA.

CONCLUSION

The use of 1 mg ml(-1) of DAP followed by 10 min of irrigation with EDTA in endodontic regeneration procedure may have no negative effects on the attachment and proliferation of DPSCs.

The use of traditional and novel techniques to determine the hardness and indentation properties of immature radicular dentin treated with antibiotic medicaments followed by ethylenediaminetetraacetic acid

Objective:

The objective was to investigate the effect of intracanal antibiotic medicaments followed by ethylenediaminetetraacetic acid (EDTA) on the indentation properties and hardness of radicular dentin using a BioDent reference point indenter and a traditional microhardness technique, respectively.

Materials and Methods:

Specimens with intact root canal dentin surfaces and polished radicular dentin specimens were obtained from immature human premolars. Each type of specimen was randomly assigned (n = 10 per group) and treated with either double antibiotic paste (DAP) for 4-week followed by EDTA for 5 min, triple antibiotic paste (TAP) for 4-week followed by EDTA for 5 min, EDTA for 5 min or Hank's balanced salt solution (control). The BioDent reference point indentor and Vickers microhardness tester were used to measure the indentation properties of root canal surfaces and the hardness of polished dentin specimens, respectively. One-way ANOVA followed by Fisher's protected least significant differences were used for statistical analyses.

Results:

Both types of radicular dentin treated with antibiotic pastes and/or EDTA had a significant increase in the majority of indentation properties and a significant reduction in hardness compared to the untreated dentin. Furthermore, treatment of dentin with antibiotic pastes and EDTA caused significant increases in indentation properties and a significant reduction in hardness compared to EDTA-treated dentin. However, the RPI technique was not able to significantly differentiate between DAP + EDTA and TAP + EDTA-treated dentin.

Conclusion:

Dentin treated with antibiotic medicaments followed by EDTA had a significant increase the indentation properties and significantly reduction in hardness of radicular dentin.

Evaluation of surface topography changes in three NiTi file systems using rotary and reciprocal motion: An atomic force microscopy study

AIM

To evaluate the surface topography changes in three nickel-titanium (NiTi) file systems using either rotary or reciprocal motion using atomic force microscopy (AFM), and to determine the effect of scanning area on the AFM results in this study.

METHODOLOGY

Five points on a F2 Protaper file, R25 Reciproc file, and a Primary file from WaveOne systems were scanned preoperatively in 1 × 1 and 5 × 5 µm(2) with an AFM device that can scan an intact (not sectioned) file. One standardized resin block was used for each instrument, according to the manufacturer's recommendations. Points were re-scanned postoperatively using the same AFM and settings. Root-mean-square (RMS) and roughness average (Ra) values were obtained. The preoperative and postoperative surface topographies were compared separately in terms of RMS and Ra values. The surface topography change scores were analyzed using Kruskal-Wallis and Mann-Whitney U tests using a 0.10 significance level.

RESULTS

There were no significant differences preoperatively among the NiTi file systems in 1 × 1 or 5 × 5 µm(2) areas. Postoperatively, the WaveOne Primary had more surface irregularities (significant for 5 × 5 µm(2) scan in Ra evaluation).

CONCLUSIONS

Three-dimensional AFM images of instrument surfaces showed topographic irregularities preoperatively and postoperatively. AFM results differ depending on the scanning area and file used.

Effect of EDTA on attachment and differentiation of dental pulp stem cells

INTRODUCTION

In regenerative endodontics, it is believed that EDTA induces odontoblast differentiation by releasing growth factors from the dentin matrix. The aim of this study was to evaluate the effect of EDTA on the attachment and differentiation of dental pulp stem cells (DPSCs). We also investigated whether the behavioral changes of DPSCs could be caused by biochemical components released from EDTA-treated dentin.

METHODS

Cells were obtained from human third molars, and the stem-like nature of the cells was investigated by flow cytometric analysis. DPSCs were seeded on EDTA-treated and untreated dentin slices. After 3 days of culture, cell attachment was evaluated by cell density, fibronectin 1 gene expression level using quantitative real-time polymerase chain reaction, and scanning electron microscopy. After 21 days of culture, the expression of differentiation genes was investigated by quantitative real-time polymerase chain reaction, and calcification was observed using alizarin red S staining. To investigate the EDTA-induced growth factor release, DPSCs were cultured with or without direct contact with the EDTA-treated dentin surface.

RESULTS

After 3 days of culture, both the cell density and fibronectin expression level were significantly higher in the EDTA-treated dentin group. After 3 weeks, the DPSCs on the EDTA-treated dentin surfaces showed higher expression levels of dentin sialophosphoprotein and dentin matrix protein 1, whereas the DPSCs cultured without direct contact with the EDTA-treated dentin surfaces did not exhibit these findings.

CONCLUSIONS

Our results showed that EDTA induced cell attachment and odontoblastic/osteoblastic differentiation, which was observed only in the group in which the DPSCs were placed in direct contact with the EDTA-treated dentin surfaces. These findings suggest that EDTA is beneficial for achieving successful outcomes in regenerative endodontics.