Biomimetic Conditioning of Human Dentin Using Citric Acid

Evaluation of the effect of different irrigation solutions used in regenerative endodontic treatment of necrotic molar teeth with open apex on postoperative pain- randomized clinical trial

OBJECTIVES

This study evaluates the effect of different irrigation solutions for postoperative pain in the regenerative endodontic treatments (RET) of necrotic teeth with open apex.

MATERIALS AND METHODS

This study included necrotic, deeply carious lower molars of 42 patients. Access cavities of the teeth were opened and working lengths were measured at the first visit. In Group 1, the root canals were irrigated with 1.5% sodium hypochlorite (NaOCl) and 17% Ethylenediaminetetraacetic-acid (EDTA), in Group 2, with 1.5% NaOCl and 10% citric acid, and in the Group 3, with 1.5% NaOCl and 9% Etidronic acid (HEDP) mixture solution. Final irrigation was performed with distilled water. The canals were dried, filled with calcium hydroxide paste, and sealed with Cavit. Postoperative pain was assessed using a numerical rating scale, and Paracetamol was prescribed. At the second visit, calcium hydroxide was removed with 1.5% NaOCl, irrigated with chelators, and sealed with Sure-Seal PT 3 mm below the cementoenamel junction before composite resin filling.

RESULTS

Postoperative pain was higher in Group 3 (p < 0.05), but analgesic consumption did not show a significant difference (p > 0.05).

CONCLUSIONS

HEDP caused significantly more postoperative pain than EDTA and citric acid (p < 0.05). While the study provided information regarding the effects of irrigation solutions on postoperative pain, further research is needed as it did not include detailed assessments of long-term periapical healing and apex closure.

CLINICAL RELEVANCE

When HEDP is used as a chelation agent in RETs, it shows a higher degree of postoperative pain than EDTA and citric acid solutions.

CLINICAL TRIAL REGISTRATION

The study protocol was registered at www.

CLINICALTRIALS

gov (ID: NCT06386991).

A laboratory study to assess the physico-chemical properties of BioRoot RCS and BioRoot Flow exposed to citric acid and EDTA irrigating solutions

OBJECTIVE

To assess physico-chemical properties of BioRoot RCS (powder-to-liquid formulation) and BioRoot Flow (pre-mixed formulation) after exposure to citric acid (CA) and EDTA.

METHODS

BioRoot RCS and BioRoot Flow specimens (5 × 2 mm) were incubated for 28 days at 37 °C before being treated with test solution (distilled water, 17% EDTA, 10% CA, 20% CA or 40% CA). Changes in mass, ion release (inductively coupled plasma optical emission spectroscopy), phase composition (X-ray diffraction and Raman spectroscopy), surface morphology (scanning electron microscopy and energy dispersive spectroscopy) were evaluated. The Shapiro-Wilk, Levene and one-way ANOVA, followed by Tukey's test, were used for statistical analysis (p < 0.05).

RESULTS

The greatest mass loss, ion release and surface morphological changes (pores and cracks) of BioRoot RCS and BioRoot Flow occurred in 10% and 20% CA. No significant differences were identified between BioRoot RCS and BioRoot Flow in distilled water and EDTA (p > 0.05), whereas BioRoot Flow was significantly more soluble than BioRoot RCS in all CA solutions (p < 0.001). The main phase identified for both materials was zirconium oxide, which remained unaffected by the solutions.

CONCLUSIONS

Within the limitations of the study, 10% and 20% CA were more effective than distilled water, 17% EDTA and 40% CA in terms of dissolving BioRoot RCS and BioRoot Flow. The BioRoot Flow was significantly more soluble in all CA solutions than BioRoot RCS.

CLINICAL SIGNIFICANCE

10% and 20% CA solutions may have a potential to be used as a solvent for hydraulic calcium silicate sealers during endodontic retreatment.

Chitosan-based endodontic irrigation solutions and TGF-β1 treatment: Creating the most favourable environment for the survival and proliferation of stem cells of the apical papilla in vitro

BACKGROUND

The dental pulp's environment is essential for the regulation of mesenchymal stem cells' homeostasis and thus, it is of great importance to evaluate the materials used in regenerative procedures.

AIM

To assess in vitro (i) the effect of chitosan nanoparticles, 0.2% chitosan irrigation solution, Dual Rinse®, 17% EDTA, 10% citric acid and 2.5% NaOCl on DSCS viability; (ii) the effect of different concentrations of TGF-β1 on DCSC proliferation; and (iii) whether treatment with TGF-β1 following exposure to the different irrigation solutions could compensate for their negative effects.

METHODOLOGY

(i) DSCS were treated with three dilutions (1:10, 1:100 and 1:1000) of the six irrigation solutions prepared in DMEM for 10 and 60 min to assess the effect on viability. (ii) The effect of different concentrations (0, 1, 5 and 10 ng/mL) of TGF-β1 on DCSC proliferation was assessed at 1, 3 and 7 days. (iii) The proliferative effect of TGF-β1 following 10-min exposure to 1:10 dilution of each irrigation solution was also tested. We used MTT assay to assess viability and proliferation. We performed statistical analysis using Prism software.

RESULTS

(i) The different endodontic irrigation solutions tested showed a significant effect on cell viability (p ≤ .0001). Significant interactions between the endodontic irrigation solutions and their dilutions were also found for all parameters (p ≤ .0001). Chitosan nanoparticles and 0.2% chitosan irrigation solution were the least cytotoxic to DSCS whilst 2.5% NaOCl was the most cytotoxic followed by 17% EDTA. (ii) TGF-β1 at concentrations of 1 and 5 ng/mL resulted in significantly higher proliferation compared to the control group. (iii) Exposure to 17% EDTA or 2.5% NaOCl for 10 min was sufficient to make DSCS cells refractory to the proliferative effects of TGF-β1. DSCS groups treated with TGF-β1 following exposure to chitosan nanoparticles, 0.2% chitosan irrigation solution, Dual Rinse® and 10% CA demonstrated significantly higher proliferation compared to non-TGF-β1-treated groups (p ≤ .0001, p ≤ .0001, p ≤ .0001 and p = .01 respectively).

CONCLUSIONS

The current study offers data that can be implemented to improve the outcome of regenerative endodontic procedures by using less toxic irrigation solutions and adding TGF-β1 to the treatment protocol.

The effect of citric acid on mineralisation and vascular endothelial growth factor secretion from apical papilla stem cells

OBJECTIVE

To investigate the influence of citric acid on the osteogenic and angiogenic potential of stem cells from apical papillae (SCAPs).

MATERIALS AND METHODS

Stem cells from apical papillae were isolated from freshly extracted third permanent molars. These cells were treated with 20 and 100 μM citric acid. Alizarin red staining was used to evaluate mineral deposition. The secreted levels of vascular endothelial growth factor (VEGF) were assessed by ELISA on days 18, 24 and 28. Immunofluorescence analysis was performed to assess the expression of surface markers after exposure to 20 and 100 μM citric acid.

RESULTS

Different mineralisation patterns were observed. Supplemented with citric acid, media showed more diffuse and less dense crystals. On day 18, most VEGF was secreted from the cells with no added citric acid. On day 24, there was a significant increase (p < 0.05) in the levels of VEGF secreted from cells treated with 20 μM citric acid. On day 28, cells from the control group did not secrete VEGF. There was a reduction in the levels of VEGF secreted by cells treated with 20 μM citric acid and a significant increase in the cells exposed to 100 μM citric acid (p < 0.05).

CONCLUSION

Citric acid can promote the differentiation of SCAPs and angiogenesis.

What is the impact of Endodontic Irrigant Solutions on the Viability of Stem Cells from Apical Papilla in an in-vitro setting: A Systematic Review

Background

The success of regenerative endodontic procedures (REPs) is significantly influenced by the choice of endodontic irrigant solution. However, the impact of these solutions on the viability of stem cells from the apical papilla (SCAP), a critical component of the REP, remains a subject of ongoing debate.

Objective

This study aimed to investigate the effects of various endodontic irrigant solutions on the viability of stem cells from the apical papilla in an in vitro setting.

Methods

A systematic literature search was conducted using databases such as PubMed/Medline, Scopus, the Cochrane Library, Web of Science, Embase, gray literature, and reference lists up to August 2023. The search was limited to in vitro studies investigating the impact of endodontic irrigant solutions on SCAP viability. The risk of bias in these studies was evaluated using the Joanna Briggs Institute's checklist.

Results

Of the 131 articles retrieved, 14 were selected for review. The effects of eighteen different root canal irrigants, such as ethylenediaminetetraacetic acid, sodium hypochlorite, chlorhexidine, and citric acid, on the viability of SCAPs were evaluated. The risk-of-bias analysis showed a high risk in sample randomization and size justification but a low risk in other areas.

Discussion

The effects of endodontic irrigant solutions on the viability of SCAPs are concentration dependent. Concentrations higher than 1.5% sodium hypochlorite, 2 % chlorhexidine, 10 % citric acid, and 2.5 % EDTA significantly reduced cell viability. However, additional research is necessary to determine the effect of these irrigants on tissue regeneration.

Effect of Vehicles and Irrigation Solutions and Methods on Removal of Double Antibiotic Paste from Root Canals: Insights from High-performance Liquid Chromatography Analysis

INTRODUCTION

In regenerative endodontics, eradicating antibiotic residues from root canals is imperative, given their detrimental effects on human apical papilla stem cells. Previous antibiotic removal studies lacked precision in identifying types and quantities of residual antibiotics. High-performance liquid chromatography (HPLC) enhances sensitivity and specificity, enabling accurate detection and quantification of residual drugs. Using HPLC analysis, this study explored the influence of vehicles and irrigation solutions and methods on double antibiotic paste (DAP) removal from root canals.

METHODS

Two DAP formulations, each containing 5 mg/mL ciprofloxacin and metronidazole, were created using distinct vehicles: macrogol and propylene glycol (MP) or hydroxypropyl methylcellulose (HPMC). Subsequently, 5 μL of DAP was applied to 200 simulated immature teeth with open apices (n = 100 per formulation) and cultured for 28 days at 37°C. Samples were then divided into 11 groups (n = 20 per group), and canals were irrigated with 17% ethylenediaminetetraacetic acid or 10% citric acid, employing a positive pressure syringe or passive ultrasonic irrigation. The irrigation solution and dentin sample from each tooth were evaluated via HPLC for ciprofloxacin and metronidazole quantification.

RESULTS

Citric acid exhibited significantly superior efficacy in antibiotic removal from root canals, with no observable effect of irrigation methods on drug removal. The HPMC-based DAP formulation significantly enhanced ciprofloxacin removal compared with MP-based DAP.

CONCLUSIONS

For antibiotic paste removal from root canals, citric acid is effective, and HPMC is a preferable vehicle over MP. Overall, HPLC is a valuable method for detecting, removing, and quantifying residual antibiotics in root canals.

Effect of Calcium Silicate-Based Intracanal Medicament and Calcium Hydroxide on Growth Factor TGF-β1 Release from Root Canal Dentine

Effective root canal disinfection and the subsequent release of natural growth factors from dentin are crucial to the success of regenerative endodontic procedures. This study evaluated the effect of newly introduced calcium silicate-based temporary intracanal medicament Bio-C Temp and calcium hydroxide-based material UltraCal XS on the release of transforming growth factor β1 (TGF-β1) from root canal dentin. Twenty-two intact and fully developed human premolars from patients aged 15-18 were shaped and irrigated according to the current clinical recommendations. The teeth were then gently split in half, and the root canal dentin of paired samples was covered with Bio-C Temp or UltraCal XS. After 3 weeks of incubation, the specimens were conditioned with 17% EDTA and the collected solution was subjected to the quantification of the released TGF-β1 by performing an ELISA. One-way analysis of variance (ANOVA), followed by Tukey's test, was selected to determine the statistically significant differences between the groups at the 0.95 confidence level. The highest mean value of released TGF-β1 (1993.1 pg/mL) was detected in the control group, where the root canal dentin was conditioned with 17% EDTA alone. Regarding the experimental groups, Bio-C Temp released a statistically significantly higher amount of TGF-β1 (282.14 pg/mL) compared to UltraCal XS (114.28 pg/mL; p = 0.0158). Bio-C Temp affected the release of growth factors from root canal dentin less than UltraCal XS and may therefore serve as an intracanal medicament for regenerative endodontic procedures.

Impact of using XP-endo finisher and nanobubble water during EDTA dentin conditioning on TGF-β1 release in regenerative endodontic procedures

INTRODUCTION

Transforming Growth Factor-Beta 1 (TGF-β1) plays a crucial role in the success of Regenerative Endodontic Procedures (REPs) as they directly impact the proliferation and differentiation of stem cells. TGF-β1 is released by conditioning of the dentin matrix using 17% EDTA. EDTA was found to have deleterious effects on dentin especially in immature teeth with fragile dentin walls. Decreasing the irrigation time was reported to decrease these effects. Accordingly, enhancement and activation of the EDTA solution to maintain its efficiency in TGF-β1 release from dentin and thus compensating the reduction in irrigation time was employed. EDTA solution was enhanced by adding Nanobubble (NB) water which contains oxygen filled cavities less than 200 nm in diameter. Additionally, EDTA was activated with XP-endo Finisher rotary file. The aim of this study was to assess the impact of NB enhancement and/or XP-endo Finisher activation of the EDTA solution on the TGF-β1 release from dentin.

METHODS

Fifty standardized root segments with open apex were allocated to two main groups according to whether EDTA was enhanced with NB water or not, and within each group whether XP-endo Finisher activation was used or not in addition to a Negative Control group. The concentration of the released TGF-β1 in the root canal was measured using enzyme-linked immunosorbent assay (ELISA). The statistical analysis was done using the Shapiro- Wilk, Kolmogorov Smirnov, ANOVA and Post-hoc Tukey tests.

RESULTS

All groups released a considerable amount of TGF-β1 with the highest values in the EDTA/NB/XP group, followed by EDTA/NB, EDTA/DW/XP, EDTA/DW and Negative Control groups respectively.

CONCLUSIONS

The results of this study suggest that NBs can promote the success of REPs since it revealed a significant increase in the TGF-β1 release following its use in the enhancement of the EDTA solution. A comparable effect was obtained by XP-endo finisher activation of the EDTA solution. The combined use of NBs and XP-endo Finisher can be a promising addition in REPs. Accordingly, Enhancement and activation of the EDTA solution may compensate decreasing the EDTA irrigation time attempted to avoid the deleterious effect of EDTA on dentin.

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.

Citric Acid Conditioning as an Alternative to EDTA for Growth Factors Release and Stem Cell Response in Regenerative Endodontics: A Systematic Review of In Vitro Studies

INTRODUCTION

Citric acid (CA) conditioning may be a promising alternative to ethylenediaminetetraacetic acid (EDTA) in regenerative endodontic procedures, as reported to improve growth factors' release from dentin. This review systematically investigated the effect of CA conditioning on the growth factors release from dentin and cell behavior compared to EDTA conditioning.

METHODS

Searches were conducted (PubMed/MEDLINE, Scopus, Web of Science, Embase, SciELO, Cochrane Library, and grey literature) until May-2023. Only in vitro studies that evaluated the effects of CA on growth factors' release from dentin and cell behavior outcomes compared to EDTA were included. The studies were critically appraised using a modified Joanna Briggs Institute's checklist. Meta-analysis was unfeasible.

RESULTS

Out of the 335 articles screened, nine were included. Among these, three studies used dentin discs/roots from permanent human teeth; the rest combined them with stem cells. 10% CA for 5 or 10 minute was the most used protocol. Meanwhile, EDTA concentrations ranged from 10% to 17%. In eight studies examining the release of growth factors, five reported a significant release of transforming growth factor-β after dentin conditioning with 10% CA compared to 17% EDTA. Regarding cell behavior (6 studies), three studies assessed cell viability. The findings revealed that 10% CA conditioning showed cell viability similar to those of 17% EDTA. Additionally, in two out of three studies, it was observed that 10% CA conditioning did not affect cell morphology. The studies had a low risk of bias.

CONCLUSIONS

The use of 10% CA to condition dentin for 5-10 minutes resulted in a notable transforming growth factor -β1 release, but its cell responses were similar to those of EDTA.

Effects of EDTA and saline as the final irrigation in regenerative endodontic procedures on the migration, proliferation, and differentiation of human stem cells from the apical papilla

OBJECTIVES

To evaluate the effect of EDTA and saline as the final irrigation in regenerative endodontic procedures (REPS) on the attachment, proliferation, migration, and differentiation of stem cells from the apical papilla (SCAPs).

MATERIALS AND METHODS

Dentin specimens from 140 human third molars were irrigated with various protocols-group 1: normal sterile saline (NSS), group 2: EDTA, group 3: EDTA then 5 mL NSS, or group 4: EDTA then 20 mL NSS. The specimens were used in cell assays. For cell proliferation, SCAPs were seeded on dentin, and the cell viability on days 1, 3, and 7 was determined using an MTT assay. At day 3, the attached cells' morphology was observed using SEM, and cell migration was investigated using a transwell migration assay. The ALP activity and odonto/osteogenic differentiation gene expression were evaluated at days 7, 14, and 21 using an ALP activity assay and RT-qPCR.

RESULTS

On days 3 and 7, group 4 demonstrated more viable cells than group 1 (p < 0.01). The amount of migrated cells in groups 2, 3, and 4 was greater compared with group 1 (p < 0.05). Moreover, SCAP differentiation was similar between groups.

CONCLUSIONS

Irrigating dentin with EDTA alone or with EDTA then NSS promoted SCAP migration. However, a final irrigation with 20 mL NSS after EDTA promoted SCAP proliferation without affecting their differentiation.

CLINICAL RELEVANCE

When using a blood clot as a scaffold, a final flushing with 20 mL NSS after EDTA could be beneficial for clinical REP protocols.

Update on citric acid use in endodontic treatment: a systematic review

This systematic review aims to analyse the available evidence concerning the use of citric acid (CA) in endodontics treatment and to assess its results in terms of different considerations: effect on smear layer removal, influence on sealer bond strength, activation effect by means of sonic or ultrasonic devices, effects on dentine surface, antibacterial activity, and effectiveness boost for regenerative procedures, releasing growth factors from dentin. To evaluate the results of CA as a final irrigant and compare them to other chelating agents. This review followed the PRISMA checklist. An electronic search was conducted in MEDLINE (OVID), Scopus (Elsevier) and the Web of Science (Thomson Reuters) databases. Risk of bias of included studies was evaluated using the modified CONSORT checklist and the PRIRATE checklist 2020 guidelines. 39 studies fulfilled the eligibility criteria to be included in this review: 27 in vitro studies using extracted human teeth, 10 in vitro studies using human dentin disks, and 2 RCT. Citric acid has proven to be effective in smear layer removal, showing better results in coronal and middle root thirds, improving its effect when combined with manual dynamic activation. There is no agreement regarding citric acid effect on sealer adhesion and adaptation to root canal walls due to heterogeneity within studies. Citric acid irrigation can decrease dentine microhardness and cause decalcification and erosion, especially when used before NaOCl. Citric acid has proven to be beneficial in regenerative endodontic procedures due to higher TGF-β1 release.Trial registration: Prospero database CRD42021267055.

Influence of ethylenediaminetetraacetic acid on regenerative endodontics: a systematic review

BACKGROUND

The effects of ethylenediaminetetraacetic acid (EDTA) on regenerative endodontic procedures (REPs) are controversial, because, despite releasing growth factors from dentine, some studies show negative effects on cell behaviour.

OBJECTIVES

To investigate the influence of the use of EDTA in REP on the growth factors' release, cell behaviour, and tissue regeneration.

METHODS

A systematic search was conducted (PubMed/Medline, Scopus, Cochrane Library, Web of Science, Embase, OpenGrey, and reference lists) up to February 2021. Only in vivo and in vitro studies evaluating the effects of EDTA on the biological factors of dentine, pulp/periapical tissues, and cell behaviour were eligible. Studies without a control group or available full text were excluded. The growth factors' release was the primary outcome. Risk of bias in the in vitro and in vivo studies was performed according to Joanna Briggs Institute's Checklist and SYRCLE's RoB tool, respectively.

RESULTS

Of the 1848 articles retrieved, 36 were selected. Among these, 32 were in vitro, three animal studies, and one with both models. The EDTA concentrations ranged from 3%-15%, at different times. Regarding growth factors' release (17 studies), 15 studies found significant transforming growth factor (TGF)-β release after dentine conditioning with EDTA, and most found no influence on vascular endothelial growth factor (VEGF) release. Regarding cell behaviour (26 studies), eight studies showed no influence of EDTA-treated dentine on cell viability; whereas, five, nine, and six studies showed higher cell migration, adhesion, and differentiation, respectively. No influence of EDTA conditioning was observed in animal studies. In vitro studies had a low risk of bias, whereas animal studies had high risk of bias. Meta-analysis was unfeasible.

DISCUSSION

This review found that EDTA increased TGF-β release and improved cell activity. However, well-designed histological analyses using immature teeth models are needed.

CONCLUSIONS

High quality in vitro evidence suggests that EDTA-treated dentine positively influences TGF-β release, cell migration, attachment, and differentiation; further research to evaluate its influence on tissue regeneration is necessary due to low methodological quality of the animal studies.

Effect of Maleic acid root conditioning on release of Transforming Growth factor β1 from infected root canal dentin

INTRODUCTION

Chemically released growth factors play a vital role in regenerative endodontics Transforming growth factor (TGF- β1) is one of the most extensively studied bioactive molecule that promotes cell proliferation, differentiation, and chemotaxis. The goal of the current research was to analyze the effect of 7% Maleic acid (MA) root conditioning of an infected root canal on the release of (TGF- β1).

METHODS

Single rooted human teeth were decoronated and the canals were enlarged with peeso reamer. The samples were divided into biofilm and non-biofilm groups. Subsequently, all the samples of both the groups were flushed with 10 ml of each irrigant, namely, 1.5% NaOCl, 7% MA, 17% EDTA, combination of 1.5% NaOCl with 17% EDTA or 7% MA for 10 minutes each. TGF-β1 was estimated quantitatively utilizing ELISA Kit.

RESULTS

TGF- β1 release was lowest among the biofilm samples when compared to non-biofilm amongst all the groups. 7% MA with 1.5% sodium hypochlorite (NaOCl) rendered higher amounts of growth factor release in contrast to combination of 17% EDTA and 1.5% NaOCl in both biofilm and non-biofilm groups (P<0.048). The non-biofilm samples treated with 7% MA alone illustrated higher growth factor release when compared to 17% EDTA only (P<0.006), but there was no significant difference in growth factor release among the biofilm samples treated with 7% MA and 17% EDTA.

CONCLUSION

Bacterial biofilms modified the release of TGF- β1. 7% MA was observed to be significantly more efficacious than 17% EDTA in TGF- β1 growth factor release from radicular dentin.

Effect of citric acid versus ethylenediaminetetraacetic acid on radiographic root development in regenerative endodontic treatment: An animal study

INTRODUCTION

Regenerative endodontic treatment was introduced aiming to reinforce the root and enable further root development. In the process of dentin mineralization, bioactive molecules are entrapped in the dentin matrix, which can be later released by rinsing the dentin with chelating agents. This study aimed to compare the effects of citric acid and ethylenediaminetetraacetic acid (EDTA) on radiographic root development in regenerative endodontic treatment in an animal model.

METHODS

Premolars of three beagle dogs were used in this study. The teeth at one side of the jaw were irrigated with EDTA according to the regeneration protocol of the American Association of Endodontists (AAE). The teeth in the other quadrant were irrigated with citric acid in the second treatment session. Follow-up radiographs were obtained at six months, and the primary and final data were analyzed in SPSS using the Analysis of covariance (ANCOVA).

RESULTS

There was no significant difference between the two irrigating solutions regarding the increase in root length (P=0.668); however, EDTA showed significantly superior efficacy in increasing the root dentin thickness compared with citric acid (P=0.022).

CONCLUSIONS

Within the limitations of this study, the use of citric acid versus EDTA was not superior on radiographic root development in regenerative endodontic treatment.

Effect of Different Root Canal Irrigant Solutions on the Release of Dentin-Growth Factors: A Systematic Review and Meta-Analysis

Irrigant solutions are used to promote dentin-growth factors (GF) release for regenerative endodontics. This review aimed to evaluate the reports comparing the release of GFs using different root canal irrigant solutions. Eligible studies compared the in vitro GF release in human teeth after the use of at least two distinct solutions. A search was conducted on Pubmed, Scopus, Web of Science, and Lilacs on 11 August 2021. Risk of bias was assessed using SciRAP. Study characteristics and quantitative data were extracted, and meta-analyses were performed for the mean difference (95% confidence interval) of the release of transforming growth factors Beta 1 (TGF-β1) by EDTA compared to other irrigants. Of sixteen eligible studies, eight were included in quantitative analysis. ELISA assays showed higher TGF-β1 release from 10% EDTA compared to 10% citric acid (p < 0.00001). Immunogold assays showed higher levels of TGF-β1 for 17% EDTA (p < 0.00001) compared to 10% citric acid. GRADE identified a low to very low certainty of evidence. These results point to an increased release of TGF-β1 in dentin treated with EDTA. The high heterogeneity and very low certainty of the evidence demand further studies before EDTA indication as a better irrigant for regenerative endodontics. Registration: CRD42020160871 (PROSPERO).

The effect of different irrigation solutions and activation techniques on the expression of growth factors from dentine of extracted premolar teeth

AIM

To evaluate in a laboratory study, the effect of different canal irrigant solutions and activation techniques on transforming growth factor (TGF-β1), insulin growth factor-1 (IGF-1), bone morphogenetic protein-7 (BMP-7) and vascular endothelial growth factor-A (VEGF-A) release levels from the dentine of extracted premolar teeth.

METHODOLOGY

Seventy premolar teeth with single root and canal were used. The lengths of the root segments were standardized to 12 mm, and the root canals were prepared up to size 100 with hand files. All surfaces of the teeth were covered with nail polish except the inner root canal surface. The root canals were irrigated with 1.5% NaOCl. Ten teeth were allocated to the control group. The remaining sixty teeth were divided into 2 main groups according to the chelating agent used (17% EDTA, 10% Citric acid; CA) and 3 subgroups (n = 10) according to irrigation activation technique (conventional syringe irrigation (CSI), passive ultrasonic irrigation (PUI) and Er:YAG laser activation). After the activation procedure, the root segments were placed into eppendorf tubes containing 1 mL of phosphate-buffered saline solution and kept at 37℃. TGF-β1, IGF-1, BMP-7 and VEGF-A release levels from dentine were measured using the enzyme-linked immunosorbent assay (ELISA) method at 24 h and at day 7. The volume of root canals was calculated using cone-beam computed tomography. The growth factor levels were calculated in ng/mL except VEGF-A (pg/ml). Normality analysis of the data was evaluated with the Kolmogorov-Smirnov test. Statistical analysis was performed using the Mann-Whitney-U and Wilcoxon tests.

RESULTS

Regardless of the activation type and sampling time, EDTA caused significantly more IGF release than did CA, whereas EDTA and CA were equally effective for the release of the other growth factors. For either EDTA or CA, the lowest and highest growth factor release levels were observed in the CSI and Er:YAG laser groups, respectively (p < .05). All of the growth factors were released significantly more at 24 h than on day 7 (p < .05).

CONCLUSIONS

Irrigation activation techniques with EDTA or CA increased the release levels of all growth factors from the dentine of canal walls in extracted premolar teeth.

Simulation Insight into the Synergic Role of Citrate and Polyaspartic Peptide in Biomineralization

Hydroxyapatite (HAP) is one of the most important inorganic components in biological minerals such as bones and teeth. More than 90% of the total citrate is accumulated in human bones and other biomineralized tissues. In addition, mineralizing proteins are enriched in glutamate and aspartate residues, which are important for their mineral-regulating properties. However, how citrate ions (CITs) and/or acidic amino acids regulate the formation of HAP is still unclear. In this work, molecular dynamics simulations were performed to study how CIT regulates the adsorption behavior of polyaspartic acid (PASP) on the HAP surface in the calcium phosphate solution. The simulation results indicate that PASP can be used as an ion chelator to complex Ca²⁺ and can serve as templates for HAP mineralization by templating the distribution of Ca²⁺ on its surface, which are attributed to the -COO^- and α-helix structure. Most importantly, the orientation distributions of PASP in all systems are narrower with the help of CIT, thereby PASP can be adsorbed on the HAP surface stably with a "lying-down" orientation. This indicates that CIT can be used as a bridging agent to bond the acidic peptide to the HAP surface in biomineralization. Thus, the synergic role of CIT and the acidic peptide on the HAP surface were revealed in this work, which can provide new insights into the interfacial phenomena during the biomineralization.

Effect of Natural and Artificial Dentin Conditioners on the Release of Vascular Endothelial Growth Factor

INTRODUCTION

The purpose of this study was to observe the release of vascular endothelial growth factor (VEGF) after conditioning with etidronic acid (also known as 1-hydroxyethylidene-1 and 1-bisphosphonate [HEDP]) and phytic acid (inositol hexakisphosphate [IP6]) in comparison with EDTA on human dentin disks and cylinders.

METHODS

Human dentin disks were disinfected and prepared by the standardized method. Seventeen percent EDTA, 9% HEDP, 1% IP6, and distilled water (5 minutes) were used to immerse dentin disks. The dentin cylinders were prepared by following disinfection and the standardized preparation method to achieve a truncated cone-shaped canal with a 1-mm open apex. The dentin cylinder samples were irrigated with sodium hypochlorite (5 mL/5 minutes) and then rinsed with 17% EDTA, 9% HEDP, 1% IP6 and distilled water (5 mL/5 min). Enzyme-linked immunosorbent essay was performed to measure VEGF release. One-way analysis of variance was used to compare the mean release of VEGF between study groups and controls at a significance level of .05. A post hoc Tukey test was used for multiple comparisons between study groups.

RESULTS

Among conditioners, HEDP released more VEGF from both disks and cylinders. In cylinders, VEGF release by HEDP was significantly greater than the other conditioners, whereas in disks the release of VEGF was similar with all conditioners.

CONCLUSIONS

The release of VEGF by 9% HEDP and 1% IP6 was comparable with 17% EDTA from dentin disks; however, HEDP demonstrated more release from dentin cylinders than EDTA and IP6.

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.

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.

Biomimetic Aspects of Restorative Dentistry Biomaterials

Biomimetic has emerged as a multi-disciplinary science in several biomedical subjects in recent decades, including biomaterials and dentistry. In restorative dentistry, biomimetic approaches have been applied for a range of applications, such as restoring tooth defects using bioinspired peptides to achieve remineralization, bioactive and biomimetic biomaterials, and tissue engineering for regeneration. Advancements in the modern adhesive restorative materials, understanding of biomaterial-tissue interaction at the nano and microscale further enhanced the restorative materials' properties (such as color, morphology, and strength) to mimic natural teeth. In addition, the tissue-engineering approaches resulted in regeneration of lost or damaged dental tissues mimicking their natural counterpart. The aim of the present article is to review various biomimetic approaches used to replace lost or damaged dental tissues using restorative biomaterials and tissue-engineering techniques. In addition, tooth structure, and various biomimetic properties of dental restorative materials and tissue-engineering scaffold materials, are discussed.

Surface and structural changes in root dentine by various chelating solutions used in regenerative endodontics

AIM

To evaluate the effects of the prolonged use of various irrigant solutions used during regenerative endodontic procedures on the physical and chemical structure of root canal dentine in extracted human teeth.

METHODOLOGY

Sixtyroot dentine samples from extracted, single-rooted, human teeth were assigned to 10 groups. Eight groups were irrigated with 1.5% NaOCl for 5 min, followed by 3%, 10%, 17% EDTA or 10% citric acid (CA) for 5 or 10 min. One group received only NaOCl irrigation, and samples with only distilled water irrigation were used as a control group. The changes in microhardness and flexural strength were determined using Vickers and 3-point flexural tester, respectively. Molecular and elemental compositions were recorded using FTIR and EDS spectroscopy. Data were analysed using one-way anova, Kruskal-Wallis and Mann-Whitney U tests.

RESULTS

The application of 1.5% NaOCl for 5 min did not affect the mineral content or microhardness of dentine (P > 0.05). However, it significantly decreased the dentine collagen peak values (P < 0.05), which was similar to the control group after the use of chelating agents (EDTA and 10% of CA) (P > 0.05). The effect of EDTA on the inorganic content was not concentration and time dependent (P > 0.05). CA resulted in a significantly greater reduction in the inorganic contents compared with the control and EDTA groups (P < 0.05). Regardless of the time, EDTA and CA significantly decreased dentine microhardness compared to the control (P < 0.05) with the greatest reduction in the CA groups (P < 0.05). NaOCl alone was associated with the lowest flexural strength, while none of the other irrigation regimens significantly decreased the flexural strength compared to the control group (P> 0.05).

CONCLUSIONS

Use of 1.5% NaOCl for 5 min decreased the collagen content of samples of human dentine from extracted teeth while EDTA and 10% citric acid mostly affected the inorganic content and microhardness of dentine surfaces. None of the irrigant solutions significantly decreased the mechanical properties of the entire dentine specimen.

Transforming Growth Factor Beta 1 Distribution and Content in the Root Dentin of Young Mature and Immature Human Premolars

INTRODUCTION

Transforming growth factor beta 1 (TGF-β1) is a key morphogen in regenerative endodontics; yet, its location within the hard tissue phase of dentin and its availability in mature roots have not been fully elucidated.

METHODS

Young mature (n = 8) and immature (n = 11) roots from sound premolars were obtained from 13 orthodontic patients aged 17 ± 1 and 12 ± 1 years, respectively. Roots were cleaned of organic remnants in 5% sodium hypochlorite. The width of the minor foramen was measured using a digital microscope. TGF-β1 distribution was assessed in 3 roots per group by immunostaining combined with confocal laser scanning microscopy. The root dentin of the remaining 13 roots was powdered and decalcified in 17% EDTA to determine the overall levels of hard tissue-embedded TGF-β1 by enzyme-linked immunosorbent assay. Data were compared between groups using the Student t test (α = .05).

RESULTS

The minor foramen was 168 ± 49 μm versus 557 ± 295 μm in mature compared with immature roots (P < .05). TGF-β1 was highly stainable toward the pulp space in both groups. It was clearly associated with peritubular dentin and apparently absent in nontubular outer dentin. TGF-β1 content was 115 ± 31 pg and 74 ± 35 pg/100 mg mature versus immature root dentin, respectively (P > .05).

CONCLUSIONS

TGF-β1 is deposited into the peritubular dentin. It should be possible to release this molecule in regenerative endodontic procedures from young mature roots as well as immature roots.

Effect of Different Dentin Conditioning Agents on Growth Factor Release, Mesenchymal Stem Cell Attachment and Morphology

INTRODUCTION

EDTA has been considered the gold standard in regenerative endodontic treatments. The aim of this study was to evaluate the effects of different dentin conditioning agents other than EDTA on released growth factors, mesenchymal stem cell attachment, and morphology.

METHODS

Transforming growth factor beta 1, vascular endothelial growth factor, bone morphogenetic protein 2, and fibroblast growth factor 2 release from prepared dentin discs conditioned with 17% EDTA, 10% citric acid, 1% phytic acid (IP6), or 37% phosphoric acid were quantified using the enzyme-linked immunosorbent assay after final irrigation and after 3 days of adipose-derived mesenchymal stem cell (adMSC) seeding. Forty root fragments were prepared from extracted single-rooted teeth. The morphology and attachment of adMSCs on the conditioned root fragments were observed using a scanning electron microscope. Data for growth factor quantification were analyzed using 1-way analysis.

RESULTS

The highest transforming growth factor beta 1 release was observed after citric acid treatment followed by phosphoric acid; there was no significant difference between them, but compared with EDTA and 1% IP6, there were significant differences observed. The enzyme-linked immunosorbent assay detected a very minor exposure of vascular endothelial growth factor and fibroblast growth factor 2 after dentin conditioning, but there were no significant differences between the groups. The greatest bone morphogenetic protein 2 release was observed in the 1% IP6 group, but there were no significant differences between the groups. Three days of adMSC seeding after dentin conditioning has made a dramatic increase in all of the growth factors, and phosphoric acid appeared to be the most effective agent with significant differences compared with the remaining groups. Scanning electron microscopic observations showed that none of the conditioning solutions had an adverse effect on stem cell proliferation and attachment to root dentin. Different cell morphologies like round, oblong, flat, and well-attached cells with developed filopodia were observed in the dentin-conditioned groups.

CONCLUSIONS

Phosphoric acid conditioning could be useful and may have beneficial effects in regenerative endodontic treatments.