EDTA conditioning of dentine promotes adhesion, migration and differentiation of dental pulp stem cells

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.

Regenerative endodontic treatment of necrotic permanent teeth with pre-eruptive intracoronal radiolucency: a case report

Pre-eruptive intracoronal radiolucency is a rare dental anomaly with unclear aetiology, generally asymptomatic and diagnosed through routine radiographs. Failure to diagnose and treat it early can lead to rapid pulp damage, potentially compromising root development. The presented clinical report describes a mandibular second premolar with pre-eruptive intracoronal radiolucency that caused early pulp necrosis with arrest of root formation and emphasises the endodontic management using regenerative endodontic therapy.

Effect of photobiomodulation therapy on TGF-β release from dentin, migration and viability of dental pulp stem cells in regenerative endodontics treatment: An ex vivo study

BACKGROUND AND AIM

Regenerative endodontic procedures (REPs) are oriented by the principles of tissue engineering, incorporating dental pulp stem cells (DPSC), crucial growth factors like Transforming growth factor-β (TGF-β1), and scaffolds to facilitate the regeneration of dental pulp tissues. The present study aimed to investigate the effect of photobiomodulation (PBM) therapy, using an 808 nm diode laser on cellular modulation mechanisms in REPs.

METHOD AND MATERIAL

A total of 108 human dentin discs obtained from intact single root teeth were randomly assigned into six groups (n = 8): 1. Positive control (EDTA), 2. PBM-1 (3 J/cm2), 3. PBM-2 (5 J/cm2), 4. EDTA+PBM-1, 5. EDTA+PBM-2, and 6. Negative control (NaOCl). Then, an extract solution was prepared from each disc and the concentration of released TGF-β1 from the discs was measured using enzyme-linked immunosorbent assay (ELISA). Moreover, the extract solution was added to DPSC culture medium to evaluate cell viability and migration through MTT assay and scratch test, respectively.

RESULT

The group exposed to PBM-1 showed the highest cell viability, while treatment with EDTA and EDTA+PBM-2 decreased cellular viability. Also, the PBM-treated groups showed significantly higher release of TGF-β1 compared to the negative control. EDTA and EDTA+PBM-1 showed the highest release among all the groups. No significant difference was found between EDTA and EDTA+PBM-1, as well as between PBM-1 and PBM-2. Moreover, the PBM-1 group exhibited the highest migration after 24 h, which was significantly greater than other groups, except for the PBM-2 group.

CONCLUSION

According to the obtained data, 808 nm mediated-PBM (3 J/cm2), both independently and in conjunction with EDTA, enhanced the release of TGF-β1 from dentin and improved cell viability and migration of DPSCs. It seems that, PBM under the specific parameters employed in this study, could be an effective adjunctive therapy in REPs.

Treatment of an apical cyst with platelet concentrate - a case report

Apical cysts are typically caused by dental pulp disease and are difficult to treat. In the majority of cases, surgical intervention is required. The rate of success after apical osteotomy varies between 60% and 91%. The introduction of platelet concentrates in treating chronic apical periodontitis is a promising direction for achieving quick and secure results. This article examines the healing of a sizable apical cyst after conservative surgical intervention and the application of platelet concentrate.

Epigenetic therapeutics in dental pulp treatment: Hopes, challenges and concerns for the development of next-generation biomaterials

This opinion-led review paper highlights the need for novel translational research in vital-pulp-treatment (VPT), but also discusses the challenges in translating evidence to clinics. Traditional dentistry is expensive, invasive and relies on an outmoded mechanical understanding of dental disease, rather than employing a biological perspective that harnesses cell activity and the regenerative-capacity. Recent research has focussed on developing minimally-invasive biologically-based 'fillings' that preserve the dental pulp; research that is shifting the paradigm from expensive high-technology dentistry, with high failure rates, to smart restorations targeted at biological processes. Current VPTs promote repair by recruiting odontoblast-like cells in a material-dependent process. Therefore, exciting opportunities exist for development of next-generation biomaterials targeted at regenerative processes in the dentin-pulp complex. This article analyses recent research using pharmacological-inhibitors to therapeutically-target histone-deacetylase (HDAC) enzymes in dental-pulp-cells (DPCs) that stimulate pro-regenerative effects with limited loss of viability. Consequently, HDAC-inhibitors have the potential to enhance biomaterial-driven tissue responses at low concentration by influencing the cellular processes with minimal side-effects, providing an opportunity to develop a topically-placed, inexpensive bio-inductive pulp-capping material. Despite positive results, clinical translation of these innovations requires enterprise to counteract regulatory obstacles, dental-industry priorities and to develop strong academic/industry partnerships. The aim of this opinion-led review paper is to discuss the potential role of therapeutically-targeting epigenetic modifications as part of a topical VPT strategy in the treatment of the damaged dental pulp, while considering the next steps, material considerations, challenges and future for the clinical development of epigenetic therapeutics or other 'smart' restorations in VPT.

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

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

DLP printed hDPSC-loaded GelMA microsphere regenerates dental pulp and repairs spinal cord

Dental pulp regeneration is ideal for irreversible pulp or periapical lesions, and in situ stem cell therapy is one of the most effective therapies for pulp regeneration. In this study, we provided an atlas of the non-cultured and monolayer cultured dental pulp cells with single-cell RNA sequencing and analysis. Monolayer cultured dental pulp cells cluster more closely together than non-cultured dental pulp cells, suggesting a lower heterogeneous population with relatively consistent clusters and similar cellular composition. We successfully fabricated hDPSC-loaded microspheres by layer-by-layer photocuring with a digital light processing (DLP) printer. These hDPSC-loaded microspheres have improved stemness and higher multi-directional differentiation potential, including angiogenic, neurogenic, and odontogenic differentiation. The hDPSC-loaded microspheres could promote spinal cord regeneration in rat spinal cord injury models. Moreover, in heterotopic implantation tests on nude mice, CD31, MAP2, and DSPP immunofluorescence signals were observed, implying the formation of vascular, neural, and odontogenetic tissues. In situ experiments in minipigs demonstrated highly vascularized dental pulp and uniformly arranged odontoblast-like cells in root canals of incisors. In short, hDPSC-loaded microspheres can promote full-length dental pulp regeneration at the root canals' coronal, middle, and apical sections, particularly for blood vessels and nerve formation, which is a promising therapeutic strategy for necrotic pulp.

Molecules Inducing Dental Stem Cells Differentiation and Bone Regeneration: State of the Art

Teeth include mesenchymal stem cells (MSCs), which are multipotent cells that promote tooth growth and repair. Dental tissues, specifically the dental pulp and the dental bud, constitute a relevant source of multipotent stem cells, known as dental-derived stem cells (d-DSCs): dental pulp stem cells (DPSCs) and dental bud stem cells (DBSCs). Cell treatment with bone-associated factors and stimulation with small molecule compounds are, among the available methods, the ones who show excellent advantages promoting stem cell differentiation and osteogenesis. Recently, attention has been paid to studies on natural and non-natural compounds. Many fruits, vegetables, and some drugs contain molecules that can enhance MSC osteogenic differentiation and therefore bone formation. The purpose of this review is to examine research work over the past 10 years that has investigated two different types of MSCs from dental tissues that are attractive targets for bone tissue engineering: DPSCs and DBSCs. The reconstruction of bone defects, in fact, is still a challenge and therefore more research is needed; the articles reviewed are meant to identify compounds useful to stimulate d-DSC proliferation and osteogenic differentiation. We only consider the results of the research which is encouraging, assuming that the mentioned compounds are of some importance for bone regeneration.

Outcome of Regenerative Endodontic Procedures in Non-Vital Immature Permanent Teeth Using Two Intracanal Medications: A Prospective Randomized Clinical Study

INTRODUCTION

This randomized clinical trial aimed to assess and compare the long-term clinical and radiographic outcomes of Regenerative Endodontic Procedures (REP) in treating non-vital immature permanent teeth using two intra-canal medicaments.

METHODS

Forty-five patients yielding a total of 50 anterior and posterior non-vital immature teeth were randomly divided into 2 groups. REP utilizing either non-setting calcium hydroxide (Ca(OH)₂) (n=25) or modified triple antibiotic paste (TAP) (n=25), as intra-canal medicaments were performed. NeoMTA Plus (Avalon Biomed Inc™, Houston, Texas, USA) was applied for coronal sealing. Cases were followed up clinically and radiographically for 36 months. Survival rate, success rate, and clinical outcome measures were analyzed. Preoperative and recall radiographs were evaluated for dimensional changes in root length, dentin thickness, apical diameter, and periapical radiolucency.

RESULTS

At 36 months follow up, success and survival rates were 81.6%, and 100% respectively, in which 79.4% of cases showed complete resolution of periapical radiolucency, with no significant difference between non-setting Ca(OH)2 and modified TAP groups (P>0.050). The cumulative changes in root length, root dentin thickness and apical diameter, throughout the study period, were observed in 47.9%, 77.1%, and 89.6 %, of cases respectively, with no significant differences between both groups (P≥ 0.39). Intra-canal calcifications were detected in 60% of cases with no significant difference between both groups (P=0.77).

CONCLUSIONS

REP, using either non-setting Ca(OH)₂ or modified TAP as intra-canal medicament, exhibited high success and survival rates, over a follow up period of 36 months, with equally favorable clinical and radiographic outcome data.

Pulp-Dentin Complex Regeneration with Cell Transplantation Technique Using Stem Cells Derived from Human Deciduous Teeth: Histological and Immunohistochemical Study in Immunosuppressed Rats

The aim of this study was to histologically verify the performance of pulp-derived stem cells used in the pulp-dentin complex regeneration. Maxillary molars of 12 immunosuppressed rats were divided into two groups: the SC (stem cells) group, and the PBS (just standard phosphate-buffered saline) group. After pulpectomy and canal preparation, the teeth received the designated materials, and the cavities were sealed. After 12 weeks, the animals were euthanized, and the specimens underwent histological processing and qualitative evaluation of intracanal connective tissue, odontoblast-like cells, intracanal mineralized tissue, and periapical inflammatory infiltrate. Immunohistochemical evaluation was performed to detect dentin matrix protein 1 (DMP1). In the PBS group, an amorphous substance and remnants of mineralized tissue were observed throughout the canal, and abundant inflammatory cells were observed in the periapical region. In the SC group, an amorphous substance and remnants of mineralized tissue were observed throughout the canal; odontoblasts-like cells immunopositive for DMP1 and mineral plug were observed in the apical region of the canal; and a mild inflammatory infiltrate, intense vascularization, and neoformation of organized connective tissue were observed in the periapical region. In conclusion, the transplantation of human pulp stem cells promoted partial pulp tissue neoformation in adult rat molars.

In vitro, ex vivo, and in vivo models for dental pulp regeneration

Based on the concept of tissue engineering (Cells-Scaffold-Bioactive molecules), regenerative endodontics appeared as a new notion for dental endodontic treatment. Its approaches aim to preserve dental pulp vitality (pulp capping) or to regenerate a vascularized pulp-like tissue inside necrotic root canals by cell homing. To improve the methods of tissue engineering for pulp regeneration, numerous studies using in vitro, ex vivo, and in vivo models have been performed. This review explores the evolution of laboratory models used in such studies and classifies them according to different criteria. It starts from the initial two-dimensional in vitro models that allowed characterization of stem cell behavior, through 3D culture matrices combined with dental tissue and finally arrives at the more challenging ex vivo and in vivo models. The travel which follows the elaboration of such models reveals the difficulty in establishing reproducible laboratory models for dental pulp regeneration. The development of well-established protocols and new laboratory ex vivo and in vivo models in the field of pulp regeneration would lead to consistent results, reduction of animal experimentation, and facilitation of the translation to clinical practice.

Comparison of the effect of NaOCL, curcumin, and EDTA on differentiation, proliferation, and adhesion of dental pulp stem cells

Introduction

This study examined the effect of 1.5% NaOCl, 17% EDTA, and curcumin on the proliferation, attachment, and differentiation of dental pulp stem cells (DPSCs) placed on the dentin specimens.

Methods

MTT assay was performed to evaluate the proliferation of DPSCs on the dentin specimens treated with different concentrations of NaOCl, 17% EDTA, and curcumin (0.97-250 μM). Cell-adhering ability of DPSCs was tested via the LDH assay to calculate the attached DPSCs. In addition, the western blotting assay was performed to investigate the expression levels of fibronectin as a cell-adhesion marker and analyze the expressions level of differentiation markers, including DMP-1, OCN, ALP, and DSPP, to detect the odontogenic potential of hDPCs.

Results

NaOCl had lower toxicity on DPSCs at lower concentrations (P < 0.001). The cytotoxicity of irrigants increased with increased dosage. The difference between the cell-adhesion ability of NaOCl and curcumin was not significant (∼4.4 MU/mL), whereas EDTA (∼3.8 MU/mL) exhibited the lowest release of LDH and less damage to hDPSCs. Regarding fibronectin expression, the pattern differed between irrigants in inducing cell adhesion. NaOCl increased fibronectin expression more than EDTA and curcumin. All the treated groups upregulated the expression of DSPP, DMP-1, OCN, and ALP compared to the control group, in which NaOCl showed a higher effect on the overexpression of differentiation markers.

Conclusion

The results showed that all the tested irrigants could be used in regenerative endodontic treatment. However, as an herbal-based and biocompatible irrigant, curcumin exhibited fewer adverse effects than NaOCl and EDTA.

Biological Properties of Dental Pulp Stem Cells Isolated from Inflamed and Healthy Pulp and Cultured in an Inflammatory Microenvironment

INTRODUCTION

The aim of this study was to assess whether the biological characteristics of dental pulp stem cells (DPSCs), such as viability, adhesion to dentin, mineralization, and release of immunomodulatory cytokines, are affected by the inflammatory status of the donor tissue and/or the sustained inflammatory environment.

METHODS

DPSCs were isolated from pulps from 3 caries-free teeth (healthy or hDPSCs), and from 3 teeth with irreversible pulpitis or deep caries (unhealthy DPSCs or uDPSCs). The cells were cultured in odontogenic and osteogenic media with or without lipopolysaccharides. Viability was analyzed by MTT assay at days 1, 3, 5, and 7; adhesion to dentin was evaluated through an environmental scanning electron microscope after 48 hours and through MTT assay; mineralization was analyzed with alizarin red staining after 21 days; and the release of proinflammatory (interleukin 6) and immunosuppressive cytokines (interleukin 10) was measured with the enzyme-linked immunosorbent assay after 24 hours and 7 days.

RESULTS

The inflammatory status of the pulp significantly reduced the viability and mineralization capacity of the DPSCs, although it did not affect the adhesion capacity to dentin or the secretion of the proinflammatory interleukin. The inflammatory microenvironment (lipopolysaccharide) only had a significant impact on the secretion of interleukin 6, which was augmented after 7 days.

CONCLUSIONS

The inflammatory status of the dental pulp should be taken into account when the use of DPSCs is intended either for research and/or for application in reparative or regenerative therapies.

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.

Effects of ethylenediaminetetraacetic acid on stem cells from the apical papilla: In vitro study

Background/purpose

Ethylenediaminetetraacetic acid (EDTA) is used as an irrigant in regenerative endodontic treatment. The present study aimed to investigate the effects of EDTA on stem cells from apical papilla (SCAPs) in vitro.

Materials and methods

Human SCAPs were isolated and characterised. The cells were treated with media supplemented with EDTA at concentrations ranging from 1.25% to 17%. Cell proliferation and apoptosis were examined using MTT assay and annexin V/propidium iodide staining. Cell migration was determined by a scratch assay. Gene expression was evaluated using a real-time polymerase chain reaction. Mineral deposition, a hallmark of osteogenesis in vitro, was determined using alizarin red s staining.

Results

Overall, SCAPs exhibited mesenchymal stem cell characteristics. EDTA treatment at 2.50% and 1.25% did not significantly exhibit cytotoxicity and alter cell morphology. However, EDTA attenuated cell proliferation and reduced MKI67 mRNA expression in SCAPs. Further, EDTA significantly induced early cell apoptosis at 48 h. Cell migration was delayed with EDTA treatment. After maintaining SCAPs in an osteogenic induction medium, EDTA diminished mineral deposition by SCAPs on day 14.

Conclusion

EDTA treatment exhibits adverse effects on SCAPs in vitro. Hence, EDTA exposure to periapical tissues should be avoided to minimise the negative impacts on SCAPs cells in regenerative processes.

Biomimetic Approaches in Clinical Endodontics

In the last few decades, biomimetic concepts have been widely adopted in various biomedical fields, including clinical dentistry. Endodontics is an important sub-branch of dentistry which deals with the different conditions of pulp to prevent tooth loss. Traditionally, common procedures, namely pulp capping, root canal treatment, apexification, and apexigonesis, have been considered for the treatment of different pulp conditions using selected materials. However, clinically to regenerate dental pulp, tissue engineering has been advocated as a feasible approach. Currently, new trends are emerging in terms of regenerative endodontics which have led to the replacement of diseased and non-vital teeth into the functional and healthy dentine-pulp complex. Root- canal therapy is the standard management option when dental pulp is damaged irreversibly. This treatment modality involves soft-tissue removal and then filling that gap through the obturation technique with a synthetic material. The formation of tubular dentine and pulp-like tissue formation occurs when stem cells are transplanted into the root canal with an appropriate scaffold material. To sum up tissue engineering approach includes three components: (1) scaffold, (2) differentiation, growth, and factors, and (3) the recruitment of stem cells within the pulp or from the periapical region. The aim of this paper is to thoroughly review and discuss various pulp-regenerative approaches and materials used in regenerative endodontics which may highlight the current trends and future research prospects in this particular area.

A Compilation of Study Models for Dental Pulp Regeneration

Efforts to heal damaged pulp tissue through tissue engineering have produced positive results in pilot trials. However, the differentiation between real regeneration and mere repair is not possible through clinical measures. Therefore, preclinical study models are still of great importance, both to gain insights into treatment outcomes on tissue and cell levels and to develop further concepts for dental pulp regeneration. This review aims at compiling information about different in vitro and in vivo ectopic, semiorthotopic, and orthotopic models. In this context, the differences between monolayer and three-dimensional cell cultures are discussed, a semiorthotopic transplantation model is introduced as an in vivo model for dental pulp regeneration, and finally, different animal models used for in vivo orthotopic investigations are presented.

Regenerative endodontic therapy for external inflammatory lateral resorption following traumatic dental injuries: Evidence assessment of best practices

BACKGROUND

External inflammatory lateral resorption (EILR) following dental trauma is a severe complication that can lead to significant root loss and tooth extraction.

OBJECTIVE

The aim of this project was to review current evidence in the literature on regenerative endodontic therapy (RET) for EILR following traumatic injuries and assess the best treatment practices.

METHODS

Publications appearing in PubMed, from January 1, 2001 to January 9, 2022 were studied. Inclusion criteria were: (a) Publications in English; (b) Publications on RET and EILR; (c) Teeth subjected to dental trauma; and (d) Presence of intracanal bleeding and blood clots. Exclusion criteria were: (a) Conference proceedings; (b) Lectures; (c) Abstracts; and (d) Letters to editor; (e) Non-English publications.

RESULTS

355 publications were analysed. Nine met all inclusion criteria. In 10 (58.8%) teeth, triple antibiotic paste was used for an average of 26 days. Double antibiotic paste was used in 3 (17.6%) teeth for an average of 14 days. In 3 (17.6%) cases, calcium hydroxide (Ca(OH)₂ ) was used for 14 days and negative pressure irrigation was applied once on 1 (6%) tooth.

DISCUSSION

Using RET to treat EILR has some advantages compared to long term CA(OH)₂ dressing. RET requires shorter dressing time compared to CA(OH)₂ . This can significantly improve patient compliance. Additionally, in immature teeth, RET helps to arrest root resorption leading to continued root maturogenesis and revascularization. It is recommended that a meticulous follow-up should be conducted when RET is performed to assure early detection of treatment failure.

CONCLUSIONS

RET appears to be a good treatment modality producing biologic repair and improving prognosis in cases of EILR in post-traumatic tooth/pulp injuries. The key limitation of this study is that all publications included were either case reports or case series that usually tend to report successful outcome.

Clinical Outcome and Comparison of Regenerative and Apexification Intervention in Young Immature Necrotic Teeth-A Systematic Review and Meta-Analysis

This systematic review aimed to evaluate interventions individually and compare the clinical outcome of young, immature teeth treated with regenerative endodontic therapy (RET) and apexification procedure. The protocol was registered with PROSPERO (International Prospective Register of Systematic Reviews), bearing the registration number CRD42021230284. A bibliographic search in the biomedical databases was conducted in four databases—PubMed, CENTRAL, EMBASE and ProQuest—using searching keywords and was limited to studies published between January 2000 and April 2022 in English. The search was supplemented by manual searching, citation screening and scanning of all reference lists of selected paper. The study selection criteria were randomized clinical trial, prospective clinical studies and observational studies. The search found 32 eligible articles, which were included in the study. The quality assessment of the studies was performed using the Cochrane risk of bias tool for randomized control trials and non-randomized clinical studies. The meta-analysis was performed using Review Manager software (REVMAN, version 5). The results indicated that a clinicians’ MTA apexification procedure was more successful compared to calcium hydroxide. In RET, apical closure and overall success rate is statistically same for both apical platelet concentrates (APCs) and blood clots (BC). Both interventions have similar survival rates; however, RET should be preferred in cases where the root development is severely deficient, there is insufficient dentine and the tooth’s prognosis is hopeless even with an apexification procedure.

Final irrigation protocols affect radicular dentin DMP1-CT expression, microhardness, and biochemical composition

OBJECTIVE

To evaluate the effect of several final irrigation protocols on radicular dentin microhardness, biochemical composition, and DMP1-CT expression.

MATERIALS AND METHODS

A total of 140 single-rooted human teeth were prepared with WaveOne Gold files and randomly distributed into 7 groups (n = 20) according to the final irrigation protocol: distilled water (DW); sodium hypochlorite-EDTA (NaOCl-EDTA); EDTA (EDTA); EDTA-NaOCl (EDTA-NaOCl); EDTA-chlorhexidine (EDTA-CHX); passive ultrasonic irrigation (PUI:NaOCl-EDTA); and PUI:NaOCl-EDTA-NaOCl. Dentin microhardness (n = 10) was evaluated in the root canal lumen using Vickers hardness tester. Immunohistochemical analysis (n = 5) was used to evaluate DMP1-CT expression. Dentin ultrastructure and biochemical composition were evaluated by using Raman and energy dispersive X-ray analysis (EDAX) (n = 5) with a scanning electron microscope (SEM). Analysis of variance (ANOVA) and Tukey test were performed (p˂0.05).

RESULTS

Raman spectra of the organic content and DMP1-CT expression were lower at the lumen canal in EDTA-NaOCl, PUI:NaOCl-EDTA, and PUI:NaOCl-EDTA-NaOCl when compared to control (p < 0.05). EDAX showed reduced values for calcium and phosphorus in EDTA-NaOCl, PUI:NaOCl-EDTA, and PUI:NaOCl-EDTA-NaOCl. SEM microphotography's showed completely cleaned dentin, permeable tubules, and dentin erosion, mainly when PUI was used. NaOCl-EDTA presented significantly higher microhardness values than PUI:NaOCl-EDTA-NaOCl (p < 0.05). PUI:NaOCl-EDTA-NaOCl exhibited the lowest Vickers hardness values of all groups.

CONCLUSION

The final irrigation protocols that used a final rinse with NaOCl and PUI showed a detrimental effect on radicular dentin DMP1-CT expression, biochemical composition, and microhardness.

CLINICAL RELEVANCE

The adequate irrigation protocol could be advantageous to preserve the radicular dentin ultrastructure, promote adequate adhesion, and sustain favorable conditions for biomineralization and regeneration.

Dental Pulp Cells Conditioning Through Poly(I:C) Activation of Toll-Like Receptor 3 (TLR3) for Amplification of Trophic Factors

INTRODUCTION

Regeneration of the pulp-dentin complex hinges on functionally diverse growth factors, cytokines, chemokines, signaling molecules, and other secreted factors collectively referred to as trophic factors. Delivery of exogenous factors and induced release of endogenous dentin-bound factors by conditioning agents have been explored towards these goals. The aim of this study was to investigate a promising regeneration strategy based on the conditioning of dental pulp cells (DPCs) with polyinosinic-polycytidylic acid [poly(I:C)] for amplification of endogenous trophic factors.

METHODS

DPCs were isolated from human dental pulps, propagated in culture, and treated with an optimized dose of poly(I:C). MTT assay and metabolite analysis were conducted to monitor the cytotoxicity of poly(I:C). ELISA and qPCR assays were performed to quantify induction of trophic factors in response to DPC conditioning. Statistical significance was P < .05.

RESULTS

Analysis of 32 trophic factors involved in Wnt signaling, cell migration and chemotaxis, cell proliferation and differentiation, extracellular matrix (ECM) remodeling and angiogenesis, and immunoregulation revealed that DPCs abundantly express many trophic factors including AMF, BDNF, BMP2, FGF1, FGF2, FGF5, HGF, MCP1, NGF, SDF1, TGFβ1, TIMP1, TIMP2, TIMP3, and VEGF-A, many of which were further induced by DPC conditioning; induction, which was significant for BDNF, EGF, HGF, LIF, MCP1, SDF1, IL6, IL11, MMP9 and TIMP1. Both DPCs proliferation and lactate production (P < .05) were inhibited by 8 μg/ml poly(I:C) relative to the control.

CONCLUSIONS

In vitro DPC conditioning through poly(I:C) activation of TLR3 led to amplification of trophic factors involved in tissue repair. The strategy offers promise for endodontic regeneration and tooth repair and warrants further investigation.

A critical analysis of clinical research methods to study regenerative endodontics

Regenerative endodontic treatment such as revitalization provides a treatment option for immature teeth with pulp necrosis. The main difference to the alternative procedure, the apical plug, is the induction of a blood clot inside the canal as a scaffold for healing and new tissue formation. Due to the biology-based and minimally-invasive nature of the treatment, revitalization has raised considerable interest in recent years. Whereas the procedure is fairly new and recommendations from endodontic societies have been in place only for a few years, the treatment protocol has evolved over the past two decades. Evidence has been created, not only from laboratory and animal work, but also from clinical studies including case reports, cohort studies and eventually prospective randomized controlled clinical trials, systematic reviews and meta-analyses. However, the research methods and clinical studies with subsequent reports oftentimes present with methodical limitations, which makes it difficult to objectively assess the value of this treatment modality. Several open questions remain, including the need for a more differentiated indication of revitalization after different traumatic injuries, the long-term prognosis of treated teeth and the true benefits for the patient. Therefore, this review aims to identify and reflect on such limitations, scrutinizing study design, diagnostic tools, procedural details and outcome parameters. A core outcome set is also proposed in this context, which can be considered in future clinical investigations. These considerations may lead to a more detailed and stringent planning and execution of future studies in order to create high-quality evidence for the treatment modality of revitalization and thus provide more robust data, create a larger body of knowledge for clinicians and further specify current recommendations.

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.

Human Amnion Epithelial Cells: A Potential Cell Source for Pulp Regeneration?

The aim of this study was to analyze the suitability of pluripotent stem cells derived from the amnion (hAECs) as a potential cell source for revitalization in vitro. hAECs were isolated from human placentas, and dental pulp stem cells (hDPSCs) and dentin matrix proteins (eDMPs) were obtained from human teeth. Both hAECs and hDPSCs were cultured with 10% FBS, eDMPs and an osteogenic differentiation medium (StemPro). Viability was assessed by MTT and cell adherence to dentin was evaluated by scanning electron microscopy. Furthermore, the expression of mineralization-, odontogenic differentiation- and epithelial–mesenchymal transition-associated genes was analyzed by quantitative real-time PCR, and mineralization was evaluated through Alizarin Red staining. The viability of hAECs was significantly lower compared with hDPSCs in all groups and at all time points. Both hAECs and hDPSCs adhered to dentin and were homogeneously distributed. The regulation of odontoblast differentiation- and mineralization-associated genes showed the lack of transition of hAECs into an odontoblastic phenotype; however, genes associated with epithelial–mesenchymal transition were significantly upregulated in hAECs. hAECs showed small amounts of calcium deposition after osteogenic differentiation with StemPro. Pluripotent hAECs adhere on dentin and possess the capacity to mineralize. However, they presented an unfavorable proliferation behavior and failed to undergo odontoblastic transition.

Engineering a novel stem cells from apical papilla - macrophages organoid for regenerative endodontics

INTRODUCTION

Three-dimension (3D) tissue-construct with a heterogeneous cell population is critical to understand the interactions between immune cells and stem cells from apical papilla (SCAP) in the periapical region for developing treatment strategies in regenerative endodontics. This study aims to develop and characterize a 3D tissue-construct with binary cell system for studying the interactions between SCAP and macrophages in presence of lipopolysaccharide (LPS - pro-inflammatory) and interleukin-4 (IL-4 - anti-inflammatory) environments.

METHODS

SCAP and macrophages were seeded in the 3D printed dumbbell-shaped molds to generate tissue-constructs with binary cell population. Two experimental (LPS and IL-4) and control (non-stimulation) conditions were applied to the tissue-constructs to determine the characteristics of the tissue-construct, volume of viable cells and their morphology using a confocal laser scanning microscopy from 0 to 7 days period. Experiments were conducted in triplicates and data were analyzed with trend analysis and two-way analysis of variance at the significance of p < 0.05.

RESULTS

The tissue-constructs revealed distinct SCAP-macrophage interaction in pro-/anti-inflammatory environments. SCAP displayed characteristic self-organization as a cap-shaped structure in the tissue-construct. The growth of cells and cell-to-cell as well as cell-to-matrix interactions resulted in 70% and 30% decreased dimension of the tissue graft on the SCAP side and macrophage side respectively at day 7 (p < 0.0001). The tissue environments influenced macrophages-SCAP interactions, resulting in altered viable cell volume (p < 0.05), morphology and structural organization.

CONCLUSIONS

This study developed and characterized an apical papilla organoid in a 3D collagen based tissue-construct for studying SCAP-macrophage crosstalk in tissue regeneration as well as repair.

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.

Isolation of Endogenous TGF-β1 from Root Canals for Pulp Tissue Engineering: A Translational Study

Simple Summary

Tissue engineering of the dental pulp has been a goal of dental research for years. In this translational study, a chairside protocol is designed using endogenous dentin matrix proteins as signaling molecules for pulp regeneration. These bioactive molecules can be isolated from root canals by ultrasonic-activated irrigation, further processed chairside, and mixed with a hydrogel. The scaffold material is to be injected into the root canal and effect cell homing, i.e., allowing stem cells from the periapical space to migrate into the root canal. The aim of this innovative approach is the formation of an innervated and vascularized connective tissue that resembles the pulp in form and function.

Abstract

Cell homing for dental pulp tissue engineering has been advocated as a feasible approach to regenerate dental pulp in a clinical setting. In order to develop a translational protocol for clinical application, we wanted to determine the effects of disinfectants on the availability of growth factors from the root canal, the amount that can be obtained in this context, and whether they can be processed for use in tissue engineering procedures. The extraction of growth factors should also be confirmed in a clinical setting. Root canals were prepared in 36 extracted mature teeth, and the amount of TGF-β1 in solution was quantified after different irrigation protocols (sodium hypochlorite, chlorhexidine) and after intracanal medication (calcium hydroxide). Centrifugal filters with a cut-off of 10,000 Da and 3000 Da were used for efficient concentration, and volumes and amounts of retained TGF-β1 were measured at different time points. During conventional endodontic treatment, ethylenediaminotetraacetic acid (EDTA) solution was collected after ultrasonic activation from the root canals of mature teeth of 38 patients, and growth factor content was quantified via enzyme-linked immunosorbent assay (ELISA). Irrigation with sodium hypochlorite reduced TGF-β1 release into EDTA. This effect was partially reversed by canal enlargement after the use of sodium hypochlorite and by subsequent use of calcium hydroxide. A few minutes of centrifugation with a cut-off of 10,000 Da reduced the initial volume of the irrigant by 90% and led to a continuous increase in concentration to the same extent. Furthermore, TGF-β1 was obtained from root canals of mature teeth during endodontic treatment in quantities that have been shown to elicit desirable cellular responses in a subsequent clinical application. A mixture with a suitable scaffold material and injection into the root canal has the potential to promote dental pulp regeneration.

Present status and future directions - Vital pulp treatment and pulp preservation strategies

Therapeutic strategies focussed on the pulp preservation, are important when managing vital teeth with deep caries and an exposed pulp. These vital pulp treatments (VPTs); however, are not new, with indirect and direct pulp capping procedures being described as a therapy for carious teeth for over a century. As a result of unpredictable outcomes, the traditional indications for VPT particularly when the pulp was exposed were limited to the treatment of immature teeth with incomplete root formation. Over the last 20 years, the advent of regenerative endodontics and the promotion of biologically based therapies aimed at reducing intervention have reinvigorated VPT with new waves of basic science and clinical research indicating a role for VPT not only in mature cariously affected teeth, but also in teeth with signs and symptoms indicative of irreversible pulpitis. Driven by new materials such as hydraulic calcium silicate cements, a better understanding of pulpal immunity and biology as well and improved tissue handling, VPT has been at the forefront of treatment recommendations made by global Cariology and Endodontic organizations. Care must be exercised, however, as key gaps in scientific knowledge remain alongside severe limitations in educational dissemination amongst dentists. Although research has highlighted that carious injury to the dentine–pulp complex stimulates a wide range of responses and that the interaction between infection, inflammation and repair will eventually impact on the outcome of pulpitis, our ability to accurately and objectively diagnose the true inflammatory state of the pulp remains poor. An overreliance on symptoms leaves clinicians with subjective, crude diagnostic tools by which to inform treatment planning and decision‐making, which results in large variations in the treatments offered to patients. Not only is there an urgent need to develop preoperative and intraoperative diagnostic tools, but there is also a paucity of the high‐quality comparative evidence required to answer the most important questions and justify treatment options. The aim of this review was to consider the current status of VPT and to discuss the principle problems that are hindering clinical acceptance of these techniques. Potential solutions and opportunities are offered to suggest ways that VPT may become a more consistently prescribed evidenced‐based treatment in dental practice.

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 Hydroxyapatite Microspheres, Amoxicillin-Hydroxyapatite and Collagen-Hydroxyapatite Composites on Human Dental Pulp-Derived Mesenchymal Stem Cells

In this study, the preparation and characterization of three hydroxyapatite-based bioactive scaffolds, including hydroxyapatite microspheres (HAps), amoxicillin–hydroxyapatite composite (Amx–HAp), and collagen–hydroxyapatite composite (Col–HAp) were performed. In addition, their behavior in human dental pulp mesenchymal stem cell (hDPSC) culture was investigated. HAps were synthesized through the following methods: microwave hydrothermal, hydrothermal reactor, and precipitation, respectively. hDPSCs were obtained from samples of third molars and characterized by immunophenotypic analysis. Cells were cultured on scaffolds with osteogenic differentiation medium and maintained for 21 days. Cytotoxicity analysis and migration assay of hDPSCs were evaluated. After 21 days of induction, no differences in genes expression were observed. hDPSCs highly expressed the collagen IA and the osteonectin at the mRNA. The cytotoxicity assay using hDPSCs demonstrated that the Col–HAp group presented non-viable cells statistically lower than the control group (p = 0.03). In the migration assay, after 24 h HAps revealed the same migration behavior for hDPSCs observed compared to the positive control. Col–HAp also provided a statistically significant higher migration of hDPSCs than HAps (p = 0.02). Migration results after 48 h for HAps was intermediate from those achieved by the control groups. There was no statistical difference between the positive control and Col–HAp. Specifically, this study demonstrated that hydroxyapatite-based bioactive scaffolds, especially Col-Hap, enhanced the dynamic parameters of cell viability and cell migration capacities for hDPSCs, resulting in suitable adhesion, proliferation, and differentiation of this osteogenic lineage. These data presented are of high clinical importance and hold promise for application in therapeutic areas, because Col–HAp can be used in ridge preservation, minor bone augmentation, and periodontal regeneration. The development of novel hydroxyapatite-based bioactive scaffolds with clinical safety for bone formation from hDPSCs is an important yet challenging task both in biomaterials and cell biology.

Alkaline activation of endogenous latent TGFβ1 by an injectable hydrogel directs cell homing for in situ complex tissue regeneration

Utilization of the body's regenerative potential for tissue repair is known as in situ tissue regeneration. However, the use of exogenous growth factors requires delicate control of the dose and delivery strategies and may be accompanied by safety, efficacy and cost concerns. In this study, we developed, for the first time, a biomaterial-based strategy to activate endogenous transforming growth factor beta 1 (TGFβ1) under alkaline conditions for effective in situ tissue regeneration. We demonstrated that alkaline-activated TGFβ1 from blood serum, bone marrow fluids and soaking solutions of meniscus and tooth dentin was capable of increasing cell recruitment and early differentiation, implying its broad practicability. Furthermore, we engineered an injectable hydrogel (MS-Gel) consisting of gelatin microspheres for loading strong alkaline substances and a modified gelatin matrix for hydrogel click crosslinking. In vitro models showed that alkaline MS-Gel controllably and sustainably activated endogenous TGFβ1 from tooth dentin for robust bone marrow stem cell migration. More importantly, infusion of in vivo porcine prepared root canals with alkaline MS-Gel promoted significant pulp-dentin regeneration with neurovascular stroma and mineralized tissue by endogenous proliferative cells. Therefore, this work offers a new bench-to-beside translation strategy using biomaterial-activated endogenous biomolecules to achieve in situ tissue regeneration without the need for cell or protein delivery.

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Nonphysiological pH activates latent TGFβ1 in various tissue sources.

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Alkaline activation of endogenous TGFβ1 directs cell homing.

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Biomaterial-activated endogenous TGFβ1 induces regeneration of complex tissues.

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).

Direct effect of transforming growth factor-beta 1 (TGF-β1) on human apical papilla cell proliferation and mineralisation

Firstly, this study investigated the direct effect of Transforming Growth Factor-beta 1 at 10, 5, 2.5 and 1.25 ng mL^-1 on human apical papilla cell proliferation and mineralisation. Cell proliferation was examined at 0, 2, 4, 6, 24, 48, 72, 96 and 120 h using Alamar Blue^TM assay. Cell mineralisation was examined at day 21 with a quantitative Alizarin Red S staining. Secondly, the study aimed to estimate the amount of Transforming Growth Factor-beta 1 (TGF-β1) released from the dentin after root canal irrigation. The solution collected from a root canal after rinsing with various protocols (normal saline solution, ethylenediaminetetraacetic acid or chlorhexidine) was analysed with an enzyme-linked immunosorbent assay. Data were statistically analysed using a one-way analysis of variance. The results, from the first part, revealed cell proliferation reduction in all experimental groups presented with TGF-β1. The higher concentration generated more deteriorating effects. Cell mineralisation was highest in a group with TGF-β1 at 1.25 ng mL^-1 (P < 0.05). For the growth factor released from dentin, the highest amount was detected only when ethylenediaminetetraacetic acid was associated with the irrigation (P < 0.05). In summary, the direct effects of TGF-β1 on cell proliferation and differentiation were diverse, depending on concentration. The release of TGF-β1 from root dentin can be achieved after rinsing with ethylenediaminetetraacetic acid.

The effect of changing apical foramen diameter on regenerative potential of mature teeth with necrotic pulp and apical periodontitis

OBJECTIVE

The aim of the present study was to evaluate the regenerative potential of permanent necrotic mature teeth with different apical foramen diameters in comparison to conventional endodontic treatment.

METHODS

Pulp necrosis and periapical pathosis were induced in premolars (144 roots) in six mongrel dogs. The infected teeth were divided into six groups; conventional root canal treatment (RCT) group prepared up to apical preparation sizes #F3 ProTaper file, regenerative endodontic therapy (RET) groups; groups RET-F3, RET-F4, and RET-F5 where regenerative endodontic procedures were applied after apical preparation up to sizes #F3, F4, and F5 ProTaper file, respectively, control groups; and positive (P) and negative (N) groups included infected and healthy teeth respectively. Each group (12 teeth with 24 roots each) was further subdivided into two subgroups (6 teeth with 12 roots each) according to the evaluation periods 1 and 3 months; each group was equally randomized in the upper and lower jaws during each evaluation period.

RESULTS

The inflammatory cell counts for the RCT group were statistically significantly higher than that of all RET groups at the first period and only significantly higher than RET-F5 at the second period. The enlargement of the apical foramen to #F5 showed no statistically significant difference with #F4 regarding the inflammatory cell count, tissue in-growth inside the root canal, and percentage of bone resorption. The tissue formed after RET was not true pulp tissue and is considered tissue repair with connective tissue, dilated blood vessels, and cementum-like structures.  CONCLUSION: Increasing the apical size diameter was associated with less inflammatory cell count, less percentage of bone resorption, more tissue ingrowth, and more percentage of new hard tissue formation inside root canal. The minimum apical diameter that should be enlarged for RET is 0.4 mm.

CLINICAL RELEVANCE

RET could be used as an alternative procedure to RCT for the treatment of mature teeth with necrotic pulp and apical periodontitis.

Exploiting dentine matrix proteins in cell-free approaches for periradicular tissue engineering

The recent discovery of mesenchymal stem cells within periapical lesions (PL-MSC) has presented novel opportunities for managing periradicular diseases in adult teeth by way of enhancing tissue regeneration. This discovery coincides with the current paradigm shift toward biologically driven treatment strategies in endodontics, which have typically been reserved for non-vital immature permanent teeth. One such approach that shows promise is utilizing local endogenous non-collagenous dentine extracellular matrix components (dECM) to recruit and upregulate the intrinsic regenerative capacity of PL-MSCs in situ. At picogram levels, these morphogens have demonstrated tremendous ability to enhance the cellular activities in in vitro and in vivo animal studies that would otherwise be necessary for periradicular regeneration. Briefly, these include proliferation, viability, migration, differentiation, and mineralization. Therefore, topical application of dECMs during ortho- or retrograde root canal treatment could potentially enhance and sustain the regenerative mechanisms within diseased periapical tissues that are responsible for attaining favorable clinical and radiographic outcomes. This would provide many advantages when compared with conventional antimicrobial-only therapies for apical periodontitis (AP), which do not directly stimulate healing and have had stagnant success rates over the past five decades despite significant advances in operative techniques. The aim of this narrative review was to present the novel concept of exploiting endogenous dECMs as clinical tools for treating AP in mature permanent teeth. A large scope of literature was summarized to discuss the issues associated with conventional treatment modalities; current knowledge surrounding PL-MSCs; composition of the dECM; inductive potentials of dECM morphogens in other odontogenic stem cell niches; how treatment protocols can be adapted to take advantage of dECMs and PL-MSCs; and finally, the challenges currently impeding successful clinical translation alongside directions for future research.

Improvement of apical papilla cell attachment after erbium, chromium-doped yttrium, scandium, gallium, and garnet laser application: a study in an ex vivo immature tooth model

The purposes of this study were (1) to investigate the direct effect of an Er,Cr:YSGG laser on human apical papilla cell (APC) proliferation and mineralization and (2) to examine the effect of Er,Cr:YSGG laser, when applied to an ex vivo immature tooth model, on APC attachment. An Er,Cr:YSGG laser at various power outputs (0.1, 0.5, and 1 W) was used at different positions (2, 5, or 8 mm from the cells) to irradiate cultured APCs. APC proliferation and mineralization were assessed at various intervals. For the cell attachment evaluation, ex vivo tooth models containing dentin samples were irrigated with either EDTA or normal saline solution (NSS) and supplemented with laser activation. Fibronectin-positive-staining cells were counted and analyzed. The number of APCs was significantly greater when power outputs of 0.1 W and 0.5 W were used than when 1 W was used (P < 0.05). The close contact of laser application, at 2 and 5 mm, exerted a negative effect on cell proliferation at 24 and 48 h. The application at 8 mm did not show the deterioration effect. APC mineralization was reduced after laser irradiation, regardless of the power and the tip positioning, at 21 days. APC attachment in all laser-activated groups was significantly greater than in the groups without laser. The use of Er,Cr:YSGG laser significantly promoted APC attachment on the root canal dentin.

Platform technologies for regenerative endodontics from multifunctional biomaterials to tooth-on-a-chip strategies

OBJECTIVES

The aim of this review is to highlight recent progress in the field of biomaterials-mediated dental pulp tissue engineering. Specifically, we aim to underscore the critical design criteria of biomaterial platforms that are advantageous for pulp tissue engineering, discuss models for preclinical evaluation, and present new and innovative multifunctional strategies that hold promise for clinical translation.

MATERIALS AND METHODS

The current article is a comprehensive overview of recent progress over the last 5 years. In detail, we surveyed the literature in regenerative pulp biology, including novel biologic and biomaterials approaches, and those that combined multiple strategies, towards more clinically relevant models. PubMed searches were performed using the keywords: "regenerative dentistry," "dental pulp regeneration," "regenerative endodontics," and "dental pulp therapy."

RESULTS

Significant contributions to the field of regenerative dentistry have been made in the last 5 years, as evidenced by a significant body of publications. We chose exemplary studies that we believe are progressive towards clinically translatable solutions. We close this review with an outlook towards the future of pulp regeneration strategies and their clinical translation.

CONCLUSIONS

Current clinical treatments lack functional and predictable pulp regeneration and are more focused on the treatment of the consequences of pulp exposure, rather than the restoration of healthy dental pulp.

CLINICAL RELEVANCE

Clinically, there is great demand for bioinspired biomaterial strategies that are safe, efficacious, and easy to use, and clinicians are eager for their clinical translation. In particular, we place emphasis on strategies that combine favorable angiogenesis, mineralization, and functional tissue formation, while limiting immune reaction, risk of microbial infection, and pulp necrosis.

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.

Fabrication of Vascularized DPSC Constructs for Efficient Pulp Regeneration

Dental pulp regeneration is a promising approach to restore the vitality of necrotic teeth. We have previously reported the fabrication of scaffold-free cell constructs containing only dental pulp stem cells (DPSCs) and their ability to form pulp-like tissue in the pulpless tooth. However, the DPSC construct could not build pulp-like tissue with a full root length because it is difficult to induce blood vessels from a small root canal foramen. Therefore, we hypothesized that vascular structure could be preformed in the DPSC construct by employing endothelial differentiation capability of DPSCs, and vascularized constructs might facilitate dental pulp regeneration in the pulpless tooth. In this study, vascularized DPSC constructs were fabricated by inducing endothelial differentiation, and then we investigated the behavior of differentiated DPSCs, the internal structure of cell constructs, and their pulp regenerative ability in vivo. We observed that DPSCs positive for CD31 and von Willebrand factor were localized at the outer layer of constructs and formed a reticulated lumen structure. The cells constituting the outer layer of the construct expressed endothelial differentiation markers at higher levels than cells in the inner part. These results indicated that DPSCs in the outer layer differentiated into endothelial cells and formed vascular-like structures in the cell construct. Next, a vascularized DPSC construct was transplanted into the human pulpless tooth that was implanted into immunodeficient mice in the subcutaneous space. After 6 wk of implantation, the vascularized construct formed pulp-like tissues with higher density of human CD31-positive blood vessels when compared with specimens implanted with a DPSC construct without prevascularization. These results suggest that the vascular structure formed in the DPSC construct facilitated the blood supply and enhanced pulp regeneration. This study demonstrates that a vascularized DPSC construct is a prospective biomaterial as an implant for novel dental pulp regeneration.

Demineralized Dentin Matrix Particle-Based Bio-Ink for Patient-Specific Shaped 3D Dental Tissue Regeneration

Demineralized dentin matrix (DDM)-based materials have been actively developed and are well-known for their excellent performance in dental tissue regeneration. However, DDM-based bio-ink suitable for fabrication of engineered dental tissues that are patient-specific in terms of shape and size, has not yet been developed. In this study, we developed a DDM particle-based bio-ink (DDMp bio-ink) with enhanced three-dimensional (3D) printability. The bio-ink was prepared by mixing DDM particles and a fibrinogen–gelatin mixture homogeneously. The effects of DDMp concentration on the 3D printability of the bio-ink and dental cell compatibility were investigated. As the DDMp concentration increased, the viscosity and shear thinning behavior of the bio-ink improved gradually, which led to the improvement of the ink’s 3D printability. The higher the DDMp content, the better were the printing resolution and stacking ability of the 3D printing. The printable minimum line width of 10% w/v DDMp bio-ink was approximately 252 μm, whereas the fibrinogen–gelatin mixture was approximately 363 μm. The ink’s cytocompatibility test with dental pulp stem cells (DPSCs) exhibited greater than 95% cell viability. In addition, as the DDMp concentration increased, odontogenic differentiation of DPSCs was significantly enhanced. Finally, we demonstrated that cellular constructs with 3D patient-specific shapes and clinically relevant sizes could be fabricated through co-printing of polycaprolactone and DPSC-laden DDMp bio-ink.

Regenerative Endodontic Procedures for the Treatment of Necrotic Mature Teeth with Apical Periodontitis: A Systematic Review and Meta-analysis of Randomized Controlled Trials

INTRODUCTION

Regenerative endodontic procedures (REPs) are intended to repair and regenerate part of the pulp-dentin complex. The aim of this study was to systematically appraise the existing evidence on the effectiveness of REPs on mature teeth with pulp necrosis and apical periodontitis.

METHODS

Electronic database and hand searches were performed on 8 databases of published and unpublished literature from inception to January 3, 2021, for the identification of randomized controlled trials (RCTs) or prospective clinical trials. The related key words included "regenerative," "pulp revascularization," "revitalization procedure," and "necrotic mature teeth." A random effects meta-analysis was conducted assessing success as the main outcome treatment. Risk of bias was assessed through the Cochrane Risk of Bias 2.0 tool, and the quality of the evidence was assessed with the Grading of Recommendations Assessment, Development and Evaluation approach.

RESULTS

Of the 337 initial hits, 4 RCTs were eligible for inclusion, whereas 3 were included in the quantitative synthesis. Overall, there was no difference in the relative risk for a successful/unsuccessful treatment outcome between REPs or conventional treatment (3 studies, relative risk = 1.03; 95% confidence interval, 0.92-1.15; P = .61; heterogeneity I² = 0.0%, P = .53; prediction interval = 0.51-2.09). Risk of bias ranged from low to raising some concerns, whereas the quality of the evidence was graded as moderate.

CONCLUSIONS

Based on moderate-quality evidence, REPs appear as a viable treatment alternative for mature necrotic teeth with periapical lesions at present. Furthermore, well-designed RCTs might also provide confirmatory evidence in this respect while also framing a backbone for standardization of the therapeutic protocol of REPs.

Effect of Optimized Irrigation With Photon-Induced Photoacoustic Streaming on Smear Layer Removal, Dentin Microhardness, Attachment Morphology, and Survival of the Stem Cells of Apical Papilla

BACKGROUND AND OBJECTIVES

This study aimed to evaluate the effect of optimized irrigation with photon-induced photoacoustic streaming (PIPS) activation of different irrigants (distilled water or ethylenediaminetetraacetic acid [EDTA]) on smear layer removal, dentin microhardness, attachment morphology, and survival of stem cells of the apical papilla (SCAP) in an organotypic root canal model.

STUDY DESIGN/MATERIALS AND METHODS

A total of 144 standardized root segments were randomly allocated into 6 groups for irrigation: (i) NaOCl group, (ii) NaOCl + EDTA group, (iii) NaOCl + PIPS (distilled water) group, (iv) NaOCl + PIPS (EDTA) group, (v) NaOCl + EDTA + PIPS (distilled water) group, and (vi) NaOCl + EDTA + PIPS (EDTA) group. Each group was divided into four subgroups for assessment: (i) dentin cleanliness; (ii) dentin microhardness; (iii) cell attachment morphology; and (iv) viable SCAP quantification.

RESULTS

Compared with the control groups, the NaOCl + EDTA + PIPS (EDTA) group showed higher efficiency in smear layer removal and in increasing SCAP viability with more stretched cellular morphology. There were no statistically significant differences in either smear layer removal effect, dentin microhardness, attachment morphology, or survival of SCAP among the other groups when optimized with PIPS (distilled water or EDTA) (P > 0.05).

CONCLUSIONS

Our findings indicated that irrigation optimized with PIPS activation of EDTA for 40 seconds was conducive to smear layer removal without additional dentin microhardness decrease. Additionally, this irrigation created more cell-friendly dentin conditioning than other approaches, which was beneficial for the attachment and survival of SCAP. Lasers Surg. Med. © 2021 Wiley Periodicals LLC.

Regeneration of pulp-dentin complex using human stem cells of the apical papilla: in vivo interaction with two bioactive materials

OBJECTIVES

To compare the regenerative properties of human stem cells of the apical papilla (SCAPs) embedded in a platelet-rich plasma (PRP) scaffold, when implanted in vivo using an organotypic model composed of human root segments, with or without the presence of the bioactive cements - ProRoot MTA or Biodentine.

MATERIAL AND METHODS

SCAPs were isolated from third molars with incomplete rhizogenesis and expanded and characterized in vitro using stem cell and surface markers. The pluripotency of these cells was also assessed using adipogenic, chondrogenic, and osteogenic differentiation protocols. SCAPs together with a scaffold of PRP were added to the root segment lumen and the organotypic model implanted on the dorsal region of immunodeficient rats for a period of 4 months.

RESULTS

Presence of SCAPs induced de novo formation of dentin-like and pulp-like tissue. A barrier of either ProRoot MTA or Biodentine did not significantly affect the fraction of sections from roots segments observed to contain deposition of hard material (P > 0.05). However, the area of newly deposited dentin was significantly greater in segments containing a barrier of Biodentine compared with ProRoot MTA (P < 0.001).

CONCLUSIONS AND CLINICAL RELEVANCE

SCAPs offer a viable alternative to other dental stem cells (DSCs) in their regenerative properties when enclosed in the microenvironment of human tooth roots. The present study also suggests that the presence of bioactive materials does not hinder or impede the formation of new hard tissues, but the presence of Biodentine may promote greater mineralized tissue deposition.

Clinical cell-based versus cell-free regenerative endodontics: clarification of concept and term

There is no consensus on the true meaning of clinical regenerative endodontics, and there is confusion over the concept and the term. Commonly used terms include revitalization and revascularization. The clinical methods for endodontic revitalization procedures and the tissue engineering concept differ depending on whether there is exogenous delivery of cells - called cell therapy, or not. Here, in this review, the difference is clarified by emphasizing the correct terminology: cell-free versus cell-based regenerative endodontic therapy (CF-RET versus CB-RET). The revitalization procedures practised clinically do not fit into the modern tissue engineering concepts of pulp regeneration but can be categorized as CF-RET. The modern tissue engineering concept in pulp regeneration is a CB-RET, which so far is at the clinical trial stage. However, histological examination of teeth following regenerative endodontic treatments reveals healing with repair derived from stem cells that originate from the periodontal, bone and other tissues. The aim of regenerative endodontics is regeneration of the pulp-dentine complex. This review discusses why CF-RET is unlikely to regenerate a pulp-dentine complex with current protocols. The American Association of Endodontists and the European Society of Endodontology have not yet recommended autologous stem cell transplantation (CB-RERT) which aspires for regeneration. Therefore, an understanding of the concept, term, difficulties and differences in current protocols is important for the clinician. However, rather than being discouraged that ideal regeneration has not been achieved to date, repair can be an acceptable outcome in clinical regenerative endodontics as it has also been accepted in medicine. Repair should also be considered in the context that resolution of the clinical signs/symptoms of pulp necrosis/apical periodontitis is generally reliably obtained in clinical regenerative endodontics.

The trends of dental biomaterials research and future directions: A mapping review

Objective

This literature research aimed to compare, contrast and quantify the innovations in the most commonly used dental biomaterials.

Methodology

Original research articles based on experimental dental biomaterials published between 2007 and 2019 were retrieved and reviewed. A search of electronic databases, PubMed, Scopus, and Web of Science indexed dental/biomaterials journals, has been conducted. The inclusion criteria in this research were: synthesis of experimental dental materials, whereas commercial dental materials, review articles, and clinical trials (case reports) were excluded.

Results

It was found that the amount of publications related to dental subgingival implants, computer-aided modeling ceramics, aesthetic restorative materials, adhesives cements, ceramics, bioceramics, endodontic materials, bioactive scaffolds, stem cells, and guided-tissue membranes had increased significantly from 2007. At the same time, the number of publications related to dental cements, silver amalgam, and dental alloys has decreased. For characterization of dental materials it was noted that mechanical properties were tested mostly for restorative materials. On the other hand, biological properties were most assessed for dental subgingival implants and endodontic materials, however, physical properties predominantly for bioceramics.

Conclusion

It is concluded that to meet clinical demands there was more focus on restorative materials that provided better aesthetics, including resin composites, adhesive resin composites (luting cements), zirconia, and other ceramics. The boost in laboratory and animal research related to bioceramics was attributed to their regenerative potential. This current literature study will help growing researchers to consider and judge the direction to which research might be guided in order to plan prospective research projects.

EDTA Promotes the Mineralization of Dental Pulp In Vitro and In Vivo

INTRODUCTION

Dentin regeneration is one of the main goals of vital pulp treatment in which the biological properties of dental pulp cells (DPCs) need to be considered. In our previous study, we showed that EDTA could enhance the stromal cell-derived factor 1 alpha-induced migration of DPCs. The purpose of this study was to explore the effects of EDTA on the mineralization of dental pulp in vitro and in vivo.

METHODS

DPCs were obtained from human premolars or third molars. Alkaline phosphatase assays and alizarin red S staining were used to examine the degree of differentiation and mineralized nodule formation of DPCs. Real-time polymerase chain reaction and Western blot analysis were performed to detect the messenger RNA and protein expressions of mineralization-related markers in DPCs. Extracellular-regulated protein kinase and Smad inhibitors were used to study the roles of these 2 signaling pathways in this process. In addition, pulp exposures were created on 18 premolars of 2 beagle dogs (>12 months) using a high-speed dental handpiece. The experimental group (n = 9) was treated with 12% EDTA for 5 minutes, and the control group (n = 9) was treated with sterile saline for the same duration. Mineral trioxide aggregate was used for direct pulp capping followed by glass ionomer cement sealing. Samples were collected 3 months later, and the regenerated dentin was assessed by micro-computed tomographic and histologic analyses.

RESULTS

Exposure to 12% EDTA promoted the activity of alkaline phosphatase, the formation of mineralized nodules, and the messenger RNA and protein expressions of mineralization-related markers in DPCs. Furthermore, the process of 12% EDTA enhancing the differentiation of DPCs was mediated by the extracellular-regulated protein kinase 1/2 signaling pathway and inhibited by the Smad2/3 signaling pathway. In vivo, compared with the control group, more regenerated dentin that had fewer tunnel defects was formed in the 12% EDTA-treated group.

CONCLUSIONS

Our results showed that 12% EDTA could promote the mineralization of dental pulp in vitro and in vivo.

Regenerative Endodontic Procedures, Disinfectants and Outcomes: A Systematic Review

AIMS

This systematic review aims to identify and synthesise available evidence to determine the clinical and radiographic outcomes of REP involving any disinfection irrigant together with a non-antibiotic intracanal medicament.

METHODS

Experimental and observational studies evaluating the outcomes of REP in immature non-vital permanent teeth in 6-16 year olds, where the protocol used any type of disinfectant irrigant together with a non-antibiotic intracanal medicament (non-setting calcium hydroxide) were included. Data was narratively synthesised and presented in respect to the primary outcome (elimination of symptoms and infection) and secondary outcomes (increase in root length/width; positive response to vitality testing; patient-reported outcomes; adverse effects).

MAIN FINDINGS

1628 studies were identified, of which five met the eligibility criteria for inclusion in the review. Studies included one randomised control trial and four observational studies. All five studies showed an absence of clinical signs and symptoms for all teeth postoperatively with radiographic resolution or absence of pathology following the disinfection stages of the REP used. Choice of secondary outcomes were inconsistent but included further root development, coronal discolouration and root canal calcifications postoperatively. There was a high risk of bias in all five studies and subsequently the quality of the evidence base was judged to be low.

PRINCIPLE CONCLUSIONS

REP using a non-antibiotic disinfectant approach appears capable of providing satisfactory outcomes for a non-vital immature permanent tooth. Further high-quality research is required before solid recommendations towards clinical practice guidelines for the disinfection portion of REP can be implemented.

Advanced Biomaterials and Techniques for Oral Tissue Engineering and Regeneration-A Review

The reconstruction or repair of oral and maxillofacial functionalities and aesthetics is a priority for patients affected by tooth loss, congenital defects, trauma deformities, or various dental diseases. Therefore, in dental medicine, tissue reconstruction represents a major interest in oral and maxillofacial surgery, periodontics, orthodontics, endodontics, and even daily clinical practice. The current clinical approaches involve a vast array of techniques ranging from the traditional use of tissue grafts to the most innovative regenerative procedures, such as tissue engineering. In recent decades, a wide range of both artificial and natural biomaterials and scaffolds, genes, stem cells isolated from the mouth area (dental follicle, deciduous teeth, periodontal ligament, dental pulp, salivary glands, and adipose tissue), and various growth factors have been tested in tissue engineering approaches in dentistry, with many being proven successful. However, to fully eliminate the problems of traditional bone and tissue reconstruction in dentistry, continuous research is needed. Based on a recent literature review, this paper creates a picture of current innovative strategies applying dental stem cells for tissue regeneration in different dental fields and maxillofacial surgery, and offers detailed information regarding the available scientific data and practical applications.