Regenerative Endodontic Treatment of an Immature Necrotic Molar with Arrested Root Development by Using Recombinant Human Platelet-derived Growth Factor: A Case Report

An innovative cell-based transplantation therapy for an immature permanent tooth in an adult: a case report

BACKGROUND

Immature teeth with necrotic pulps present multiple challenges to clinicians. In such cases, regenerative endodontic procedures (REPs) may be a favorable strategy. Cells, biomaterial scaffolds, and signaling molecules are three key elements of REPs. Autologous human dental pulp cells (hDPCs) play an important role in pulp regeneration. In addition, autologous platelet concentrates (APCs) have recently been demonstrated as effective biomaterial scaffolds in regenerative dentistry, whereas the latest generation of APCs-concentrated growth factor (CGF), especially liquid phase CGF (LPCGF)-has rarely been reported in REPs.

CASE PRESENTATION

A 31-year-old woman presented to our clinic with the chief complaint of occlusion discomfort in the left mandibular posterior region for the past 5 years. Tooth #35 showed no pulp vitality and had a periodontal lesion, and radiographic examination revealed that the tooth exhibited extensive periapical radiolucency with an immature apex and thin dentin walls. REP was implemented via transplantation of autologous hDPCs with the aid of LPCGF. The periodontal lesion was managed with simultaneous periodontal surgery. After the treatment, the tooth was free of any clinical symptoms and showed positive results in thermal and electric pulp tests at 6- and 12-month follow-ups. At 12-month follow-up, radiographic evidence and three-dimensional models, which were reconstructed using Mimics software based on cone-beam computed tomography, synergistically confirmed bone augmentation and continued root development, indicating complete disappearance of the periapical radiolucency, slight lengthening of the root, evident thickening of the canal walls, and closure of the apex.

CONCLUSION

hDPCs combined with LPCGF represents an innovative and effective strategy for cell-based regenerative endodontics.

Pulp regeneration treatment using different bioactive materials in permanent teeth of pediatric subjects

Background and Objectives

The present systematic review aims to assess the success rate of the pulp regeneration treatment, according to the American Association of Endodontists (AAE) criteria, using different bioactive materials in permanent teeth of pediatric subjects (6-17 years of age).

Materials and Methods

The study protocol was registered on PROSPERO and adhered to the Preferred Reporting Items for Systematic Reviews and Meta-analyses statement. The question formulation was accomplished using the PICO model, and an electronic search was carried out on Scopus, MEDLINE/PubMed, Web of Science, and Cochrane databases till April 1, 2023. A total of 30 studies were established to fulfill the inclusion criteria of this systematic review.

Results

A total of 273 teeth have been treated with pulp regeneration treatment. By comparing different biomaterials and the success criteria defined by the AAE, the material associated with a higher success rate was found to be the white mineral trioxide aggregate. However, the overall success rate of pulp regeneration treatment was reported for 248 out of 273 teeth (91.20%).

Conclusions

Data obtained support the potential that regenerative endodontics aids in continuing root development in permanent immature teeth. Further studies are needed for a more extensive evaluation of the use of different biomaterials and the success rate in regenerative endodontics.

The capability of regenerative endodontics to promote the complete root formation in immature permanent teeth with different initial pre-operative conditions

OBJECTIVES

To describe the potential possibility of complete root formation after regenerative endodontic procedures (REPs) in immature permanent teeth with different initial pre-operative conditions.

MATERIALS AND METHODS

Children who underwent REPs in the Department of Pediatric Dentistry, Peking University School and Hospital of Stomatology, Beijing, China, from January 2013 to December 2022 were enrolled. Whether the tooth achieved complete root formation was determined using post-operative periapical radiography. The potential possibility of complete root formation after REPs in immature permanent teeth with different initial conditions is discussed.

RESULTS

A total of 428 teeth from 401 patients were included, of which 258 (60.2%) achieved complete root formation. In cases that achieved complete root formation, the most serious type of trauma was avulsion, the teeth with the worst initial root development were less than one-third of the development (stages 6-7), and the longest duration of the presence of apical lesions in the tooth before the first visit was more than 180 days. There is a significant difference in the root formation of teeth with different initial developmental stages and diagnoses.

CONCLUSIONS

The active period of continued root formation was 5-21 months post-operatively. The higher the initial stage of root development and the shorter the duration of the presence of apical lesions in the tooth before the first visit, the greater the possibility of root formation. However, complete root formation may still be expected after REPs in severely injured immature permanent teeth and teeth with poor initial pre-operative root development conditions (less than stage 7) at the first visit. This is also true for teeth with long-term and large-scale apical lesions.

Effectiveness of endodontic tissue engineering in treatment of apical periodontitis: A systematic review

BACKGROUND

Regenerative endodontics has evolved in recent years with tissue engineering concepts in particular appearing promising. Endodontic tissue engineering (ETE) describes the various approaches based on the orthograde introduction of scaffolds or biomaterials (with or without cells) into the root canal to achieve pulp tissue regeneration. There are currently no systematic reviews investigating whether ETE is a suitable method for the treatment of endodontic disease in both mature and immature permanent teeth.

OBJECTIVES

The purpose of this systematic review was to determine the effectiveness of ETE in permanent teeth with pulp necrosis in comparison with conventional endodontic treatment.

METHODS

We searched MEDLINE, Embase and the Cochrane Library for published reports as well as Google Scholar for grey literature up to November 2021. Included were studies of patients with permanent immature or mature teeth and pulp necrosis with or without signs of apical periodontitis (P) comparing ETE (I) with calcium hydroxide apexification, apical plug and root canal treatment (C) in terms of tooth survival, pain, tenderness, swelling, need for medication (analgesics and antibiotics), radiographic evidence of reduction in apical lesion size, radiographic evidence of normal periodontal ligament space, function (fracture and restoration longevity), the need for further intervention, adverse effects (including exacerbation, restoration integrity, allergy and discolouration), oral health-related quality of life (OHRQoL), presence of sinus tract and response to sensibility testing (O). An observation period of at least 12 months was mandatory (T) and the number of patients in human experimental studies or longitudinal observational studies had to be at least 20 (10 in each arm) at the end (S). Risk of bias was appraised using the Cochrane risk-of-bias (RoB 2) tool. Two authors independently screened the records, assessed full texts for eligibility and evaluated risk of bias. Heterogeneity of outcomes and limited body of evidence did not allow for meta-analysis.

RESULTS

Two randomized clinical trials investigating cell transplantation approaches with a total of 76 participants (40 treated immature teeth and 36 treated mature teeth) were included for qualitative analysis. Both studies had moderate concerns in terms of risk of bias. Due to the lack of homogeneity a meta-analysis was not possible. Tooth survival for ETE, root canal treatment and apexification was 100% after 12 months. Teeth treated with ETE showed a higher number of cases with positive pulpal responses to sensitivity tests and with blood perfusion compared with root canal treatment or apexification.

DISCUSSION

This systematic review highlights that there is limited evidence for ETE approaches. Even though the results of this review suggest a high survival with ETE in mature and immature teeth, there is a moderate risk of bias due to methodological limitations in the included studies, so the overall results should be interpreted with caution. Lack of a robust control group was a common problem during literature screening, and outcomes besides dental survival were reported inconsistently. Future clinical trials need to address methodical as well as assessment concerns and report long-term results.

CONCLUSION

The benefits and high survival rates reported for ETE techniques suggest that this procedure might be an alternative to conventional procedures for permanent teeth with pulpal necrosis. However, more appropriate studies are needed to derive clinical recommendations.

REGISTRATION

PROSPERO (CRD42021266350).

Regenerative endodontic treatment of an immature incisor tooth with a novel platelet-rich product: A five-year follow-up case report

This case report presents a five-year follow-up and the management of a necrotic, immature incisor tooth treated by a novel platelet-rich plasma/platelet extract solution and platelet-rich fibrin (PRP-PES/PRF) and the restoration by using a stress-reduced direct composite restoration (SRDC) technique. The patient with a broken maxillary lateral tooth was referred to our clinic. Extra/intra-oral examinations were within normal limits. The nonvital tooth having an apical lesion and open-apical apex was treated with a regenerative endodontic treatment procedure (REP), and further root development with continued apical closure was shown in the follow-ups up to 60 months. In conclusion, the SRDC and PRP-PES/PRF combination can be an opportunity for the teeth requiring post-restoration. In contrast to the treatment strategy susceptible to weakening or fracturing the patient's tooth root, the REP approach may lead to a better prognosis for the patient's tooth.

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.

Expert consensus on regenerative endodontic procedures

Regenerative endodontic procedures (REPs) is a biologic-based treatment modality for immature permanent teeth diagnosed with pulp necrosis. The ultimate objective of REPs is to regenerate the pulp-dentin complex, extend the tooth longevity and restore the normal function. Scientific evidence has demonstrated the efficacy of REPs in promotion of root development through case reports, case series, cohort studies, and randomized controlled studies. However, variations in clinical protocols for REPs exist due to the empirical nature of the original protocols and rapid advancements in the research field of regenerative endodontics. The heterogeneity in protocols may cause confusion among dental practitioners, thus guidelines and considerations of REPs should be explicated. This expert consensus mainly discusses the biological foundation, the available clinical protocols and current status of REPs in treating immature teeth with pulp necrosis, as well as the main complications of this treatment, aiming at refining the clinical management of REPs in accordance with the progress of basic researches and clinical studies, suggesting REPs may become a more consistently evidence-based option in dental treatment.

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.

Odontogenic Differentiation Induced by TGF-β1 Binding Peptide-Modified Bioglass

Emerging evidence suggests that growth factors are crucial in regenerative endodontic therapy. To achieve the desired effects, the systematic administration of supraphysiologic concentrations of exogenous growth factors is commonly performed, but this is usually associated with high costs, technique, and safety issues. Here, we describe a novel biomaterial that can manipulate endogenous growth factors without the need for adding exogenous growth factors. Transforming growth factor β1 binding peptide (TGFp) was grafted onto the surface of a neutral pH phytic acid-derived bioactive glass (PSC) to synthesize modified bioactive glass (PSC-TGFp). Fourier transform infrared spectroscopy and thermogravimetric analysis results demonstrated that the TGFp was successfully grafted to the surface of the PSC. Scanning electron microscopy and x-ray diffraction showed that PSC-TGFp possessed good in vitro bioactivity. After soaking in simulated body fluid for 24 h, hydroxyapatite formed on the surface of PSC-TGFp. Enzyme-linked immunosorbent assay showed that PSC-TGFp could capture endogenous transforming growth factor β1 from dentin matrix-extracted proteins (DMEP) and release it slowly over 21 d. Cytologic experiments revealed that PSC-TGFp after adsorbing DMEP could enhance the adhesion, migration, viability, and odontogenic differentiation of stem cells from apical papilla. The results highlight that PSC-TGFp may be a promising biomaterial to manipulate endogenous growth factors for regenerative endodontic therapy in the future.

Pro-angiogenic potential of a functionalized hydrogel scaffold as a secretome delivery platform: An innovative strategy for cell homing-based dental pulp tissue engineering

Angiogenesis is a key process that provides a suitable environment for successful tissue engineering and is even more crucial in regenerative endodontic procedures, since the root canal anatomy limits the development of a vascular network supply. Thus, sustainable and accelerated vascularization of tissue-engineered dental pulp constructs remains a major challenge in cell homing approaches. This study aimed to functionalize a chitosan hydrogel scaffold (CS) as a platform loaded with secretomes of stem cells from human exfoliated deciduous teeth (SHEDs) and evaluate its bioactive function and pro-angiogenic properties. Initially, the CS was loaded with SHED secretomes (CS-S), and the release kinetics of several trophic factors were assessed. Proliferation and chemotaxis assays were performed to analyze the effect of functionalized scaffold on stem cells from apical papilla (SCAPs) and the angiogenic potential was analyzed through the Matrigel tube formation assay with co-cultured of human umbilical vein endothelial cells and SCAPs. SHEDs and SCAPs expressed typical levels of mesenchymal stem cell surface markers. CS-S was able to release the trophic factors in a sustained manner, but each factor has its own release kinetics. The CS-S group showed a significantly higher proliferation rate, accelerated the chemotaxis, and higher capacity to form vascular-like structures. CS-S provided a sustained and controlled release of trophic factors, which, in turn, improved proliferation, chemotaxis and all angiogenesis parameters in the co-culture. Thus, the functionalization of chitosan scaffolds loaded with secretomes is a promising platform for cell homing-based tissue engineering.

Mesenchymal Stem Cells Based Treatment in Dental Medicine: A Narrative Review

Application of mesenchymal stem cells (MSC) in regenerative therapeutic procedures is becoming an increasingly important topic in medicine. Since the first isolation of dental tissue-derived MSC, there has been an intense investigation on the characteristics and potentials of these cells in regenerative dentistry. Their multidifferentiation potential, self-renewal capacity, and easy accessibility give them a key role in stem cell-based therapy. So far, several different dental stem cell types have been discovered and their potential usage is found in most of the major dental medicine branches. These cells are also researched in multiple fields of medicine for the treatment of degenerative and inflammatory diseases. In this review, we summarized dental MSC sources and analyzed their treatment modalities with particular emphasis on temporomandibular joint osteoarthritis (TMJ OA).

Microenvironment Influences Odontogenic Mesenchymal Stem Cells Mediated Dental Pulp Regeneration

Dental pulp as a source of nutrition for the whole tooth is vulnerable to trauma and bacterial invasion, which causes irreversible pulpitis and pulp necrosis. Dental pulp regeneration is a valuable method of restoring the viability of the dental pulp and even the whole tooth. Odontogenic mesenchymal stem cells (MSCs) residing in the dental pulp environment have been widely used in dental pulp regeneration because of their immense potential to regenerate pulp-like tissue. Furthermore, the regenerative abilities of odontogenic MSCs are easily affected by the microenvironment in which they reside. The natural environment of the dental pulp has been proven to be capable of regulating odontogenic MSC homeostasis, proliferation, and differentiation. Therefore, various approaches have been applied to mimic the natural dental pulp environment to optimize the efficacy of pulp regeneration. In addition, odontogenic MSC aggregates/spheroids similar to the natural dental pulp environment have been shown to regenerate well-organized dental pulp both in preclinical and clinical trials. In this review, we summarize recent progress in odontogenic MSC-mediated pulp regeneration and focus on the effect of the microenvironment surrounding odontogenic MSCs in the achievement of dental pulp regeneration.

Pulp Regeneration in an Immature Maxillary Central Incisor Using Hyaluronic Acid Hydrogel

Pulp regenerative procedure is one of the treatment options for endodontically involved immature permanent teeth. The regenerative endodontic procedure was performed in a child of 9 years. After thorough canal disinfection using triple antibiotic paste for 21 days, bleeding was induced from the apex to provide for the stem cells. After that hyaluronic acid (HA) hydrogel was introduced into the canal space to act as injectable scaffold for pulp regeneration. This was followed by mineral trioxide aggregate placement to provide tight seal from the coronal aspect. Later, the tooth was restored with composite restoration. This approach offers the clinicians great opportunity to physiologically strengthen the immature root walls. The present report presents a regenerative endodontic procedure with HA hydrogel for a traumatized central incisor with arrested root development. The continued root development in the present case suggests that this treatment option may be able to resume the root maturation process in immature teeth with open apices.

Different Approaches to the Regeneration of Dental Tissues in Regenerative Endodontics

(1) Background: The regenerative procedure has established a new approach to root canal therapy, to preserve the vital pulp of the tooth. This present review aimed to describe and sum up the different approaches to regenerative endodontic treatment conducted in the last 10 years; (2) Methods: A literature search was performed in the PubMed and Cochrane Library electronic databases, supplemented by a manual search. The search strategy included the following terms: “regenerative endodontic protocol”, “regenerative endodontic treatment”, and “regenerative endodontics” combined with “pulp revascularization”. Only studies on humans, published in the last 10 years and written in English were included; (3) Results: Three hundred and eighty-six potentially significant articles were identified. After exclusion of duplicates, and meticulous analysis, 36 case reports were selected; (4) Conclusions: The pulp revascularization procedure may bring a favorable outcome, however, the prognosis of regenerative endodontics (RET) is unpredictable. Permanent immature teeth showed greater potential for positive outcomes after the regenerative procedure. Further controlled clinical studies are required to fully understand the process of the dentin–pulp complex regeneration, and the predictability of the procedure.

What is the best long-term treatment modality for immature permanent teeth with pulp necrosis and apical periodontitis?

PURPOSE

To evaluate and assess the current knowledge about apexification and regenerative techniques as a meaningful treatment modality and to map the scientific evidence for the efficacy of both methods for the management of traumatised immature teeth with pulp necrosis and apical periodontitis.

METHODS

This systematic review searched five databases: PubMed, Web of Science, Cochrane Library, Ovid (Medline), and Embase. Published articles written in English were considered for inclusion. The following keywords were used: Regenerative endodontic treatment OR regenerat* OR revital* OR endodontic regeneration OR regenerative endodontics OR pulp revascularization OR revasculari* OR 'traumatized immature teeth'. Only peer-reviewed studies with a study size of at least 20 cases followed up for 24 months were included. Eligibility assessment was performed independently in a blinded manner by three reviewers and disagreements were resolved by consensus. Subgroup analyses were performed on three clinical outcomes: survival, success, and continued root development.

RESULTS

Seven full texts out of 1359 citations were included and conventional content analysis was performed. Most of the identified citations were case reports and case series.

CONCLUSIONS

In the present systematic review, the qualitative analysis revealed that both regenerative and apexification techniques had equal rates of success and survival and proved to be effective in the treatment of immature necrotic permanent teeth. Endodontic regenerative techniques appear to be superior to apexification techniques in terms of stimulation of root maturation, i.e. root wall thickening and root lengthening. Knowledge gaps were identified regarding the treatment and follow-up protocols for both techniques.

Endodontic regeneration: hard shell, soft core

A loss of organs or the destruction of tissue leaves wounds to which organisms and living things react differently. Their response depends on the extent of damage, the functional impairment and the biological potential of the organism. Some can completely regenerate lost body parts or tissues, whereas others react by forming scars in the sense of a tissue repair. Overall, the regenerative capacities of the human body are limited and only a few tissues are fully restored when injured. Dental tissues may suffer severe damage due to various influences such as caries or trauma; however, dental care aims at preserving unharmed structures and, thus, the functionality of the teeth. The dentin-pulp complex, a vital compound tissue that is enclosed by enamel, holds many important functions and is particularly worth protecting. It reacts physiologically to deleterious impacts with an interplay of regenerative and reparative processes to ensure its functionality and facilitate healing. While there were initially no biological treatment options available for the irreversible destruction of dentin or pulp, many promising approaches for endodontic regeneration based on the principles of tissue engineering have been developed in recent years. This review describes the regenerative and reparative processes of the dentin-pulp complex as well as the morphological criteria of possible healing results. Furthermore, it summarizes the current knowledge on tissue engineering of dentin and pulp, and potential future developments in this thriving field.

Retrospective evaluation of endodontic case reports published in the International Endodontic Journal and the Journal of Endodontics for their compliance with the PRICE 2020 guidelines

AIM

To evaluate, retrospectively, the quality of previously published case reports in Endodontics according to the PRICE 2020 guidelines.

METHODOLOGY

An electronic literature search was conducted in PubMed database on 12 March 2020, to identify case reports published during the last five years in the International Endodontic Journal and the Journal of Endodontics. For each of the included case reports, information regarding fulfilment of each of the items of the PRICE 2020 guidelines was extracted as '0' (not present in the manuscript), '1' (present in the manuscript) and 'NA' (not applicable) and translated into a score (percentage of items fulfilled). Additionally, the percentage of papers fulfilling each item was calculated.

RESULTS

Overall, 70 endodontic case reports were identified. The scores of the papers ranged between 56.41% and 79.55%, with a mean score of 70.26 ± 4.36% (SD). The percentage of papers fulfilling each item of the applicable PRICE 2020 items ranged widely, between 0% and 100%. The median of the percentage of all the items (n = 47) was 97.01% and mean 73.33 ± 36.28% (SD). The lowest scores were recorded for specific items in the following domains: 'Case Report Information'-Items 6c, 6g-i, 'Patient Perspective'-Item 8a and 'Quality of Images'-Items 12c-d.

CONCLUSIONS

Several areas with low reporting rates were identified in case reports published over the last 5 years in Endodontics. Authors should be encouraged to follow the PRICE 2020 guidelines in order to increase the quality and improve reproducibility of their case reports.

Regenerative endodontic therapy of immature permanent molars with pulp necrosis: a cases series and a literature review

AIM

To present the application and the outcome of the regenerative endodontic therapy (RET) in a series of symptomatic immature mandibular molars with pulp necrosis and apical periodontitis and to review the relevant literature for the documentation of the procedure as a potential treatment option.

METHODS

Three young male patients were referred with pain in the left mandibular region resulting from pulp necrosis and apical periodontitis of the first permanent molar. Regenerative endodontic approach was performed for the complete resolution of the lesions and the thickening of the apical root canal walls. The databases of Medline, Pubmed and Google Scholar were also searched for articles in which a regenerative approach has been undertaken for the endodontic management of immature permanent molars with pulp necrosis and apical periodontitis.

RESULTS

Follow-up examinations showed that the teeth remained functional without any signs or symptoms. Final radiographic examination at 12, 18 and 36 months, respectively, revealed complete resolution of the lesions and complete apical closure in the two out of three cases. The search of the literature revealed the existence of only 25 clinical articles in which necrotic immature molars were treated by the regenerative approach. The total number of the treated teeth were 46.

CONCLUSIONS

Regenerative endodontic approach may be applied in posterior non-vital molar teeth with a possible favorable outcome. However, the literature support for the documentation of the procedure as a predictable and reproducible treatment option in posterior immature molar teeth is at present limited.

Alternative to Avoid Tooth Discoloration after Regenerative Endodontic Procedure: A Systematic Review

Abstract This systematic review aimed to evaluate whether alternative materials to conventional triple antibiotic paste (TAP - metronidazole, ciprofloxacin, and minocycline) and grey mineral trioxide aggregate (GMTA) could avoid tooth discoloration in teeth submitted to Regenerative Endodontic Procedure (REP). It was also investigated if dental bleaching is able to reverse the color of darkened teeth due to REP. The search was conducted in four databases (Medline via PubMed, Scopus, ISI Web of Science and BVS - Virtual health library), following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. The retrieved papers were uploaded in the software EndNoteTM and two reviewers independently selected the studies and extracted the data. Only studies in humans (case reports, case series, clinical trials) were included in the review. From 1,122 potentially eligible studies, 83 were selected for full-text analysis, and 38 were included in the review. The included studies were mainly case reports (76.3 %). The studies described a total of 189 teeth submitted to REP. From these, about 54% of teeth presented some degree of discoloration. Most teeth presenting color alteration were treated with TAP, especially when combined with GMTA. Only three studies performed dental bleaching to restore the color of teeth and neither bleaching technique was able to restore the original color of the crowns. The use of alternative materials to TAP and GMTA, such as double antibiotic paste or Ca(OH)2 pastes and white mineral trioxide aggregate or BiodentineTM, reduces the occurrence of tooth discoloration.

Regenerative Endodontics for Adult Patients

The goal of endodontics is to save teeth. Since inception, endodontic treatments are performed to obturate disinfected root canals with inert materials such as gutta-percha. Although teeth can be saved after successful endodontic treatments, they are devitalized and therefore susceptible to reinfections and fractures. The American Association of Endodontists (AAE) has made a tremendous effort to revitalize disinfected immature permanent teeth in children and adolescents with diagnoses including pulp necrosis or apical periodontitis. The American Dental Association (ADA) in 2011 issued several clinical codes for regenerative endodontic procedures or apical revascularization in necrotic immature permanent teeth in children and adolescents. These AAE and ADA initiatives have stimulated robust interest in devising a multitude of tissue engineering approaches for dental pulp and dentin regeneration. Can the concept of regenerative endodontics be extended to revitalize mature permanent teeth with diagnoses including irreversible pulpitis and/or pulp necrosis in adults? The present article was written not only to summarize emerging findings to revitalize mature permanent teeth in adult patients but also to identify challenges and strategies that focus on realizing the goal of regenerative endodontics in adults. We further present clinical cases and describe the biological basis of potential regenerative endodontic procedures in adults. This article explores the frequently asked question if regenerative endodontic therapies should be developed for dental pulp and/or dentin regeneration in adults, who consist of the great majority of endodontic patients.

Pulp Regeneration Concepts for Nonvital Teeth: From Tissue Engineering to Clinical Approaches

Following the basis of tissue engineering (Cells-Scaffold-Bioactive molecules), regenerative endodontic has emerged as a new concept of dental treatment. Clinical procedures have been proposed by endodontic practitioners willing to promote regenerative therapy. Preserving pulp vitality was a first approach. Later procedures aimed to regenerate a vascularized pulp in necrotic root canals. However, there is still no protocol allowing an effective regeneration of necrotic pulp tissue either in immature or mature teeth. This review explores in vitro and preclinical concepts developed during the last decade, especially the potential use of stem cells, bioactive molecules, and scaffolds, and makes a comparison with the goals achieved so far in clinical practice. Regeneration of pulp-like tissue has been shown in various experimental conditions. However, the appropriate techniques are currently in a developmental stage. The ideal combination of scaffolds and growth factors to obtain a complete regeneration of the pulp-dentin complex is still unknown. The use of stem cells, especially from pulp origin, sounds promising for pulp regeneration therapy, but it has not been applied so far for clinical endodontics, in case of necrotic teeth. The gap observed between the hope raised from in vitro experiments and the reality of endodontic treatments suggests that clinical success may be achieved without external stem cell application. Therefore, procedures using the concept of cell homing, through evoked bleeding that permit to recreate a living tissue that mimics the original pulp has been proposed. Perspectives for pulp tissue engineering in the near future include a better control of clinical parameters and pragmatic approach of the experimental results (autologous stem cells from cell homing, controlled release of growth factors). In the coming years, this therapeutic strategy will probably become a clinical reality, even for mature necrotic teeth.

Regenerative endodontics: a comprehensive review

The European Society of Endodontology and the American Association for Endodontists have released position statements and clinical considerations for regenerative endodontics. There is increasing literature on this field since the initial reports of Iwaya et al. (Dental Traumatology, 17, 2001, 185) and Banchs & Trope (Journal of Endodontics, 30, 2004, 196). Endogenous stem cells from an induced periapical bleeding and scaffolds using blood clot, platelet rich plasma or platelet-rich fibrin have been utilized in regenerative endodontics. This approach has been described as a 'paradigm shift' and considered the first treatment option for immature teeth with pulp necrosis. There are three treatment outcomes of regenerative endodontics; (i) resolution of clinical signs and symptoms; (ii) further root maturation; and (iii) return of neurogenesis. It is known that results are variable for these objectives, and true regeneration of the pulp/dentine complex is not achieved. Repair derived primarily from the periodontal and osseous tissues has been shown histologically. It is hoped that with the concept of tissue engineering, namely stem cells, scaffolds and signalling molecules, that true pulp regeneration is an achievable goal. This review discusses current knowledge as well as future directions for regenerative endodontics. Patient-centred outcomes such as tooth discolouration and possibly more appointments with the potential for adverse effects needs to be discussed with patients and parents. Based on the classification of Cvek (Endodontics and Dental Traumatology, 8, 1992, 45), it is proposed that regenerative endodontics should be considered for teeth with incomplete root formation although teeth with near or complete root formation may be more suited for conventional endodontic therapy or MTA barrier techniques. However, much is still not known about clinical and biological aspects of regenerative endodontics.

Long-term treatment outcomes in immature permanent teeth by revascularisation using MTA and GIC as canal-sealing materials: a retrospective study

BACKGROUND

Pulp revascularisation with MTA sealing has been accepted as an alternative treatment for non-vital immature permanent teeth. Successful revascularisation cases with GIC sealing were also reported, but lack of long-term researches.

AIM

To evaluate long-term outcomes of revascularisation using MTA and GIC as canal-sealing materials in non-vital immature permanent teeth.

DESIGN

Clinical and radiographic data of 60 non-vital immature permanent teeth treated with revascularisation (36.8 ± 12.4 months of follow-up) were reviewed. Of these, 28 teeth were sealed with MTA, and 32 with GIC. Tooth survival, success rate, and increases in root length and dentine wall thickness were evaluated.

RESULTS

Teeth in MTA group showed a similar survival rate (96%) to GIC group (100%). The success rate in MTA group (93%) was greater than that in GIC group (59%). Eight of fourteen failed teeth due to recurrent apical disease (seven teeth in GIC group and one in MTA group) achieved complete root development. There was no statistically significant difference in root length or dentine wall thickness increase between the groups.

CONCLUSIONS

Long-term outcome of revascularisation in non-vital immature permanent teeth sealed with GIC was not as good as that with MTA. Although more recurrent apical disease developed, results on root development were acceptable in GIC sealed cases.

Mineral trioxide aggregate and other bioactive endodontic cements: an updated overview - part II: other clinical applications and complications

Mineral trioxide aggregate (MTA) is a dental material used extensively for vital pulp therapies (VPT), protecting scaffolds during regenerative endodontic procedures, apical barriers in teeth with necrotic pulps and open apices, perforation repairs as well as root canal filling and root-end filling during surgical endodontics. A number of bioactive endodontic cements (BECs) have recently been introduced to the market. Most of these materials have calcium and silicate in their compositions; however, bioactivity is a common property of these cements. These materials include the following: BioAggregate, Biodentine, BioRoot RCS, calcium-enriched mixture cement, Endo-CPM, Endocem, EndoSequence, EndoBinder, EndoSeal MTA, iRoot, MicroMega MTA, MTA Bio, MTA Fillapex, MTA Plus, Neo MTA Plus, Ortho MTA, Quick-Set, Retro MTA, Tech Biosealer, and TheraCal LC. It has been claimed that these materials have properties similar to those of MTA but without the drawbacks. In Part I of this review, the available information on the chemical composition of the materials listed above was reviewed and their applications for VPT was discussed. In this article, the clinical applications of MTA and other BECs will be reviewed for apexification, regenerative endodontics, perforation repair, root canal filling, root-end filling, restorative procedures, periodontal defects and treatment of vertical and horizontal root fractures. In addition, the literature regarding the possible drawbacks of these materials following their clinical applications is reviewed. These drawbacks include their discolouration potential, systemic effects and retreatability following use as a root filling material. Based on selected keywords, all publications were searched regarding the use of MTA as well as BECs for the relevant clinical applications. Numerous publications were found regarding the use of BECs for various endodontic applications. The majority of these investigations compared BECs with MTA. Despite promising results for some materials, the number of publications using BECs for various clinical applications was limited. Furthermore, most studies had several methodological shortcomings and low levels of evidence.

Regenerative Endodontics

Regenerative endodontics has been defined as “biologically based procedure designed to replace damaged structures, including dentin and root structures, as well as cells of the pulp–dentin complex.” This is an exciting and rapidly evolving field of human endodontics for the treatment of immature permanent teeth with infected root canal systems. These procedures have shown to be able not only to resolve pain and apical periodontitis but continued root development, thus increasing the thickness and strength of the previously thin and fracture-prone roots. In the last decade, over 80 case reports, numerous animal studies, and series of regenerative endodontic cases have been published. However, even with multiple successful case reports, there are still some remaining questions regarding terminology, patient selection, and procedural details. Regenerative endodontics provides the hope of converting a nonvital tooth into vital one once again.

GelMA-Encapsulated hDPSCs and HUVECs for Dental Pulp Regeneration

Pulpal revascularization is commonly used in the dental clinic to obtain apical closure of immature permanent teeth with thin dentinal walls. Although sometimes successful, stimulating bleeding from the periapical area of the tooth can be challenging and in turn may deleteriously affect tooth root maturation. Our objective here was to define reliable methods to regenerate pulp-like tissues in tooth root segments (RSs). G1 RSs were injected with human dental pulp stem cells (hDPSCs) and human umbilical vein endothelial cells (HUVECs) encapsulated in 5% gelatin methacrylate (GelMA) hydrogel. G2 RSs injected with acellular GelMA alone, and G3 empty RSs were used as controls. White mineral trioxide aggregate was used to seal one end of the tooth root segment, while the other was left open. Samples were cultured in vitro in osteogenic media (OM) for 13 d and then implanted subcutaneously in nude rats for 4 and 8 wk. At least 5 sample replicates were used for each experimental group. Analyses of harvested samples found that robust pulp-like tissues formed in G1, GelMA encapsulated hDPSC/HUVEC-filled RSs, and less cellularized host cell-derived pulp-like tissue was observed in the G2 acellular GelMA and G3 empty RS groups. Of importance, only the G1, hDPSC/HUVEC-encapsulated GelMA constructs formed pulp cells that attached to the inner dentin surface of the RS and infiltrated into the dentin tubules. Immunofluorescent (IF) histochemical analysis showed that GelMA supported hDPSC/HUVEC cell attachment and proliferation and also provided attachment for infiltrating host cells. Human cell-seeded GelMA hydrogels promoted the establishment of well-organized neovasculature formation. In contrast, acellular GelMA and empty RS constructs supported the formation of less organized host-derived vasculature formation. Together, these results identify GelMA hydrogel combined with hDPSC/HUVECs as a promising new clinically relevant pulpal revascularization treatment to regenerate human dental pulp tissues.

The impact of autologous platelet concentrates on endodontic healing: a systematic review

The current literature was reviewed to determine the impact of autologous platelet concentrates (APCs) on endodontic healing. All types of clinical study designs concerning any kind of endodontic treatment involving the application of APCs were included. Two independent reviewers searched three databases (PubMed, Embase, and Cochrane Library) for studies, complemented by hand search, until 16/1/2016. From the 423 identified records, 48 articles met the inclusion criteria. Selected randomized controlled clinical trials (RCTs) underwent Cochrane Collaboration's risk-of-bias assessment and data extraction. Only two RCTs showed low risk of bias. There was considerable heterogeneity between the RCTs with regard to the type of therapy, type of APCs, assessment method, and study quality, and therefore the data could not be analyzed quantitatively. The included case reports/series and non-randomized comparative studies underwent qualitative analysis with the revised Methodological Index for Non-Randomized Studies (MINORS) and data extraction. The two comparative non-randomized studies scored qualitatively high, though the MINORS-scores of the case series and reports were dispersed. APCs were involved in five endodontic treatment modalities, namely apexification, regenerative endodontic procedures, pulpotomy, apical surgery, and treatment of endo-perio/perio-endo lesions. APCs seem to accelerate postoperative bone healing, augment the patients' postoperative quality of life, aid further root development, and support maintenance/regaining of pulp vitality. No adverse events were reported. APCs in endodontic treatments seem to contribute to the healing of soft and hard tissues, though there is a lack of long-term high quality clinical trials and standardized treatment protocols.

Infection and Pulp Regeneration

The regeneration of the pulp-dentin complex has been a great challenge to both scientists and clinicians. Previous work has shown that the presence of prior infection may influence the characteristics of tissues formed in the root canal space after regenerative endodontic treatment. The formation of ectopic tissues such as periodontal ligament, bone, and cementum has been observed in the root canal space of immature necrotic teeth with apical periodontitis, while the regeneration of dentin and pulp has been identified in previously non-infected teeth.  The current regenerative endodontic therapy utilizes disinfection protocols, which heavily rely on chemical irrigation using conventional disinfectants. From a microbiological point of view, the current protocols may not allow a sufficiently clean root canal microenvironment, which is critical for dentin and pulp regeneration. In this article, the significance of root canal disinfection in regenerating the pulp-dentin complex, the limitations of the current regenerative endodontic disinfection protocols, and advanced disinfection techniques designed to reduce the microorganisms and biofilms in chronic infection are discussed.