Efficacy of platelet-rich plasma as a scaffold in regenerative endodontic treatment

Regenerative endodontic therapy: From laboratory bench to clinical practice

BACKGROUND

Maintaining the vitality and functionality of dental pulp is paramount for tooth integrity, longevity, and homeostasis. Aiming to treat irreversible pulpitis and necrosis, there has been a paradigm shift from conventional root canal treatment towards regenerative endodontic therapy.

AIM OF REVIEW

This extensive and multipart review presents crucial laboratory and practical issues related to pulp-dentin complex regeneration aimed towards advancing clinical translation of regenerative endodontic therapy and enhancing human life quality.

KEY SCIENTIFIC CONCEPTS OF REVIEW

In this multipart review paper, we first present a panorama of emerging potential tissue engineering strategies for pulp-dentin complex regeneration from cell transplantation and cell homing perspectives, emphasizing the critical regenerative components of stem cells, biomaterials, and conducive microenvironments. Then, this review provides details about current clinically practiced pulp regenerative/reparative approaches, including direct pulp capping and root revascularization, with a specific focus on the remaining hurdles and bright prospects in developing such therapies. Next, special attention was devoted to discussing the innovative biomimetic perspectives opened in establishing functional tissues by employing exosomes and cell aggregates, which will benefit the clinical translation of dental pulp engineering protocols. Finally, we summarize careful consideration that should be given to basic research and clinical applications of regenerative endodontics. In particular, this review article highlights significant challenges associated with residual infection and inflammation and identifies future insightful directions in creating antibacterial and immunomodulatory microenvironments so that clinicians and researchers can comprehensively understand crucial clinical aspects of regenerative endodontic procedures.

Regenerative Strategies in Dentistry: Harnessing Stem Cells, Biomaterials and Bioactive Materials for Tissue Repair

Advanced bioengineering, popularly known as regenerative dentistry, has emerged and is steadily developing with the aim of replacement of lost or injured tissues in the mouth using stem cells and other biomaterials. Conventional therapies for reparative dentistry, for instance fillings or crowns, mainly entail the replenishment of affected tissues without much concern given to the regeneration of tissues. However, these methods do not enable the natural function and aesthetics of the teeth to be maintained in the long term. There are several regenerative strategies that offer the potential to address these limitations to the extent of biologically restoring the function of teeth and their components, like pulp, dentin, bone, and periodontal tissues. Hence, stem cells, especially dental tissue derived stem cells, such as dental pulp stem cells, periodontal ligament stem cells, or apical papilla stem cells, are quite promising in this regard. These stem cells have the potentiality of generating precise dental cell lineages and thus are vital for tissue healing and renewal. Further, hydrogels, growth factors, and synthetic scaffolds help in supporting the stem cells for growth, proliferation, and differentiation into functional tissues. This review aims at describing the process of stem cell-based tissue repair biomaterials in dental regeneration, and also looks into the practice and prospects of regenerative dentistry, analysing several case reports and clinical investigations that demonstrate the efficacy and limitations of the technique. Nonetheless, the tremendous potential for regenerative dentistry is a reality that is currently challenged by biological and technical constraints, such as scarcity of stem cell sources, inadequate vascularization, and the integration of the materials used in the procedure. As we move forward, the prospects for regenerative dentistry are in subsequent developments of stem cell technology, biomaterial optimization, and individualized treatment methods, which might become increasingly integrated in dental practices globally. However, there are regulatory, ethical and economic issues that may pose a hurdle in the further advancement of this discipline.

Comparative Evaluation of Autologous Platelet Aggregates Versus Blood Clot On The Outcome Of Regenerative Endodontic Therapy: A Systematic Review and Meta-Analysis

Background

Regenerative endodontics represents a transformative approach to dental care, revitalizing necrotic teeth. This systematic review and meta-analysis evaluated the role of autologous platelet aggregates compared to the traditional blood clot method in regenerative endodontics.

Material and Methods

A systematic search was conducted in PubMed, Scopus, EBSCO, Open Grey, and Google Scholar between 1st-12th August 2024. Case series, RCTs, retrospective studies, and case reports were included. Meta-analysis on RCTs and case series utilized RevMan 5.4 software, with p=0.05 as the significance level. The JBI risk of bias tool and GRADE system assessed study quality.

Results

Nineteen studies met inclusion criteria, of which 13 were evaluated for risk of bias-11 showed low risk, and 2 were moderate. Rates of complete apical closure using PRF, BC, PRP, and CGF scaffolds ranged from 61.76% to 100%. Statistical analysis revealed no significant differences between autologous platelet aggregates and BC for outcomes such as complete apical closure (BC vs. PRP: p=0.28; BC vs. PRF: p=0.36), positive vitality (BC vs. PRP: p=0.70; BC vs. PRF: p=0.36), healing response (BC vs. PRF: p=0.23), and overall success score (BC vs. PRP: p=0.62).

Conclusions

BC remains an effective primary scaffold for non-vital teeth with open apexes. PRP and PRF are viable alternatives when intracanal blood induction is challenging. Overall, platelet aggregates and BC showed comparable clinical and radiographic outcomes. Key words:Apexogenesis, Autologous Platelet Aggregates, Blood Clot, Immature Tooth, Regenerative Endodontics.

Time-Dependent Morphological Changes in Traumatic Immature Teeth With Necrotic Pulps Following Regenerative Endodontic Treatment: A Retrospective Study

BACKGROUND/AIM

Regenerative endodontic treatment is a promising approach for healing periapical lesions and continuous root maturation. Although previous studies have reported its outcomes, the dynamics of morphological changes over time remain unclear. Therefore, this study aimed to evaluate changes in the periapical status and root dimensions over a 60-month follow-up period.

MATERIALS AND METHODS

The follow-up duration, periapical status changes, calcific barrier formation, degree of apical closure and radiographic root area changes were compared with those of the last follow-up in this retrospective study. Radiographic root area changes were calculated as the difference between the total root and total canal areas.

RESULTS

Fifty-eight patients (81 teeth) underwent regenerative endodontic treatment during the study period, of whom 32 patients (36 teeth, 62%) were included. The survival and success rates of the treated teeth were 100% and 94.4%, respectively. All teeth developed a calcific bridge in the cervical third of the root canal, indicating the presence of vital tissue. Apical narrowing (partial or total) was observed in 75% of the cases. The root maturation stage affected the percentage increase in the radiographic root area. Teeth in Cvek stages II-III showed a higher radiographic root area increase than more mature teeth. All tooth radiographic root areas increased significantly in the initial 20 months of the treatment and moderately thereafter.

CONCLUSIONS

Regenerative endodontic treatment is a safe approach for traumatised immature teeth. The presence of a radiographic calcified bridge may be an early indication of treatment success. The main complete tooth morphological changes occur after approximately 20 months posttreatment. These findings may help clinicians better understand the time-dependent changes in the root morphology after treatment, improve the follow-up schedule and predict the progress of healing during follow-up visits.

Platelet-rich plasma: A bibliometric and visual analysis from 2000 to 2022

BACKGROUND

Platelet-rich plasma (PRP) is an integral biotherapeutic modality with evolving significance in the medical domain. Despite its expanding applications, a comprehensive bibliometric evaluation is essential to understand its development and impact.

METHODS

The Web of Science core collection subject search identified articles pertinent to PRP applications. Analytical tools, including CiteSpace, VOSviewer, Bibliometrix (R-Tool for R-Studio), TBtools, SCImago Graphica, Origin, and Excel, facilitated the bibliometric scrutiny. This examination spanned dimensions ranging from geographical and institutional contributions to thematic shifts and keyword prevalence.

RESULTS

A corpus of 5167 publications was analyzed, with the United States, particularly the Hospital for Special Surgery, emerging as major contributors. The American Journal of Sports Medicine was identified as the primary journal, and Anitua Eduardo as the leading author in the domain. Keyword analysis highlighted evolving research themes, with a shift from traditional applications in orthopedics and dentistry to emerging areas such as dermatology, aesthetics, and chronic pain management.

CONCLUSION

The bibliometric analysis of PRP research reveals a multifaceted array of applications across various medical disciplines and highlights areas requiring further exploration, particularly in standardization, personalization, and safety. Future advancements in PRP research will necessitate innovative exploration, ethical considerations, and rigorous scientific validation to fully harness the therapeutic potential of PRP and related therapies.

Comparative Evaluation of Platelet-rich Fibrin and Treated Dentin Matrix in Regenerative Endodontic Treatment of Nonvital Immature Permanent Teeth: A Randomized Clinical Trial

AIM

Clinical and radiographic evaluation of the efficacy of platelet-rich fibrin (PRF) and treated dentin matrix (TDM) in regenerative endodontic treatment and periapical healing of nonvital immature permanent teeth with chronic apical periodontitis.

MATERIALS AND METHODS

Twenty-four children aged between 7 and 11 years, each presenting with a nonvital immature permanent upper central incisor, were selected. They were randomly allocated into two groups (n = 12), group I (PRF) and group II (TDM). Baseline clinical findings were recorded, and preoperative cone-beam computed tomography (CBCT) was taken. Follow-up was done clinically for 15 months at 3-month intervals (3, 6, 9, 12, and 15 months), and CBCT was taken at the end of the 15-month follow-up. Root length, apical diameter, radiographic root area (RRA), and size of the periapical lesion were quantitively assessed at the end of follow-up period and compared to the preoperative CBCT.

RESULTS

Clinical success was 100% in both groups by the end of the follow-up period. Radiographically, after a 15-month follow-up, there was a significant increase in root length and RRA, and there was also a significant reduction in apical diameter and lesion size within each group (p < 0.05). However, there was no statistically significant difference between both groups regarding the mean percentage of increase in root length and mean percentage of reduction of apical diameter (p > 0.05). On the other hand, PRF showed more increase in RRA and more reduction in lesion size, with a statistically significant difference between both groups (p < 0.05).

CONCLUSION

Both PRF and TDM were clinically successful. Platelet-rich fibrin showed better radiographic outcomes and periapical healing.

CLINICAL SIGNIFICANCE

Platelet-rich fibrin is a viable scaffold to aid further root development and resolution of periapical lesions of nonvital immature permanent teeth. Further studies with different forms of TDM are needed to assess the efficacy of TDM in regenerative endodontic treatment of nonvital immature permanent teeth. How to cite this article: Asal MA, Elkalla IH, Awad SM, et al. Comparative Evaluation of Platelet-rich Fibrin and Treated Dentin Matrix in Regenerative Endodontic Treatment of Nonvital Immature Permanent Teeth: A Randomized Clinical Trial. J Contemp Dent Pract 2024;25(6):563-574.

Allogeneic Bone Marrow Mesenchymal Stromal Cell Transplantation Induces Dentin Pulp Complex-like Formation in Immature Teeth with Pulp Necrosis and Apical Periodontitis

INTRODUCTION

Dental pulp regeneration is challenging in endodontics. Cellular therapy is an alternative approach to induce dental pulp regeneration. Mesenchymal stromal cells (MSCs) have the capacity to induce dental pulp-like tissue formation. In this study, we evaluated the capacity of allogeneic bone marrow MSCs (BM-MSCs) to regenerate pulp following necrosis and apical periodontitis in children's permanent immature apex teeth.

METHODS

Patients aged 8 to 12 years with pulp necrosis and apical periodontitis were evaluated. The study included 15 teeth (13 incisors and 2 molars) from 14 patients (8 boys and 6 girls). Radiographic evaluation showed periapical radiolucency and immature apex teeth. There was no response to cold or electric pulp testing. The root canal of each tooth was cleaned, shaped, and Ca(OH)2 used as an interappointment medication. Cryopreserved allogeneic BM-MSCs were thawed, expanded, incorporated into preclotted platelet-rich plasma, and implanted into the tooth's pulp cavity. They were sealed with bioceramic cement and composite. Sensibility, apical foramen, calcium deposits within the root canal, and resolution of periapical lesions were evaluated in each tooth over the following 12 months.

RESULTS

Based on 9 variables established for dental pulp-like tissue regeneration, all MSC-treated teeth showed evidence of successful regeneration. Clinical and radiographic evaluation of the treated teeth showed periapical lesion healing, sensitivity to cold and electricity, decreased width of the apical foramen, and mineralization within the canal space.

CONCLUSIONS

Transplantation of allogeneic MSCs induces the formation of dental pulp-like tissue in permanent immature apex teeth with pulp necrosis and apical periodontitis. Implant of MSCs constitutes a potential therapy in regenerative endodontics in pediatric dentistry. Future studies incorporating a larger sample size may confirm these results.

Does the use of different scaffolds have an impact on the therapeutic efficacy of regenerative endodontic procedures? A systematic evaluation and meta-analysis

BACKGROUND

In the regenerative endodontic procedures, scaffolds could influence the prognosis of affected teeth. Currently, there is controversy regarding the postoperative evaluation of various scaffolds for pulp regeneration. The objective of this study was to access whether other scaffolds, used alone or in combination with blood clot (BC), are more effective than BC in regenerative endodontic procedures.

METHODS

We systematically search the PubMed, the Cochrane Central Register of Controlled Trials (CENTRAL), Embase, and Google Scholar databases. Randomized controlled trials examining the use of BC and other scaffold materials in the regenerative endodontic procedures were included. A random effects model was used for the meta-analysis. The GRADE method was used to determine the quality of the evidence.

RESULTS

We screened 168 RCTs related to young permanent tooth pulp necrosis through electronic and manual retrieval. A total of 28 RCTs were related to regenerative endodontic procedures. Ultimately, 12 articles met the inclusion criteria and were included in the relevant meta-analysis. Only 2 studies were assessed to have a low risk of bias. High quality evidence indicated that there was no statistically significant difference in the success rate between the two groups (RR=0.99, 95% CI=0.96 to 1.03; 434 participants, 12 studies); low-quality evidence indicated that there was no statistically significant difference in the increase in root length or root canal wall thickness between the two groups. Medium quality evidence indicated that there was no statistically significant difference in pulp vitality testing between the two groups.

CONCLUSIONS

For clinical regenerative endodontic procedures, the most commonly used scaffolds include BC, PRP, and PRF. All the different scaffolds had fairly high clinical success rates, and the difference was not significant. For regenerative endodontic procedures involving young permanent teeth with pulp necrosis, clinical practitioners could choose a reasonable scaffold considering the conditions of the equipment and patients.

Evaluation of the efficacy of injectable platelet-rich fibrin versus platelet-rich plasma in the regeneration of traumatized necrotic immature maxillary anterior teeth: A randomized clinical trial

BACKGROUND/AIM

This study aimed at comparing the regenerative potential of injectable platelet-rich fibrin (i-PRF) (Group 1) and platelet-rich plasma (Group 2) scaffolds.

MATERIALS AND METHODS

Twenty-three patients, aged from 9 to 24 years, having 24 immature traumatized necrotic maxillary anterior teeth, were enrolled. Teeth trauma was confirmed by patients' history. Preoperative three-dimensional scans were done. In the first visit, canals were irrigated with 1.5% sodium hypochlorite then medicated with calcium hydroxide. After 2 weeks, patients were randomly assigned into one of the treatment groups (n = 12). The platelet concentrate was applied after centrifuging 10 mL of autologous venous blood with respect to the centrifugation protocol for each platelet concentrate. Patients were recalled at 6 and 12 months posttreatment, during which clinical and radiographic examinations and assessment of pulp sensitivity were done. Three-dimensional scanning was done after 12 months. The increase in root length and decrease in root canal diameters were calculated at three canal levels. Statistical analysis was done using the paired t-test and the independent t-test. The significance level was set at p < .05.

RESULTS

There was no statistically significant difference between both groups regarding the increase in root length, decrease in coronal and middle canal diameters and the response to the electric pulp tester. Group (1) showed significantly greater decrease in apical canal diameter than Group (2) (p = .008).

CONCLUSION

I-PRF can be considered as a valid regenerative scaffold for clinical use and with regards to the easier preparation technique, it is more recommended than platelet-rich plasma.

Recent Achievements in the Development of Biomaterials Improved with Platelet Concentrates for Soft and Hard Tissue Engineering Applications

Platelet concentrates such as platelet-rich plasma, platelet-rich fibrin or concentrated growth factors are cost-effective autologous preparations containing various growth factors, including platelet-derived growth factor, transforming growth factor β, insulin-like growth factor 1 and vascular endothelial growth factor. For this reason, they are often used in regenerative medicine to treat wounds, nerve damage as well as cartilage and bone defects. Unfortunately, after administration, these preparations release growth factors very quickly, which lose their activity rapidly. As a consequence, this results in the need to repeat the therapy, which is associated with additional pain and discomfort for the patient. Recent research shows that combining platelet concentrates with biomaterials overcomes this problem because growth factors are released in a more sustainable manner. Moreover, this concept fits into the latest trends in tissue engineering, which include biomaterials, bioactive factors and cells. Therefore, this review presents the latest literature reports on the properties of biomaterials enriched with platelet concentrates for applications in skin, nerve, cartilage and bone tissue engineering.

Clinical, Radiographic, and Histologic Outcomes of Regenerative Endodontic Treatment in Human Immature Teeth Using Different Biological Scaffolds: A Systematic Review and Meta-analysis

BACKGROUND

Biological scaffolds such as blood clot (BC), platelet-rich plasma (PRP), platelet- rich fibrin (PRF), and platelet pellet (PP) are used in regenerative endodontic treatments (RETs).

OBJECTIVE

To systematically and quantitatively evaluate clinical, radiographic, and histologic outcomes of RET studies using different biological scaffolds.

METHODS

MEDLINE, Scopus, Cochrane library, and Embase were searched to identify studies on RET procedures with any scaffold type performed on immature non-vital human teeth, employing any type of biological scaffold. Clinical, radiographic, and histologic outcomes were extracted. Cochrane collaboration risk of bias tool and Newcastle-Ottawa scale were used for quality assessment. Random and fixed model meta-analysis was carried out with 95% confidence interval.

RESULTS

Thirty-two studies were included in the qualitative analysis from the primarily retrieved 1895 studies. Only one study had high risk of bias and 71.8% of the studies had high quality. None of the studies reported any histologic findings. Thirty studies were included in meta-analysis. Clinical success rate of RET using either BC, PRP, or PRF was >99%. Furthermore, 32%, 23%, and 27% of BC, PRP, and PRF cases regained vitality, respectively. Periapical healing was seen in 67%, 75%, and 100% of BC, PRP, and PRF cases, respectively. There was no statistical difference between BC, PRP, or PRF regarding clinical success or any radiographic outcomes.

CONCLUSION

There was no significant difference between BC, PRP, and PRF in terms of clinical and radiographic outcomes. When it is difficult or dangerous to induce bleeding in root canals, PRP and PRF may be employed instead.

Scaffolds for Dentin-Pulp Complex Regeneration

Background and Objectives: Regenerative dentistry aims to regenerate the pulp-dentin complex and restore those of its functions that have become compromised by pulp injury and/or inflammation. Scaffold-based techniques are a regeneration strategy that replicate a biological environment by utilizing a suitable scaffold, which is considered crucial for the successful regeneration of dental pulp. The aim of the present review is to address the main characteristics of the different scaffolds, as well as their application in dentin-pulp complex regeneration. Materials and Methods: A narrative review was conducted by two independent reviewers to answer the research question: What type of scaffolds can be used in dentin-pulp complex regeneration? An electronic search of PubMed, EMBASE and Cochrane library databases was undertaken. Keywords including "pulp-dentin regeneration scaffold" and "pulp-dentin complex regeneration" were used. To locate additional reports, reference mining of the identified papers was undertaken. Results: A wide variety of biomaterials is already available for tissue engineering and can be broadly categorized into two groups: (i) natural, and (ii) synthetic, scaffolds. Natural scaffolds often contain bioactive molecules, growth factors, and signaling cues that can positively influence cell behavior. These signaling molecules can promote specific cellular responses, such as cell proliferation and differentiation, crucial for effective tissue regeneration. Synthetic scaffolds offer flexibility in design and can be tailored to meet specific requirements, such as size, shape, and mechanical properties. Moreover, they can be functionalized with bioactive molecules, growth factors, or signaling cues to enhance their biological properties and the manufacturing process can be standardized, ensuring consistent quality for widespread clinical use. Conclusions: There is still a lack of evidence to determine the optimal scaffold composition that meets the specific requirements and complexities needed for effectively promoting dental pulp tissue engineering and achieving successful clinical outcomes.

Regenerative endodontic procedures in immature permanent teeth with pulp necrosis: the impact of microbiology on clinical and radiographic outcome

Aims

The current study aimed to determine how the disinfection strategy for regenerative endodontic procedures (REPs) influences overall bacterial load and REP outcomes. Different bacterial species in the teeth were also examined in this study.

Methods

A previously reported non-randomized controlled clinical research on REP ± leukocyte and platelet-rich fibrin gathered microbial samples from 14 of 29 patients during REP (LPRF). Four microbiological samples were obtained in two treatment sessions. S1 and S2 were taken before and after the first irrigation with 1.5% NaOCl and saline. Samples S3 and S4 were obtained before and after rinsing with 17% EDTA in the second treatment session. Microbial samples were identified using a quantitative polymerase chain reaction with species-specific primers.

Results

The total bacterial load recovered from patients showed a significant (p < 0.05) decrease after the first treatment and was maintained throughout the second treatment. Fusobacterium nucleatum, Treponema denticola, and Enterococcus faecalis were the most prevalent species in root canals, detected in all analyzed cases (100%), followed by Prevotella intermedia and Tannerella forsythia, both in six of 14 (42.9%) cases. The presence of these abundant species was significantly reduced after sample S1 was obtained. Parvimonas micra was present in four of 14 (28.6%) cases and Actinomyces naeslundii in two of 14 (14.3%) cases. Filifactor alocis, Porphyromonas endodontalis, and Porphyromonas gingivalis were each detected in only one of 14 (7.1%) cases. No statistical correlation could be made between bacterial species and clinical or radiographic outcomes due to the small sample size. In the LPRF group, two cases required retreatment due to early post-treatment flare-up, and two other cases presented radiographically presented a persistent apical periodontitis 3 years after treatment. In the control group, all analyzed cases were clinically asymptomatic after treatment, and radiographically, the final periapical index score at the last recall revealed healthy periapices.

Conclusion

The REP disinfection protocol of the present study seems to be satisfactorily effective in reducing the total bacterial load, omitting clinical symptoms and inducing periapical bone healing in immature permanent teeth with pulp necrosis. However, LPRF seems to prevent these outcomes from being achieved and should consequently therefore not be recommended in REPs.

Deciphering the Cell-Specific Effect of Osteoblast-Macrophage Crosstalk in Periodontitis

In periodontitis, the bone remodeling process is disrupted by the prevalent involvement of bacteria-induced proinflammatory macrophage cells and their interaction with osteoblast cells residing within the infected bone tissue. The complex interaction between the cells needs to be deciphered to understand the dominant player in tipping the balance from osteogenesis to osteoclastogenesis. Yet, only a few studies have examined the crosstalk interaction between osteoblasts and macrophages using biomimetic three-dimensional (3D) tissue-like matrices. In this study, we created a cell-laden 3D tissue analog to study indirect crosstalk between these two cell types and their direct synergistic effect when cultured on a 3D scaffold. The cell-specific role of osteoclast differentiation was investigated through osteoblast- and proinflammatory macrophage-specific feedback studies. The results suggested that when macrophages were exposed to osteoblasts-derived conditioned media from the mineralized matrix, the M1 macrophages tended to maintain their proinflammatory phenotype. Further, when osteoblasts were exposed to secretions from proinflammatory macrophages, they demonstrated elevated receptor activator of nuclear factor-κB ligand (RANKL) expression and decreased alkaline phosphate (ALP) activities compared to osteoblasts exposed to only osteogenic media. In addition, the upregulation of tumor necrosis factor-alpha (TNF-α) and c-Fos in proinflammatory macrophages within the 3D matrix indirectly increased the RANKL expression and reduced the ALP activity of osteoblasts, promoting osteoclastogenesis. The contact coculturing with osteoblast and proinflammatory macrophages within the 3D matrix demonstrated that the proinflammatory markers (TNF-α and interleukin-1β) expressions were upregulated. In contrast, anti-inflammatory markers (c-c motif chemokine ligand 18 [CCL18]) were downregulated, and osteoclastogenic markers (TNF receptor associated factor 6 [TRAF6] and acid phosphatase 5, tartrate resistant [ACP5]) were unchanged. The data suggested that the osteoblasts curbed the osteoclastogenic differentiation of macrophages while macrophages still preserved their proinflammatory lineages. The osteoblast within the 3D coculture demonstrated increased ALP activity and did not express RANKL significantly different than the osteoblast cultured within a 3D collagen matrix without macrophages. Contact coculturing has an anabolic effect on bone tissue in a bacteria-derived inflammatory environment.

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).

Endodontic Tissue Regeneration: A Review for Tissue Engineers and Dentists

The paradigm shift in the endodontic field from replacement toward regenerative therapies has witnessed the ever-growing research in tissue engineering and regenerative medicine targeting pulp-dentin complex in the past few years. Abundant literature on the subject that has been produced, however, is scattered over diverse areas of knowledge. Moreover, the terminology and concepts are not always consensual, reflecting the range of research fields addressing this subject, from endodontics to biology, genetics, and engineering, among others. This fact triggered some misinterpretations, mainly when the denominations of different approaches were used as synonyms. The evaluation of results is not precise, leading to biased conjectures. Therefore, this literature review aims to conceptualize the commonly used terminology, summarize the main research areas on pulp regeneration, identify future trends, and ultimately clarify whether we are really on the edge of a paradigm shift in contemporary endodontics toward pulp regeneration.

Evaluation of the effectiveness of different treatment approaches in preventing coronal discoloration caused by regenerative endodontic treatment

OBJECTIVES

This study aimed to evaluate the effectiveness of Teethmate desensitizer, a dentin bonding agent (DBA), Nd:YAG laser, and Er:YAG laser, which provides dentin tubule occlusion in the pulp chamber with different mechanisms, in preventing tooth discoloration due to regenerative endodontic treatment.

MATERIALS AND METHODS

One hundred five extracted maxillary human incisors with single roots and single canals were included in the study. The apical third of each tooth was resected below the enamel-cementum junction (CEJ) to obtain a standard root length as 10 ± 1 mm. Root canal preparation was performed using the ProTaper Next files up to X5. Root canals were prepared with Gates Glidden (# 2-4) burs to simulate the immature root apex and an apical diameter of 1.1 ± 0.1 mm was obtained. The teeth were randomly divided into 7 groups (n = 15): DBA, Teethmate, Nd:YAG, Er:YAG, Biodentine, Blood, and Negative Control. Relevant dentin tubule occlusion methods were applied to DBA, Teethmate, Nd:YAG, and Er:YAG groups. Following dentin tubule occlusion procedures, Biodentine was placed on the blood clot after filling the root canals with blood up to 4 mm below the CEJ. No dentin tubule occlusion procedure was applied for Blood and Biodentine groups. Color measurement was performed with the spectrophotometer Vita Easyshade Advance before treatment, immediately after treatment, and at days 7, 30, and 90. Data were converted to L*a*b color values of Commission International de I'Eclairage (CIE L*a*b) and ΔE values were calculated. Two-way ANOVA and post hoc Tukey test (p = 0.05) were performed for statistical analysis.

RESULTS

A clinically detectable color change was observed in all groups except for the negative control (ΔE ≥ 3,3). It was observed that Biodentine used alone has a potential for discoloration. It was determined that as the contact time with blood increased, tooth discoloration increased. However, no significant difference was found between dentin tubule occlusion methods in preventing color change (p > 0.05).

CONCLUSIONS

It was determined that no dentin tubule occlusion method could 100% prevent discoloration caused by RET.

CLINICAL RELEVANCE

DBA and Teethmate, which do not have a significant difference in terms of preventing color change, are considered to be suitable for dentin tubule occlusion due to their ease of application and low cost compared to Nd:YAG laser and Er:YAG laser.

The efficacy of concentrated growth factor and platelet-rich fibrin as scaffolds in regenerative endodontic treatment applied to immature permanent teeth: a retrospective study

BACKGROUND

The aim of this retrospective study was to compare the efficacy of concentrated growth factor (CGF) and platelet-rich fibrin (PRF) as scaffolds in regenerative endodontic therapy (RET).

METHODS

Necrotic immature permanent teeth treated with regenerative endodontic therapy during January 2018 to August 2022 were divided into the CGF and PRF groups according to the scaffold. The CGF and PRF groups included 7 and 6 teeth, respectively. The efficacy of regenerative endodontic therapy was analyzed based on the clinical and radiological outcomes at three different follow up periods: T1 (3-6 months), T2 (6-12 months) and T3 (12-24 months). Statistical analysis was performed using the independent T test, Mann-Whitney test and Fisher's exact test at a significance level of 0.05.

RESULTS

The success rate of each stage in both groups was 100%. Through quantitative comparison of radiographic outcomes, there was no statistically significant difference between the two groups in terms of root development and periapical lesion healing at each stage, except that the increase rate of radiographic root area in PRF group in the T3 stage was above one in CGF group with statistically significance.

CONCLUSIONS

Both CGF and PRF had a similar clinical performance regarding resolution of clinical signs and symptoms, periapical lesion healing, and continued root development as scaffolds in RET. Further prospective studies with large samples for longer follow-up periods are needed.

Different endodontic treatments induced root development of two nonvital immature teeth in the same patient: A case report

BACKGROUND

Pulp revascularization is a novel way to treat immature teeth with periapical disease, and the technique has become increasingly well established in recent years. By puncturing the periapical tissue, bleeding is induced, and a blood clot is formed in the root canal. The blood clot acts as a natural bioscaffold onto which mesenchymal stem cells from periapical tissue can be seeded and restore pulp vascularity, thus promoting root development as well as apical closure. Although the effect of pulp revascularization is ideal, there are certain requirements for the apical condition of the teeth. The apical barrier technique and apexification are still indispensable for teeth that cannot achieve ideal blood clot formation. In addition, a meta-analysis of several clinical studies concluded that pulp revascularization has no significant advantages over other treatments.

CASE SUMMARY

A 10-year-old girl complained of pain in the right upper and lower posterior teeth for 2 d. Clinical and radiological examinations revealed that both the right maxillary and mandibular second premolars were immature with periapical radiolucency. The right maxillary second premolar was treated by pulp revascularization, while the right mandibular second premolar was treated by conventional apical barrier surgery after revascularization failed. The purpose of this report is to compare the different root maturation processes induced by the pulp revascularization and apical barrier techniques in the same patient in homonymous teeth from different jaws. Twelve months of follow-up showed that the apical foramen of both teeth presented a clear tendency to close; however, the tooth treated with pulp revascularization showed a significant increase in root length as well as root canal wall thickness.

CONCLUSION

For the treatment of nonvital immature teeth, pulp revascularization showed a superior therapeutic effect in comparison with the apical barrier technique.

Effect of Intracoronal Sealing Biomaterials on the Histological Outcome of Endodontic Revitalisation in Immature Sheep Teeth-A Pilot Study

The influence of intracoronal sealing biomaterials on the newly formed regenerative tissue after endodontic revitalisation therapy remains unexplored. The objective of this study was to compare the gene expression profiles of two different tricalcium silicate-based biomaterials alongside the histological outcomes of endodontic revitalisation therapy in immature sheep teeth. The messenger RNA expression of TGF-β, BMP2, BGLAP, VEGFA, WNT5A, MMP1, TNF-α and SMAD6 was evaluated after 1 day with qRT-PCR. For evaluation of histological outcomes, revitalisation therapy was performed using Biodentine (n = 4) or ProRoot white mineral trioxide aggregate (WMTA) (n = 4) in immature sheep according to the European Society of Endodontology position statement. After 6 months' follow-up, one tooth in the Biodentine group was lost to avulsion. Histologically, extent of inflammation, presence or absence of tissue with cellularity and vascularity inside the pulp space, area of tissue with cellularity and vascularity, length of odontoblast lining attached to the dentinal wall, number and area of blood vessels and area of empty root canal space were measured by two independent investigators. All continuous data were subjected to statistical analysis using Wilcoxon matched-pairs signed rank test at a significance level of p < 0.05. Biodentine and ProRoot WMTA upregulated the genes responsible for odontoblast differentiation, mineralisation and angiogenesis. Biodentine induced the formation of a significantly larger area of neoformed tissue with cellularity, vascularity and increased length of odontoblast lining attached to the dentinal walls compared to ProRoot WMTA (p < 0.05), but future studies with larger sample size and adequate power as estimated by the results of this pilot study would confirm the effect of intracoronal sealing biomaterials on the histological outcome of endodontic revitalisation.

Is Revascularization the Treatment of Choice for Traumatized Necrotic Immature Teeth? A Systematic Review and Meta-Analysis

Regenerative endodontic treatment (RET) has been considered a reliable procedure to treat immature necrotic teeth; however, the effect of dental trauma on the prognosis of RET is questionable. This systematic review aimed to evaluate the current level of evidence for revascularization techniques (the RET) in the management of traumatized necrotic immature permanent teeth with or without periapical radiolucent areas. Four electronic databases-PubMed, Web of Science, Scopus, and Embase-were searched until November 2022. Only randomized clinical trials, cohort studies, and case-control studies with a minimum of 10 cases and 12 months of follow-ups were included. The search identified 363 preliminary results. After discarding the duplicates and screening the titles, abstracts, and full texts, 13 articles were considered eligible. The results showed that RET techniques seemed to have high survival and success rates, 93.8% and 88.3%, respectively, in the treatment of traumatized necrotic immature permanent teeth. Root maturation with RET techniques seemed to be lower in traumatized teeth. Future studies are needed to evaluate root maturation in traumatized teeth using 3-dimensional radiographic evaluations. In addition, the lack of literature on the studies comparing RET and apexification (calcium hydroxide or an MTA) in the treatment of traumatized necrotic immature teeth highlights the necessity for high-level clinical studies comparing these treatment modalities.

Effect of Intracanal Scaffolds on the Success Outcomes of Regenerative Endodontic Therapy - A Systematic Review and Network Meta-analysis

INTRODUCTION

The scaffolds used in regenerative endodontic therapy (RET) provide structural support for cells so that they can adhere to the scaffolds and also are crucial for cellular proliferation and differentiation. The objective of this network meta-analysis was to compare effects of different intracanal scaffolds on success outcomes of RET.

METHODS

PubMed/Medline, EMBASE, Cochrane, CINAHL, Scopus, and Web of Science databases were searched. Studies evaluating and/or comparing clinical and/or radiographic success of RET using different scaffolds with a minimum of 12 months follow-up were included. The Cochrane Collaboration risk of bias (ROB) tool and appropriate tools from Joanna Briggs Institute were used for the assessment of ROB. A network meta-analysis was performed to compare the primary outcome (clinical success) and other success outcomes (root maturation, and pulpal sensibility) using different scaffolds.

RESULTS

Twenty-seven studies fulfilled the desired inclusion criteria of which 25 had a low ROB whereas 2 had a moderate ROB. Clinical success of RET using platelet-rich plasma (PRP), blood clot (BC), and platelet-rich fibrin (PRF) scaffolds ranged between 91.66%-100%, 84.61%-100%, and 77%-100% respectively. The different scaffolds did not show any statistically significant difference in clinical success (PRF vs BC [P = 1.000], PRP vs BC [P = 1.000], and PRF vs PRP [P = .999]), apical root closure (PRF vs BC [P = 1.000], PRP vs BC [P = .835], PRF vs PRP [P = .956]), and pulp sensibility (PRF vs BC [P = .980], PRP versus BC [P = .520], and PRF vs PRP [P = .990]).

CONCLUSION

The intracanal scaffolds used during RET did not result in significant differences in regard to clinical success, root maturation, and pulpal sensibility.

Are platelet concentrate scaffolds superior to traditional blood clot scaffolds in regeneration therapy of necrotic immature permanent teeth? A systematic review and meta-analysis

BACKGROUND

The effectiveness of platelet concentrates in promoting root development of necrotic immature permanent teeth is unclear. The present study evaluated whether the platelet concentrate protocol was superior to the traditional blood clot protocol in regeneration therapy.

METHODS

We searched Electronic databases, such as PubMed, Cochrane Library, ClinicalTrials and EMBASE. Randomized controlled trial studies, cohort studies, case-control studies and cross-sectional studies were included, in which platelet-rich concentrates were tested for periapical healing and root development, with the blood clot treatment protocol as the control group. Clinical and radiographic outcomes were considered. Selected articles were assessed for risk of bias. Pooled risk ratios (risk ratio, RR) were calculated for clinical success, responses to cold and electric pulp tests, periapical lesions, apex closure, root lengthening, and thickening of the dentin walls. Subgroup meta-analysis were conducted according to the type of platelet concentrate used.

RESULTS

Of the 1272 screened studies, 13 randomized controlled studies, 2 case-control studies and 1 cohort study were selected, in which 465 immature necrotic permanent teeth, particularly incisors and premolars, were treated. Of these 465 teeth, 457 (98.2%) in both the control and experimental groups remained clinically asymptomatic for the entire study duration, whereas eight (1.8%) showed signs and symptoms of failure, including spontaneous pain, sensitivity to percussion or reinfection. Compared with control teeth, teeth treated with PRP achieved better apical healing than BC group (RR 1.13, 95% CI 1.01-1.26, P = 0.03), and teeth treated with platelet concentrates showed improved apical closure (RR 1.04, 95% CI 0.86-1.25, P = 0.69), root lengthening (RR 1.01, 95% CI 0.74-1.39, P = 0.93), and thickening of the dentin walls (RR 1.35, 95% CI 0.95-1.93, P = 0.09), although these differences were not statistically significant.

CONCLUSIONS

Platelet concentrates can be used as successful scaffolds for regenerative endodontic treatment of necrotic immature permanent teeth, and PRP as a scaffold may achieve better periapical healing of teeth with periapical inflammation, although they did not differ significantly from conventional blood clot scaffolds in development of the root.

Neural Regeneration in Regenerative Endodontic Treatment: An Overview and Current Trends

Pulpal and periapical diseases are the most common dental diseases. The traditional treatment is root canal therapy, which achieves satisfactory therapeutic outcomes-especially for mature permanent teeth. Apexification, pulpotomy, and pulp revascularization are common techniques used for immature permanent teeth to accelerate the development of the root. However, there are obstacles to achieving functional pulp regeneration. Recently, two methods have been proposed based on tissue engineering: stem cell transplantation, and cell homing. One of the goals of functional pulp regeneration is to achieve innervation. Nerves play a vital role in dentin formation, nutrition, sensation, and defense in the pulp. Successful neural regeneration faces tough challenges in both animal studies and clinical trials. Investigation of the regeneration and repair of the nerves in the pulp has become a serious undertaking. In this review, we summarize the current understanding of the key stem cells, signaling molecules, and biomaterials that could promote neural regeneration as part of pulp regeneration. We also discuss the challenges in preclinical or clinical neural regeneration applications to guide deep research in the future.

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.

Use of scaffolds and regenerative materials for the treatment of immature necrotic permanent teeth with periapical lesion: Umbrella review

BACKGROUND

Current treatment of immature necrotic permanent teeth with a periapical lesion is regenerative endodontics, which is based on tissue engineering under the triade of stem cells, scaffolds and bioactive molecules.

OBJECTIVES

This Umbrella Review was aimed to evaluate the success of scaffold and regenerative materials used for the treatment of these teeth, in terms of apical closure, tooth length increase, widening of root canal walls, tissue vitality and periapical lesion repair.

METHODS

An extensive literature research was carried out in the Medline, ISI Web of Science, and Scopus databases for relevant systematic reviews matching the keyword search strategy. Based on inclusion and exclusion criteria, reviewers independently rated the quality of each study to determine their level of evidence. Methodological quality assessment of each article was obtained using A Measurement Tool to Assess Systematic Reviews (AMSTAR)-2 tool, and risk of bias was assessed with the Risk of Bias in Systematic Reviews (ROBIS) tool.

RESULTS

After removing duplicates, 155 articles were found; from which 133 were excluded for being non-relevant and 15 other due to exclusion criteria. One more was discarded after methodological quality evaluation, for a total of six articles remaining. The most common scaffold used was the blood clot, others used were poly lactic-co-glycolic acid and platelet-rich fibrin matrix. The most common regeneration material used was Mineral Trioxide Aggregate (MTA), followed by Biodentine. An increase in tooth length and widening of root canal walls were reported in all selected studies with different proportions, as well as periapical lesion repair. ROBIS analysis showed that only one article had low bias, two were classified as unclear bias, while the remaining three had high risk of bias.

DISCUSSION

An exhaustive literature search was carried out applying language filters, high-quality indexed journals, year of publication, which ensures the best quality articles were included. Blood clot was the most used scaffold as is the most easy to place inside the canal and does not require to extract blood from the patient. The use of MTA and Biodentine as sealing materials has been associated with thickening of canal walls, apical closure and reduced signs and symptoms of apical periodontitis. However, most of the included reviews assessed were case reports and only in a few of them were clinical trials included. There is also a lack of risk of bias analysis in most reviews.

CONCLUSION

The blood clot is the most common scaffold used for inducing regeneration during the treatment of immature necrotic teeth. Tooth length increase and widening of root canal walls are the most common criteria used in the studies as success indicators. MTA and Biodentine did not show differences in the results analysed. Quality assessment and bias risk evaluation showed that it is necessary to design better studies with rigorous methodology to recommend a trustable and predictable protocol for the treatment of immature necrotic permanent teeth with periapical lesions.

REGISTRATION

International Prospective Register of Systematic Reviews (PROSPERO) CRD42021248404.

The Four Pillars for Successful Regenerative Therapy in Endodontics: Stem Cells, Biomaterials, Growth Factors, and Their Synergistic Interactions

Endodontics has made significant progress in regenerative approaches in recent years, thanks to advances in biologically based procedures or regenerative endodontic therapy (RET). In recent years, our profession has witnessed a clear conceptual shift in this therapy. RET was initially based on a blood clot induced by apical bleeding without harvesting the patient’s cells or cell-free RET. Later, the RET encompassed the three principles of tissue engineering, stromal/stem cells, scaffolds, and growth factors, aiming for the regeneration of a functional dentin pulp complex. The regenerated dental pulp will recover the protective mechanisms including innate immunity, tertiary dentin formation, and pain sensitivity. This comprehensive review covers the basic knowledge and practical information for translational applications of stem cell-based RET and tissue engineering procedures for the regeneration of dental pulp. It will also provide overall information on the emerging technologies in biological and synthetic matrices, biomaterials, and signaling molecules, recent advances in stem cell therapy, and updated experimental results. This review brings useful and timely clinical evidence for practitioners to understand the challenges faced for a successful cell-based RET and the importance of preserving or reestablishing tooth vitality. The clinical translation of these current bioengineering approaches will undoubtedly be beneficial to the future practice of endodontics.

Tissue Characteristics in Endodontic Regeneration: A Systematic Review

The regenerative endodontic procedure (REP) represents a treatment option for immature necrotic teeth with a periapical lesion. Currently, this therapy has a wide field of pre-clinical and clinical applications, but no standardization exists regarding successful criteria. Thus, by analysis of animal and human studies, the aim of this systematic review was to highlight the main characteristics of the tissue generated by REP. A customized search of PubMed, EMBASE, Scopus, and Web of Science databases from January 2000 to January 2022 was conducted. Seventy-five human and forty-nine animal studies were selected. In humans, the evaluation criteria were clinical 2D and 3D radiographic examinations. Most of the studies identified a successful REP with an asymptomatic tooth, apical lesion healing, and increased root thickness and length. In animals, histological and radiological criteria were considered. Newly formed tissues in the canals were fibrous, cementum, or bone-like tissues along the dentine walls depending on the area of the root. REP assured tooth development and viability. However, further studies are needed to identify procedures to successfully reproduce the physiological structure and function of the dentin–pulp complex.

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.

Treatment of Necrotic Anterior and Posterior Teeth with Regenerative Endodontic Procedures Using PRF as a Scaffold: A Retrospective Study

We assessed the impact of regenerative endodontic procedures (REP) using a platelet-rich fibrin (PRF) scaffold on necrotic immature permanent anterior and posterior teeth based on the following parameters: periapical healing, changes in root development, and associations between increases in the radiographic root area (RRA), and degree of root to apical closure. The study included 50 teeth consisting of 57 roots (36 anterior and 21 posterior) treated between 2017 and 2019, with an average follow-up of two years. Complete periapical healing was achieved in 91.2% teeth, and uncertain healing was achieved in 8.8%. RRA increased in 95% of teeth and root lengthening was achieved in 86% teeth (without any mutual effect). Apical closure was significantly associated with tooth location (89% and 30% of the posterior and anterior roots, respectively). Trauma was the most common aetiology of necrotic anterior teeth, whereas caries was the only aetiology of necrotic posterior teeth. REP using PRF scaffold achieved a high success rate for periapical healing and root maturation in both anterior and posterior necrotic immature teeth. The favourable results obtained in posterior teeth may encourage the use of REP for treating necrotic immature permanent posterior teeth.

Biomaterial scaffolds for clinical procedures in endodontic regeneration

Regenerative endodontic procedures have been rapidly evolving over the past two decades and are employed extensively in clinical endodontics. These procedures have been perceived as valuable adjuvants to conventional strategies in the treatment of necrotic immature permanent teeth that were deemed to have poor prognosis. As a component biological triad of tissue engineering (i.e., stem cells, growth factors and scaffolds), biomaterial scaffolds have demonstrated clinical potential as an armamentarium in regenerative endodontic procedures and achieved remarkable advancements. The aim of the present review is to provide a broad overview of biomaterials employed for scaffolding in regenerative endodontics. The favorable properties and limitations of biomaterials organized in naturally derived, host-derived and synthetic material categories were discussed. Preclinical and clinical studies published over the past five years on the performance of biomaterial scaffolds, as well as current challenges and future perspectives for the application of biomaterials for scaffolding and clinical evaluation of biomaterial scaffolds in regenerative endodontic procedures were addressed in depth.

•

Overview of biomaterials for scaffolding in regenerative endodontics are presented.

•

Findings of preclinical and clinical studies on the performance of biomaterial scaffolds are summarized.

•

Challenges and future prospects in biomaterial scaffolds are discussed.

Endodontic pulp revitalization in traumatized necrotic immature permanent incisors: Early failures and long-term outcomes-A longitudinal cohort study

AIM

This prospective cohort study evaluates clinical and radiographical outcomes of endodontic pulp revitalization (PR) of traumatized necrotic incisors.

METHODOLOGY

Pulp revitalization was performed in 75 traumatized necrotic immature incisors from 71 patients. The radiographic outcome measures were continued root formation (width and length), root resorption, apex closure, periapical index, and root development stage. The clinical outcome measures were percussion pain, palpation pain, pathological tooth mobility, swelling, sinus tract, ankylosis, crown discolouration, response to pulp sensitivity test, and subjective pain. Treatment outcomes were categorized as a success based on the absence of clinical symptoms and when radiographic evidence was present for apical healing and continued root development. The performed statistical tests were repeated measures anova, pairwise comparisons of interactions (t-test), McNemar's test, and linear regression model.

RESULTS

In 45 of 75 teeth (60%), PR was successful with the resolution of clinical and radiographic signs and continued root development. PR failed due to the absence of bleeding (n = 19) and persistent infection (n = 11). PR showed statistically significant increases in root length (11%), and dentinal wall thickness (30%), root maturation (pre-operative 3.38 [CI 1.88; 4.88]; post-operative 4.04, [CI 2.56; 5.52]) apical closure (71.4%), healing of pre-operative apical periodontitis (100%), and healing of pre-operative inflammatory root resorptions (100%). Three predictive variables for continued root maturation were identified - root development stage at entry (p = .0001, β 0.649), [CI 0.431; 0.867], trauma to the soft tissues (p = .026, β -0.012), [CI -0.0225; -0.015], and pre-operative dentinal wall thickness (p = .009, β -0.001); [CI -0.001; 0.0001].

CONCLUSIONS

Our findings indicate that PR provides satisfactory clinical and radiographical outcomes in traumatized necrotic incisors. The failed cases were related to lack of bleeding and persistent infections, indicating that new techniques are needed to improve the predictability of PR.

Successful regenerative endodontic treatment in a tooth with incomplete root apex and posttreatment apical periodontitis: A case report

This case report describes the procedure and outcome of regenerative endodontic treatment (RET) in a tooth with incomplete root apex and posttreatment apical periodontitis. A 44-year-old patient was referred to the endodontist because of a periapical lesion on tooth #21 and a recent episode of acute periapical abscess. On clinical and radiographic examination, this tooth presented with tenderness to percussion and palpation, periapical radiolucent lesion, external apical resorption, and incomplete apex formation. After coronal access, the filling material was removed, and the canal was gently prepared with hand files, using 1% NaOCl as the main irrigant followed by final irrigation with 17% EDTA, activated with XP-endo Finisher (FKG Dentaire, La Chaux-de-Fonds, Switzerland). The root canal was filled with a double antibiotic paste with ciprofloxacin and metronidazole (1:1). After three weeks, RET was performed by stimulating bleeding into the canal, and when a clot was formed, a bioceramic (EndoSequence BC Sealer, Brasseler USA, Savannah, GA) plug was placed on it, followed by coronal restoration. The tooth remained asymptomatic since RET was concluded. Clinical and radiographic follow-ups showed complete repair of the apical periodontitis lesion and the absence of symptoms after eight months. This satisfactory outcome was confirmed after 34 months.

Key words:Bioceramic material; ciprofloxacin; metronidazole; persistent apical periodontitis; regenerative endodontic treatment.

Changes in Migratory Speed Rate of Human Dental Pulp Stromal Cells Cultured in Advanced Platelet-Rich Fibrin

OBJECTIVE

 Migratory speed rate evaluation of human dental pulp stromal cells (hDP-SCs) is one of the important steps in dental pulp regeneration. Therefore, the aim of the study is to analyze various concentrations of advanced platelet-rich fibrin (A-PRF) culture media toward hDP-SCs' migratory speed rate evaluations.

MATERIALS AND METHODS

 The hDP-SCs were divided into four groups: control: hDP-SCs in Dulbecco's modified Eagle medium + 10% fetal bovine serum group; hDP-SCs in 1% A-PRF group; hDP-SCs in 5% A-PRF group; and hDP-SCs in 10% A-PRF group, which were planted in 24-well (5 × 10⁴ cell/well). The migratory speed rate of all groups was measured by using cell migration assay (scratch wound assay) after 24 hours. Cell characteristics were evaluated under microscope (Inverted microscope, Zeiss, Observer Z1, UK) that can be read through image-J interpretation. This image J represented the measurement of migratory speed rate (nm/h) data. Statistical analysis was conducted using one-way analysis of variance and post hoc Tamhane's test (p < 0.05) (IBM SPSS Statistics Software, version 22.0).

RESULTS

 There was a statistically significant difference in the migratory speed rates of hDP-SCs among various concentration groups of A-PRF (1, 5, and 10%) compared with the control group.

CONCLUSION

The increase in the migratory speed rate of hDP-SCs was highest in 10% A-PRF group.

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.

Intracanal calcification following regenerative endodontic treatment: a systematic review and meta-analysis

OBJECTIVES

Calcification is a common finding in endodontic cases after regenerative endodontic therapy (RET). We aimed to identify the prevalence of intracanal calcification after RET and to compare intracanal calcification outcomes in RET using either calcium hydroxide [Ca(OH)₂] or antibiotics.

MATERIALS AND METHODS

We searched PubMed, Web of Science, ProQuest Dissertations & Theses, and Scopus databases for clinical, cross-sectional, case-control, and cohort RET studies published until May 2020 in the English language and reporting a calcified case after RET. The Cochrane risk-of-bias tool for randomized trials and Risk of Bias In Non-randomized Studies of Interventions were used for bias assessment. Meta-analyses were performed, overall and separately, for intracanal medicaments using a random-effects model with weighted inverse variance methods. Subgroup analysis was performed according to the calcification type.

RESULTS

Eight studies were included. The overall prevalence of intracanal calcification after RET was 30.7% (95% confidence interval [CI]: 0.15-0.45,[Formula: see text]=92.6%), 46.5% with Ca(OH)₂ vs. 25.8% with antibiotic-based intracanal medicaments. Subgroup analyses for complete calcification outcome showed a higher prevalence of complete calcification in the Ca(OH)₂ group (46.5%, 95% CI: 0.17-0.68,[Formula: see text]%) than in the antibiotic group (10%, 95% CI: - 0.04-0.43,[Formula: see text]%).

CONCLUSIONS

Based on the studies included, available evidence shows a statistically significant association between complete calcification and Ca(OH)₂ paste as an intracanal medicament. Other contributing factors, such as blood clot formation and follow-up time, might also play an essential role in forming intracanal calcification.

CLINICAL RELEVANCE

This study highlights the significant association between complete calcification and Ca(OH)₂ paste.

Evaluation of the Treatment Protocols in the Management of Pulpally Involved Young Permanent Teeth in Children: A Systematic Review and Meta-analysis

Background

In children with young permanent teeth, dental caries and traumatic injuries are the most common problems leading to pulp necrosis. Since, root development is completed in two to three years after eruption of the tooth into the oral cavity, loss of pulp vitality in young permanent tooth creates distinctive problems. In spite of exceeding availability of treatment procedures there is a need to search for a substantial procedure to treat young permanent teeth effectively.

Aim

The aim of this systematic review was to evaluate the treatment protocols in the management of pulpally involved young permanent teeth in children.

Method

Systematic search was conducted on databases PubMed, Cochrane, and Google Scholar among studies published from 1st January 2010 till 31st May 2020. Studies meeting the inclusion criteria were included in the review and were then assessed for quality with the help of predetermined criteria which categorized studies into high, medium, and low.

Results

Search strategy yielded 4,846 articles. After screening through titles and abstracts, 33 articles remained which were further screened for full text. At the end, 14 articles were included in systematic review. Furthermore, the included articles were statistically evaluated by meta-analysis.

Conclusion

In apexogenesis and apexification procedures, newer biomimetic materials like mineral trioxide aggregate and biodentine have more success rate than conventionally used calcium hydroxide. Among regenerative endodontic procedures platelet-rich plasma and platelet- rich fibrin showed better results.

Clinical significance

To amend clinician perceptions towards acceptance of the newer regenerative procedures and their effectiveness in management of young permanent tooth.

How to cite this article

Saxena N, Hugar SM, Soneta SP, et al. Evaluation of the Treatment Protocols in the Management of Pulpally Involved Young Permanent Teeth in Children: A Systematic Review and Meta-analysis. Int J Clin Pediatr Dent 2022;15(S-1):S103–S113.

Regenerative Endodontic Procedures in Immature Permanent Teeth With Dental Trauma: Current Approaches and Challenges

After dental trauma to immature permanent teeth (IPT), there can be pulpitis, necrotic, and periapical periodontitis, which will halt further root development. Traditional endodontic root canal treatments and apexification cannot revitalize the necrotic pulp to revitalize the tooth to promote further root development. As a consequence, IPT with thin dentinal walls can be prone to fracture and if a fracture occurs, the patient will likely suffer the loss of the tooth. In an attempt to save IPT, there has been a growing interest among dentists to use regenerative endodontic procedures (REPs) to revitalize a replace dental pulp to continue root development and strengthen the dentinal walls to help prevent a subsequent loss of the tooth. However, the effectiveness of REPs and the precise methods to successfully accomplish REPs are controversial. Therefore, the objective of this review is to compare the different approaches to REPs in case reports by highlighting their advantages and limitations.

"Meta-analysis of regenerative endodontics outcomes with antibiotics pastes and calcium hydroxide. The apex of the iceberg"

PORPOSE

The aim of this study was to evaluate, through a meta-analysis, the predictability of Regenerative Endodontic therapies with antibiotic pastes and calcium hydroxide [Ca(OH)2], related to four variables as follows: root dentin wall thickening, apical closure, apical repair and root lengthening.

METHODS

Literature electronic searches were performed in Pubmed - MEDLINE, Scopus and Lilacs-BVS platforms using appropriate search terms, Mesh (Medical Subject Headings), DeCS (Health Sciences Descriptors) and Boolean operators comprising articles published between 2009 and 2020. Thirty-two original indexed papers were included making a total of 758 regenerative endodontic procedures. A descriptive meta-analysis was performed.

RESULTS

Dentin wall thickening was present in 66% (CI95: 58%-73%) of the cases treated with antibiotic paste, while when Ca(OH)2 was used, a percentage of 53% (CI95: 26%-78%), was obtained. When antibiotic paste was used, apical closure was found in the 66% (CI95: 58%-73%) of the regenerative endodontic procedures, while when Ca(OH)2 was used, 88% (CI95: 80%-93%) of the cases were found to reach apical closure. Root lengthening and apical repair were found satisfactory for both disinfection protocols.

CONCLUSIONS

There could be differences between the two treatments since a higher percentage of root dentin wall thickening was found when using antibiotic pastes, while a higher percentage of apical closure was found when calcium hydroxide was used. Development of more clinical studies would be necessary in order to confirm the observed differences. The proposed approach could provide a useful contribution for endodontists when planning regenerative endodontic procedures, so as to guide decision-making to the best elective treatment and to select the appropriate disinfection method in accordance with preoperative radiographic diagnosis of root development stage, then increasing the predictability of regenerative endodontic treatment and reducing potential risk of root fractures.

Regenerative Endodontic Procedure of Immature Permanent Teeth with Leukocyte and Platelet-rich Fibrin: A Multicenter Controlled Clinical Trial

INTRODUCTION

The aim of this nonrandomized, multicenter controlled clinical trial was to evaluate the impact of leukocyte-platelet-rich fibrin (LPRF) on regenerative endodontic procedures (REPs) of immature permanent teeth in terms of periapical bone healing (PBH) and further root development (RD).

METHODS

Healthy patients between 6-25 years with an inflamed or necrotic immature permanent tooth were included and divided between the test (= REP + LPRF) and control (= REP-LPRF) group depending on their compliance and the clinical setting (university hospital or private practice). After receiving REP ± LPRF, the patients were recalled after 3, 6, 12, 24, and 36 months. At each recall session, the teeth were clinically and radiographically (by means of a periapical radiograph [PR]) evaluated. A cone-beam computed tomographic (CBCT) imaging was taken preoperatively and 2 and 3 years postoperatively. PBH and RD were quantitatively and qualitatively assessed.

RESULTS

Twenty-nine teeth with a necrotic pulp were included, from which 23 (9 test and 14 control) were analyzed. Three teeth in the test group had a flare-up reaction in the first year after REP. Except for 2 no shows, all the analyzed teeth survived up to 3 years after REP, and, in case of failure, apexification preserved them. Complete PBH was obtained in 91.3% and 87% of the cases based on PR qualitative and quantitative evaluation, respectively, with no significant difference between the groups with respect to the baseline. The PR quantitative change in RD at the last recall session with respect to the baseline was not significant (all P values > .05) in both groups. The qualitative assessment of the type of REP root healing was nonuniform. In the test group, 55.6% of the teeth presented no RD and no apical closure. Only 50% of the 14 teeth assessed with CBCT imaging presented complete PBH. Regarding volumetric measurements on RD 3 years after REP for the change with respect to the baseline in root hard tissue volume, mean root hard tissue thickness, and apical area, the control group performed significantly in favor of RD than the test group (P = .03, .003, and 0.05 respectively). For the volumetric change 3 years after REP with respect to the baseline in root length and maximum root hard tissue thickness, no significant difference (P = .72 and .4, respectively) was found between the groups. The correlation between the PR and CBCT variables assessing RD was weak (root lengthening) to very weak (root thickening).

CONCLUSIONS

REP-LPRF seems to be a viable treatment option to obtain PBH and aid further RD of necrotic immature permanent teeth. Caution is needed when evaluating REP with PR.

CONSORT Compliance in Randomized Clinical Trials of Regenerative Endodontic Treatments of Necrotic Immature Teeth: A Scoping Review

INTRODUCTION

This study aimed to investigate methodological quality of clinical trials in regenerative endodontics and its compliance with the CONSORT statement.

METHODS

An electronic search was performed in 8 electronic databases. Only clinical trials whose participants underwent regenerative endodontic treatment on necrotic permanent immature teeth were included. Quality assessment was performed using the Cochrane Collaboration's Risk of Bias Tool (RoB, version 2.0). Compliance of articles with the CONSORT guidelines was assessed by a tool with scales: 0 = no description, 1 = deficient, and 2 = adequate description, totaling a maximum score of 32 points. The Mann-Whitney and Kruskal-Wallis tests were used to compare the scores among journals, studies, country, income levels, and publication periods. Spearman correlation analyses were performed between CONSORT compliance scores and 2019 journal CiteScore values, publication year, and quality assessment.

RESULTS

Twenty studies were included. The average CONSORT compliance score was 20.95 (±6.19). The better reported items were the description of the interventions performed in the trials (100%), followed by the description of the number of patients analyzed, losses and exclusions (90%), and the hypothesis tested (85%). Within the 20 studies, 3 articles were classified as "low risk of bias," 8 studies were classified as "some concerns," and 9 studies were considered "high risk of bias." Studies carried out in countries with higher income levels presented higher CONSORT scores. Significant moderate correlations were found between the CONSORT score and the percentage of risk of bias in low-risk domains (rs = 0.63; 95% CI, 0.31-0.94; P = .003) and the overall risk of bias categories (rs = 0.76; 95% CI, 0.54-0.98; P = .001).

CONCLUSIONS

The adequacy of reporting based on the CONSORT checklist items of regenerative endodontic trials was low with a moderate to high risk of bias.

Platelet-Rich Plasma Induces Autophagy and Promotes Regeneration in Human Dental Pulp Cells

Regenerative endodontic procedures using autologous platelet-rich plasma (PRP) can improve the biologic outcome of treatment. However, its mechanism of action on improving pulp regeneration is not fully elucidated. Autophagy was recently shown to be related to tissue repair and osteogenesis. Therefore, the objective of this study was to investigate the effect of PRP in dental pulp regeneration and to elucidate the role of autophagy involved in this process. Human dental pulp cells (hDPCs) were isolated from healthy dental pulp and co-cultured with an increasing concentration of PRP. Cellular migration and proliferation were determined by scratch assay, transwell assay, and cell-counting kit 8 assay. Osteogenic differentiation was clarified by using alkaline phosphatase staining, alizarin red staining, and real-time polymerase chain reaction (RT-PCR) to measure the gene expression levels of alkaline phosphatase, collagen-1, osteocalcin, dentin matrix protein 1, and dentin sialophosphoprotein. Autophagic bodies were observed by transmission electron microscopy and the expression of autophagy marker light chain 3B (LC3B) was determined by immunofluorescence staining. The mRNA and protein expression level of LC3B and Beclin-1 were quantified by qRT-PCR and western blotting. The effect of PRP on cellular migration, proliferation, and osteogenic differentiation was further investigated in the milieu of autophagy activator, rapamycin, and inhibitor, 3-methyladenine. Results showed that PRP promoted cell migration, proliferation, and osteogenic differentiation. Autophagic bodies were strongly activated and the expression level of LC3B and Beclin-1 was significantly promoted by PRP. Autophagy inhibition suppressed PRP-induced hDPCs migration, proliferation, and osteogenic differentiation, whereas autophagy activator substantially augmented PRP-stimulated migration, proliferation, and differentiation. Taken together, these findings suggested that PRP could effectively promote regenerative potentials associated with autophagy.

PRP and PRF-Subgroups and Divisions When Used in Dentistry

Blood derivates, such as platelet-rich plasma (PRP) and platelet-rich fibrin (PRF), are autogenous sources of many growth factors that are involved in the healing and regeneration of tissues, and for this reason, are used in dentistry treatments. This fact also contributes to the growing interest in these biomaterials in regenerative personalized medicine. The multitude of platelet-rich forms creates many possibilities for their use. This semi-systematic review describes and compares the methods of obtaining properties and potential uses of these materials in personalized treatments.

Regenerative Endodontic Therapy in the Management of Nonvital Immature Permanent teeth: A Systematic Review and Meta-analysis

This meta-analysis is intended to evaluate the reliability of evidences published in current regenerative endodontic publications in a critical way. This meta-analysis is used to summarize and analyze the various clinical and radiographic findings associated with nonvital immature permanent teeth which have been treated with regenerative endodontic techniques. We also intend to significantly evaluate the worth of facts provided in the previous published literature. A structured electronic search by authors was undertaken in August 2020 using MEDLINE and PubMed search engine. The chosen parameters studied in this systematic review were presented in flowcharts and were summarized. We observed a good accomplishment rates in terms of survival of the treated tooth and also in resolution of any associated pathology in the apical areas; on contrary, our results in relation to apex closure along with constant root development, our findings from various studies were quiet variable. Regenerative endodontic procedures are constantly being restructured and enhanced to benefit present-day dentistry in all likely ways. Still, many factors that are important for the success of regenerative endodontic treatment outcomes still remain unexplained. There are still numerous gaps in our expertise at the present stage of this study.

Novel Approaches for the Treatment of Necrotic Immature Teeth Using Regenerative Endodontic Procedures: A Systematic Review and Meta-Analysis

The induction of a blood clot allowing apical revascularization with a subsequent apical closure was reported several decades ago. Recent research has been focused on examining different scaffolds for regenerative endodontic procedures (REPs). The aim of this study was to analyze the main outcomes in novel REP reported in the literature. The search was conducted using six databases. Only clinical trials aiming at the study of scaffolds for REP in the treatment of necrotic immature teeth were included. The risk of bias was assessed by the Risk of Bias 2 tool. Additionally, the quality of the included studies was assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) criteria. A summary of individual studies and a meta-analysis were performed. Relative risks of data from clinical success and root length changes were used from the studies, and these were combined using a random-effects meta-analysis. The meta-analysis results reveal that the main outcomes showed no differences between the patients who received REP with scaffolds or only REP. Limitations include that the certainty of evidence was low and that there was significant heterogeneity in the scaffolds used in the included studies. The data suggest that the blood clot remains as the gold standard for REP.

Effects of various thicknesses and levels of mineral trioxide aggregate coronal plugs on nanoleakage and fracture resistance in revascularization: An in vitro study

The aim of this study was to evaluate the effects of mineral trioxide aggregate (MTA) applied at varying levels and thickness in the cervical region of the root on the leakage and fracture resistance of the simulated immature teeth. 3 study groups (n = 16) (Group 1: 2 mm MTA, Group 2: 4 mm MTA, Group 3: 2 mm MTA+2 mm RMGIC below cementoenamel junction) and 2 control groups (Group 4: Complete canal obturation, Group 5: No coronal plug) were used for the study. Nanoleakage was measured using a micro-computed tomography system. For the fracture resistance test, a universal testing machine was used. The amount of silver nitrate penetration decreased while MTA thicknesses increased (P < 0.001). However, the placement of MTA as a thicker layer did not make any additional contribution on the fracture resistance (P > 0.05). The 4-mm coronal MTA plug can be suggested in RETs for its superior sealing and reinforcement abilities.

Roles of Dental Mesenchymal Stem Cells in the Management of Immature Necrotic Permanent Teeth

Dental caries and trauma always lead to pulp necrosis and subsequent root development arrest of young permanent teeth. The traditional treatment, apexification, with the absence of further root formation, results in abnormal root morphology and compromises long-term prognosis. Regeneration endodontics procedures (REPs) have been developed and considered as an alternative strategy for management of immature permanent teeth with pulpal necrosis, including cell-free and cell-based REPs. Cell-free REPs, including revascularization and cell homing with molecules recruiting endogenous mesenchymal stem cells (MSCs), have been widely applied in clinical treatment, showing optimistic periapical lesion healing and continued root development. However, the regenerated pulp-dentin complex is still absent in these cases. Dental MSCs, as one of the essentials of tissue engineering, are vital seed cells in regenerative medicine. Dental MSC-based REPs have presented promising potential with pulp-dentin regeneration in large animal studies and clinical trials via cell transplantation. In the present review, we summarize current understanding of the biological basis of clinical treatments for immature necrotic permanent teeth and the roles of dental MSCs during this process and update the progress of MSC-based REPs in the administration of immature necrotic permanent teeth.