Exosomes as Promising Therapeutic Tools for Regenerative Endodontic Therapy.

Pulpitis is a common and frequent disease in dental clinics. Although vital pulp therapy and root canal treatment can stop the progression of inflammation, they do not allow for genuine structural regeneration and functional reconstruction of the pulp-dentin complex. In recent years, with the development of tissue engineering and regenerative medicine, research on stem cell-based regenerative endodontic therapy (RET) has achieved satisfactory preliminary results, significantly enhancing its clinical translational prospects. As one of the crucial paracrine effectors, the roles and functions of exosomes in pulp-dentin complex regeneration have gained considerable attention. Due to their advantages of cost-effectiveness, extensive sources, favorable biocompatibility, and high safety, exosomes are considered promising therapeutic tools to promote dental pulp regeneration. Accordingly, in this article, we first focus on the biological properties of exosomes, including their biogenesis, uptake, isolation, and characterization. Then, from the perspectives of cell proliferation, migration, odontogenesis, angiogenesis, and neurogenesis, we aim to reveal the roles and mechanisms of exosomes involved in regenerative endodontics. Lastly, immense efforts are made to illustrate the clinical strategies and influencing factors of exosomes applied in dental pulp regeneration, such as types of parental cells, culture conditions of parent cells, exosome concentrations, and scaffold materials, in an attempt to lay a solid foundation for exploring and facilitating the therapeutic strategy of exosome-based regenerative endodontic procedures.

Correlation between pulp sensibility and magnetic resonance signal intensity following regenerative endodontic procedures in mature necrotic teeth- a retrospective cohort study.

BACKGROUND: With increasing studies being published on regenerative endodontic procedures (REPs) as a treatment modality for mature necrotic teeth, the assessment of outcomes following regenerative endodontic procedures has become more challenging and the demand for a better understanding of the regenerated tissues following this treatment is rising. The study aimed to correlate cold, electric pulp testing (EPT), and magnetic resonance imaging (MRI) signal intensity (SI) in mature necrotic teeth treated with regenerative endodontic procedures. METHODOLOGY: This retrospective cohort study included eighteen adult patients who experienced tooth necrosis in mature maxillary anterior teeth recruited from the outpatient clinic, Conservative Dentistry Department, Faculty of Dentistry, Alexandria University, Alexandria, Egypt from July 2017 until December 2018 with 12 months of follow-up. regenerative endodontic procedures via blood clot were performed. The canals were instrumented by ProTaper Next (PTN) files until final sizes X3 or X5. Biodentine was used as cervical plug material. Pre and post-operative clinical follow-up was done where the patients' responses to cold and electric pulp testing were given a scoring system and were compared to the normal contralateral tooth. Pre and post-operative magnetic resonance imaging signal intensity of both the involved tooth and its contralateral at the middle and the apical thirds of the root canals were assessed after 3, 6, and 12 months. Data was analyzed using the ANOVA, Friedman and Bonferroni tests. Significance was set at a p-value < 0.05. RESULTS: All 18 teeth scored a baseline score of "2" for cold and electric pulp testing. There was a significant difference between scores of the cold test at baseline and 12-month follow-up (p < 0.001). There was a significant difference between scores of the electric pulp testing of baseline and 12-month follow-up (p < 0.001). There was a moderately significant indirect (inverse) correlation between magnetic resonance imaging signal intensity and cold test in both the middle and apical thirds at 12 months. No significant correlations were detected between magnetic resonance imaging signal intensity and electric pulp testingat any of the time intervals (p > 0.05). CONCLUSION: Magnetic resonance imaging is a successful non-invasive method to assess outcomes of regenerative endodontic procedures and correlating it with another reliable method of assessing pulpal responses, cold test, could validate these outcomes. CLINICAL TRIAL REGISTRATION: The study was registered with ClinicalTrials.gov (ID: NCT03804450).

Dental Pulp Cell Transplantation Combined with Regenerative Endodontic Procedures Promotes Dentin Matrix Formation in Mature Mouse Molars.

Regenerative endodontic procedures (REPs) are promising for dental pulp tissue regeneration; however, their application in permanent teeth remains challenging. We assessed the potential combination of an REP and local dental pulp cell (DPC) transplantation in the mature molars of C57BL/6 mice with (REP + DPC group) or without (REP group) transplantation of DPCs from green fluorescent protein (GFP) transgenic mice. After 4 weeks, the regenerated tissue was evaluated by micro-computed tomography and histological analyses to detect odontoblasts, vasculogenesis, and neurogenesis. DPCs were assessed for mesenchymal and pluripotency markers. Four weeks after the REP, the molars showed no signs of periapical lesions, and both the REP and REP + DPC groups exhibited a pulp-like tissue composed of a cellular matrix with vessels surrounded by an eosin-stained acellular matrix that resembled hard tissue. However, the REP + DPC group had a broader cellular matrix and uniquely contained odontoblast-like cells co-expressing GFP. Vasculogenesis and neurogenesis were detected in both groups, with the former being more prominent in the REP + DPC group. Overall, the REP was achieved in mature mouse molars and DPC transplantation improved the outcomes by inducing the formation of odontoblast-like cells and greater vasculogenesis.

Cell-Based Regenerative Endodontics for the Treatment of Irreversible Pulpitis: AnIn VivoInvestigation.

INTRODUCTION: This study aims to investigate the ability of umbilical cord mesenchymal stem cells (UC-MSC) to enhance the regeneration of pulp-dentin complex in immature permanent teeth with irreversible pulpitis. METHODS: A total of 32 mandibular premolar teeth with immature apices in 5 dogs were used in this in-vivo randomized controlled trial (RCT). Eight healthy teeth without pre-existing pathosis served as the positive control samples and received no treatment, while in another 8 teeth, the pulp was completely extirpated (negative control). Class V cavities were prepared to induce inflammation in the remaining 16 teeth (groups 3 and 4) and the pulp was extirpated 2-4 mm short of the radiographic apex. Of the 16, the 8 teeth in group 4 received 1 mL of cord blood stem cells with a hydrogel scaffold. Blood clots were covered with mineral trioxide aggregates at the cementoenamel junction in the experimental groups, and teeth were filled with RMGI and composite. Three months later, block sections were removed for histologic evaluations for the evaluation of postoperative apical closure, degree of inflammation, and presence of normal pulp tissue. The data were statistically analyzed with the chi-square test (P < .05). RESULTS: All teeth with complete pulp extirpation demonstrated pulpal necrosis with no postoperative closure of their apices, while apical closure was seen in all the teeth in the remaining groups. There was a statistically significant (P < .001) difference in the presence of inflammation and normal pulp tissue between the experimental groups. The teeth in group 3 showed normal pulp tissue extending to the level of MTA, but there was inflammation within the canal space. In contrast, the teeth in the UC-MSC group demonstrated organized, normal pulp tissue with no inflammation. CONCLUSION: Based on these results, the regeneration of the pulp-dentin complex is possible with no inflammation when UC-MSCs are used and 2-4 mm of the apical pulp remains intact in immature teeth with irreversible pulpitis.

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.

Analysis of the achievement of primary and secondary goals and influencing factors in single-rooted immature permanent teeth after regenerative endodontic procedures: a retrospective study.

OBJECTIVE: This study explored the achievement of primary and secondary goals and factors influencing their achievement in regenerative endodontic procedures (REPs) for immature permanent teeth. METHODS: Dental records of all patients who received REPs for immature permanent teeth at the Department of Pediatric Dentistry, Peking University School and Hospital of Stomatology between January 2012 and January 2023 were retrieved. The evaluation of the primary goal was based on medical and radiographic records. The achievement of the primary goal was defined as the absence of clinical signs and symptoms, such as pain, swelling, or sinus tract and the absence of periapical radiolucency, as assessed on postoperative periapical radiographs. The achievement of secondary goal represented increased root wall thickness and/or increased root length, that is, continued root development. Periapical radiographs before and after treatment were used to evaluate the achievement of the secondary goal. The secondary goal was required to be achieved alongside the achievement of primary goal. RESULTS: A total of 436 teeth (136 anterior and 300 posterior teeth) were included in this study, 96.1% of which demonstrated achievement of the primary goal. Signs of failure (17 teeth) included crown fracture and uncontrolled and recurrent periapical lesions. In addition, 77.8% of teeth demonstrated achievement of the secondary goal, and more than half of the teeth exhibited a complete root development. Evaluation factors included patients' age, sex, tooth type, etiology, preoperative periapical lesion, duration of clinical signs and symptoms, follow-up period, and stage of root development. The achievement of the primary and secondary goals were significantly related to age and tooth type (p < 0.05). CONCLUSIONS: Children with a younger initial visit age are more likely to achieve primary and secondary goals. Additionally, posterior teeth had an advantage over anterior teeth in achieving primary and secondary goals.

[Retrospective evaluation of treatment outcomes in immature teeth treated with regenerative endodontic procedures with an over-36-month review].

OBJECTIVE: To evaluate the clinical outcomes of immature teeth treated with regenerative endodontic procedures with an over-36-month review, to identify potential contributing factors of root deve-lopment, and to provide new reference for long-time prognosis of regenerative endodontic procedures. METHODS: We recruited teeth that had undergone regenerative endodontic procedures at the Department of Pediatric Dentistry in Peking University School and Hospital of Stomatology from January 2013 to June 2017 and had a follow-up period of more than 36 months.Clinical and radiographic records were collected.We evaluated the treatment outcomes and summarized different patterns of root development.Changes in root length, root canal wall thickness were compared between preoperative and recall radiographs.A statistical analysis was performed using software SPSS 22.0 to identify potential contributing factors of root development. RESULTS: In this study, 84 teeth were recruited and the mean follow-up period was (44.7±19.3) months.The longest follow-up period was 81 months.Sixty-eight teeth (81.0%) were clinical success with bony healing, and 55 teeth (80.9%) gained the continued root development.Forty teeth completed root development with apical closure.The rate of the apical closure reached 58.8%.Twenty-four teeth gained normal root morphology with the increasing of root length and canal wall thickness and apical closure.The rate of continued root development was 92.5% in teeth with broken central cusp and 58.3% in teeth with trauma, which was statistically significant (P < 0.05).There was a statistically significant difference (P < 0.05) between the root development rates of teeth with different induced bleeding heights (orifice/middle/tip of the root)(92.9%/81.0%/63.2%). CONCLUSION: Most of the teeth treated with regenerative endodontic procedures achieved continued root development with an over 36-month follow-up.However, the patterns of root development were different.The morphology of some teeth were close to the physiological state.Etiology and the height of induced bleeding are two factors significantly associated with the rate of the continued development root.

Histologic and Electron Microscopic Characterization of a Human Immature Permanent Premolar with Chronic Apical Abscess 16 Years after Regenerative Endodontic Procedures.

Previous studies have reported successful clinical outcomes after regenerative endodontic procedures (REPs) for immature permanent teeth with pulpal infection. However, it remains unclear whether the procedures promote true regeneration or repair. This case report describes the histologic and electron microscopic characteristics of a human immature permanent premolar with a chronic apical abscess that was treated with an REP. Tooth #20 of a 9-year-old girl underwent an REP. At the 6-year follow-up, the patient was asymptomatic, and closure of the apex and thickening of the dentinal walls were observed. However, 16 years after the procedure, apical periodontitis recurred, necessitating apical surgery. The resected root fragments were obtained during the surgery and analyzed using micro-computed tomography, light microscopy, and scanning electron microscopy. Distinct dentinal tubules and interglobular dentin were observed in the regenerated hard tissue. Cementum-like tissue and a root canal were also observed in the apical fragment. The regenerated root tissue in this case exhibited a structure similar to the native root structure. Therefore, we believe that cell-free REPs possess regenerative potential for teeth diagnosed with pulp necrosis and chronic apical abscess.

Multimodal Imaging of Dental Pulp Healing Patterns Following Tooth Autotransplantation and Regenerative Endodontic Treatment.

INTRODUCTION: Understanding the healing process of dental pulp after tooth autotransplantation (TAT) and regenerative endodontic treatment (RET) of immature teeth is important both clinically and scientifically. This study aimed to characterize the pattern of dental pulp healing in human teeth that underwent TAT and RET using state-of-the-art imaging techniques. MATERIALS AND METHODS: This study examined 4 human teeth, 2 premolars that underwent TAT, and 2 central incisors that received RET. The premolars were extracted after 1 year (case 1) and 2 years (case 2) due to ankylosis, while the central incisors were extracted after 3 years (cases 3 and 4) for orthodontic reasons. Nanofocus x-ray computed tomography was used to image the samples before being processed for histological and immunohistochemical analysis. Laser scanning confocal second harmonic generation imaging (SHG) was used to examine the patterns of collagen deposition. A maturity-matched premolar was included as a negative control for the histological and SHG analysis. RESULTS: Analysis of the 4 cases revealed different patterns of dental pulp healing. Similarities were observed in the progressive obliteration of the root canal space. However, a striking loss of typical pulpal architecture was observed in the TAT cases, while a pulp-like tissue was observed in one of the RET cases. Odontoblast-like cells were observed in cases 1 and 3. CONCLUSIONS: This study provided insights into the patterns of dental pulp healing after TAT and RET. The SHG imaging sheds light on the patterns of collagen deposition during reparative dentin formation.

3D Organoids for Regenerative Endodontics.

Apical periodontitis is the inflammation and destruction of periradicular tissues, mediated by microbial factors originating from the infected pulp space. This bacteria-mediated inflammatory disease is known to interfere with root development in immature permanent teeth. Current research on interventions in immature teeth has been dedicated to facilitating the continuation of root development as well as regenerating the dentin-pulp complex, but the fundamental knowledge on the cellular interactions and the role of periapical mediators in apical periodontitis in immature roots that govern the disease process and post-treatment healing is limited. The limitations in 2D monolayer cell culture have a substantial role in the existing limitations of understanding cell-to-cell interactions in the pulpal and periapical tissues. Three-dimensional (3D) tissue constructs with two or more different cell populations are a better physiological representation of in vivo environment. These systems allow the high-throughput testing of multi-cell interactions and can be applied to study the interactions between stem cells and immune cells, including the role of mediators/cytokines in simulated environments. Well-designed 3D models are critical for understanding cellular functions and interactions in disease and healing processes for future therapeutic optimization in regenerative endodontics. This narrative review covers the fundamentals of (1) the disease process of apical periodontitis; (2) the influence and challenges of regeneration in immature roots; (3) the introduction of and crosstalk between mesenchymal stem cells and macrophages; (4) 3D cell culture techniques and their applications for studying cellular interactions in the pulpal and periapical tissues; (5) current investigations on cellular interactions in regenerative endodontics; and, lastly, (6) the dental-pulp organoid developed for regenerative endodontics.

Regeneration of a large bony lesion with advanced-platelet rich fibrin: case report / Regeneración de una lesión ósea de gran tamaño con fibrina rica en plaquetas: reporte de caso

Introduction: This case report analyzes the regeneration potential of advanced-platelet rich fibrin (A-PRF) in large bony lesions. Advanced-platelet rich fibrin provides various growth factors which aids in faster healing. Materials and Methods: Patient presented with peri-apical radiolucency. CBCT showed bony radiolucency in teeth 31, 32, 41, 42. A full mouth mucoperiosteal flap was raised and a cyst lining was enucleated. Apicoectomy was done with respect to 31, 32, 41, 42 along with and retrograde with a preparation of APRF clots were placed in the bony cavity. Results: Post-op CBCT at 6 months showed a significant difference in size and bone density of the lesion. Conclusions: Advanced-platelet rich fibrin has shown promising results in reducing the size of bony defect and periapical lesion in this case.

Introducción: Este caso clínico demuestra el potencial de regeneración de la fibrina rica en plaquetas avanzada (A-PRF) en lesiones óseas de gran tamaño. La fibrina rica en plaquetas avanzada proporciona varios factores de crecimiento que ayudan a una curación más rápida. Materiales y Métodos: El paciente se presentó con radiolucencia periapical. Tomografía computarizada de haz cónico mostró radiolucencia ósea en los dientes 31, 32, 41, 42. Se levantó un colgajo mucoperióstico de boca completa y se enucleó el revestimiento del quiste. Se realizó apicectomía con respecto a 31, 32, 41, 42, y se colocó una preparación de APRF se colocaron coágulos en la cavidad ósea. Resultados: La tomografía computarizada de haz cónico postoperatorio a los 6 meses mostró una diferencia significativa en el tamaño y la densidad ósea de la lesión. Conclusión: La fibrina rica en plaquetas avanzada ha mostrado resultados prometedores en la reducción del tamaño del defecto óseo y la lesión periapical en este caso.

Regenerative endodontic therapy in mature teeth with necrotic pulp and apical periodontitis using two disinfection protocols.

OBJECTIVE: This study compared the effect of diode laser (DL) 980 nm and double antibiotic paste (DAP) on response of mature teeth with necrotic pulp and apical periodontitis to regenerative endodontic therapy in a dog model. METHODS: Pulp necrosis and periapical pathosis were induced in 40 mature double rooted premolars in four 2-year-old mongrel dogs. These teeth were randomly divided according to disinfection protocol into four equal groups (10 teeth each/20 roots), group I: DAP; group II: DL980 nm; group III: positive control (without treatment) and group IV: negative control (untouched teeth). These groups were further subdivided into 2 subgroups (5 teeth each/10 roots) according to evaluation period, subgroup (A): one month and subgroup (B): three months. Revascularization techniques were performed using bleeding induction and application of platelet rich fibrin (PRF). The coronal cavities were sealed with mineral trioxide aggregate (MTA) and glass ionomer cement. The inflammatory response, vital tissue in-growth, new hard tissue formation and bone resorption were assessed. Statistical analysis was done utilizing ANOVA, Tukey's post hoc and paired t tests. RESULTS: In both subgroups, there were no significant differences between DAP and DL980 in terms of inflammatory cell count, vital tissue in-growth, new hard tissue formation and bone resorption (P ≤ 0.05). CONCLUSION: Diode laser 980 nm can alternate DAP as a disinfection method of the root canal during RET for mature necrotic teeth, therefore it may accelerate regenerative endodontic therapy for both the patient and dentist and allows for RET in a single appointment.

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

OBJECTIVES: To evaluate the effect of EDTA and saline as the final irrigation in regenerative endodontic procedures (REPS) on the attachment, proliferation, migration, and differentiation of stem cells from the apical papilla (SCAPs). MATERIALS AND METHODS: Dentin specimens from 140 human third molars were irrigated with various protocols-group 1: normal sterile saline (NSS), group 2: EDTA, group 3: EDTA then 5 mL NSS, or group 4: EDTA then 20 mL NSS. The specimens were used in cell assays. For cell proliferation, SCAPs were seeded on dentin, and the cell viability on days 1, 3, and 7 was determined using an MTT assay. At day 3, the attached cells' morphology was observed using SEM, and cell migration was investigated using a transwell migration assay. The ALP activity and odonto/osteogenic differentiation gene expression were evaluated at days 7, 14, and 21 using an ALP activity assay and RT-qPCR. RESULTS: On days 3 and 7, group 4 demonstrated more viable cells than group 1 (p < 0.01). The amount of migrated cells in groups 2, 3, and 4 was greater compared with group 1 (p < 0.05). Moreover, SCAP differentiation was similar between groups. CONCLUSIONS: Irrigating dentin with EDTA alone or with EDTA then NSS promoted SCAP migration. However, a final irrigation with 20 mL NSS after EDTA promoted SCAP proliferation without affecting their differentiation. CLINICAL RELEVANCE: When using a blood clot as a scaffold, a final flushing with 20 mL NSS after EDTA could be beneficial for clinical REP protocols.

Review of guidance for the selection of regenerative endodontics, apexogenesis, apexification, pulpotomy, and other endodontic treatments for immature permanent teeth.

This review guidance is a work in progress because the limitations of regenerative endodontics are still being discovered. The endodontic treatments for immature permanent teeth with a necrotic pulp can vary considerably among endodontic practitioners. Whereas, regenerative endodontic treatments are growing in popularity and are creating ever more complex treatment protocols, involving revascularization and/or autologous platelet-rich plasma and scaffolds to elicit host stem cell de novo tissue formation to reestablish the vitality of immature teeth for the purpose of continuing root maturation. Despite much evolving controversy about their potential benefits, risks, prognosis, and contraindications, this review is aimed to discuss how to ensure that regenerative endodontic treatments are successful, by strictly adhering to case selection criteria, and following precise steps to accomplish and monitor the success of the treatment. A review of the endodontic literature was performed, together with practical observations of the problems and outcomes of performing regenerative endodontic treatments. Traditionally, apexification has long been the treatment of choice provided to immature teeth with a necrotic pulp. Regenerative endodontics may be provided as an alternative to apexification, if the tooth and patient meet all the case selection criteria, and if there are no contraindications. Regenerative endodontics has the unique potential advantage of being able to continue the root development in immature permanent teeth, thereby potentially saving the teeth for the lifetime of the patient. Whereas, conventional endodontic root canal treatment, Cvek partial pulpotomy, apexogenesis, and apexification, should always be provided when these treatments are more likely to benefit the patient because they can be more successful than regenerative endodontics.

Regenerative endodontic procedure combined with non-surgical root canal treatment in an immature permanent maxillary molar: A 7-year follow-up case report.

The aim of this report is to present the results of a personalised endodontic treatment for an immature molar, using regenerative endodontic procedure (REP) combined with non-surgical root canal treatment (NSRCT), with 7 years of follow-up. The tooth#3 presented combined endodontic pathologies in each root, with different pulpal and periapical status. A REP in the palatal (P) canal and a NSCRT in the mesio-buccal (MB) and disto-buccal (DB) canals were performed. Absence of clinical signs/symptoms and continuous palatal root development with apical closure were observed over 4-years. After 5-years an apical lesion in the MB root was observed. Both MB canals were selectively retreated by completely filling them with TotalFill BC RRM Fast Set putty. After 7-years, the tooth remained functional and the apical lesion was resolving. The palatal root was completely mature. This case report reveals the potential for use of combined treatment approaches for immature multirooted teeth.

Regenerative endodontic treatment of immature permanent teeth after mechanical instrumentation with XP-Endo Finisher.

INTRODUCTION: The traditional treatment of immature permanent teeth with necrotic pulp involves creating an apical barrier by using calcium hydroxide or an MTA plug for an extended period of time. A novel therapeutic approach called regenerative endodontic procedures (REP) is used to allow root development to continue.

Failure of Regenerative Endodontic Procedures: Case Analysis and Subsequent Treatment Options.

INTRODUCTION: Regenerative endodontic procedures (REPs) are considered effective treatments for immature necrotic permanent teeth, with favorable outcomes. However, failed cases require subsequent treatment. This study aimed to review and analyze failed cases after REPs and suggest a treatment algorithm to aid clinical decision-making. METHODS: A total of 111 REP cases were selected that were conducted between 2015 and 2020. Clinical outcomes were assessed based on clinical and radiographic evaluations. The criteria for failure included persistence of clinical signs or symptoms and/or periapical radiolucency showing persistent apical periodontitis. Cases requiring any treatment intervention, including extraction, were also considered failures. RESULTS: Sixteen cases were included as failures. The etiology of pulpal disease was stratified into dental trauma (56%), dens evaginatus (25%), and dental caries (12.5%), with the remaining one case having an undocumented cause. The primary reasons for treatment failure were persistent infection (81.3%) and root resorption (18.7%). The identification time of failure varied, with 6 cases (37.5%) detected in less than 6 months and 10 cases (62.5%) later than 6 months after REPs. Sixteen failed cases received 5 different interventions: second REPs, apexification, conventional root canal treatment, surgical approach, and extraction. CONCLUSIONS: Interventions for failed REPs are challenging. Consideration of the treatability of the tooth, accessibility to the canal, and the presence of an apical seat might be key factors in clinical decision-making to obtain a successful outcome.

Deciduous Tooth Pulp Autotransplantation for the Regenerative Endodontic Treatment of Permanent Teeth With Pulp Necrosis: A Case Series.

INTRODUCTION: In young individuals, deciduous tooth pulp might be used as a natural, biologic scaffold for the regenerative endodontic treatment (RET) of young permanent teeth with necrotic pulps and apical periodontitis. The present case series demonstrates the clinical and radiographic outcomes of a novel RET using deciduous pulp autotransplantation in traumatized, necrotic young permanent incisors. METHODS: Five previously traumatized maxillary incisors of four 8- to 11.5-year-old patients were treated with a RET protocol that used 2.5% NaOCl irrigation and placement of calcium hydroxide dressing in the first visit. After 4 weeks, the intracanal medication was removed, and the whole pulp tissue harvested from the neighboring maxillary deciduous canine was transplanted into the disinfected root canal without induced apical bleeding. Following placement of a mineral trioxide aggregate coronal barrier, the access cavities were restored with acid-etch resin composite. The root canals of donor primary canines were filled with calcium hydroxide-iodoform paste and were restored as with the permanent incisors. RESULTS: Three patients were followed-up for 24 months, and 1 patient for 12 months. All teeth demonstrated radiographic evidence of complete periapical healing, slight increase in dentinal wall thickness, and continued apical closure in the absence of clinical symptoms. A positive response to cold test was obtained in 1 incisor at 12 months and 2 at 24 months. CONCLUSIONS: Based on 12- and 24-month clinical and radiographic findings, the present cases demonstrate a favorable outcome of a RET protocol using deciduous pulp autotransplantation in young permanent incisors with pulp necrosis.

Regenerative Endodontic Treatment Using Periapical Blood or Circulating Blood as Scaffold: A Volumetric Analysis.

INTRODUCTION: Circulating blood is a readily available scaffold when enough bleeding cannot be induced from periapical tissues during regenerative endodontic treatments (RETs). The aim of this investigation was to compare the radiographic outcome (ie, linear and 3-dimensional volumetric) of RET using periapical blood or circulating blood as scaffolds in sheep immature mandibular incisors. METHODS: Thirty-two immature sheep mandibular central incisors were randomly assigned to the following groups (n = 8): the positive control groups, the pulps were removed without any treatment; the periapical blood group, RET was performed using periapical blood as the scaffold; the circulating blood group, RET was performed using circulating blood as the scaffold; and the negative control group, intact teeth without any treatment. After 8 months, micro-computed tomographic images of mandibular blocks were taken to assess the following: root length, root thickness at the midroot and cementoenamel junction levels, and the incidence of apical closure. Root structures were segmented, and root volumes were calculated and analyzed statistically. RESULTS: RET using periapical blood and circulating blood resulted in increases in root length and root wall thickness at the midroot and cementoenamel junction levels, the incidence of apical closure, and root volume (P < .05). There were no significant differences between the RET groups and the negative control group regarding linear measurements (ie, root length, root thickness, and apical closure) (P > .05). The root volumes of the 2 RET groups were similar (P > .05) and were less than those observed in the negative control group (P < .05). CONCLUSIONS: There were no significant radiographic differences between the RET groups using periapical blood and circulating blood as scaffolds. RET resulted in less root volume compared with normal root development.