Success and Complication Rates of Revascularization Procedures for Immature Necrotic Teeth: A Systematic Review

Frequently, adolescents exhibit instances of immature necrotic teeth, which are identifiable by their slender root walls and unclosed root tips. The lack of a natural narrowing near the root's end creates difficulty when using standard endodontic procedures, making the effective sealing of the immature root canal difficult or impractical. Revascularization therapy surfaces as a prospective strategy for addressing the management of undeveloped, non-vital, immature, necrotic teeth. Notwithstanding this, apexification continues to hold prominence in the preferences of clinicians owing to its perceived predictability in treatment outcomes. A systematic investigation was conducted involving various search engines and databases, covering the period from 2001 to 2023. The main aim of this investigation was to find randomized clinical trials that compared the efficacy of revascularization therapy to apexification for treating immature necrotic teeth. The evaluation included a thorough examination of both clinical and radiographic outcomes assessing the success rates and complications. Out of the 850 identified articles, 15 studies were chosen for comprehensive analysis. Notable dissimilarities were not identified between the revascularization therapy and apexification groups concerning parameters such as rates of periapical healing, overall effectiveness/invalidation, and apical closure. However, concentrating on measurable factors, it became clear that the revascularization treatment group displayed a notable rise in root length compared to the apexification group. Both revascularization endodontic therapy and apexification demonstrated effectiveness in addressing periapical periodontitis healing and open apex closure. Pulp revascularization stood out for its notable efficacy in enhancing root elongation and thickening, all while having a reduced likelihood of treatment being deemed ineffective overall.

Apexification with a bioceramic reparative cement: a case report

The aim of this case report is to describe the treatment of a maxillary right central incisor with pulpal necrosis and incomplete root formation. The 14-year-old patient had experienced trauma to both maxillary central incisors approximately 2 years earlier. Therapy consisted of apexification with a bioceramic reparative cement to form an apical plug. After the clinical and radiographic evaluations, the clinician opened the crown, performed the chemical-mechanical preparation, and placed calcium hydroxide-based medication. At the next appointment, 24 days later, the intracanal medication was removed through passive ultrasonic instrumentation; the canal was dried; and the bioceramic cement was inserted into the apical portion with the aid of a mineral trioxide aggregate holder. A sterile cotton ball, moistened with distilled water, was used to maneuver the material in the apical region, and a periapical radiograph was exposed to confirm the correct placement of the bioceramic reparative cement. The canal was filled with gutta percha cones and a bioceramic root canal sealer. All procedures were performed with the aid of microscopic magnification. Clinical and radiographic evaluations at the 18-month follow-up visit showed that the treated tooth was asymptomatic, suggesting that the bioceramic reparative cement is effective for apexification.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Root Maturation of an Immature Dens Invaginatus Despite Unsuccessful Revitalization Procedure: A Case Report and Recommendations for Educational Purposes

BACKGROUND

The clinical management of teeth with complex dens invaginatus (DI) malformations and apical periodontitis may be challenging due to the lack of routine. The aim of this case report is to describe the endodontic treatment of an immature tooth with DI and to discuss strategies for preclinical training for teeth with such malformations.

CASE REPORT

A 9-year-old male presented with an immature maxillary incisor with DI (Oehlers Type II) and apical periodontitis which was diagnosed by cone beam computed tomography (CBCT). Revitalization was initially attempted but then abandoned after failure to generate a stable blood clot. Nevertheless, considerable increase in both root length and thickness could be detected after medication with calcium hydroxide followed by root canal filling with MTA as an apical plug.

CONCLUSIONS

The endodontic management of teeth with DI requires thorough treatment planning. In immature teeth, under certain conditions, root maturation may occur even with conventional apexification procedures. From an educational perspective, different strategies including CBCT and 3D-printed transparent tooth models for visualization of the complex internal morphology and redesigned 3D-printed replica with various degrees of difficulty for endodontic training, can be used to overcome the challenges associated with endodontic treatment of such teeth.

Apical pressures generated by several canal irrigation methods: A laboratory study in a maxillary central incisor with an open apex

Aim

A laboratory study to determine the apical pressure generated by seven canal irrigation methods in an anterior tooth with an open apex.

Methodology

Canal irrigation was performed on a 3D‐printed central maxillary incisor with an open apex (maximum diameter of 2.1 mm). Ultrasonically activated irrigation (UAI), sonic activation (EDDY), negative pressure irrigation (EndoVac), the self‐adjusting file (SAF) and the XP‐endo Finisher were employed at tooth length (TL), TL—1 mm, TL—2 mm and TL—3 mm. UAI was tested at three intensity levels additionally. Hydrodynamic irrigation with RinsEndo was performed in the pulp chamber, at the canal orifice, the coronal third, the middle of the canal and at TL. Er:YAG laser activation, at four frequency settings, was performed in the pulp chamber and at the orifice of the canal. The pressure of the fluid towards the canal terminus generated by activation was directly transferred to a pressure sensor with a range of 0 to 120 mmHg and a response time of ≤0.5 ms. The critical threshold for apical extrusion of the irrigant was set at 5.73 mmHg (lower limit of the central venous pressure: 5.88 ± 0.15 mmHg). Each experiment was repeated ten times. The tests were followed by descriptive analyses (maximum, mean, standard deviation, 95% confidence interval).

Results

EndoVac, the SAF, the XP‐endo Finisher, and UAI never exceeded the critical threshold at any insertion depth or intensity level. Er:YAG laser activation exceeded the critical threshold exclusively at frequency settings that varied from the manufacturer's recommendation. EDDY at TL and RinsEndo at any insertion depth exceeded the critical threshold in 100% of the measurements. EDDY at TL—1,—2, and—3 mm crossed the critical threshold in 30%, 10%, and 20% of the measurements, respectively.

Conclusions

In a simulated maxillary central incisor with an open apex, irrigation with EndoVac, Er:YAG laser activation, UAI, the SAF, and the XP‐endo Finisher generated apical pressures below the critical threshold of 5.73 mmHg. By contrast, using EDDY and RinsEndo for irrigation produced higher apical pressures that exceeded the critical threshold.

Clinical and Radiographic Outcomes of Immature Teeth Treated with Different Treatment Protocols of Regenerative Endodontic Procedures: A Retrospective Cohort Study

Regenerative endodontic procedure (REP) is a progressive treatment modality for immature permanent teeth with necrotic pulp. The ambiguousness about the predictability of REP outcome in relation to complete disinfection of the root canal system and the occurrence of discoloration still exists. The aim of this retrospective study was to analyze two treatment protocols on clinical success rate, radiographic root development and the occurrence of discoloration. Eighteen patients were treated by a single operator by either treatment protocol according to the American Association of Endodontists (AAEP, n = 9) or a modified protocol (MP, n = 9) with the use of 5% sodium hypochlorite and sandblasting. Patients were followed up after 3, 6, 9, 12, 18 and 24 months and clinical success, radiographic root development and the occurrence of discoloration were assessed. The clinical success of MP was significantly higher in two years follow-up (p = 0.015), but the change in radiographic root area was higher for AAEP (p = 0.017) and the occurrence of discoloration was higher in AAEP (p = 0.029). The use of 5% sodium hypochlorite for a longer period of time leads to a higher success rate. The sandblasting of the access cavity reduces the occurrence of discoloration.

Improving pulp revascularization outcomes with buccal fat autotransplantation

Several techniques have been introduced to improve the pulp revascularization outcomes. The use of the tissue graft can create more practical tissue regeneration, provide vascular supply, and enhance tissue healing. The aim of the present study was to investigate the histologic and molecular outcomes of pulp revascularization with buccal fat autotransplantation. Fifty-six open apex roots from four dogs aged 4-6 months were randomly allocated to five groups of endodontic regeneration models: Group 1 (negative control, n = 4); Group 2 (control and without intervention, n = 4); Group 3 (blood clot, n = 16); Group 4 (buccal fat autotransplantation, n = 16); and Group 5 (blood clot plus buccal fat autotransplantation, n = 16). After 3 months, the extracted dog teeth were analyzed by histological and immunohistochemical techniques. Furthermore, real-time quantitative polymerase chain reactions were implemented to assess the gene expression profiles of dentin sialophosphoprotein (DSPP), dentin matrix protein (DMP), collagen I (COL1), and alkaline phosphatase (ALP) on regenerated tissue in the root canals. There were no significant differences in the severity of inflammation and necrosis between intervention groups. Immunohistochemical analysis showed significant differences among the study groups in expression level of extracellular glycoproteins such as fibronectin, laminin, and tenascin C. Group 5 showed an increase in the expression of DMP1 and COL1 genes. The expression of DSPP gene increased significantly in Group 4. The expression of ALP gene increased significantly in Group 3. Using this procedure may open new fields of research for regenerative endodontic procedure in which tissue autotransplant, particularly adipose tissue, may improve the outcomes of pulp revascularization.

Comparative evaluation of calcium release of the apical plugs formed by mineral trioxide aggregate, Biodentine, and EndoSequence root repair material with and without 2% triple antibiotic powder: An in vitro study

BACKGROUND

Apical plug formation by mineral trioxide aggregate (MTA), Biodentine, and EndoSequence root repair material (RRM) is an excellent alternative technique to the conventional apexification procedure. Several antimicrobial agents have been incorporated in MTA and Biodentine to boost their antimicrobial efficacy. Considering the polymicrobial nature of root canal infection, a combination of potent antimicrobials like triple antibiotic powder (TAP) would be needed to address the diverse flora encountered. Calcium release is the consequential factor in the clinical excellence of these cements.

AIM

The aim of the study was to evaluate and compare the calcium released from the apical plugs formed by MTA, Biodentine, and EndoSequence RRM with and without incorporation of 2% TAP.

METHODS

Ninety single-rooted teeth were divided into (n = 15) Group A: MTA + 2% TAP, Group B: MTA, Group C: Biodentine + 2% TAP, Group D: Biodentine, Group E: EndoSequence RRM + 2% TAP, and Group F: EndoSequence RRM to form the 4 mm apical plugs. Each sample tooth was then immersed in 10 ml of deionized water. Evaluation of calcium release was done on days 7, 15, and 30 using an atomic absorption spectrophotometer. Data were analyzed using one-way analysis of variance, post hoc test, and unpaired t-test.

RESULTS

Calcium released was maximum for Group E compared to Group F (P < 0.05), maximum for Group C compared to Group D, and was maximum for Group A compared to Group B (P < 0.05) at days 7, 15 and 30.

CONCLUSION

Incorporation of 2% TAP resulted in increased calcium ions released from MTA, Biodentine, and EndoSequence RRM.

Revascularization and vital pulp therapy in immature molars with necrotic pulp and irreversible pulpitis: A case report with two-year follow-up

Management of teeth with inflamed pulp has been always a challenge. Revascularization and vital pulp therapy are suggested as procedures for successful treatment of immature molars diagnosed with pulp necrosis and irreversible pulpitis, respectively.

Evaluation of the Apical Complex and the Coronal Pulp as a Stem Cell Source for Dentin-pulp Regeneration

INTRODUCTION

This study compared the stemness and differentiation potential of stem cells derived from the apical complex (apical complex cells [ACCs]) and coronal pulp (dental pulp stem cells [DPSCs]) of human immature permanent teeth with the aim of determining a more suitable source of stem cells for regeneration of the dentin-pulp complex.

METHODS

ACC and DPSC cultures were established from 13 human immature permanent teeth using the outgrowth method. The proliferation capacity and colony-forming ability of ACCs and DPSCs were evaluated. ACCs and DPSCs were analyzed for mesenchymal stem cell markers using flow cytometry. The adipogenic and osteogenic differentiation potential of ACCs and DPSCs were evaluated using the quantitative real-time polymerase chain reaction and histochemical staining. ACCs and DPSCs were transplanted subcutaneously in immunocompromised mice using macroporous biphasic calcium phosphate as a carrier. The histomorphologic characteristics of the newly formed tissues were verified using hematoxylin-eosin staining and immunohistochemical staining. Quantitative alkaline phosphatase analysis and quantitative real-time polymerase chain reaction using BSP, DSPP, POSTN, and ColXII were performed.

RESULTS

ACCs and DPSCs showed similar cell proliferation potential and colony-forming ability. The percentage of mesenchymal stem cell markers was similar between ACCs and DPSCs. In the in vitro study, ACCs and DPSCs showed adipogenic and osteogenic differentiation potential. In the in vivo study, ACCs and DPSCs formed amorphous hard tissue using macroporous biphasic calcium phosphate particles. The quantity and histomorphologic characteristics of the amorphous hard tissue were similar in the ACC and DPSC groups. Formation of periodontal ligament-like tissue, positive to Col XII, was observed in ACC transplants, which was absent in DPSC transplants.

CONCLUSIONS

ACCs and DPSCs showed similar stemness, proliferation rate, and hard tissue-forming capacity. The notable difference was the periodontal ligament-like fiber-forming capacity of ACCs, which indicates the presence of various lineages of stem cells in the apical complex compared with the coronal pulp. Regarding regeneration of the dentin-pulp complex, the coronal pulp can be a suitable source of stem cells considering its homogenous lineages of cells and favorable osteo/odontogenic differentiation potential.

Treatment of immature teeth with nonvital pulps in adults: a prospective comparative clinical study comparing MTA with Ca(OH)2

AIM

To evaluate and compare the influence of various predictors on outcomes of apexification using either mineral trioxide aggregate (MTA) or calcium hydroxide (CH) in permanent immature anterior teeth with necrotic pulps and periapical lesions of adults.

METHODOLOGY

Ninety immature teeth with necrotic pulps and periapical lesions on adult patients (aged 18-40 years) were treated with MTA (45 teeth) or CH (45 teeth) between 2015 and 2018. Patients of both groups were recalled for follow-up examinations after the first intervention at 1,3,6 and 12 months for the first year, every 6 months for the second year and every year thereafter until the end of the study (median 32.3 months). The treatment outcome based on clinical and radiographic criteria was assessed by calibrated examiners and dichotomized as 'healed+healing' or 'not healed'. The age, gender, stage of root development, preoperative signs and symptoms of apical periodontitis and size of periapical lesion were recorded. The cumulative success proportion and mean time were analysed with the Kaplan-Meier test. The generalized logrank statistic was used to describe prognostic clinical variables. Fisher's exact test was applied for the evaluation of the healing rates.

RESULTS

Thirty-nine of the 45 teeth treated with MTA were available for recall. Of these, 29 teeth (74%) revealed calcific apical barrier formation with complete resolution of periapical lesions, 7 teeth (18%) were healing, and 3 teeth (8%) had persistent disease. Thirty-four of the 45 teeth in the CH group were available for recall. Of these, 27 teeth (79%) had complete healing of periapical lesions and had calcific barrier formation, 4 teeth (12%) were healing, and the remaining 3 teeth (9%) had not healed. The survival rate of teeth treated with MTA was similar to the survival rates observed in teeth treated with CH (90% and 91%, respectively, P > 0.05). The generalized logrank statistic revealed that the cumulative success rate of both materials was not significantly different (P > 0.05). None of the tested predictors had an influence on the treatment outcomes of teeth in both groups (P > 0.05).

CONCLUSIONS

Apexification with both MTA and CH was associated with similar treatment outcomes. MTA may be proposed as a material for apexification treatment in immature teeth of adult patients due to the shorter treatment time associated with its use.

An In vivo Study to Compare Anti Microbial Activity of Triantibiotic Paste, 2% Chlorhexidine Gel, and Calcium Hydroxide on Microorganisms in the Root Canal of Immature Teeth

Aims and Objectives:

Intracanal medication plays an important role in disinfecting the root canal from various microorganisms. There are various intracanal medication frequently used by practitioners based on the efficacy of the same, therefore to compare antimicrobial activity of a triple antibiotic paste with chlorhexidine gel and calcium hydroxide against microorganisms in the root canal used as irrigating solution.

Materials and Methods:

The present study was conducted on 88 single rooted (central and lateral incisors), asymptomatic, nonvital, and necrotic teeth. Individuals included were between the ages of 12–15 years with no systemic complications. Overall, 88 teeth were divided randomly into four groups on the basis of treatment they were given, with each group having 22 teeth. Each group was assigned to one intervention group namely 2% chlorhexidine gel group, calcium hydroxide group, triantibiotic paste group, and the normal saline group. Triantibiotic paste was prepared from ciprofloxacin Hydrochloride 500 mg+ Metronidazole 400 mg+ Tetracycline 500 mg. Two samples were collected from individual tooth to assess the change in the extent of total colony forming units.

Results:

Mean log¹⁰ bacterial count among the triantibiotic paste was 5.222 preirrigation which was decreased to 0.653. Maximum percentage of log¹⁰ bacterial count was decreased among triantibiotic paste group of 87.20% while control group of normal saline has recorded a decrease of 54.65% in bacterial count. Among all the four groups, there was a decrease of 73.51% of bacterial count.

Conclusion:

From the above results, it was concluded that triantibiotic paste demonstrated the highest efficacy against bacterial pathogen when used as irrigating solution.

Cytokine Expression of Stem Cells Originating from the Apical Complex and Coronal Pulp of Immature Teeth

INTRODUCTION

The aim of this study was to measure and compare the expression levels of cytokines from developing apical complex cells (DACCs) and dental pulp stem cells (DPSCs) of the immature tooth.

METHODS

DPSC-conditioned medium (CM) and DACCs-CM were obtained from human young teeth, and 174 cytokines secreted from each CM were identified and compared. A cytokine membrane array and enzyme-linked immunosorbent assay were used to measure and compare the expression levels of the cytokines. Immunocytochemistry targeting insulin-like growth factor-1 and neurotrophin-3 was additionally performed.

RESULTS

There were statistically significant differences in the expression levels of 25 cytokines: 22 and 3 were expressed more strongly in DPSCs-CM and DACCs-CM, respectively. Odontoblast differentiation-related cytokines were more strongly expressed in DPSCs-CM, while cell-proliferation-related cytokines were more strongly expressed in DACCs-CM. Proinflammatory and anti-inflammatory cytokines were predominantly expressed in DPSCs-CM and DACCs-CM, respectively.

CONCLUSIONS

DPSCs may exert a stronger paracrine effect than DACCs on regeneration of the dentin-pulp complex, in terms of odontoblast differentiation.

Enhanced regeneration potential of mobilized dental pulp stem cells from immature teeth

OBJECTIVES

We have previously demonstrated that dental pulp stem cells (DPSCs) isolated from mature teeth by granulocyte colony-stimulating factor (G-CSF)-induced mobilization method can enhance angiogenesis/vasculogenesis and improve pulp regeneration when compared with colony-derived DPSCs. However, the efficacy of this method in immature teeth with root-formative stage has never been investigated. Therefore, the aim of this study was to examine the stemness, biological characteristics, and regeneration potential in mobilized DPSCs compared with colony-derived DPSCs from immature teeth.

MATERIALS AND METHODS

Mobilized DPSCs isolated from immature teeth were compared to colony-derived DPSCs using methods including flow cytometry, migration assays, mRNA expression of angiogenic/neurotrophic factor, and induced differentiation assays. They were also compared in trophic effects of the secretome. Regeneration potential was further compared in an ectopic tooth transplantation model.

RESULTS

Mobilized DPSCs had higher migration ability and expressed more angiogenic/neurotrophic factors than DPSCs. The mobilized DPSC secretome produced a higher stimulatory effect on migration, immunomodulation, anti-apoptosis, endothelial differentiation, and neurite extension. In addition, vascularization and pulp regeneration potential were higher in mobilized DPSCs than in DPSCs.

CONCLUSIONS

G-CSF-induced mobilization method enhances regeneration potential of colony-derived DPSCs from immature teeth.

Regenerative Characteristics of Apical Papilla-derived Cells from Immature Teeth with Pulpal and Periapical Pathosis

INTRODUCTION

The purpose of this study was to ascertain the regenerative characteristics of apical papilla-derived cells (APDCs) from immature teeth with pulpal and periapical pathosis and thus to provide proof-of-principle evidence for further regenerative endodontic research.

METHODS

Pulpal and periapical pathosis was induced in immature permanent double-rooted premolars of beagles, which were randomly assigned to experimental treatment groups: group AO (n = 14), pulp disruption and access left open; group PS (n = 14), supragingival plaque suspension-soaked cotton pellet was introduced, and access was sealed; and control (n = 7), untreated. The teeth were extracted at 2- and 4-week periods after experimental treatments. APDCs were cultured from the extracted teeth, and their cellular proliferation, differentiation characteristics, and stemness were assessed. The data were statistically analyzed.

RESULTS

After 4 weeks of intentional pulpal and periapical pathosis induction period, all teeth in group PS showed features of apical periodontitis with necrotic pulp, and their APDCs showed significantly increased proliferation rate and osteogenic/odontogenic differentiation capabilities (P < .05). The stemness was maintained in all APDCs, although the stem cell population was smaller in group PS at 2-week period when the inflammatory responses were most fulminant (P < .05).

CONCLUSIONS

The APDCs from immature teeth retained the regenerative characteristics with the differences according to their pulpal and periapical pathosis. The results of this study partly provide the evidence for regenerative endodontic research.

Nonsurgical management of a large periapical lesion associated with an immature tooth displaying external inflammatory resorption

Immature nonvital teeth can often be associated with periapical lesions. Presence of external inflammatory resorption can complicate the treatment plan. A 21-year-old female patient presented with a large periapical lesion in relation to teeth 11 and 12. Tooth 11 was an immature tooth undergoing external inflammatory resorption. Aspiration through the root canal was carried out to evacuate the purulent fluid in the periapical lesion. Triple antibiotic paste was then placed as an intracanal medicament for a period of 2 weeks, followed by calcium hydroxide therapy for a period of 2 months. Mineral trioxide aggregate was then placed as an apical barrier to a thickness of about 4 mm. Obturation of the remainder of the canal space was done after 48 h. Complete periapical healing was evident after 1 year and 6 months. Nonsurgical healing of a large periapical lesion associated with an immature tooth displaying external inflammatory resorption can be successfully achieved.

Direct pulp capping in an immature incisor using a new bioactive material

Preservation of the pulp in a traumatized immature fractured incisor tooth is of prime importance in order to achieve apexogenesis, a natural apical closure. The main factor influencing this is pulpal protection by a bioactive material proving optimum marginal seal in preventing any microleakage. This case report presents an 8-year-old female diagnosed with Ellis Class 3 fracture of immature tooth 11 involving the mesial pulp horn. Under rubber dam isolation, a partial pulpotomy was performed and the pulp was sealed using a new bioactive material BIODENTINE to stimulate apexogenesis, dentine replacement and pulp protection. The fractured segment was reattached for optimum esthetics, which was a concern for the patient. The patient was followed-up for 1, 3, 6 and 12 months, which revealed continued apical closure and maintenance of pulp vitality. The patient remained asymptomatic. This case report provides evidence for the potential use of Biodentine as an effective pulp capping material in the future.

Revascularization of immature permanent teeth with apical periodontitis

The aim of this minireview was to identify and review the scientific evidence regarding regenerative endodontic protocols claiming to revascularize permanent immature teeth with apical periodontitis. The literature was identified using the PubMed/MEDLINE, Scopus, Scirus, EMBASE and Cochrane databases up to February 2013. Studies were selected independently by two different researchers (kappa index: 0.88), based on established inclusion/exclusion criteria. The methodological quality of the reviewed papers was classified as high, medium or low (HQ, MQ, LQ). The search strategy identified 285 titles. Nine studies, both human and animal based, were selected after application of the criteria (LQ:5; MQ:4). In most of these studies (seven of nine), the revascularization protocol included a triple antibiotic combination as canal disinfectant for a period of 1-4 weeks after blood clot formation (LQ:5; MQ:4), although there is no clear consensus about the treatment protocol. Two studies reported tooth discoloration after the revascularization process (LQ:2), and only three (LQ:1; MQ:2) reported a success rate of 54.9% in dogs and 73.6% and 80% in humans, respectively. Revascularization of immature permanent teeth with apical periodontitis is possible and preferable to apexification. Nevertheless, there is a widespread lack of randomized clinical trials and blinded measures. In addition, the small sample sizes that are common in these studies as well as the generally low quality of the analysed publications require the results to be viewed with caution. There is a high risk of bias, with a low quality of available information, for developing clinical guidelines for regenerative endodontic protocols; rigorous randomized clinical trials are therefore needed.

A novel three-dimensional scaffold for regenerative endodontics: materials and biological characterizations

An electrospun nanocomposite fibrous material holds promise as a scaffold, as well as a drug-delivery device to aid in root maturogenesis and the regeneration of the pulp-dentine complex. A novel three-dimensional (3D) nanocomposite scaffold composed of polydioxanone (PDS II®) and halloysite nanotubes (HNTs) was designed and fabricated by electrospinning. Morphology, structure, mechanical properties and cell compatibility studies were carried out to evaluate the effects of HNTs incorporation (0.5-10 wt% relative to PDS w/w). Overall, a 3D porous network was seen in the different fabricated electrospun scaffolds, regardless of the HNT content. The incorporation of HNTs at 10 wt% led to a significant (p < 0.0001) fibre diameter increase and a reduction in scaffold strength. Moreover, PDS-HNTs scaffolds supported the attachment and proliferation of human-derived pulp fibroblast cells. Quantitative proliferation assay performed with human dental pulp-derived cells as a function of nanotubes concentration indicated that the HNTs exhibit a high level of biocompatibility, rendering them good candidates for the potential encapsulation of distinct bioactive molecules. Collectively, the reported data support the conclusion that PDS-HNTs nanocomposite fibrous structures hold potential in the development of a bioactive scaffold for regenerative endodontics.