Root Maturation in Teeth Treated by Unsuccessful Revitalization: 2 Case Reports

Root Canal Dentin Microhardness after Contact with Antibiotic Medications: An In Vitro Study

Background: Antibiotic pastes used as intracanal medication in cases of revascularization therapy might cause negative effects on tooth properties, such as a reduction in dentin microhardness. This in vitro study investigated dentin microhardness in three different locations distancing from the canal lumen after 20 days of treatment with a tri-antibiotic paste (ciprofloxacin, metronidazole, and minocycline), and with a double-antibiotic paste (ciprofloxacin and metronidazole), with calcium hydroxide [Ca(OH)2] UltracalTM XS-treated dentin as comparison. Material and Methods: Human mandibular premolars (n = 48) had the root canals cleaned and shaped and were used to produce dentin slices. Dentin slices remained immersed in the medications for 20 days. The Knoop microhardness (KHN) test was performed before (baseline/Day-0) and after treatment (Day-20) with the medications. Indentations were made at 25 µm, 50 µm, and 100 µm distances from the root canal lumen. The KHN was compared intra-group using Wilcoxon's test. Independent groups were compared using Mann-Whitney's and Kruskal-Wallis' tests, at α = 5%. Results: The microhardness in all the tested groups was reduced at Day-20 in comparison with Day-0 (p < 0.001) (intra-group comparison/same distances). The Day-0 values were similar, and the Day-20 values were higher for the Ca(OH)2 group (p < 0.05) (comparison between groups/same distances). Conclusions: Calcium hydroxide for 20 days would be preferred rather than antibiotic pastes to minimize the expected reduction in dentin microhardness during regenerative procedures.

Treatment outcomes of regenerative endodontic procedures in nonvital mature permanent teeth: a retrospective study

OBJECTIVES

This retrospective study was undertaken to clinically and radiographically evaluate the long-term outcomes of regenerative endodontic procedures (REPs) for nonvital mature permanent teeth, to analyze predictors influencing treatment outcomes.

METHODS

Nonvital mature permanent teeth treated by REPs with a minimum follow-up period of 6 months were included from 2015 to 2017. Treatment outcomes were categorized as success and failure. The periapical status and lesion healing were assessed in terms of the periapical index (PAI) and the percentage changes in periapical radiolucency (PARL) area. The clinical and radiographic outcomes of REPs were assessed by Mann-Whitney test at different follow-up period. Kaplan-Meier curves and Univariate Cox regression analysis were conducted to assess the success and identify potential predictors affecting outcomes, respectively.

RESULTS

A total of 37 mature teeth with an average follow-up of 4.3 years satisfied the criteria, and 89.2% of the teeth had a successful outcome. Significant differences in PAI scores were found between each period with respect to the baseline (p < .05). Among different periods, there was a significant difference between intervals of 3-6 months and 7-12 months (p = .039) and no significant difference between each interval of more than 12 months (p > .05). Eighty-seven percent of teeth with preoperative PARL presented completely healed. REPs significantly decreased the PARL area at the interval of 7-12 months compared to 3-6 months (p = .025), with no significant difference between each interval of more than 12 months (p > .05). No significant predictor was found for the success of outcome (p > .05). Thirteen teeth (35.1%) regained pulp sensibility, and 40.5% of the teeth exhibited intracanal calcification.

CONCLUSIONS

Within the limitations of this study, REPs provided a high long-term success rate and promoted the resolution of PARL as a biologically-based alternative treatment option for nonvital mature teeth.

CLINICAL RELEVANCE

REPs provide a high long-term success rate and promoted healing of apical periodontitis comparable with reported outcomes for root canal therapy of mature teeth.

Is Etiology a Key Factor for Regenerative Endodontic Treatment Outcomes?

INTRODUCTION

This study aimed to evaluate treatment outcomes of regenerative endodontic treatment (RET) in nonvital immature permanent teeth due to developmental malformation and trauma, and to analyze the influence of etiology on the prognosis.

METHODS

Fifty-five cases were included and divided into a malformation group (n=33) and a trauma group (n=22). Treatment outcomes were classified as healed, healing and failure. Root development was evaluated in terms of root morphology and the percentage changes in root length, root width and apical diameter during a follow-up period of 12 to 85 months (mean 30.8 months).

RESULTS

The mean age and the mean degree of root development in the trauma group were significantly younger than that in the malformation group. The success rate of RET was 93.9% (81.8% healed, 12.1% healing) in the malformation group and 90.9% (68.2% healed, 22.7% healing) in the trauma group, showing no statistically significant difference. The proportion of type I-III root morphology in the malformation group (97%, 32/33) was significantly higher than that in the trauma group (77.3%, 17/22) (P<0.05), whereas there was no significant difference in the percentage changes of root length, root width and apical diameter between the two groups. Six cases (6/55, 10.9%) showed no significant root development (type IV-V) (1 in the malformation group and 5 in the trauma group). Six cases (6/55, 10.9%) revealed intracanal calcification.

CONCLUSIONS

RET achieved reliable outcomes regarding the healing of apical periodontitis and continued root development. The etiology seems to influence the outcome of RET. Malformation cases presented with a better prognosis than trauma cases after RET.

Gelatin methacryloyl hydrogel as an injectable scaffold with multi-therapeutic effects to promote antimicrobial disinfection and angiogenesis for regenerative endodontics

Regenerative endodontics represents a paradigm shift in dental pulp therapy for necrotic young permanent teeth. However, there are still challenges associated with attaining maximum root canal disinfection while supporting angiogenesis and preserving resident stem cells viability and differentiation capacity. Here, we developed a hydrogel system by incorporating antibiotic-eluting fiber-based microparticles in gelatin methacryloyl (GelMA) hydrogel to gather antimicrobial and angiogenic properties while prompting minimum cell toxicity. Minocycline (MINO) or clindamycin (CLIN) was introduced into a polymer solution and electrospun into fibers, which were further cryomilled to attain MINO- or CLIN-eluting fibrous microparticles. To obtain hydrogels with multi-therapeutic effects, MINO- or CLIN-eluting microparticles were suspended in GelMA at distinct concentrations. The engineered hydrogels demonstrated antibiotic-dependent swelling and degradability while inhibiting bacterial growth with minimum toxicity in dental-derived stem cells. Notably, compared to MINO, CLIN hydrogels enhanced the formation of capillary-like networks of endothelial cells in vitro and the presence of widespread vascularization with functioning blood vessels in vivo. Our data shed new light onto the clinical potential of antibiotic-eluting gelatin methacryloyl hydrogel as an injectable scaffold with multi-therapeutic effects to promote antimicrobial disinfection and angiogenesis for regenerative endodontics.

Preoperative factors analysis on root development after regenerative endodontic procedures: a retrospective study

Background

Regenerative endodontic procedures (REPs) have achieved clinical success on the immature permanent teeth with pulp necrosis, and can promote root development. However, preoperative factors and their effects on root development of REPs have not been definitely concluded. The aim of this study was to investigate the preoperative factors that may influence the root development of REPs.

Methods

A total of 116 teeth in 110 patients treated with REPs in the Paediatric Dentistry Department and Endodontics Department from 2013 to 2017 were included in this study. Preoperative factors including aetiology, age, diagnosis and initial root morphology were collected retrospectively, and the associations between these factors and root development after REPs were analysed by Fisher's exact test and multivariate logistic regression model.

Results

The overall rate of root development after REPs was 89.7%. The dens evaginatus group showed a higher rate (98.8%) in root development than the trauma group (67.6%) (P < 0.01). There was no significant difference among the different age groups (7–13 years old) or among different diagnoses groups (P > 0.05). And it showed in the trauma group that the teeth with apical foramen sizes larger than 3 mm significantly promoted root development than those smaller than 3 mm (P < 0.01). Multivariate logistic regression indicated that aetiology was significantly correlated with root development of REPs (OR: 0.07, 95% CI 0.007, 0.627, P < 0.05).

Conclusions

The REPs promoted more root developments in the dens evaginatus group than the trauma group, indicating that aetiology may be correlated with the root development of REPs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-022-02412-x.

10-Year Follow-up of Previously-Traumatized Immature Permanent Incisors Sustaining Second and Third Traumatic Injuries After Revascularization Treatment: Case reports

The long-term prognosis of previously traumatized immature permanent teeth treated with guided endodontic repair is well documented, but little is known about how these teeth respond to further traumatic injury after treatment. This case report presents the 10-year clinical and radiographic findings of two patients with traumatized maxillary incisors who underwent guided endodontic repair treatment and sustained two further traumatic injuries. Three crown-fractured maxillary central incisors with pulp necrosis were treated with a protocol that used 2.5% NaOCl irrigation, 3-4 week medication with calcium hydroxide or ciprofloxacin-metronidazole paste, induction of apical bleeding, and coronal sealing with mineral trioxide aggregate. One tooth sustained subluxation and a crown fracture after 20 months and 7 years, respectively. Two other teeth had a luxation injury at 9 months and subluxation 6.5 years after the regenerative treatment. One subluxated and one luxated tooth remained free of symptoms for 10 years with radiographic evidence of progressive root canal calcification, while the other luxated incisor required root canal treatment after 7.5 years. Although teeth treated with the so-called "regenerative" endodontic techniques do not possess true pulp tissue, the reparative tissue may respond to traumatic injuries in a similar manner to teeth with normal pulps.

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 conducted between 2015-2020. 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 six cases (37.5%) detected in less than six months and ten cases (62.5%) later than six months after REPs. Sixteen failed cases received five different interventions: second REPs, apexification, conventional root canal treatment, surgical approach, and extraction.

CONCLUSION

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.

Combined conventional and regenerative treatment in molars with coexistent closed and open apices: A case series

Regenerative endodontic treatment (RET) may not be suitable in some necrotic young permanent molars due to coexistent roots with closed and open apices, and/or inadequate apical bleeding in one or more roots. Here, we present a combined treatment approach utilising conventional root canal treatment in the closed-apex roots and RET on the open-apex roots of necrotic young molars. The closed-apex roots of 8 molars received root fillings, and their open-apex roots were treated with a regenerative endodontic procedure. In another molar, the failed RET on one root was retreated by conventional root canal filling, preserving other revitalised roots. After 4-6 years, all teeth showed periapical healing in the absence of clinical symptoms. The combined conventional and regenerative treatment approach can yield favourable healing outcomes in necrotic, young molar roots with different levels of apical closure. Likewise, failed revitalised roots can be retreated separately with conventional root filling.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Pulp regeneration with hemostatic matrices as a scaffold in an immature tooth minipig model

Control of blood clotting in root canal systems is one of the most critical and difficult concerns for regenerative endodontics therapy (RET). The purpose of this study was to investigate the effects of using gelatin- and fibrin-based hemostatic hydrogels as a scaffold on pulp regeneration in a minipig model. Cell viability of human dental pulp stem cells cultured three-dimensionally in gelatin-based and fibrin-based scaffolds was evaluated by MTT and live/dead assay. RET was performed on 24 immature premolars with an autologous blood clot (PC), gelatin-based and fibrin-based hemostatic matrices (GM and FM), or without the insertion of a scaffold (NC). The follow-up period was 12 weeks. Radiographic and histologic assessments for pulp regeneration were performed. Gelatin-based scaffolds exhibited significantly higher cell viability than fibrin-based scaffolds after 15 days (P < 0.05). The PC and GM groups showed favorable root development without inflammation and newly mineralized tissue deposited in the root canal system, while FM group presented inflammatory changes with the continuation of root development. The NC group exhibited internal root resorption with periapical lesions. The application of GM in RET led to favorable clinical outcomes of root development without inflammatory changes compared to conventional RET. Our results suggest that GM may serve as a viable regenerative scaffold for pulp regeneration.

Clinical Outcomes of Immature Teeth Treated with Regenerative Endodontic Procedures-A San Antonio Study

INTRODUCTION

Factors that influence clinical outcomes for regenerative endodontic procedures (REPs) are unknown. This retrospective study aimed to assess tooth healing, root development, pulp vitality, and esthetics post-REPs and categorize them into clinician- and patient-centered outcomes. Furthermore, this study identified significant predictors affecting such outcomes.

METHODS

Immature permanent teeth diagnosed with pulp necrosis treated with REPs between 2008 and 2018 with a minimum of 1-year follow-up were included. Outcomes included success and survival rates, changes in root development using 2-dimensional radiographic root area (RRA) and 3-dimensional measurements, pulp vitality, and tooth discoloration. Predictor variables of success included age, sex, etiology of pulp necrosis (PN), type of medicament, sodium hypochlorite (NaOCl) concentration, type of biomaterial used over the blood clot, and preoperative apical diagnosis. Statistical analyses included Cox proportional hazard analyses and generalized regression models.

RESULTS

Fifty-one teeth with an average of 2.1 years of follow-up satisfied the criteria. The survival rate was 92%. The success rate was 84.3% with age, etiology of PN, type of medicament, and NaOCl concentration being significant predictors of failure. Root development occurred in 91.4% of cases with age, sex, etiology of PN, type of medicament, NaOCl concentration, and apical diagnosis being significant predictors for RRA change. Positive pulp sensibility responses were associated with greater RRA change, and, finally, the type of biomaterial was a significant predictor for tooth discoloration after treatment.

CONCLUSIONS

REPs provide a high survival rate. Patient and clinical factors may affect outcomes, and this knowledge may help to define the criteria for optimal treatment planning of REPs.

Effects of radiopaque double antibiotic pastes on the proliferation, alkaline phosphatase activity and mineral deposition of dental pulp stem cells

OBJECTIVE

The aim of this study was to investigate the effects of two radiopaque agents, barium sulfate (BaSO₄) or zirconium oxide (ZrO₂) in double antibiotic paste (DAP), on the proliferation and mineral deposition of human dental pulp stem cells (DPSC).

MATERIALS AND METHODS

Radiopaque antimicrobial medicaments composed of methylcellulose (MC) thickening polymer with BaSO₄ or ZrO₂ and either 1 or 5 mg/mL DAP (equal portions of metronidazole and ciprofloxacin) were used to investigate DPSC proliferation after 3 days, and alkaline phosphatase (ALP) activity and mineral deposition after 7 and 14 days. Radiopaque agents without DAP and Ca(OH)₂ were used as controls.

RESULTS

MC-BaSO₄ DAP and MC-ZrO₂ DAP at 1 or 5 mg/mL had no adverse effect on DPSC proliferation, compared to the media and MC controls. MC-ZrO₂ (DAP-free) greatly increased ALP activity after 7 days. DPSC mineral deposition was modestly reduced at 7 days by MC-BaSO₄ DAP and MC-ZrO₂ DAP, but not by DAP-free radiopaque agents, and was most reduced by 5 mg/mL DAP in the 14-day cultures.

CONCLUSIONS

MC-BaSO₄ or MC-ZrO₂ medicaments containing up to 5 mg/mL of DAP supported the proliferation and early osteogenic differentiation of DPSC. Low DAP concentrations and short culture times led to more favorable effects on ALP activity and mineral deposition by DPSC. The findings suggest that radiopaque agents added for the purpose of detecting whether medicaments occupy the full extent of the root canal may have clinical applications. Radiopaque antibiotic medicaments containing low DAP concentrations may be an alternative to Ca(OH)₂ for regenerative endodontic procedures.

Influence of Adjuncts to Irrigation in the Disinfection of Large Root Canals

INTRODUCTION

The aims of this study were to evaluate the effectiveness of disinfection methods and determine the most promising irrigation protocol for regenerative endodontics in teeth with large root canals.

METHODS

Sterilized root samples with 0.8-mm wide apical foramen (n = 94) were prepared from human mandibular premolars. Ninety-two samples were infected with Enterococcus faecalis for 21 days and biofilm formation was verified using scanning electron microscopy (n = 2). The 90 infected samples were randomly assigned into 9 groups: no intervention (initial), 1.5% NaOCl irrigation (1.5 N), 2.5% NaOCl irrigation (2.5 N), 1.5 N + intermittent passive ultrasonic irrigation (PUI), 1.5 N + intermittent canal brushing with Navitip FX (NFX), 1.5 N + intermittent XP-endo Finisher (XPF), 1.5 N + circumferential filing (CF), 1.5 N + 1-min Self-adjusting File (SAF), and 1.5 N + mechanical instrumentation using #90‒110 files (MI). Subsequently, the root canal walls were shaved for microbial analysis. The mean colony-forming units (CFUs) were determined and analyzed using 1-way analysis of variance.

RESULTS

The mean CFU count was lowest in the MI group (63.5 CFU/mL), followed by the NFX, XPF, SAF, 2.5 N, CF, PUI, 1.5 N, and initial groups. The remaining bacteria in the 1.5 N group was 3.6-fold higher than that of the PUI group; 4- to 5-fold higher than that of the 2.5 N, CF, and SAF groups; and 22-fold and 36-fold higher than that of the XPF and NFX groups, respectively. The 2.5 N and 1.5 N groups with adjunctive treatments, excluding the PUI group, had significantly fewer remaining bacteria compared with the 1.5 N group (P < .05).

CONCLUSIONS

Performing various procedures supplemental to 1.5 N improved large root canal disinfection. Adjunctive NFX most effectively reduced the number of bacteria without dentin removal.

Pulp-dentin regeneration: current approaches and challenges

Regenerative endodontic procedures for immature permanent teeth with apical periodontitis confer biological advantages such as tooth homeostasis, enhanced immune defense system, and a functional pulp-dentin complex, in addition to clinical advantages such as the facilitation of root development. Currently, this procedure is recognized as a paradigm shift from restoration using materials to regenerate pulp-dentin tissues. Many studies have been conducted with regard to stem/progenitor cells, scaffolds, and biomolecules, associated with pulp tissue engineering. However, preclinical and clinical studies have evidently revealed several drawbacks in the current clinical approach to revascularization that may lead to unfavorable outcomes. Therefore, our review examines the challenges encountered under clinical conditions and summarizes current research findings in an attempt to provide direction for transition from basic research to clinical practice.

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

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

Regenerative endodontics: a comprehensive review

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

Retreatment of failed revascularization/revitalization of immature permanent tooth - A case report

The aim of this article is to describe the clinical case of the non-surgical retreatment of a failed revascularization/revitalization treatment (RRT). The retreatment was preceded by two sessions including an interim medication with calcium hydroxide and a modified irrigation protocol containing a highly-concentrated sodium hypochlorite and prolonged usage of ethylenediaminetetraacetic acid (EDTA) to reverse unacceptable side effects of hypochlorite. During a 15- month follow-up, the healing of the periapical lesion, increased thickening of root canal walls and maturation of root was apparent. The repeated RRT represents a possible treatment modality for s failed RRT. Key words:Retreatment, revascularization, revitalization, maturogenesis, immature tooth.

Root Canal Filling after Revascularization/Revitalization

INTRODUCTION

Revascularization/revitalization therapy is considered an alternative procedure for management of teeth with an immature apex and necrotic pulp, mainly when root development is interrupted in the early phases of formation. However, this clinical treatment protocol should be considered a permanent procedure?

METHOD

A maxillary central incisor with a previous and successful RR treatment was intentionally filled with a biocompatible material with the periapical tissues due to the patient's lack of adherence to the follow-up protocol.

RESULTS

The 20-month follow-up showed absence of clinical, radiological and tomographic signs and symptoms of an endodontic re-infection.

CONCLUSION

This case demonstrates that once the increased thickening of the canal walls, incrementing the root length, apical closure and the total resolution of the apical lesion are observed, the main canal of a previously treated tooth with an RR procedure can be filled.

Pulpo-Periodontal Regeneration: Management of Partial Failure Revascularization

The aim of this work is to present a case of management of an open apex on a lower molar by using tissue engineering, with two endodontic procedures in the same tooth. We had to resort to pulp regeneration on the distal root and apexification with MTA on the mesial roots after the failure of regenerative therapy on those ones. The management consisted in scheduling regular follow-ups combined with X-rays. After 24 months, the radiological control has shown pulpo-periodontal regeneration associated with walls thickening and distal root elongation and periapical ad integrum healing.