Drawbacks and unfavorable outcomes of regenerative endodontic treatments of necrotic immature teeth: a literature review and report of a case

Limited Evidence Suggests Benefits of Single Visit Revascularization Endodontic Procedures - A Systematic Review

Abstract Revascularization endodontic procedures commonly require multiple treatment sessions. However, single visit procedures may be advantageous from the clinical and patient management standpoints. The purpose of this review was to evaluate the outcomes of single-visit revascularization endodontic procedures for the management of immature permanent teeth with non-vital pulp. Two electronic databases (Scopus and PubMed) were searched, from their inception to July 2018, for studies that assessed clinical and/or radiographic and/or histologic outcomes of single-visit revascularization endodontic procedures performed in immature permanent teeth with non-vital pulp. Case reports, animal studies and clinical trials were included. The quality of case reports was appraised by Joanna Briggs Institute Critical Appraisal Checklist for Case Reports. The quality of randomized clinical trials was assessed by the revised Cochrane risk of bias tool for randomized trials. The risk of bias for animal studies was assessed using SYRCLE’s risk of bias tool. Tabulation followed by narrative synthesis was used to draw conclusions. Seven studies satisfied the selection criteria. Five were classified as case reports, one as a randomized clinical trial and one as animal study. The latter presented with a high risk of bias, whilst the remaining showed a low risk. The evidence supporting the potential use of single-visit revascularization endodontic procedures is scarce. Successful single-visit revascularization endodontic procedures commonly include the use of high concentrations of sodium hypochlorite and EDTA combined with the use of agitation systems. Further clinical trials with long term follow up are needed to confirm the results of the current review.

Comparative Study between Revitalization of Necrotic Immature Permanent Anterior Teeth with and without Platelet Rich Fibrin: A Randomized Controlled Trial

OBJECTIVES

This study was conducted to evaluate the effect of platelet rich fibrin (PRF) during revitalization of necrotic immature permanent anterior teeth after 6 months and 1 year follow up period. The following treatment protocols; Group A: revitalization using blood clot scaffold only, and Group B: revitalization using blood clot and PRF.

STUDY DESIGN

twenty-two patients (7-12 years old) suffering from immature necrotic permanent maxillary central incisors were randomly selected and randomly allocated into 2 groups. Clinical examinations were performed to detect any pain or swelling during the follow up period. Standardized radiographs were digitally evaluated for changes in root length, periapical radiolucency size, presence of apical or cervical calcific bridges.

RESULTS

After a follow-up period of 12 months, most of the cases showed radiographic evidence of periapical healing and showed calcific bridges either cervical and/or apical. No significant differences were shown between both groups.

CONCLUSIONS

The revitalization procedures succeeded to show continued development of roots in teeth with necrotic pulps. The use of PRF was not essential for repair but it helped during the procedures.

Coronal tooth discoloration induced by regenerative endodontic treatment using different scaffolds and intracanal coronal barriers: a 6-month ex vivo study

Objective

The aim of this study was to evaluate discoloration of teeth undergoing regenerative endodontic procedures (REPs) using blood clot or platelet-rich fibrin (PRF) as the scaffolds and different calcium silicate-based materials as the intracanal coronal barriers in an ex vivo model.

Materials and Methods

Forty-eight bovine incisors were prepared and disinfected using 1 mg/mL double antibiotic paste (DAP). The specimens were then randomly divided into 2 groups (n = 24) according to the scaffolds (blood or PRF). After placement of scaffolds each group was divided into 2 subgroups (n = 12) according to the intracanal coronal barriers (ProRoot MTA or Biodentine). The pulp chamber walls were sealed with dentin bonding agent before placement of DAP and before placement of scaffolds. The color changes (∆E) were measured at different steps. The data were analyzed using 2-way analysis of variance.

Results

Coronal discoloration induced by DAP was not clinically perceptible (ΔE ≤ 3.3). Regarding the type of the scaffold, coronal discoloration was significantly higher in blood groups compared with PRF groups at the end of REP and after 1 month (p < 0.05). However, no significant difference was found between PRF and blood clot after 6 months (p > 0.05). Considering the type of intracanal coronal barrier, no significant difference existed between ProRoot MTA and Biodentine (p > 0.05).

Conclusions

With sealing the dentinal tubules of pulp chamber with a dentin bonding agent and application of DAP as an intracanal medicament, coronal color change of the teeth following the use of PRF and blood sealed with either ProRoot MTA or Biodentine was not different at 6-month follow-up.

Clinical, Radiographic, and Histologic Outcome of Regenerative Endodontic Treatment in Human Teeth Using a Novel Collagen-hydroxyapatite Scaffold

INTRODUCTION

Histologic examination of teeth after regenerative endodontic treatment (RET) shows that the type, quality, and quantity of tissues formed in the root canal space are not predictable. The aim of this study was to examine clinically, radiographically, and histologically the outcome of RET in immature noninfected human teeth using SynOss Putty (Collagen Matrix Inc, Oakland, NJ) as a scaffold.

METHODS

Three pairs of maxillary/mandibular first premolars in 3 patients scheduled for extraction were included. Sensibility tests confirmed the presence of vital pulps. After informed consent, anesthesia, and rubber dam isolation, the pulps were removed. RET was performed using the following scaffolds: SynOss Putty + blood in both teeth in patient #1, SynOss Putty with or without blood in patient #2, and SynOss Putty + blood or blood only in patient #3. After a follow-up period of 2.5-7.5 months, the teeth were clinically and radiographically evaluated, extracted, and examined histologically.

RESULTS

Patients remained asymptomatic after treatment. Radiographic examination of the teeth showed signs of root development after treatment. In teeth treated with SynOss Putty + blood, histologic examination showed formation of intracanal mineralized tissue around the scaffold particles solidifying with newly formed cementumlike tissue on the dentinal walls. The tooth treated with SynOss Putty without blood showed the formation of a periapical lesion. The tooth treated with a blood clot only showed tissues of periodontal origin growing into the root canal space.

CONCLUSIONS

SynOss Putty + blood showed a predictable pattern of tissue formation and mineralization when used as a scaffold for RET in human immature noninfected teeth. The newly formed mineralized tissue solidifies with newly formed cementum on the dentinal walls.

Effect of ultrasonic activation on dentinal tubule penetration of calcium silicate-based cements

This study investigated the dentinal tubule penetration of mineral trioxide aggregate (MTA), NeoMTA Plus and Biodentine placed by either manual condensation or ultrasonic activation in simulated open apex model. Standardized divergent open apex models were created using palatal roots of 60 human maxillary molars and divided into six groups according to the used cements and activation methods (n = 10): MTA-manual condensation, MTA-ultrasonic activation, NeoMTA Plus-manual condensation, NeoMTA Plus-ultrasonic activation, Biodentine-manual condensation, Biodentine-ultrasonic activation. For the measurement of penetration, the cements were mixed with 0.1% Rhodamin B and 6-mm apical portions of each root canal were obturated in an orthograde direction. The roots were embedded into acrylic blocks, and 1-mm-thick sections were obtained at 3 mm from the apex. Specimens were mounted onto glass slides and scanned under a confocal laser scanning microscope (CLSM) and stereomicroscope. Dentinal tubule penetration areas, depth and percentage were measured using LSM and ImageJ software. The data were analyzed using two-way analysis of variance (anova) with Bonferroni correction (α = 0.05). No correlation was found between stereomicroscope and CLSM analyses (p > .05). CLSM analysis showed no significant differences between MTA, NeoMTA Plus, and Biodentine groups when manual condensation was used (p > .05). Ultrasonic activation did not increase the tubular penetration of MTA, NeoMTA Plus or Biodentine as compared to manual condensation of each material (p > .05). MTA, NeoMTA Plus and Biodentine showed similar tubular penetration when manual condensation was used. Ultrasonic activation of these cements had no effect on tubular penetration of each material as compared to the manual condensation counterparts.

Regenerative Endodontic Procedures Using Contemporary Endodontic Materials

Calcium hydroxide apexification and Mineral Trioxide Aggregate (MTA) apexification are classical treatments for necrotic immature permanent teeth. The first tend to fail for lack of compliance given the high number of sessions needed; the second has technical difficulties such as material manipulation and overfilling. With both techniques, the root development is interrupted leaving the tooth with a fragile root structure, a poor crown-to-root ratio, periodontal breakdown, and high risk of fracture, compromising long-term prognosis of the tooth. New scientific literature has described a procedure that allows complete root development of these specific teeth. This regenerative endodontic procedure (REP) proposes the use of a combination of antimicrobials and irrigants, no canal walls instrumentation, induced apical bleeding to form a blood clot and a tight seal into the root canal to promote healing. MTA is the most used material to perform this seal, but updated guidelines advise the use of other bioactive endodontic cements that incorporate calcium and silicate in their compositions. They share most of their characteristics with MTA but claim to have fewer drawbacks with regards to manipulation and aesthetics. The purpose of the present article is to review pertinent literature and to describe the clinical procedures protocol with its variations, and their clinical application.

Bone, Periodontal and Dental Pulp Regeneration in Dentistry: A Systematic Scoping Review

Abstract The aim of presented systematic scoping review was to investigate the actual and future clinical possibilities of regenerative therapies and their ability to regenerate bone, periodontal and pulp with histological confirmation of the nature of formed tissue. Electronic search was conducted using a combination between Keywords and MeSH terms in PubMed, Scopus, ISI-Web of Science and Cochrane library databases up to January 2016. Two reviewers conducted independently the papers judgment. Screened studies were read following the predetermined inclusion criteria. The included studies were evaluated in accordance with Arksey and O’Malley’s modified framework. From 1349 papers, 168 completed inclusion criteria. Several characterized and uncharacterized cells used in Cell Therapy have provided bone regeneration, demonstrating bone gain in quantity and quality, even as accelerators for bone and periodontal regeneration. Synthetic and natural scaffolds presented good cell maintenance, however polyglycolid-polylactid presented faster resorption and consequently poor bone gain. The Growth Factor-Mediated Therapy was able to regenerate bone and all features of a periodontal tissue in bone defects. Teeth submitted to Revascularization presented an increase of length and width of root canal. However, formed tissues not seem able to deposit dentin, characterizing a repaired tissue. Both PRP and PRF presented benefits when applied in regenerative therapies as natural scaffolds. Therefore, most studies that applied regenerative therapies have provided promising results being possible to regenerate bone and periodontal tissue with histological confirmation. However, pulp regeneration was not reported. These results should be interpreted with caution due to the short follow-up periods.

Six-Month Color Stability Assessment of Two Calcium Silicate-Based Cements Used in Regenerative Endodontic Procedures

AIM

The purpose of the present study is to assess the color stability of two calcium silicate-based cements (CSCs) used in regenerative endodontic procedures (REPs).

METHODS

A total of 40 acrylic single-rooted transparent teeth, with immature apex, were used. Root canals were filled up to 3 mm below the level of the cementoenamel junction, with either saline solution (Mineral Trioxide Aggregate (MTA)/saline and Biodentine/saline) or blood (MTA/blood and Biodentine/blood). Subsequently, ProRoot MTA^® or Biodentine^TM was placed in the root canal to create a cervical barrier. Color measurement was carried out at four different evaluation periods (3 h, 72 h, 7 days, and 6 months). Shade analysis within the L* a* b* color space was performed and color variation (∆E) calculated. The significance level for statistical analysis was set at p < 0.05.

RESULTS

The four groups showed a significant decrease in L* values over time. The ΔE value increased over time for all groups but was not statistically significant for the Biodentine/blood group. Two-way ANOVA showed no interaction between the CSC and treatment (contact with saline solution or blood). CSC used was the factor responsible for ΔE over time, inducing statistically significant color variations from T_3H to T_7D (p = 0.04) and T_3H to T_6M (p < 0.01). After 6 months, MTA/saline had 5.08 (p = 0.001) higher ΔE than Biodentine/Saline and the MTA/blood had 3.65 (p = 0.009) higher than Biodentine/blood.

CONCLUSIONS

After 6 months, regardless of blood exposure, Biodentine exhibits superior color stability compared to MTA. Biodentine might be a suitable alternative to MTA as a cervical barrier material in REPs.

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.

Tissue Engineering of Necrotic Dental Pulp of Immature Teeth with Apical Periodontitis in Dogs: Radiographic and Histological Evaluation

AIM

To evaluate tissue engineering technology to regenerate pulp-dentin like tissues in pulp canals of immature necrotic permanent teeth with apical periodontitis in dogs.

STUDY DESIGN

The study was performed on 36 teeth in 12 dogs. The experiment was carried out using split mouth design. In each dog 3 teeth were selected for implementing the study procedure. Apical periodontitis was induced in Group A and B teeth. Group (A): immature upper left 2^nd permanent incisors that were transplanted with a construct of autologous dental pulp stem cells with growth factors seeded in a chitosn hydrogel scaffold. Group (B): immature upper right 2^nd permanent incisor that received only growth factors with scaffold. A third tooth in each dog was selected randomly for isolation of dental pulp stem cells (DPSCs). Both groups were closed with a double coronal seal of white MTA (Mineral trioxide aggregate) and glass ionomer cement. Both groups were monitored radiographically for 4 months and histologically after sacrificing the animals.

RESULTS

There was no statistically significant difference in radiographic findings between group (A) and group (B) for healing of radiolucencies, while there was statistically significant difference between group (A) and group (B) regarding radicular thickening, root lengthening and apical closure. Histologically, group (A) teeth showed regeneration of pulp- dentin like tissue while group (B) teeth did not show any tissue regeneration.

CONCLUSION

Dental pulp stem cells and growth factors incorporated in chitosan hydrogel are able to regenerate pulp- dentine like tissue and help in complete root maturation of non-vital immature permanent teeth with apical periodontitis in dogs.

Effects of the nitric oxide releasing biomimetic nanomatrix gel on pulp-dentin regeneration: Pilot study

Successful disinfection alongside complete endodontic tissue regeneration and revascularization are the most desired clinical outcomes of regenerative endodontics. Despite reported clinical successes, significant limitations to the current regenerative endodontic procedure (REP) have been elucidated. To improve the current REP, an antibiotics and nitric oxide (NO) releasing biomimetic nanomatrix gel was developed. The study evaluates antibacterial effects of an antibiotics and NO releasing biomimetic nanomatrix gel on multispecies endodontic bacteria. Antibiotics, ciprofloxacin (CF) and metronidazole (MN) were mixed and encapsulated within the NO releasing biomimetic nanomatrix gel. The gel was synthesized and self-assembled from peptide amphiphiles containing various functional groups. Antibacterial effects of the antibiotics and NO releasing biomimetic nanomatrix gel were evaluated using bacterial viability assays involving endodontic microorganisms including clinical samples. Pulp-dentin regeneration was evaluated via animal-model experiments. The antibiotics and NO releasing biomimetic nanomatrix gel demonstrated a concentration dependent antibacterial effect. In addition, NO alone demonstrated a concentration dependent antibacterial effect on endodontic microorganism. An in vivo analysis demonstrated the antibiotics and NO releasing biomimetic nanomatrix gel promoted tooth revascularization with maturation of root canals. An optimal concentration of and NO releasing nanomatrix gel is suggested for its potential as a root treatment material for REP and an appropriate protocol for human trials. Further investigation is required to obtain a larger sample size and decide upon ideal growth factor incorporation.

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.

Retrieval of extruded mineral trioxide aggregate using a novel suction device

Treatment of necrotic immature permanent teeth is an exigently demanding situation for an endodontist. Regenerative endodontic procedures are being employed for such teeth in a hope to restore a functional pulp tissue and continue root development. However, currently advocated techniques may not be effective in retaining mineral trioxide aggregate (MTA) in its coronal position. The present paper describes two immature teeth with pulpal necrosis and apical periodontitis that were treated through revascularization. In both the cases, apical extrusion of the coronal MTA plug occurred. A suction tip was customized to completely retrieve the extruded material. Both cases proved out to be a clinical and radiographic success over extended follow-up periods.

Report of a case of platelet-rich fibrin-mediated revascularization of immature 12 with histopathological evaluation

The procedure of regeneration has shown promising results in the treatment of nonvital teeth with immature apices. However, the tissue being regenerated can only be confirmed through histological examination. This report describes an immature nonvital 12 with apical pathology which was treated via revascularization using 3% NaOCl and 17% ethylenediaminetetraacetic acid as irrigants; Ca(OH)2 as intracanal medicament and platelet-rich fibrin (PRF) as scaffold. On follow-up at 6 and 12 months, healing of periapical lesion, dentinal thickening, and apical closure with a canal exit forming distally were evident. The tooth, however, got fractured and was subsequently extracted at 12 months and sent for histopathological examination. It was revealed that a collagenous matrix for forming hard tissue similar to acellular cementum with a diffuse area of calcification could be seen in pulp space being attached with root canal dentin walls, suggesting that PRF may yield favorable outcomes in regenerative endodontic procedures.

Bioactivity of Photoactivated Functionalized Nanoparticles Assessed in Lipopolysaccharide-contaminated Root Canals In Vivo

INTRODUCTION

The persistence of dentin-bound lipopolysaccharides (LPS) in disinfected root canals impedes treatment outcomes of endodontic procedures. This study assessed the effects of photoactivated rose bengal-functionalized chitosan nanoparticles (CSRBnps) on LPS-contaminated root dentin in vivo using an intraosseous implantation model and neotissue formation as a marker.

METHODS

Fifty human, 3-mm-long root segments with a 1.2-mm canal lumen were divided into 5 groups (n = 10): group 1, canals not contaminated; group 2, canals contaminated with Pseudomonas aeruginosa LPS; group 3, canals contaminated and disinfected with sodium hypochlorite (NaOCl); group 4, canals contaminated and disinfected with NaOCl and calcium hydroxide; and group 5, canals contaminated and disinfected with NaOCl and CSRBnps (300 μg/mL) with photoactivation (λ = 540 nm, 40 J/cm²). Specimens were implanted into mandibles of guinea pigs, block dissected after 4 weeks, and the canal content evaluated histologically and immunohistochemically. The ingrown neotissue interface (50 μm) with dentin was characterized for fibroblasts, osteoclasts, inflammatory markers, dentin resorption, mineralization, and angiogenesis and dichotomized as type 1 (no inflammation and resorption, indicative of LPS inactivation) or type 2 (inflammation and resorption). The frequency of the observed parameters was analyzed using the Fisher exact test.

RESULTS

The outcome was categorized as type 1 in groups 1 and 5, type 2 in group 2, and mixed type 1 and 2 in groups 3 and 4. The outcomes in groups 1 and 5 (P > .05) differed significantly (P < .05) from those in groups 2, 3, and 4.

CONCLUSIONS

Disinfection of LPS-contaminated root canals with photoactivated CSRBnps in vivo supported ingrowth of neotissue without signs of inflammation or resorption, suggestive of effective inactivation of dentin-bound LPS.

VEGF/BMP-2 loaded three-dimensional model for enhanced angiogenic and odontogenic potential of dental pulp stem cells

AIM

To investigate the proliferation and differentiation potential of human dental pulp stem cells (DPSCs) in a three-dimensional culture model (TDM) by incorporation of VEGF and BMP-2.

METHODOLOGY

TDM was established using fibrin gel (fg) as a soft tissue matrix and demineralized dentine disc (dd) as a hard tissue matrix. DPSCs and vascular endothelial growth factor (VEGF) were encapsulated in fibrin gel (fg-VEGF) and then inserted into bone morphogenetic protein (BMP-2)-coated demineralized dentine discs (dd-BMP-2). DPSCs were incubated for 28 days in various fg/dd combinations in the absence or presence of VEGF and BMP-2. Proliferation and morphology of DPSCs in fibrin gel were analysed using MTT and Live&Dead assays. Release profiles of VEGF and BMP-2 from fibrin gel and dentine discs were quantified using ELISA, and the expressions of angiogenic and odontogenic differentiation markers were determined with RT-qPCR analysis. Data were analysed statistically using Wilcoxon signed rank tests, Kruskal-Wallis tests with Mann-Whitney U tests and Bonferroni adjustment. The level of significance was set at P < 0.05.

RESULTS

DPSCs were able to proliferate and showed interconnected cellular elongations in fibrin gel depending on fibrinogen concentration whilst monolayer control group showed typical fibroblast-like cell morphology. Encapsulating of VEGF in fibrin gel and BMP-2 in gelatin that was used to coat dentine discs allowed the controlled releases of growth factors, which induced angiogenic and odontogenic gene expressions by DPSCs. Higher expressions of PECAM as an angiogenic factor, and BSP, DMP-1, OCN and CBFA as odontogenic factors, were observed in TDM as compared to the other fg/dd combinations and the monolayer control group (P < 0.05).

CONCLUSIONS

TDM consisting of fibrin gel and dentine matrix allowed cell-cell interactions. TDM was highly effective in delivering both VEGF and BMP-2 that enhanced the angiogenic and odontogenic potential of DPSCs.

Revascularization-associated Intracanal Calcification: Assessment of Prevalence and Contributing Factors

INTRODUCTION

Intracanal calcifications have been reported in endodontic cases after revascularization. The purpose of the current study was to determine the incidence of intracanal calcification and potential contributing factors in retrospective revascularization cases.

METHODS

Among 37 patients who had undergone revascularization between 2010 and 2014, 29 cases were assessed with average follow-up period of 24.9 months. Clinical and radiographic examinations were performed to evaluate the treatment outcomes, eg, resolution of apical periodontitis (AP), root development, and occurrence of intracanal calcification. Radiographic assessment revealed varied calcification patterns, which were classified into calcific barrier or canal obliteration, collectively referred to as revascularization-associated intracanal calcification (RAIC).

RESULTS

All 29 cases demonstrated resolution of AP, whereas continued root development with apical closure occurred in 23 of 29 cases (79.3%). RAIC was noted in 18 of 29 cases (62.1%), among which 5 of 18 cases (27.8%) were classified as calcific barrier and 13 of 18 cases as canal obliteration (72.2%). Higher frequency of RAIC was noted in the cases with induced bleeding (16 of 23 cases, 69.6%), whereas the 6 cases without induced bleeding showed RAIC at 33.4%. Also, RAIC occurred more frequently in cases medicated with Ca(OH)₂ (10 of 13 cases, 76.9%) than in those medicated with antibiotic pastes (6 of 13 cases, 46.2%).

CONCLUSIONS

This study indicated that RAIC is common (62.1%) among cases treated with revascularization. Multiple contributing factors may include the type of medicaments and induction of intracanal bleeding. Although RAIC does not interfere with resolution of AP, some cases may progress to complete obliteration of root canals and would impede normal function of dental pulp tissues.

Regenerative Endodontics

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

Release of Growth Factors into Root Canal by Irrigations in Regenerative Endodontics

INTRODUCTION

The aim of this study was to investigate the release of growth factors into root canal space after the irrigation procedure of regenerative endodontic procedure.

METHODS

Sixty standardized root segments were prepared from extracted single-root teeth. Nail varnish was applied to all surfaces except the root canal surface. Root segments were irrigated with 1.5% NaOCl + 17% EDTA, 2.5% NaOCl + 17% EDTA, 17% EDTA, or deionized water. The profile of growth factors that were released after irrigation was studied by growth factor array. Enzyme-linked immunosorbent assay was used to validate the release of transforming growth factor (TGF)-β1 and basic fibroblast growth factor (bFGF) at 4 hours, 1 day, and 3 days after irrigation. The final concentrations were calculated on the basis of the root canal volume measured by cone-beam computed tomography. Dental pulp stem cell migration on growth factors released from root segments was measured by using Transwell assay.

RESULTS

Total of 11 of 41 growth factors were detected by growth factors array. Enzyme-linked immunosorbent assay showed that TGF-β1 was released in all irrigation groups. Compared with the group with 17% EDTA (6.92 ± 4.49 ng/mL), the groups with 1.5% NaOCl + 17% EDTA and 2.5% NaOCl + 17% EDTA had significantly higher release of TGF-β1 (69.04 ± 30.41 ng/mL and 59.26 ± 3.37 ng/mL, respectively), with a peak release at day 1. The release of bFGF was detected at a low level in all groups (0 ng/mL to 0.43 ± 0.22 ng/mL). Migration assay showed the growth factors released from root segments induced dental pulp stem cell migration.

CONCLUSIONS

The root segment model in present study simulated clinical scenario and indicated that the current irrigation protocol released a significant amount of TGF-β1 but not bFGF. The growth factors released into root canal space induced dental pulp stem cell migration.

Allogeneic stem cells derived from human exfoliated deciduous teeth (SHED) for the management of periapical lesions in permanent teeth: Two case reports of a novel biologic alternative treatment

Stem cells are the pluripotent cells that have the capacity to differentiate into other specialized cells. Recently, many experiments have been conducted to study the potentiality of stem cells in the tissue regeneration. We report two cases treated utilizing stem cells from human exfoliated deciduous teeth (SHED) in the management of periapical lesions in permanent teeth. Two normal human deciduous teeth from children, 7‒8 years of age, were collected to isolate stem cells. Two patients, one with periapical pathology alone and the other with periapical lesion along with an open apex in young permanent teeth, were selected for the study. After initial debridement of the root canals, homing of SHED was carried out and the access cavity was sealed using glass-ionomer cement. Clinical examination after 7 days, 30 days, 90 days, 180 days and 365 days revealed no symptoms. Closure of open apex and periapical tissue healing were observed radiographically at one-month review and maintained until 365-day review. Positive response to electric pulp testing was recorded for the treated teeth from the 3- to 12-month follow-ups. The treated cases demonstrated complete resolution of periapical radiolucency in a span of 30 days, which was faster than the conventional methods. SHED could be considred effective in treating the periapical lesions and open apex in permanent teeth.

Iodixanol as a Contrast Agent in a Fibrin Hydrogel for Endodontic Applications

The application of biomaterials used in regenerative endodontics should be traceable. In this study, we checked some basic effects of rendering a fibrin hydrogel radiopaque using an iodine-based contrast agent (iodixanol) approved for systemic application. Fibrin hydrogels were prepared from a fibrin sealant (Tisseel) using either an isotonic iodixanol solution (Visipaque 320, test) or Tris buffer (control) as a diluent. Gelation kinetics, radiopacity, and swelling of lyophilized hydrogels were tested using standard methods. Hydrogel structure was evaluated using scanning electron microscopy (SEM). Furthermore, iodixanol release from the test gels was assessed using spectrophotometry, and tissue compatibility was compared between test and control hydrogels using the chick chorioallantoic membrane (CAM) assay. Results were compared using pairwise t-test, p < 0.05. Iodixanol caused a 70-fold delay in gelation to 26 min in the test compared to the control hydrogels (22 ± 1 s). Radiopacity of the test gels was 1.9 ± 0.2 mm Al/mm, compared to zero in the control hydrogels. Lyophilized hydrogel swelling was strongly reduced when iodixanol was added to the hydrogel (p < 0.05). Test hydrogels had an altered SEM appearance compared to controls, and exhibited a reduced porosity. Iodixanol release from the test hydrogels reached 14.5 ± 0.5% after 120 h and then ceased. This release did not have any apparent toxic effect and neither affected the viability, nor the physiology or vascularization of the CAM of fertilized chicken eggs. Iodixanol can render a fibrin hydrogel radiopaque and maintains its tissue compatibility, yet impacts gelation kinetics and hydrogel porosity.

Vertical root fracture resistance of simulated immature permanent teeth filled with MTA using different vehicles

Background

The aim of the study is to evaluate the resistance vertical root fracture (VRF) of mineral trioxide aggregate (MTA) filled-immature permanent roots by using three different vehicles.

Material and Methods

Forty-extracted human single-rooted mandibular premolars were selected and the root length was standardized to the length of 9 mm. For simulation of immature tooth apices, peeso reamers were introduced into the root canals and the prepared roots were assigned into three experimental groups according the used vehicle (distilled water-DW, prophylene glycol-PG, chlorhexidine-CHX) and control group (n=10). To simulate a periodontal membrane, the apical 7 mm of all roots was covered with wax to obtain a 0.2- to 0.3-mm-thick layer before embedding the roots into acrylic cylinders. A vertical force was applied (1mm/min) using a universal testing machine and the maximum load (F-max) that fracture occurred and the fracture mode (splint or comminuted) was recorded. Data were presented as mean and standard deviations. Statistical analysis was performed using Kruskal-Wallis, Mann-Whitney U Test was used for multiple comparisons.

Results

There were significant differences between fracture strength of experimental groups with that of control group (p<0.05). However, no statistically significant differences were found amongst the fracture strength values of the experimental groups (p>0.05). In all groups, split fracture was the most common fracture mode.

Conclusions

MTA increases resistance of immature permanent teeth to VRF. Based on the results of this study, it can be concluded that mixing MTA with CHX or PG as the vehicle do not alter VRF resistance of simulated immature permanent roots.

Key words:Immature teeth, MTA, vehicle, vertical root fracture.

Regenerative Endodontic Treatment versus Apical Plug in Immature Teeth: Three-Year Follow-Up

This report compares and evaluates the treatment outcomes of regenerative endodontic treatment and apical plug as two accepted treatment protocols in a pair of necrotic immature maxillary central incisors of a 12-year old female. The patient was referred complaining of a dull pain and swelling in her upper lip area. She had a history of trauma to the anterior maxilla two years earlier. Both teeth were clinically diagnosed with pulp necrosis and periapical radiographs revealed that separate periapical radiolucent lesions surrounded the immature apices of both teeth. The left and right incisors were treated with apical plug and regenerative endodontic treatment, respectively, using calcium-enriched mixture (CEM) cement. The patient was followed-up for three years. During this period, both teeth were clinically asymptomatic and showed complete radiographic healing of the periapical lesions. The right central incisor showed root development. No tooth discoloration was evident. Apexification by apical plug placement and pulp regeneration are both reliable treatments for immature non-vital teeth. In order to choose the right treatment the advantages of either technique should be weighed against its drawbacks. CEM cement can be successfully applied for both purposes. This biomaterial causes less discoloration of the tooth.

Effects of Stem Cell Factor on Cell Homing During Functional Pulp Regeneration in Human Immature Teeth

Conventional root canal treatment in immature permanent teeth can lead to early tooth loss in children because root formation is discontinued. We investigated whether the stem cell factor (SCF) could facilitate cell homing in the pulpless immature root canal and promote regeneration of a functional pulp. In vitro, human mesenchymal stem cells (hMSCs) were exposed to SCF at various concentrations for assessing cell migration, proliferation, and differentiation toward odonto/osteoblasts by 3D-chemotaxis slides, WST-1 assay, and alkaline phosphatase activity, respectively. Fibrin gels were used to deliver 15 μg/mL SCF for in vivo experiments. The release kinetic of SCF was assessed in vitro. Two corresponding human immature premolars, with or without SCF, were placed at rat calvariae for 6 and 12 weeks. All tooth specimens were either analyzed histologically and the percentage of tissue ingrowth determined or the cells were extracted from the pulp space, and the mRNA level of DMP1, DSPP, Col1, NGF, and VEGF were assessed by quantitative polymerase chain reaction. In the presence of SCF, we saw an increase in hMSCs directional migration, proliferation, and odonto/osteogenic differentiation. SCF also increased the extent of tissue ingrowth at 6 weeks but not at 12 weeks. However, at this time point, the formed tissue appeared more mature in samples with SCF. In terms of gene transcription, DMP1, Col1, and VEGF were the significantly upregulated genes, while DSPP and NGF were not affected. Our results suggest that SCF can accelerate cell homing and the maturation of the pulp-dentin complex in human immature teeth.

Retreatment of failed regenerative endodontic of orthodontically treated immature permanent maxillary central incisor: a case report

A revascularization procedure was shown to be the best alternative therapy for immature teeth with necrotic pulp and apical infection. A 12 year old female with a history of trauma to her upper central incisor and a sinus tract was referred for endodontic treatment. She was an active orthodontic patient and had undergone regenerative endodontic treatment for the past 2 years. Clinical examination revealed no response to sensibility, percussion, and palpation tests. The preoperative radiograph showed an open apex and apical rarefaction. The case was diagnosed as previously treated tooth with asymptomatic apical periodontitis. Regenerative endodontic retreatment was performed, and the case was followed for 3 years. Clinical, radiographic, and cone-beam computed tomography follow-up examination revealed an asymptomatic tooth, with evidence of periapical healing and root maturation.

Outcome of Revascularization Procedure: A Retrospective Case Series

INTRODUCTION

The purpose of this retrospective case series was to investigate the outcome of the revascularization procedure in necrotic immature teeth.

METHODS

The residents and faculty members at the University of Pennsylvania endodontic department were invited to submit consecutive revascularization cases treated by them, irrespective of the outcome, during the time period of 2009 to 2012. Twenty-eight of 35 submitted necrotic immature teeth met the inclusion criteria. The treatment protocol included minimal instrumentation and irrigation with 3% sodium hypochlorite and 17% EDTA. Triple antibiotic paste was placed for a minimum of 21 days. After blood clot induction, either EndoSequence Bioceramic Putty (Brasseler, Savannah, GA) or mineral trioxide aggregate was placed below the cementoenamel junction, and composite was used as a final restoration. The follow-up period ranged from 7 to 72 months. The outcome was assessed as complete healing (the absence of clinical signs and symptoms, complete resolution of periradicular radiolucency, increase in the root dentin thickness/length, and apical closure), incomplete healing (the absence of clinical signs and symptoms, the periapical lesion completely healed without any signs of root maturation or thickening, the periapical lesion either reduced in size or unchanged with/without radiographic signs of increasing root dentin thickness/length, or apical closure), and failure (persistent clinical signs and symptoms and/or increased size of the periradicular lesion).

RESULTS

Twenty-one of 28 cases (75%) healed completely, 3 cases (10.7%) failed during the observation period and needed further treatment, and 4 cases (14%) presented with incomplete healing.

CONCLUSIONS

Within the limitation of this study, the outcome of revascularization, wherein healing of periapical periodontitis and maturation of roots occurs, is fairly high, making it a viable treatment option in comparison with apexification.

Regenerative Dentistry: Animal Model for Regenerative Endodontology

BACKGROUND

Ectopic tissue has been observed frequently in human root canal specimens when cell homing studies were performed at the dorsum of rodents. In contrast, pulp-like tissue formed when immature teeth were implanted on top of the rat calvaria. It was surmised, yet not tested, that the implantation site might affect tissue ingrowth.

METHODS

Four root sections from human immature molars cleaned with 5% sodium hypochlorite (NaOCl) followed by 17% ethylenediaminetetraacetic acid (EDTA) were implanted per rat (n = 5). Two specimens were placed at the dorsum (control), while the other two specimens were implanted at the calvaria. After 6 weeks, the specimens were investigated for histological structure, immunoreactivity to dentine sialoprotein (DSP) and bone sialoprotein (BSP), per-area percentage of tissue ingrowth, and gene expression (DSPP, COL1, NGF and VEGF). Data were statistically compared.

RESULTS

Tooth specimens placed at the calvaria generally showed pulp-like tissue and odontoblast-like cells at the dentinal wall where DSP and BSP immunoreactivity were intense. The area of tissue ingrowth was significantly larger in the specimens placed at the calvaria compared to those placed at the dorsum. DSPP was the only gene that was upregulated significantly when specimens were implanted at the calvaria.

CONCLUSION

Our findings suggest that the calvarial site is superior to the dorsum to study pulp regeneration in human teeth in the rat.

Biomimetic microenvironments for regenerative endodontics

Regenerative endodontics has been proposed to replace damaged and underdeveloped tooth structures with normal pulp-dentin tissue by providing a natural extracellular matrix (ECM) mimicking environment; stem cells, signaling molecules, and scaffolds. In addition, clinical success of the regenerative endodontic treatments can be evidenced by absence of signs and symptoms; no bony pathology, a disinfected pulp, and the maturation of root dentin in length and thickness. In spite of the various approaches of regenerative endodontics, there are several major challenges that remain to be improved: a) the endodontic root canal is a strong harbor of the endodontic bacterial biofilm and the fundamental etiologic factors of recurrent endodontic diseases, (b) tooth discolorations are caused by antibiotics and filling materials, (c) cervical root fractures are caused by endodontic medicaments, (d) pulp tissue is not vascularized nor innervated, and (e) the dentin matrix is not developed with adequate root thickness and length. Generally, current clinical protocols and recent studies have shown a limited success of the pulp-dentin tissue regeneration. Throughout the various approaches, the construction of biomimetic microenvironments of pulp-dentin tissue is a key concept of the tissue engineering based regenerative endodontics. The biomimetic microenvironments are composed of a synthetic nano-scaled polymeric fiber structure that mimics native pulp ECM and functions as a scaffold of the pulp-dentin tissue complex. They will provide a framework of the pulp ECM, can deliver selective bioactive molecules, and may recruit pluripotent stem cells from the vicinity of the pulp apex. The polymeric nanofibers are produced by methods of self-assembly, electrospinning, and phase separation. In order to be applied to biomedical use, the polymeric nanofibers require biocompatibility, stability, and biodegradability. Therefore, this review focuses on the development and application of the biomimetic microenvironments of pulp-dentin tissue among the current regenerative endodontics.

Effect of acidic solutions on the microhardness of dentin and set OrthoMTA and their cytotoxicity on murine macrophage

OBJECTIVES

To evaluate the effects of three acids on the microhardness of set mineral trioxide aggregate (MTA) and root dentin, and cytotoxicity on murine macrophage.

MATERIALS AND METHODS

OrthoMTA (BioMTA) was mixed and packed into the human root dentin blocks of 1.5 mm diameter and 5 mm height. Four groups, each of ten roots, were exposed to 10% citric acid (CA), 5% glycolic acid (GA), 17% ethylenediaminetetraacetic acid (EDTA), and saline for five minutes after setting of the OrthoMTA. Vickers surface microhardness of set MTA and dentin was measured before and after exposure to solutions, and compared between groups using one-way ANOVA with Tukey test. The microhardness value of each group was analyzed using student t test. Acid-treated OrthoMTA and dentin was examined by scanning electron microscope (SEM). Cell viability of tested solutions was assessed using WST-8 assay and murine macrophage.

RESULTS

Three test solutions reduced microhardness of dentin. 17% EDTA demonstrated severe dentinal erosion, significantly reduced the dentinal microhardness compared to 10% CA (p = 0.034) or 5% GA (p = 0.006). 10% CA or 5% GA significantly reduced the surface microhardness of set MTA compared to 17% EDTA and saline (p < 0.001). Acid-treated OrthoMTA demonstrated microporous structure with destruction of globular crystal. EDTA exhibited significantly more cellular toxicity than the other acidic solutions at diluted concentrations (0.2, 0.5, 1.0%).

CONCLUSIONS

Tested acidic solutions reduced microhardness of root dentin. Five minute's application of 10% CA and 5% GA significantly reduced the microhardness of set OrthoMTA with lower cellular cytotoxicity compared to 17% EDTA.