Regenerative Endodontic Procedures for Traumatized Immature Permanent Teeth with Severe External Root Resorption and Root Perforation.

External root resorption (ERR) is often a complication of traumatic injury to the teeth. Traditionally, external inflammatory root resorption is treated with calcium hydroxide. The outcome of ERR, especially replacement resorption, is unpredictable. The purpose of the present case report was to describe regenerative endodontic procedures (REPs) for 1 replanted avulsed tooth with severe external root resorption and root perforation (tooth #9) and 1 extruded tooth (tooth #8). A 9-year-old girl was referred for the treatment of teeth #8 and #9 4 months after the initial trauma. Clinical examination showed that tooth #9 had a sinus tract present near the periapical area, was tender to percussion and palpation, and did not respond to pulp sensibility tests. Tooth #8 responded to pulp sensibility tests. Periapical radiographic and cone-beam computed tomographic examination showed that tooth #9 had a periapical radiolucent lesion and severe ERRs with a root perforation. Tooth #9 was diagnosed with a necrotic pulp and symptomatic apical periodontitis. Regenerative endodontic procedures (REPs) were initiated. Tooth #8 became nonresponsive to pulp sensibility tests and developed a periapical lesion 12 months after REPs of tooth #9 and was also treated with REPs. The clinical symptoms and apical lesions resolved for both teeth after REPs. The severe ERRs were arrested, and root perforation was repaired for tooth #9. Teeth #8 and #9 underwent canal obliteration by hard tissue formation after REPs and were in function at 18 months and 30 months, respectively. REPs may be used to manage traumatized immature permanent teeth with a necrotic pulp and apical periodontitis associated with severe ERR and root perforation.

Modified Apexification Procedure for Immature Permanent Teeth with a Necrotic Pulp/Apical Periodontitis: A Case Series.

The current American Association of Endodontists clinical considerations for a regenerative endodontic procedure state that a regenerative procedure is suitable for immature permanent teeth with necrotic pulp when the pulp space is not needed for a post/core in the final restoration. Therefore, many immature permanent teeth with necrotic pulp that have sustained a substantial loss of coronal tooth structure either from caries or trauma are treated by apexification or mineral trioxide aggregate/Biodentine (Septodent, Lancaster, PA) apical barrier techniques in which no further root maturation would occur. This case series presents 10 immature permanent teeth with necrotic pulp in which a post/core was likely required in the future for adequate coronal restoration because of loss of substantial coronal tooth structure and a modified apexification procedure was used. All 10 cases after the modified apexification procedure showed no clinical symptoms/signs and showed radiographic evidence of healed/healing of periapical lesion after a 2-year review. Eight cases showed increased thickness of the apical root canal walls, increased apical root length, and apical closure. The overall percentage change in root length was 7.52%, in root width at the apical one third it was 18.89%, and in radiographic root area it was 15.04% at the 24- to 72-month follow-up period. This modified apexification procedure allows for the tooth to be restored with a post/core if required for the final restoration in the future as well as continued root development.

Vital pulp therapy of mature permanent teeth with irreversible pulpitis from the perspective of pulp biology.

The American Association of Endodontists (AAE) Consensus Conference Recommended Diagnostic Terminology states that mature permanent teeth clinically diagnosed with irreversible pulpitis are treated with pulpectomy and root canal filling because inflamed vital pulp is not capable of healing. Histological studies have demonstrated that clinically diagnosed irreversible pulpitis does not involve the entire pulp. A recent International Endodontic Journal Editorial suggested clinical diagnosis of pulp disease should be reassessed because of the poor correlation between clinical symptoms and pulp sensibility testing and the actual histological status of the pulp. This review identified studies in a PubMed search that provide evidence for vital pulp therapy (VPT) of mature permanent teeth with irreversible pulpitis is predictable if correctly diagnosed and properly treated. A narrative review was undertaken to outline the correlation between the clinical symptoms/signs and pulp sensibility testing and the histological findings of the pulp. Treatment procedures for permanent teeth are outlined.

Revascularization-associated Intracanal Calcification: A Case Report with an 8-year Review.

Revascularization-associated intracanal calcification (RAIC) is a common finding in immature teeth managed with regenerative endodontic treatment (RET). The aim of this report was to illustrate a case in which 2 mandibular premolar teeth developed complete canal obliteration and have been reviewed for 8 years. The 3 primary outcome goals as defined by the American Association of Endodontists after RET are resolution of signs and symptoms of pulp necrosis, further root maturation, and achievement of responses to pulp vitality testing. The teeth had been included in an earlier quantitative study in which an increase in root canal width of 72.1% and 39.6% and an increase in root length of 1.7% and 0% were reported for teeth #20 and #29, respectively. Qualitative assessments over the 8-year review period showed no pathosis and a response to electric pulp testing at the final review. A quantitative assessment at the 8-year review showed an increase of 100% for canal width because complete calcification had occurred and no substantive change in root length (-0.17% and 0.68% for teeth #20 and #29, respectively). In this report, complete RAIC occurred in both teeth over time. RAIC has the potential to complicate future endodontic or prosthodontic treatment if necessary. Therefore, it is recommended that the American Association of Endodontists clinical considerations for a regenerative endodontic procedure be updated to include the incidence of RAIC after RET.

Continued root maturation despite persistent apical periodontitis of immature permanent teeth after failed regenerative endodontic therapy.

Three immature permanent teeth with pulp necrosis and apical periodontitis were treated with regenerative endodontic therapy (RET), which included root canal disinfection with sodium hypochlorite irrigation, intra-canal medication with calcium hydroxide paste, 17% EDTA rinse, induction of periapical bleeding into the canal, collagen matrix and MTA coronal seal, and composite resin restoration of access cavities. After different periods of follow-up, it was observed that continued root maturation, especially apical closure occurred despite persistent apical periodontitis of immature permanent teeth after failed RET. This finding is of interest as the secondary goal of further root maturation occurred despite failure of the primary goal of elimination of clinical symptom/sign and periapical inflammation. The possible biological mechanisms that could allow for further root maturation to occur in spite of persistent root canal infection of immature permanent teeth are discussed. Based on these observations, the biology of wound healing of immature permanent teeth after injury is not fully understood and should be further investigated. This case report demonstrates that whilst further root maturation is considered a successful outcome for teeth treated with RET, the primary objective must be the resolution of the signs and symptoms of apical periodontitis.

Alkaline Materials and Regenerative Endodontics: A Review.

Periapical health is the primary goal of endodontic treatment in mature and immature teeth. In addition, the goals of treatment of immature teeth with arrested root development include root growth to length and maturation of the apex, as well as thickening of the canal wall. These goals are valid for immature teeth that have been subjected to trauma and dental caries or that are the result of developmental anomalies that expose the tooth to the risk of pulp necrosis and consequently result in the cessation of root maturation. Regenerative endodontic procedures (REPs) have been described as a "paradigm shift" in the treatment of immature teeth with pulp necrosis and underdeveloped roots, as there is the potential for further root maturation and return of vitality. Treatment with REPs is advocated as the treatment of choice for immature teeth with pulp necrosis. REP protocols involve the use of alkaline biomaterials, primarily sodium hypochlorite, calcium hydroxide, mineral trioxide aggregates and Biodentine, and are the essential components of a successful treatment regimen.

An Evidence-based Review of the Efficacy of Treatment Approaches for Immature Permanent Teeth with Pulp Necrosis.

INTRODUCTION: Two fundamental assumptions for teeth treated with regenerative endodontic procedures (REPs) are (1) that the clinical outcome is comparable with the traditional techniques of calcium hydroxide apexification and mineral trioxide aggregate apical barrier techniques and (2) that REPs will result in further root maturation. METHODS: A systematic review of the electronic databases (Scopus, PubMed, and Web of Science) involved a search for studies that used quantitative assessments of root maturation. The search terms were "dental pulp," "regenerative endodontic therapy," "revascularization," and "revitalization." The identified studies were further screened for cohort studies that compared clinical outcomes between teeth treated with REPs and apexification/apical barrier approaches. The primary question under review was framed according to the population, exposure, and outcome format. RESULTS: Of the 368 studies identified by the search, 6 cohort studies used quantitative assessments of any further root maturation after REPs, and a subset of 4 of these cohort studies assessed and compared clinical outcomes between the different treatment approaches. CONCLUSIONS: Immature teeth with pulp necrosis treated with REPs generally show further root maturation although the results are variable. Clinical outcomes were similar for both groups. Patient-based criteria such as tooth discoloration, indications for changing the treatment option, and number of treatment appointments are all important for discussion before electing the appropriate treatment plan for the management of immature teeth with pulp necrosis.

A review of regenerative endodontics: current protocols and future directions.

This review outlines the biological basis and clinical protocols currently used in regenerative endodontic procedures (REPs) and discuss future directions in pulp regeneration approaches. The treatment of immature teeth with REPs has been described as a 'paradigm shift' as there is the potential for further root maturation. Clinically, REPs involve disinfection of the root canal system without damaging the endogenous stem cell potential present in the apical papilla and other tissues. These stems cells are introduced into the root canal space by inducing a blood clot followed by placement of an intracanal barrier to prevent microleakage. The biological concept of REPs involves the triad of stem cells, scaffold and signalling molecules. Currently, repair rather than true regeneration of the 'pulp-dentine complex' is achieved and further root maturation is variable. However, may clinicians consider the treatment of teeth with REPs as the optimal treatment approach for immature teeth with pulp necrosis.

Endodontic Treatment Outcomes.

The primary goal of conventional endodontic treatment is prevention and/or elimination of apical periodontitis for both mature permanent teeth and immature teeth with an open apex. Besides these goals, the objectives of endodontic treatment of immature teeth include preservation of pulp vitality and often further root maturation. Robust criteria for outcome assessment are an essential determinant for any measure of treatment success for both mature and immature teeth.

Pulp and apical tissue response to deep caries in immature teeth: A histologic and histobacteriologic study.

Descriptions of the pathologic changes in the pulp and associated apical structures of human immature teeth in response to deep caries are lacking in the literature. OBJECTIVES: This article describes the histologic events associated with the radicular pulp and the apical tissues of human immature teeth following pulp inflammation and necrosis. METHODS: Twelve immature teeth with destructive caries lesions were obtained from 8 patients. Two intact immature teeth served as controls. Teeth were extracted for reasons not related to this study and immediately processed for histopathologic and histobacteriologic analyses. Serial sections were examined for the pulp conditions and classified as reversible or irreversible pulp inflammation, or pulp necrosis. Other histologic parameters were also evaluated. RESULTS: In the 3 cases with reversible pulp inflammation, tissue in the pulp chamber showed mild to moderate inflammation and tertiary dentin formation related to tubules involved in the caries process. Overall, the radicular pulp tissue, apical papilla and Hertwig's epithelial root sheath (HERS) exhibited characteristics of normality. In the 3 cases with irreversible pulp inflammation, the pulps were exposed and severe inflammation occurred in the pulp chamber, with minor areas of necrosis and infection. Large areas of the canal walls were free from odontoblasts and lined by an atubular mineralized tissue. The apical papilla showed extremely reduced cellularity or lack of cells and HERS was discontinuous or absent. In the 6 cases with pulp necrosis, the coronal and radicular pulp tissue was necrotic and colonized by bacterial biofilms. The apical papilla could not be discerned, except for one case. HERS was absent in the necrotic cases. CONCLUSION: While immature teeth with reversible pulpitis showed histologic features almost similar to normal teeth in the canal and in the apical region, those with irreversible pulpitis and necrosis exhibited significant alterations not only in the radicular pulp but also in the apical tissues, including the apical papilla and HERS. CLINICAL SIGNIFICANCE: Alterations in the radicular pulp and apical tissues help explain the outcome of current regenerative/reparative therapies and should be taken into account when devising more predictable therapeutic protocols for teeth with incomplete root formation.

Regenerative Endodontic Procedures for Traumatized Teeth after Horizontal Root Fracture, Avulsion, and Perforating Root Resorption.

INTRODUCTION: Traumatic injury to the teeth can cause horizontal root fractures and inflammatory root resorptions (external and internal). Traditionally, traumatized teeth with horizontal root fractures resulting in pulp necrosis and inflammatory root resorptions are treated with conventional root canal therapy. METHODS: A 15-year-old boy had a history of traumatic injury to mature tooth #8 resulting in horizontal root fracture and pulp necrosis of the coronal fragment. A 7-year-old girl suffered an avulsion injury to immature tooth #9, which developed inflammatory replacement resorption and subsequently root fractured 15 months later. Another 16-year-old boy also suffered a history of traumatic injury to mature tooth #8, resulting in perforating root resorption. All teeth were treated with regenerative endodontic procedures using chemomechanical debridement, calcium hydroxide/triple antibiotic paste dressing, EDTA rinse, induction of periapical bleeding into the canal space, and a coronal mineral trioxide aggregate plug. In the tooth presenting with horizontal root fracture, only the coronal fragment was treated to preserve pulp vitality in the apical fragment for possible pulp tissue regeneration. RESULTS: After regenerative endodontic procedures, clinical signs/symptoms subsided, and inflammatory osteolytic lesions resolved in all traumatized teeth. Two teeth were followed for 19 months and 1 tooth for 5 years. At the last review of the teeth with horizontal root fractures, the first case showed healing by calcified tissue and the second case showed healing by fibrous connective and hard tissue. Tooth with perforating root resorption demonstrated a decrease in size of the resorptive defect. CONCLUSIONS: Based on these case reports, regenerative endodontic procedures have the potential to be used to treat traumatized teeth with horizontal root fracture and inflammatory root resorption.

Treatment of Mature Permanent Teeth with Necrotic Pulps and Apical Periodontitis Using Regenerative Endodontic Procedures: A Case Series.

INTRODUCTION: Regenerative endodontic procedures (REPs) are usually used to treat human immature permanent teeth with necrotic pulps and/or apical periodontitis. Successful REPs result in the elimination of clinical signs/symptoms, the resolution of apical periodontitis, and, in some cases, thickening of the canal walls and/or continued root development with or without apical closure. REPs can restore the vitality of tissue in the canals of immature permanent teeth previously destroyed by infection or trauma. Vital tissue is inherited with immune defense mechanisms to protect itself from foreign invaders. Recently, REPs have also been used to successfully treat human mature permanent teeth with necrotic pulps and apical periodontitis. The purpose of this case series was to present the potential of using REPs for mature permanent teeth with necrotic pulps and apical periodontitis. METHODS: This case series consisted of 6 patients, 4 females and 2 males. The patients' ages ranged from 8-21 years old. Seven permanent teeth, 4 anterior and 3 molar teeth, with necrotic pulps and apical periodontitis were treated using REP. Radiographically, the root development of all teeth was almost completed except the apices of 2 molars, which showed slightly open. Complete chemomechanical debridement of the canals of the teeth was performed, and the canals were dressed with Metapaste (Meta Biomed Co, Ltd, Chungbuk, Korea) during treatment visits. Periapical bleeding into the canals was induced at the last treatment visit by placing a hand #20 or #25 K-file with the tip slightly bent through the apical foramina into the periapical tissues. A 3-mm thickness of mineral trioxide aggregate was placed into the coronal canals over semicoagulated blood. The access cavities were restored with either composite resin or amalgam. RESULTS: Follow-ups of the 7 teeth ranged from 8 to 26 months. The periapical lesions of 2 teeth were considered healed, and 5 teeth revealed healing. Clinical signs/symptoms were absent in all teeth at follow-up visits at different time points. None of the treated teeth responded to cold and electric pulp tests. CONCLUSIONS: This case series shows the potential of using REPs for mature teeth with necrotic pulp and apical periodontitis.

Regeneration and Repair in Endodontics-A Special Issue of the Regenerative Endodontics-A New Era in Clinical Endodontics.

Caries is the most common cause of pulp-periapical disease. When the pulp tissue involved in caries becomes irreversibly inflamed and progresses to necrosis, the treatment option is root canal therapy because the infected or non-infected necrotic pulp tissue in the root canal system is not accessible to the host's innate and adaptive immune defense mechanisms and antimicrobial agents. Therefore, the infected or non-infected necrotic pulp tissue must be removed from the canal space by pulpectomy. As our knowledge in pulp biology advances, the concept of treatment of pulpal and periapical disease also changes. Endodontists have been looking for biologically based treatment procedures, which could promote regeneration or repair of the dentin-pulp complex destroyed by infection or trauma for several decades. After a long, extensive search in in vitro laboratory and in vivo preclinical animal experiments, the dental stem cells capable of regenerating the dentin-pulp complex were discovered. Consequently, the biological concept of 'regenerative endodontics' emerged and has highlighted the paradigm shift in the treatment of immature permanent teeth with necrotic pulps in clinical endodontics. Regenerative endodontics is defined as biologically based procedures designed to physiologically replace damaged tooth structures, including dentin and root structures, as well as the pulp-dentin complex. According to the American Association of Endodontists' Clinical Considerations for a Regenerative Procedure, the primary goal of the regenerative procedure is the elimination of clinical symptoms and the resolution of apical periodontitis. Thickening of canal walls and continued root maturation is the secondary goal. Therefore, the primary goal of regenerative endodontics and traditional non-surgical root canal therapy is the same. The difference between non-surgical root canal therapy and regenerative endodontic therapy is that the disinfected root canals in the former therapy are filled with biocompatible foreign materials and the root canals in the latter therapy are filled with the host's own vital tissue. The purpose of this article is to review the potential of using regenerative endodontic therapy for human immature and mature permanent teeth with necrotic pulps and/or apical periodontitis, teeth with persistent apical periodontitis after root canal therapy, traumatized teeth with external inflammatory root resorption, and avulsed teeth in terms of elimination of clinical symptoms and resolution of apical periodontitis.

Management of Teeth with Persistent Apical Periodontitis after Root Canal Treatment Using Regenerative Endodontic Therapy.

Regenerative endodontic therapy (RET) is currently used to treat immature teeth with necrotic pulp and/or apical periodontitis. However, recently RET has been used to treat mature teeth with necrotic pulp and/or apical periodontitis and resulted in regression of clinical signs and/or symptoms and resolution of apical periodontitis. The purpose of this case report was to describe the potential of using RET to treat 2 mature teeth with persistent apical periodontitis after root canal therapy using RET. Two male patients, one 26-year old and another 12-year old, presented for retreatment of persistent apical periodontitis after root canal treatment of 2 mature teeth (#9 and #19). The gutta-percha fillings in the canals of teeth #9 and #19 were removed with Carvene gutta-percha solvent (Prevest DenPro, Jammu, India) and ProTaper Universal rotary retreatment files (Dentsply Maillefer, Ballaigues, Switzerland). The canals of both teeth were further chemomechanically debrided with rotary retreatment files and copious amounts of sodium hypochlorite irrigation and dressed with Metapaste (Meta Biomed, Chungbuk, Korea). RET was performed on teeth #9 and #19. Periapical bleeding was provoked into the disinfected root canals. The blood clots were covered with mineral trioxide aggregate plugs, and the access cavities were restored with intermediate restorative material. Teeth #9 and #19 showed regression of clinical signs and/or symptoms and healing of apical periodontitis after 13-month and 14-month follow-ups, respectively. Tooth #9 revealed narrowing of the canal space and apical closure by deposition of hard tissue. RET has the potential to be used to retreat teeth with persistent apical periodontitis after root canal therapy.

Histological observations of pulpal replacement tissue in immature dog teeth after revascularization of infected pulps.

BACKGROUND AND AIM: Many studies have examined the nature of tissue formed in the canals of immature necrotic teeth, following revascularization in animals and humans. While speculations have been made that regeneration of the pulp tissue might take place in the canal, the tissue has been found to be cementum-like, bone-like, and periodontal ligament-like. The purpose of this study was to histologically examine the tissue in the root canals in immature dog teeth that had been artificially infected and then revascularized. METHODS: Two 4- to 5-month-old mongrel dogs with immature teeth were used in the study. In one dog, four maxillary and four mandibular anterior teeth, and in another dog, four maxillary and five mandibular anterior teeth were used in the experiment. Pulp infection was artificially induced in the immature teeth. Revascularization was performed on all teeth by disinfecting the root canals with sodium hypochlorite irrigation and triple antibiotic intracanal dressing, completed with induction of intracanal bleeding, and sealed with an MTA plug. The access cavity was restored with silver amalgam. The animals were sacrificed 3 months after revascularization procedures. The revascularized teeth and surrounding periodontal tissues were removed and prepared for histological examination. RESULTS: Besides cementum-like, bone-like, and periodontal ligament-like tissues formed in the canals, residual remaining pulp tissue was observed in two revascularized teeth. In four teeth, ingrowth of alveolar bone into the canals was seen; presence of bone in the root canals has the potential for ankylosis. CONCLUSIONS: Within the limitation of this study, it can be concluded that residual pulp tissue can remain in the canals after revascularization procedures of immature teeth with artificially induced pulp infection. This can lead to the misinterpretation that true pulpal regeneration has occurred. Ingrowth of apical bone into the root canals undergoing revascularization can interfere with normal tooth eruption if ankylosis occurs.

Regeneration and Repair in Endodontics-A Special Issue of the Dentistry Journal.

Endodontics is a specialized discipline in dentistry that concerns the morphology, physiology, and pathology of the pulp-dentin complex, root, and peri-radicular tissues. [...].

Clinical and radiographic outcomes of traumatized immature permanent necrotic teeth after revascularization/revitalization therapy.

INTRODUCTION: Revascularization treatment is rapidly becoming an accepted treatment alternative for the management of endodontic pathology in immature permanent teeth with necrotic dental pulps. However, the success and timing of clinical resolution of symptoms, and radiographic outcomes of interest, such as continued hard tissue deposition within the root, are largely unknown. METHODS: In this prospective cohort study, 20 teeth were treated with a standardized revascularization treatment protocol and monitored for clinical and radiographic changes for 1 year. Standardized radiographs were collected at regular intervals, and radiographic changes were quantified. RESULTS: All 20 treated teeth survived during the 12-month follow-up period, and all 20 also met the clinical criteria for success at 12 months. As a group, the treated teeth showed a statistically significant increase in radiographic root width and length and a decrease in apical diameter, although the changes in many cases were quite small (such that the clinical significance is unclear). The within-case percent change in apical diameter after 3 months was 16% and had increased to 79% by 12 months, with 55% (11/20) showing complete apical closure. The within-case percent change in root length averaged less than 1% at 3 months and increased to 5% at 12 months. The within-case percent change in root thickness averaged 3% at 3 months and 21% at 12 months. CONCLUSIONS: Although clinical success was highly predictable with this procedure, clinically meaningful radiographic root thickening and lengthening are less predictable after 1-year of follow-up. Apical closure is the most consistent radiographic finding.

Treatment of a large cystlike inflammatory periapical lesion associated with mature necrotic teeth using regenerative endodontic therapy.

INTRODUCTION: Regenerative endodontic therapy is currently used to treat immature permanent teeth with necrotic pulp and/or apical periodontitis. However, mature teeth with necrotic pulp and apical periodontitis have also been treated using regenerative endodontic therapy. The treatment resulted in resolution of apical periodontitis, regression of clinical signs and symptoms but no apparent thickening of the canal walls, and/or continued root development. A recent study in an animal model showed that the tissues formed in the canals of mature teeth with apical periodontitis after regenerative endodontic therapy were cementumlike, bonelike, and periodontal ligament-like tissue with numerous blood vessels. These tissues are similar to the tissues observed in immature permanent teeth with apical periodontitis after regenerative endodontic therapy. METHODS: A 23-year-old woman had a history of traumatic injury to her upper anterior teeth when she was 8 years old. Subsequently, #8 developed pulp necrosis and an acute apical abscess and #7 symptomatic apical periodontitis. The apex of #8 was slightly open, and the apex of #7 was completely formed. Instead of nonsurgical root canal therapy, regenerative endodontic therapy was attempted, including complete chemomechanical debridement on #8 and #7. This was based on the premise that filling of disinfected root canals with the host's biological vital tissue might be better than filling with foreign materials. RESULTS: After regenerative endodontic therapy of #8 and #7, there was radiographic evidence of periapical osseous healing and regression of clinical signs and symptoms. The pulp cavity of #8 decreased in size, and the apex closed. The pulp cavity of #7 appeared to be obliterated by mineralized tissue. These indicated ingrowth of new vital tissue into the chemomechanically debrided canals. CONCLUSIONS: Regenerative endodontic therapy of mature teeth with apical periodontitis and apical abscess can result in the regression of clinical signs and/or symptoms and healing of apical periodontitis but no apparent thickening of the canal walls or continued root development. Filling of the disinfected canals with the host's vital tissue may be better than with foreign materials because vital tissue has innate and adaptive immune defense mechanisms.

Repair of extensive apical root resorption associated with apical periodontitis: radiographic and histologic observations after 25 years.

INTRODUCTION: Root resorption is a frequent finding in teeth with apical periodontitis. In cases of severe apical periodontitis, root resorption may involve not only cementum but also dentin. Resorbed tooth structures can only be repaired with cementum because stem cells in the periradicular tissues are not capable of differentiating into odontoblasts. This article reports the repair of extensive apical root resorption associated with apical periodontitis 25 years after treatment. METHODS: A 51-year-old man presented with pulp necrosis and symptomatic apical periodontitis in tooth #7. The periapical radiograph showed a large radiolucent periradicular lesion and severe root resorption. Nonsurgical root canal therapy was performed. Twenty-five years after treatment, a crown fracture developed, and the tooth could not be restored. The periapical radiograph revealed complete healing of the previous apical periodontitis lesion and restoration of the resorbed root structure. The tooth was removed and examined histologically. RESULTS: The apical canal was almost completely filled with a cementumlike tissue with some strands of entrapped vital uninflamed connective tissue. Areas of cementum and dentin resorption in the apical third were repaired by a combination of cellular and acellular cementum to which periodontal ligament fibers were attached. CONCLUSIONS: Root resorption caused by apical periodontitis can be restored almost to its normal structure after adequate nonsurgical root canal treatment that succeeded in controlling infection. The mechanisms behind this process are not clear but probably involve signaling pathways regulating root development, cell-cell and cell-matrix interaction, and morphogens.

Radiographic and clinical outcomes of the treatment of immature permanent teeth by revascularization or apexification: a pilot retrospective cohort study.

INTRODUCTION: This retrospective cohort study compared clinical and radiographic outcomes of endodontic treatment performed in immature nonvital permanent teeth by apexification (calcium hydroxide or apical barrier with mineral trioxide aggregate) versus revascularization. METHODS: A comprehensive chart review was performed to obtain a cohort of previously completed cases with recalls. Clinical and radiographic data were collected for 31 treated teeth (19 revascularization and 12 apexification) with an average follow-up time of 17 months and a recall rate of 63%. Tooth survival, success rate, and adverse events were analyzed. Changes in radiographic root length, width, and area were quantified. RESULTS: The majority of treated teeth survived throughout the study period, with 30 of 31 (97%) teeth surviving (18/19 [95%] revascularization and 12/12 apexification). Most cases were also clinically successful, with 27 of 31 (87%) meeting criteria for success (15/19 [78%] revascularization and 12/12 apexification; nonsignificant difference). A greater incidence of adverse events was observed in the revascularization group (8/19 [42%] vs 1/12 [11%] in apexification) (risk ratio = 5.1; P = .04; 95% confidence interval, 0.719-35.48). Although more revascularization cases than apexification cases showed an increase in radiographic root area and width, the effect was not statistically significant. CONCLUSIONS: In this study, revascularization was not superior to other apexification techniques in either clinical or radiographic outcomes. Studies with large subject cohorts and long follow-up periods are needed to evaluate outcomes of revascularization and apexification while accounting for important covariants relevant to clinical success.