Response to intracanal medication in immature teeth with pulp necrosis: an experimental model in rat molars

Influence of ethylenediaminetetraacetic acid irrigation on the regenerative endodontic procedure in an immature rat molar model

AIM

To analyse the influence of ethylenediaminetetraacetic acid (EDTA) on the repair process in immature rat molars after a regenerative endodontic procedure (REP).

METHODOLOGY

The lower first molars of 12 4-week-old Wistar rats underwent pulpectomy in the mesial root and were divided into the following groups: sodium hypochlorite (NaOCl; n = 6) - the mesial canals were irrigated with 2.5% NaOCl for 5 min, and NaOCl-EDTA (n = 6) - the canals were irrigated with 2.5% NaOCl, followed by 17% EDTA for 5 min each. After evoking bleeding using a size 10 K-file, the cavities were sealed. Three molars on the untreated side were randomly used as control (control-15 d; n = 3), and three molars from the other three rats untreated were used as immediate control (n = 3). After 15 days (NaOCl, NaOCl-EDTA and control-15 d groups) or immediately (control-immediate), the animals were euthanized, and the teeth were subjected to histologic evaluation of tissue regeneration and presence of collagen fibres. Mann-Whitney U-test was used (p < .05).

RESULTS

The experimental groups had newly formed cementum-like tissue and increased root length and thickness. Half of the specimens in NaOCl-EDTA group showed apical foramen closure, whilst the NaOCl group had partial apical closure. The experimental groups showed inflammatory infiltrate extending mainly to the medium third of the root canal. These parameters were similar between experimental groups (p > .05). Newly formed connective tissue in the pulp space was significantly higher in the NaOCl-EDTA group than in NaOCl group (p < .05). Regarding the collagen fibres, the NaOCl-EDTA group had more collagen fibres in the root tip, but there was no significant difference compared to NaOCl group, and both groups showed greater amount of immature fibres in this area; in the centre of the apical third of root canal, there was equivalence between mature and immature fibres from both groups (p > .05).

CONCLUSIONS

Ethylenediaminetetraacetic acid irrigation improved newly formed intracanal connective tissue after REP in immature molars of rats; however, EDTA did not influence cementum-like tissue formation, apical closure, inflammatory infiltrate and maturation of collagen fibres.

Tissue Characteristics in Endodontic Regeneration: A Systematic Review

The regenerative endodontic procedure (REP) represents a treatment option for immature necrotic teeth with a periapical lesion. Currently, this therapy has a wide field of pre-clinical and clinical applications, but no standardization exists regarding successful criteria. Thus, by analysis of animal and human studies, the aim of this systematic review was to highlight the main characteristics of the tissue generated by REP. A customized search of PubMed, EMBASE, Scopus, and Web of Science databases from January 2000 to January 2022 was conducted. Seventy-five human and forty-nine animal studies were selected. In humans, the evaluation criteria were clinical 2D and 3D radiographic examinations. Most of the studies identified a successful REP with an asymptomatic tooth, apical lesion healing, and increased root thickness and length. In animals, histological and radiological criteria were considered. Newly formed tissues in the canals were fibrous, cementum, or bone-like tissues along the dentine walls depending on the area of the root. REP assured tooth development and viability. However, further studies are needed to identify procedures to successfully reproduce the physiological structure and function of the dentin–pulp complex.

Effect of Duration of Root Canal Infection on the Ability of Dentin-Pulp Complex Regeneration of Immature Permanent Teeth: An Animal Study

BACKGROUND

Persistent infection is always considered the most important reason for the failure of dentin-pulp complex regeneration. The present study aims to evaluate the effect of the duration of root canal infection (from one to twelve weeks) on the ability of dentin-pulp complex regeneration.

METHODS

In this animal study, 64 roots of immature premolar teeth of four dogs were randomly divided into four groups. Positive control group; eight root canals treated with regenerative endodontic procedure (REP), negative control group; 12 infected root canals, intervention groups; 36 root canals infected with supragingival plaque (one, three, six, and 12 weeks) and treated with REP, an additional positive control group; eight normal roots. After three months, the teeth were investigated by radiographic images and immunohistochemical staining (CD31, CD34, S100 markers). In addition, DSPP gene expression was assessed using a real-time PCR technique. The results were analyzed at a significance level of 0.05.

RESULTS

Based on radiological evaluation among the intervention groups, the highest root canal development (length and width) occurred in the intervention group of one week, and the lowest radiological results were in the intervention groups of six and 12 weeks (One-way ANOVA, P <0.05). There was a significant difference between the groups in terms of CD31, CD34, S100 and, DSPP expression percentage (One-way ANOVA, P <0.05), in which the highest and lowest expression percentages belonged to the one- and 12 weeks groups, respectively, among the intervention groups.

CONCLUSION

This study demonstrated that long root canal infection decreased the ability of the body to regenerate dentin-pulp complex.

Pulp capping with mineral trioxide aggregate or Biodentine: a comparison of mineralized barrier formation and inflammatory and degenerative events

Biodentine in endodontic practice has been widely investigated, but comprehensive histological descriptions of degenerative and inflammatory responses are not covered in most of the studies that compare pulp capping materials. This study aimed to evaluate pulpal responses to mineral trioxide aggregate (MTA Angelus) and Biodentine, focusing on mineralized barrier formation and on inflammatory and degenerative events. 80 male Wistar rats were assigned to 5 groups, according to the materials used for pulp capping and coronal sealing (n=8 per group/period). The lower first molars were mechanically exposed, capped with either MTA or Biodentine, and restored with silver amalgam. In an additional test group, the teeth were capped and sealed with Biodentine. The teeth capped with gutta-percha and restored with silver amalgam served as positive control, whereas untreated teeth served as negative control. Pulpal responses and coronal sealing were evaluated after 14 or 21 days. Data was statistically analyzed by the Kruskal-Wallis and Dunn's post hoc tests (p<0.05). Biodentine and MTA presented satisfactory results, showing a milder inflammatory response (p<0.0001) and more pronounced formation of mineralized barrier (p<0.0001) compared to the teeth capped with gutta-percha. As a restorative material, Biodentine kept coronal sealing in only 37.5% of the samples. Biodentine showed favorable properties in vital pulp therapy, being similar to MTA. However, it was not effective in protecting dental pulp from microleakage during the experimental period.

Does MTA provide a more favourable histological response than other materials in the repair of furcal perforations? A systematic review

BACKGROUND

There is no consensus on which furcal perforation repair material induces a more favourable histological response. This systematic review of laboratory studies provides an overview of the studies comparing repair materials in animal models.

OBJECTIVES

To evaluate whether mineral trioxide aggregate (MTA) yields a more favourable histological response than other materials when used to repair furcal perforations in animal experimental models.

METHODS

This review followed the PRISMA checklist. The studies included various materials used to repair furcal perforations and compared the histological responses with MTA. An electronic search was conducted in EMBASE, PubMed, Scopus and Web of Science up to 2 September 2020, with no language or publication date restrictions. Studies whose full text was unavailable were excluded. The ARRIVE and SYRCLE tools were used to assess the methodological quality and risk of bias (RoB) of the studies.

RESULTS

The studies included in the qualitative synthesis were conducted in rat (n = 3) and dog (n = 17) models. They were classified as having a low quality, high methodological heterogeneity and high RoB. MTA and Biodentine, the materials most often compared, reduced the inflammatory reaction to mild over time. In addition, a mineralized tissue was formed in all studies. The response yielded by MTA was better than or equivalent to that of the other tested materials.

DISCUSSION

This review confirmed that MTA is the reference standard material for furcal perforation repair. However, research using animal models has inherent limitations, and the substantial methodological heterogeneity across the studies included should be considered. Therefore, the knowledge generated by this systematic review should be translated into clinical practice cautiously.

CONCLUSIONS

Features described in the report and quality assessment guidelines, such as PRIASE, ARRIVE and SYRCLE, should guide researchers. Despite the high RoB and the low methodological quality of the studies included, findings indicated that MTA yields a more favourable histological response than other materials in the repair of furcal perforations.

REGISTRATION

PROSPERO (CRD42020181297).

The potential of a surface pre-reacted glass root canal dressing for treating apical periodontitis in rats

AIM

To evaluate the efficacy of a prototype root canal dressing containing surface pre-reacted glass-ionomer (S-PRG) fillers on repairing induced periapical lesions in a rat model. Calcium hydroxide [Ca(OH)₂ ] was applied as a comparison in the healing process.

METHODOLOGY

The pulp chambers of the maxillary first molars in 64 male Wistar rats aged 16 weeks were opened to induce periapical lesions. After 28 days, the mesial canal of each tooth was prepared, irrigated with 2.5% sodium hypochlorite only (control group: irrigation) or followed by the respective dressing [Ca(OH)₂ group, irrigation + Ca(OH)₂ ; S-PRG group, irrigation + S-PRG] and restored with composite resin for 3 or 7 days (10/group). Four rats with healthy molars were used as blank controls. Descriptive analysis of the periapical radiographs, haematoxylin and eosin staining and immunohistochemical observation was performed 3 and 7 days after treatment. The periapical grey value, CD68 macrophages and osteoclasts (cathepsin-K) were quantified and statistically analysed with Tukey's honest significant difference test. A significant difference was achieved when P values were <0.05.

RESULTS

S-PRG and Ca(OH)₂ dressings were associated with increased periapical grey values and inhibited osteoclast activity at 3 and 7 days; a significant difference in radiographic results and the number of osteoclasts was obtained at 3 and 7 days compared with the control group (P < 0.05). Reparative tissue was observed histologically in the space of the periapical resorbed necrotic area after S-PRG and Ca(OH)₂ treatment for 3 and 7 days. The number of macrophages was significantly decreased at 3 and 7 days in the S-PRG and Ca(OH)₂ specimens when compared with the controls (P < 0.05).

CONCLUSIONS

In a rat experimental model, the S-PRG root canal dressing was comparable to Ca(OH)₂ in promoting the healing of experimentally induced periapical lesions. S-PRG paste has the potential to be used as an alternative intracanal dressing in teeth with apical periodontitis.

The Response of the Pulp-Dentine Complex, PDL, and Bone to Three Calcium Silicate-Based Cements: A Histological Study in an Animal Rat Model

Objective

The aim of this study was to histologically examine the tissue reaction of three different calcium silicate cements in the closure of perforations in rat incisor teeth. Material and Methods. An experimental lateral root perforation with pulp exposure was performed in 32 lower incisors of 16 male Wistar albino rats. They were randomly assigned into three test groups (each including eight teeth) that were filled either by Biodentine (BD) or MicroMega mineral trioxide aggregate (MM-MTA) or EndoSequence root repair material putty (ESRRM putty), besides eight unperforated incisors from the other four rats (control group). The inflammatory response and healing process were evaluated histologically and scored after one and four weeks. Differences among groups were tested by Kruskal-Wallis tests at P ≤ 0.05.

Results

In the first week, BD produced more inflammatory response in the pulpal (score 3) than other materials (score 2). Only ESRRM putty showed odontoblast-like cells in 50%, 25% dentine-like deposit, 25% evidence of bone deposition in the drilling site (score 2), and minimum periodontal ligament (PDL) necrosis and disorganization (25%, score 2). After one month, all groups had healthy pulpal tissue, but 25% of ESRRM putty retained score 1 inflammatory response, and 50% of the BD case had an incomplete palisading odontoblast layer (score 3). A thick and regular dentine bridge deposition was seen in the ESRRM putty group in comparison with MM-MTA and BD cases. The cortical plate healing in all ESRRM putty samples was complete (score 3), while an incomplete closure was seen in MM-MTA and BD groups (score 2). Both the MM-MTA and ESRRM putty groups had fully organized PDL (score 2), while in 50% of BD cases, a necrotizing area and disorganized PDL with inflammatory cells infiltration were still present. Statistically significant differences in the scores of any histologic parameters among the three tested materials were observed neither in the 1st nor in the 4th weeks of the experimental period.

Conclusion

Better tissue compatibility and repair of pulpal and periodontal tissue have been detected after lateral perforation in the root of rat incisors when treated with ESRRM putty than MM-MTA and BD. However, the difference was not significant.

Influence of photobiomodulation therapy on root development of rat molars with open apex and pulp necrosis

This study aimed to evaluate the role of photobiomodulation (PBM) in apexification and apexogenesis of necrotic rat molars with an open apex. Rat molars were exposed to the oral environment for 3 weeks. Canals were rinsed with 2.5% NaOCl and 17% EDTA, filled with antibiotic paste and sealed. After 7 days, canals were rinsed and divided into six groups (n=6): mineral trioxide aggregate (MTA); blood clot (BC); human dental pulp stem cells (hDPSC); MTA+PBM; BC+PBM; and hDPSC+PBM. In hDPSC groups, a 1% agarose gel scaffold was used. Two groups were not exposed: healthy tooth+PBM (n = 6), healthy tooth (n = 3); and one was exposed throughout the experiment: necrotic tooth (n = 3). In PBM groups, irradiation was performed with aluminum gallium indium phosphide (InGaAlP) diode laser for 30 days within 24-h intervals. After that, the specimens were processed for histological and immunohistochemical analyses. Necrotic tooth showed greater neutrophil infiltrate (p < 0.05). Necrotic tooth, healthy tooth, and healthy tooth+PBM groups showed absence of a thin layer of fibrous condensation in the periapical area. All the other groups stimulated the formation of a thicker layer of fibers (p < 0.05). All groups formed more mineralized tissue than necrotic tooth (p < 0.05). PBM associated with MTA, BC, or hDPSC formed more mineralized tissue (p < 0.05). MTA+PBM induced apexification (p < 0.05). Rabbit polyclonal anti-bone sialoprotein (BSP) antibody confirmed the histological findings of mineralized tissue formation, and hDPSC groups exhibited higher percentage of BSP-positive cells. It can be concluded that PBM improved apexification and favored apexogenesis in necrotic rat molars with an open apex.

Periradicular inflammatory response, bone resorption, and cementum repair after sealing of furcation perforation with mineral trioxide aggregate (MTA Angelus™) or Biodentine™

OBJECTIVE

This study assessed tissue responses after furcation perforation and immediate sealing with either Biodentine™ or MTA Angelus™.

MATERIAL AND METHODS

Sixty male Wistar rats were used (n = 6 per group/period). The mandibular first molars had the furcation mechanically exposed and sealed with either MTA or Biodentine™ and restored with silver amalgam. In an additional test group, teeth were sealed only with Biodentine™. Furcation sealing with gutta-percha and silver amalgam restoration served as positive control, and healthy untreated teeth were the negative control. Histological evaluation was performed after 14 or 21 days. Kruskal-Wallis and Dunn's post hoc tests were performed to analyze the extent and intensity of tissue inflammation, bone resorption, and cementum repair (p < 0.05).

RESULTS

Biodentine™ and MTA presented satisfactory results, showing a milder inflammatory response when compared to the control, regardless of the material used for coronal sealing and of the experimental period evaluated (p < 0.0001). All test groups showed less bone resorption than the positive control after 21 days (p < 0.05), and such differences were more pronounced in teeth restored with silver amalgam. Cementum repair was performed in 30% of MTA and Biodentine™ samples but not carried out in any positive control specimen.

CONCLUSIONS

Biodentine™ and MTA promoted similar responses when used to seal furcation perforations and should therefore be regarded as a promising alternative.

CLINICAL RELEVANCE

Knowledge about tissue responses to restorative materials is essential for improving root perforation sealing protocols. The present results showed that both Biodentine™ and MTA promoted appropriate periradicular tissue reactions in a preclinical test for evaluating furcation perforation treatments.

The efficacy of platelet-rich fibrin as a scaffold in regenerative endodontic treatment: a retrospective controlled cohort study

Background

Blood Clot (BC) or platelet concentrates have been used as scaffold in regenerative endodontic treatment (RET). The aim of this retrospective study was to compare the performance of platelet-rich fibrin (PRF) with BC in inducing root development and periapical lesion healing after tooth revascularization.

Methods

Five patients receiving RET using PRF as a scaffold were matched 1:1 to a previous cohort of 5 patients who underwent tooth revascularization by provoking periapical bleeding. Clinical signs and symptoms were examined at follow-ups. Periapical lesion healing and root development were monitored radiographically. The resolution of clinical signs and symptoms as well as periapical radiolucency was observed in all patients (100%).

Results

Root elongation, dentinal wall thickening and apex closure were found in most cases (80% in both groups). There was no significant difference between the groups in terms of clinical sign resolution, root development and periapical healing.

Conclusions

Within the limits of this study, PRF achieved comparable outcomes to BC in terms of clinical sign and symptom resolution, periapical lesion healing and continued root development in RET.

Histopathological, Microbiological, and Radiographic Analysis of Antimicrobial Photodynamic Therapy for the Treatment of Teeth with Apical Periodontitis: A Study in Rats' Molars

OBJECTIVE

The aim of this study was to evaluate in vivo, by histological and radiographic analysis, the response of apical tissues of rats' teeth with experimentally induced apical periodontitis, after one- and two-session endodontic treatment with and without photodynamic therapy (PDT). A microbiological analysis was also performed to verify bacterial reduction after each treatment.

BACKGROUND DATA

Studies carried out in recent years highlighted the antibacterial potential of PDT when associated with conventional endodontic therapy in vitro. Although the antimicrobial effect of PDT is well-established, tissue response to PDT in teeth with apical periodontitis lacks studies.

METHODS

Thirty-two rats' root canals were assigned to four groups: one session/PDT-[chemomechanical preparation (CMP)+root canal filling (RCF)]; two sessions/PDT- [CMP+calcium hydroxide (CH) for 14 days+RCF]; one session/PDT+ [CMP+PDT+RCF], and two sessions/PDT+ [CMP+PDT+CH for 14 days+RCF]. For microbiological evaluation, samples were collected before and after proposed treatments. For radiographic and histological analysis, the animals were euthanized after 28 days and the mandibles surgically removed.

RESULTS

PDT associated with conventional endodontic therapy was able to promote significant bacterial reduction in root canals with induced apical periodontitis, but this reduction was not significantly different to conventional endodontic therapy alone. Although radiographic evaluation showed no significant differences, histological analysis showed lower scores for neutrophils/eosinophils in PDT-treated groups and macrophages/giant cells in CH groups.

CONCLUSIONS

The use of low-level laser as light source did not promote major improvement on radiographic and histological repair, but since the number of inflammatory cells slightly decreased, it may optimize repair by modulating inflammatory process. PDT may be indicated as an adjunct to conventional endodontic therapy for teeth with apical periodontitis, in association with an interappointment dressing with CH, in an attempt to produce better conditions to stimulate repair.

Paradigm Shift from Stem Cells to Cell-Free Regenerative Endodontic Procedures: A Critical Review

Regenerative endodontic procedures of immature teeth with necrotic pulp have become a part of therapeutic endodontic spectrum and are considered as an alternative to calcium hydroxide or mineral trioxide aggregate apexification. In last decade, numerous case reports and series with usage of cell-free approaches known as revascularization, revitalization, or maturogenesis have been published. This cell-free approach prevails in clinical regenerative endodontics because of its relative ease of performance, lower financial demands, and absence of complications such as tumorigenesis of used stem cells. In this article, the integral steps of cell-free treatment approaches such as source of stem cells, possible endogenous scaffolds, sources of growth factors, and width of apical foramen in the context of sufficient disinfection of root canal system and outcome of treatment are discussed. Despite not being a fully established treatment protocol, the achieved outcomes are promising regardless of it having a reparative character than a regenerative one.

Association between Experimental Bacterial Meningitis and Periapical Lesion

INTRODUCTION

Mortality and morbidity from bacterial meningitis in African adults is significantly higher than those in better resourced settings. At the same time, the periodontal diseases are highly prevalent and can affect up to 90% of the population. Dental caries in Uganda was recorded in 40% and 62.5% of the children and adults, respectively. We hypothesize that pneumococcal meningitis could interfere in the development of periapical lesion. The aim of this study was to evaluate periapical lesion in Wistar rats subjected to pneumococcal meningitis.

MATERIALS AND METHODS

The animals were divided in control, control/periapical lesion, meningitis, and meningitis/periapical lesion groups. The surgical exposure of molars and the infection of the dental pulp were from the oral environment. Pulp necrosis was induced on the left mandibular first molars during adulthood. Dental pulps were exposed by drilling cavities on the central portion of the occlusal surface with a 1011 HL round bur in high speed to a depth nearly equal to the bur diameter. Animals were subjected to behavioral task and evaluation of the size of periodontal ligament. Data from periodontal ligament space and open field task were reported as mean ± SEM and analysed by Two-way ANOVA and paired Student's t-test, respectively.

RESULTS AND CONCLUSION

Meningitis/periapical increased the periodontal ligament space by 61% when compared with control/periapical. In the open-field task, there were no differences in the number of crossings and rearing movements between training and test session in meningitis and periapical lesion groups demonstrating habituation memory impairment. Bacterial meningitis and periapical lesion may play an important role in development of cognitive impairment.

Effects of a triple antibiotic solution on pulpal dynamics after intentionally delayed tooth replantation in mice

INTRODUCTION

This study analyzed the detailed biological events underlying pulpal dynamics evoked by 3Mix (the mixture of ciprofloxacin, metronidazole, and minocycline) solution after intentionally delayed tooth replantation because 3Mix improves pulpal healing after tooth injuries.

METHODS

The maxillary first molars of 3-week-old mice were extracted and immersed in 3Mix solution for 30 minutes in comparison with phosphate buffered saline (PBS) alone. Cell proliferation, apoptosis, and differentiation were assessed in extracted/replanted teeth during days 0-14 using immunohistochemistry, apoptosis assay, and reverse-transcriptase polymerase chain reaction.

RESULTS

3Mix solution accelerated odontoblast differentiation in the coronal pulp on day 7 and tertiary dentin formation on day 14, whereas the regenerative process was delayed in the PBS group. Cell proliferation and apoptosis occurred in the pulp of the 3Mix group during days 5-7 and subsequently decreased from days 7-14. On day 5, dentin sialophosphoprotein and nestin were first recovered in the 3Mix group, whereas expression levels for alkaline phosphatase, osteopontin, and osteocalcin increased in the PBS group. The expression levels for octamer-binding factor 3/4A and 3/4B reached the maximum level on day 1 and were sharply decreased on day 3 in both groups. High expression levels of Cd11c were first observed in the 3Mix group on day 1 and later at days 5 and 7.

CONCLUSIONS

The results suggest that the application of 3Mix may suppress osteoblast differentiation by the migration of dendritic cells to the injury site and via the activation of stem/progenitor cells, resulting in the acceleration of odontoblastlike cell differentiation.

Histologic examinations of teeth treated with 2 scaffolds: a pilot animal investigation

INTRODUCTION

A growing body of evidence is building a case for the possibility of tissue regeneration within the root canal of necrotic teeth, allowing for continued root development. However, it remains unknown what type of tissue is produced after regenerative endodontics. The purpose of this study was to use blood clots and platelet-rich plasma (PRP) as scaffolds in regenerative endodontics under ideal conditions in a ferret model to examine the tissues generated within the root canals.

METHODS

The pulps of 21 canine teeth from 7 young ferrets were extirpated using broaches without filing the canal walls. Bleeding was stimulated from the periapical tissues, and a blood clot was induced in the canal space to the level of the cementoenamel junction in 12 teeth. PRP was prepared and placed in the canals to the level of the cementoenamel junction in 9 teeth. The coronal access was sealed with mineral trioxide aggregate. Seven canines were not operated on and served as controls. Three months later, block sections including each canine and its surrounding tissues were removed for histologic evaluation. The tissues found in the canals of experimental teeth were compared with those in the control teeth.

RESULTS

Almost all of the experimental teeth showed the presence of intracanal bonelike tissue. No evidence of dentinal wall thickening or apical narrowing was noted in the experimental teeth.

CONCLUSIONS

In this experimental model, the use of either PRP or blood clots during regenerative endodontics leads to the formation of intracanal bonelike tissue without continual root maturation.

Effect of the pro-resolution lipid mediator Resolvin E1 (RvE1) on pulp tissues exposed to the oral environment

AIM

To evaluate the effects of topical Resolvin E1 (RvE1) application on infected dental pulps.

METHODOLOGY

Forty-two male Wistar rats (n = 6 per three groups/and two time periods) were used. To induce inflammation, pulps in mandibular right first molars were accessed and then left exposed to the oral environment for 24 h. After this period, topical medication with a corticosteroid/antibiotic blend, or RvE1, or its vehicle (Ethanol 0.1%) was directly applied onto the pulp tissue and teeth were restored with silver amalgam. The effects of the protocols were evaluated histologically and compared with control pulps not exposed to the oral environment. The inflammatory changes after 24 and 72 h were assessed through a scoring method and analysed using the Kruskal-Wallis test followed by Dunn's. Differences were considered significant if P < 0.05 (CI = 95%).

RESULTS

Ethanol and corticosteroid/antibiotic treatment were not effective in arresting severe inflammatory alterations of exposed pulps at 24 and 72 h (P < 0.05, CI = 95%). At both time periods, RvE1 treatment led to a reduction of tissue cellularity and extent of inflammation, whose changes were not different from control pulps (P > 0.05, CI = 95%).

CONCLUSIONS

A protective role for RvE1 in pulp inflammation was observed even in the presence of contamination, suggesting that it may be a candidate for a novel therapeutic strategy for conservative dental pulp treatment.

Revascularization of immature permanent teeth with apical periodontitis

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

Treatment options: biological basis of regenerative endodontic procedures

Dental trauma occurs frequently in children and often can lead to pulpal necrosis. The occurrence of pulpal necrosis in the permanent but immature tooth represents a challenging clinical situation because the thin and often short roots increase the risk of subsequent fracture. Current approaches for treating the traumatized immature tooth with pulpal necrosis do not reliably achieve the desired clinical outcomes, consisting of healing of apical periodontitis, promotion of continued root development, and restoration of the functional competence of pulpal tissue. An optimal approach for treating the immature permanent tooth with a necrotic pulp would be to regenerate functional pulpal tissue. This review summarizes the current literature supporting a biological rationale for considering regenerative endodontic treatment procedures in treating the immature permanent tooth with pulp necrosis.

A clinical and histological report of a tooth with an open apex treated with regenerative endodontics using platelet-rich plasma

INTRODUCTION

In patients, the outcomes of teeth with necrotic pulps and open apexes that have been treated with regenerative endodontics have always been evaluated clinically and radiographically. The purpose of this case report is to present the clinical, radiographic, and histological findings of a regenerative procedure using platelet-rich plasma (PRP) 14 months after the procedure.

METHODS

A 12-year-old boy whose maxillary second premolar tooth had been treated with regenerative endodontics was seen with a chief complaint of pain and sensitivity to cold. After clinical and radiographic examinations, a pulpal diagnosis of reversible pulpitis and normal periapical tissues was made for this tooth. Because of the patient's complaint and his guardian's insistence on either a root canal treatment or an extraction, a root canal treatment was performed in this tooth. After entry into the root canal, the soft tissue present in the canal was removed with the aid of a large barbed broach and examined histologically.

RESULTS

Examination of the tissue removed from the root canal of this tooth revealed the presence of a vital pulp-like vital connective tissue. There was no evidence of bone in the specimen. Very few inflammatory cells were noted in the periphery of the specimen.

CONCLUSIONS

Based on these findings, it appears that pulp-like tissue can be generated in a human tooth with the use of PRP as a scaffold in regenerative endodontic procedures.

Effects of the antioxidant agent tempol on periapical lesions in rats with doxorubicin-induced cardiomyopathy

INTRODUCTION

Cardiovascular diseases have been associated with increased risk of endodontic complications. This study evaluated the effects of the antioxidant agent tempol on periapical lesions in rats with doxorubicin-induced cardiomyopathy in comparison with control animals.

METHODS

Forty male Wistar rats were divided into 4 groups: (1) naïve rats orally treated with saline solution (10 mL/kg, during 21 days after periapical lesion induction); (2) naïve rats treated with tempol (30 and 50 mg/kg, during 21 days after periapical lesion induction) by oral pathway; (3) rats with doxorubicin-induced cardiomyopathy treated with saline solution by oral route (10 mL/kg, from day 3 to day 10 after initiating treatment with doxorubicin); and (4) rats with doxorubicin-induced cardiomyopathy orally treated with tempol (30 and 50 mg/kg, from day 3 to day 10 after initiating treatment with doxorubicin). Periapical lesions were induced on the first right mandibular molar tooth. After 21 days of apical periodontitis induction, the animals were killed, and the mandibles were collected for radiographic and histologic analysis.

RESULTS

The oral administration of tempol (50 mg/kg) was able to significantly prevent the establishment of periapical lesions in either control animals or rats submitted to the model of doxorubicin-induced cardiomyopathy, according to radiographic and histologic evaluation. Nevertheless, the protective effects of tempol were virtually greater in control animals in comparison with doxorubicin-treated rats, as indicated by histologic inflammatory assessment, which might be related to the increased production of free radicals under cardiomyopathy.

CONCLUSIONS

We provide novel evidence on the beneficial systemic effects of the antioxidant tempol on apical periodontitis in both control animals and rats with doxorubicin-elicited cardiomyopathy.