Extraradicular infection as the cause of persistent symptoms: a case series

Utility of Ultrasonography for Diagnosing and Differentiating Periapical Granuloma from Radicular Cyst

RATIONALE AND OBJECTIVES

This study aimed to investigate the reliability and accuracy of high-resolution ultrasonography (US) for diagnosing periapical lesions and differentiating radicular cysts from granulomas.

MATERIALS AND METHODS

This study included 109 teeth with periapical lesions of endodontic origin from 109 patients scheduled for apical microsurgery. Ultrasonic outcomes were analyzed and categorized after thorough clinical and radiographic examinations using US. B-mode US images reflected the echotexture, echogenicity, and lesion margin, while color Doppler US assessed the presence and features of blood flow of interested areas. Pathological tissue samples were obtained during apical microsurgery and subjected to histopathological examination. Fleiss' κ was used to measure interobserver reliability. Statistical analyses were performed to assess the diagnostic validity and the overall agreement between US and histological findings. The reliability of US compared to histopathological examinations was assessed based on Cohen's κ.

RESULTS

The percent accuracy of US for diagnosing cysts, granulomas, and cysts with infection based on histopathological findings was 89.9%, 89.0%, and 97.2%, respectively. The sensitivity of US diagnoses was 95.1% for cysts, 84.1% for granulomas, and 80.0% for cysts with infection. The specificity of US diagnoses was 86.8% for cysts, 95.7% for granulomas, and 98.1% for cysts with infection. The reliability for US compared to histopathological examinations was good (κ = 0.779).

CONCLUSION

The echotexture characteristics of lesions in US images correlated with their histopathological features. US can provide accurate information on the nature of periapical lesions based on the echotexture of their contents and the presence of vascularity. It can help improve clinical diagnosis and avoid overtreatment of patients with apical periodontitis.

The Effect of Unintentional AH-Plus Sealer Extrusion on Resolution of Apical Periodontitis After Root Canal Treatment and Retreatment-A Retrospective Case-control Study

INTRODUCTION

This study aimed to investigate the effect of unintentional AH Plus sealer extrusion on the outcome of nonsurgical root canal treatment and retreatment in teeth with apical periodontitis (AP) compared to teeth with AP and no sealer extrusion at the 1-year follow-up.

METHODS

In a retrospective case-control study conducted from September 2016 to September 2021, teeth presenting clinical and radiographic signs of AP prior to treatment were included. The study comprised 2 groups: AH Plus sealer extrusion group (n = 60): initial root canal treatment or nonsurgical retreatment with unintentional apical extrusion of AH Plus sealer; and no AH Plus sealer extrusion group (n = 60): underwent the same treatment types without sealer extrusion. Additional factors, including sex, age, tooth type, tooth location, and treatment type, were recorded as potential outcome predictors. At 1-year follow-up, teeth were evaluated clinically and radiographically, and outcomes were classified as favorable (healed/healing) or unfavorable (uncertain/non-healing). Statistical analyses, such as the χ2 test, logistic regression, and Mann-Whitney U test, were employed for data analysis.

RESULTS

A favorable outcome was observed in 88.4% and 85% of the cases of the AH Plus sealer extrusion and no AH Plus sealer extrusion groups, respectively. There was no statistically significant difference between the groups in terms of outcomes (P > .05) when analyzed categorically or ordinally. Of independent variables, nonsurgical retreatment showed lower healing of AP in both groups.

CONCLUSIONS

Unintentional AH Plus sealer extrusion did not affect the healing of AP. However, initial root canal treatment showed better healing of AP than nonsurgical retreatment in the presence of AH Plus sealer extrusion. The analyzed outcome predictors had no effect on treatment outcome.

The Role of Apical Periodontitis Disease in the Development of Bisphosphonate-Related Osteonecrosis of the Jaw: An Animal Study

BACKGROUND

Microorganisms and their by-products are responsible for establishing pulpal and periapical diseases. Healing is compromised in patients under bisphosphonate therapy, and the presence of periapical infections can potentially lead to the development of medication-related osteonecrosis of the jaw (MRONJ). This work aimed to evaluate if bisphosphonate therapy is a risk factor for MRONJ development in the presence of periapical lesions.

METHODS

Two groups of 10 female Wistar rats were used. The experimental group received zoledronate (0.1 mg/kg) intraperitoneally, and the control received a saline solution, three times a week for three weeks. One week after the last injection, apical periodontitis was induced through pulpal exposure in the mandibular first molars. Twenty-one days later, the animals were intravenously injected with ^99mTc-HMDP, and the radioactivity uptake by mandibular specimens was counted. In addition, sample radiographs and a histological examination were performed.

RESULTS

The bone loss was higher in the control group when compared to the experimental group (p = 0.027). ^99mTc-HMDP uptake in the control was reduced compared with the experimental group, although without statistical significance.

CONCLUSIONS

In the presence of zoledronate therapy, apical periodontitis does not increase the risk of MRONJ development, and periapical lesions have lower bone resorption when compared to the control group.

Surgical management of a lateral lesion refractory to root canal retreatment caused by an extraradicular calculus. A case report

This article describes the management of a root canal-treated maxillary central incisor displaying a radiographic lateral radiolucency and a sinus tract that persisted irrespective of root canal retreatment following high standards. Endodontic microsurgery was indicated and curettage of the pathologic tissue revealed a calculus-like material attached to the outer root surface around the exit of a large lateral canal. A non-conventional approach was chosen: No root-end resection was conducted. Instead, the calculus was removed and the apical surface was scaled and smoothed, conserving the apical structure. Retrocavities were prepared in both lateral and apical foramens and filled with a bioceramic material. Follow-up examination showed optimal soft tissue healing. One-year follow-up of radiographs revealed healing of the lateral lesion. The lesion was diagnosed as a cyst, with an infected lumen. An exuberant calculus-like material attached to the external root surface was the most likely cause of the recalcitrant lateral periradicular lesion.

Persistent pain after successful endodontic treatment in a patient with Wegener’s granulomatosis: a case report

Wegener’s granulomatosis (WG) is a condition with immune-mediated pathogenesis that can present oral manifestations. This report describes the case of a patient diagnosed with WG 14 years previously, who was affected by persistent pain of non-odontogenic origin after successful endodontic treatment. A 39-year-old woman with WG was diagnosed with pulp necrosis and apical periodontitis of teeth #31, #32, and #41, after evaluation through a clinical examination and cone-beam computed tomography (CBCT). At the first appointment, these teeth were subjected to conventional endodontic treatment. At 6- and 12-month follow-up visits, the patient complained of persistent pain associated with the endodontically treated teeth (mainly in tooth #31), despite complete remission of the periapical lesions shown by radiographic and CBCT exams proving the effectiveness of the endodontic treatments, thus indicating a probable diagnostic of persistent pain of non-odontogenic nature. After the surgical procedure was performed to curette the lesion and section 3 mm of the apical third of tooth #31, the histopathological analysis suggested that the painful condition was likely associated with the patient's systemic condition. Based on clinical, radiographic, and histopathological findings, this unusual case report suggests that WG may be related to non-odontogenic persistent pain after successful endodontic treatments.

Present status and future directions - microbiology of endodontic infections

Apical periodontitis has a microbial aetiology and is one of the most common inflammatory diseases that affect humans. Fungi, archaea and viruses have been found in association with apical periodontitis, but bacteria are by far the most prevalent and dominant microorganisms in endodontic infections. Bacterial infection of the root canal system only occurs when the pulp is necrotic or was removed for previous treatment. In some specific cases, including acute and chronic abscesses, the bacterial infection may reach the periradicular tissues. Intracanal bacteria are usually observed as sessile multispecies communities (biofilms) attached to the dentinal root canal walls. Infection in the main root canal lumen can spread to other areas of the root canal system. Although more than 500 bacterial species have been detected in endodontic infections, a selected group of 20 to 30 species are most frequently detected and may be considered as the core microbiome. There is a high interindividual variability in the endodontic microbiome in terms of species composition and relative abundance. Obligate anaerobic species are more abundant in the intraradicular bacterial communities of teeth with primary apical periodontitis, while both anaerobes and facultatives dominate the communities in post-treatment apical periodontitis. Bacterial interactions play an essential role in determining the overall virulence of the community, which has been regarded as the unit of pathogenicity of apical periodontitis. This article reviews the microbiologic aspects of endodontic infections and provides perspectives for future research and directions in the field.

A critical analysis of research methods and experimental models to study the root canal microbiome

Endodontic microbiology deals with the study of the microbial aetiology and pathogenesis of pulpal and periradicular inflammatory diseases. Research in endodontic microbiology started almost 130 years ago and since then has mostly focussed on establishing and confirming the infectious aetiology of apical periodontitis, identifying the microbial species associated with the different types of endodontic infections and determining the efficacy of treatment procedures in eradicating or controlling infection. Diverse analytical methods have been used over the years, each one with their own advantages and limitations. In this review, the main features and applications of the most used technologies are discussed, and advice is provided to improve study designs in order to properly address the scientific questions and avoid setbacks that can compromise the results. Finally, areas of future research are described.

Comparison of Apical Extrusion of Bacteria After Glide Path Preparation Between Manual K File, One G Rotary, and WaveOne Gold Glider Reciprocation Preparations

Objective:

To compare the amount of apically extruded bacteria between hand-filed preparations, rotary and reciprocation glide path preparations in curved canals of extracted teeth infected with Enterococcus faecalis.

Methods:

Forty mandibular first molar teeth were decoronated, fitted into rubber stoppers and fixed onto glass vials. The mesiobuccal canals from mandibular first molar teeth were infected with Enterococcus faecalis, then randomly assigned to one of five groups for glide path preparation: manual stainless-steel file (K-files), rotary file (One G), reciprocating file (WaveOne Gold Glider) and two control groups. After glide path preparation, 0.01 mL of saline was taken from the experimental vials. The solution was plated on tryptic soy agar and colonies of bacteria were counted as colony-forming units. The results were analysed statistically using Kruskal-Wallis and post hoc Mann-Whitney U tests.

Results:

The manual K-file group was associated with significantly more bacteria extrusion compared to the rotary and reciprocating groups (P<0.05). However, no significant difference occurred between rotary and reciprocation instruments.

Conclusion:

All instrumentation techniques resulted in a measurable amount of apical extrusion of bacteria. Manual K-files extruded the highest quantity of bacteria compared to One G rotary file and WaveOne Gold Glider reciprocation file during glide path preparation.

Biofilm models in endodontics-A narrative review

The knowledge of biofilm and its eradication from the root canal system are of utmost importance in the clinical practice of an endodontist. Various treatment strategies and protocols have been demonstrated and discussed by numerous clinicians and researchers, on these models, that play an important role in the treatment outcome . Once a biofilm model is developed by considering various factors, several methods can be used to assess the biofilms formed on these models. This review discusses the importance of biofilm models in endodontics, types of biofilm models and factors associated with developing and the methods to evaluate these models.

Preserving the vitality of teeth adjacent to a large radicular cyst in periapical microsurgery: a case report with 4-year follow-up

Background

Radicular cysts may enlarge considerably, cause extensive bone destruction, and jeopardize the integrity of the associated vital teeth. The different treatment approaches are aimed mainly at eliminating the cystic epithelial membrane while reducing the risk of injury to vital structures. Contrary to other treatment modalities, preapical surgery offers an unequivocal single occasion resolution for the patient. However, it has been associated with higher risk of collateral damages.

Case presentation

A patient presented with a large radicular cyst originating from a maxillary lateral incisor. The adjacent central and canine teeth initially failed to exhibit responses to sensibility tests but showed signs of vitality. Microsurgical management was aimed at enucleating the cystic membrane while maintaining adjacent teeth vitality. Upon careful and controlled cyst enucleation under the dental operating microscope, the neurovascular bundle of one of the involved teeth was visualized and its integrity was maintained throughout the procedure.

Results

The procedure was successful and follow up recalls revealed recovery of normal sensibility of tooth 11 and 13 with complete bone regeneration around their apices.

Conclusion

Within the limitation of the present case report, we demonstrated that complete excision of large periapical cyst can be performed without sacrificing the vitality of the adjacent teeth, by preserving the integrity of their neurovascular supply through controlled microsurgical enucleation, and by a potential apical vascular repair ensuing unintended injury. Diagnosing the pulp vitality of non-offending teeth whose apices protrude into the cystic lumen is a complex process and can be misleading. Pressure from the growing cyst can inhibit vital teeth responses to neural-based sensibility tests leading to false negative results. Thus, in such cases, the use of blood perfusion-based vitality testing is recommended for correct initial diagnosis.

Extrusion of debris with and without intentional foraminal enlargement - A systematic review and meta-analysis

This systematic review and meta-analysis was sought to assess whether intentional foraminal enlargement (IFE) is responsible for extrusion of a larger quantity of debris from extracted human teeth with fully formed apexes. Following the recommendations of Preferred Reporting Items for Systematic Review and Meta-Analysis - PRISMA, electronic and manual searches were performed to identify studies that evaluated the extrusion of debris, comparing different apical limits of instrumentation (with/without IFE). The quality of the studies selected was evaluated, and statistical analysis was conducted. To perform the meta-analysis, just 3 papers could be used. The heterogeneity was high, however; there was no statistically significant difference in relation to the extrusion of debris in teeth either submitted or not submitted to IFE. The general risk of bias was moderate. In conclusion, IFE is not responsible for extrusion of a larger quantity of debris from extracted human teeth with fully formed apexes.

Phenotypic and Genotypic Characterization of Streptococcus mutans Strains Isolated from Endodontic Infections

Streptococcus mutans plays an important role in caries etiology and eventually in systemic infections. However, it is often found in infected root canals, but the pathophysiological characteristics of strains residing in this site are largely unknown. Here, we characterized strains of S. mutans isolated from root canals of primary (PI) and secondary/persistent (SI) endodontic infections in relation to serotype and genotype; presence of genes coding for collagen binding proteins (CBPs); collagen binding activity and biofilm formation capacity; ability to withstand environmental stresses; systemic virulence in Galleria mellonella; and invasion of human coronary artery endothelial cells and human dental pupal fibroblasts. Samples from 10 patients with PI and 10 patients with SI were collected, and a total of 14 S. mutans isolates, belonging to 3 genotypes, were obtained. Of these, 13 were serotype c, and 1 was serotype k. When compared with the reference strains, the clinical isolates were hypersensitive to hydrogen peroxide. Remarkably, all 14 strains harbored and expressed the CBP-encoding gene cbm, showing increased binding to collagen, enhanced systemic virulence in G. mellonella, and ability to invade human coronary artery endothelial cells and human dental pupal fibroblasts when compared with CBP-negative strains. Whole genome sequence analysis of PI and SI isolates revealed that these strains are phylogenetically related but genetically distinct from each other. Our findings highlight the importance of CBPs in facilitating colonization and persistence of S. mutans in collagenous substrates such as root canals and their potential role in the pathogenesis of endodontic infections.

Cone-beam Computed Tomographic and Micro-computed Tomographic Evaluations of the Root Apexes of Teeth with Posttreatment Apical Periodontitis

INTRODUCTION

This study evaluated the association of different variables that may influence the outcome of root canal treatment through cone-beam computed tomographic (CBCT) and micro-computed tomography (micro-CT) assessments of root apexes obtained by endodontic microsurgery of teeth with posttreatment apical periodontitis (AP), the agreement between CBCT and micro-CT findings, and the association of these variables with symptoms or lesion size.

METHODS

Clinical and CBCT records and root apexes obtained by endodontic microsurgery from 11 cases of symptomatic AP and 22 cases of asymptomatic AP were available. Apical root specimens were further scanned using micro-CT imaging. CBCT parameters included periapical radiolucency size, apical extent/density of root canal filling, and occurrence of procedural errors. Micro-CT images evaluated the same parameters plus the presence of filling material in lateral canals and ramifications, the volume of the filled/nonfilled apical root canal, and the percentage of the nonfilled canal space. The agreement between CBCT/micro-CT observations was evaluated.

RESULTS

Mandibular teeth, a lesion size <5 mm, a nonfilled volume <0.04 mm³, and the decreased percentage of the nonfilled canal volume were significantly associated with symptomatic AP. Maxillary teeth and inadequate apical filling density were significantly associated with larger lesions. Agreement between CBCT/micro-CT scores varied from fair (procedural errors) to satisfactory (extent/density of filling).

CONCLUSIONS

Tooth location, lesion size, the nonfilled apical canal volume, and the percentage of the nonfilled apical canal volume were associated with symptomatic AP. In addition, lesion size was significantly associated with tooth location and apical root canal filling density. CBCT imaging may not provide a reliable evaluation of procedural errors associated with posttreatment disease.

Prevalence of Bacteria of Genus Actinomyces in Persistent Extraradicular Lesions-Systematic Review

Actinomyces are anaerobic, rod-shaped, Gram-positive bacteria. They are associated with persistent extraradicular endodontic infections, with possible involvement of the soft tissues of the maxillofacial district. Many studies reported conflicting data on the presence of bacteria of the genus Actinomyces in endodontic infections. The aim of this systematic review of the literature was to determine the real prevalence of such bacteria in primary and/or secondary endodontic infections and in cases of persistence with extraradicular involvement. This systematic review was performed according to the PRISMA protocol. A search was carried out through the Scopus and PubMed databases of potentially eligible articles through the use of appropriate keywords. The literature research resulted in preliminary 2240 records which, after the elimination of overlaps and the application of inclusion and exclusion criteria, led to the inclusion of 46 articles focusing on three outcomes (primary outcome: number of teeth with the presence of a persistent extraradicular infection in which the presence of Actinomyces was ascertained; secondary outcome: number of teeth with endodontic infection in which the presence of Actinomyces was assessed; tertiary outcome: difference in the prevalence of bacteria of the genus Actinomyces between primary endodontic infections and secondary endodontic infections). Results of the meta-analysis show how bacteria of the genus Actinomyces are present in primary and secondary intraradicular infections and in those with persistence with a prevalence (ratio between teeth with actinomyces and teeth with infection) ranging from 0.091 up to 0.130 depending on the subgroups analyzed.

3D Apicoectomy Guidance: Optimizing Access for Apicoectomies

When conventional endodontic treatment resources are depleted, endodontic surgery becomes an alternative treatment for apical periodontitis to remove unreachable infected areas and seal the root canal. Digital workflows have been used more frequently in many dental applications in recent years. In endodontics, virtual 3-dimensional (3D) planning and endodontic guidance are new aspects important for the treatment of complex cases. This report aimed to present 3D Apicoectomy Guidance, a novel method of performing guided ultraconservative endodontic surgery with conventional implant-guided drills, and to describe its application in a case with a complex anatomic scenario and intimate contact with the maxillary sinus. Implantology computer software, as well as cone-beam computed tomography images and a digital scanning 3D impression, enabled virtual planning of the surgical procedure. Subsequently, a 3D template was produced to guide the instruments used in the osteotomy and root resection. The patient was completely asymptomatic at the 1-week follow-up visit. Cone-beam computed tomography scans were performed at 1 and 6 months after surgery and showed that resection of the apex of the root was performed accurately and that a thin dentin slice remained distally, preventing the rupture of the sinus membrane. The patient remained asymptomatic, and the tissue healed normally. The method used was shown to be very straightforward and reliable. This method allowed the patient to be treated expeditiously with very precise tissue removal.

Microbiological aspects of traumatic injuries

After traumatic injuries to teeth, microorganisms may invade the compromised pulp tissue and initiate pulp infection and periapical inflammation. In addition to bone resorption that typically accompanies pulp necrosis, root resorption frequently occurs. Root resorption has several variants that may occur shortly after the trauma or at a later stage. The pathological changes seen after traumatic injuries to teeth are invariably linked to the presence of microbial irritants. The presence of bacterial biofilms in the dental pulp space can be treated with regenerative or therapeutic endodontic procedures. However, necrosis of periodontal ligament is usually terminal for the tooth involved. In this review, the sources of bacteria after traumatic injuries are discussed. The types and role of microorganisms involved in the pathogenesis of endodontic pathosis after traumatic injuries are presented, and contemporary approaches for the management of these conditions are reviewed. Contemporary antimicrobial strategies are discussed. The rationale for the use of systemic and topical antimicrobials is presented. Finally, novel approaches to the use of antimicrobial therapies, particularly in regenerative procedures, are reviewed.

Apical periodontitis associated with a calculus-like deposit: A case report of a rare fan-shaped manifestation

Introduction

Bacterial biofilms can be calcified. Granulomas or cystic lesions are the most commonly found entities in endodontics. Surprisingly, this case report presents a rare radiopaque image, in a fan shape, of a calculus-like deposit in the periapical region of the maxillary left central incisor.

Case presentation

A 34-year-old male, with a history of trauma, presented with apical periodontitis associated with an uncommon image, similar to a calculus-like deposit adhered to the apical region of the maxillary left central incisor. Nonsurgical endodontic intervention was performed, followed by apicoectomy and histopathological analysis of the collected material. The results of the biopsy were not compatible with a cyst or granuloma but showed fibrous connective tissue with calcified areas.

Discussion

Correct diagnosis in endodontics is possible with a well-conducted anamnesis, complementary imaging exams and, in some cases, histopathological analysis. The periapical calculus-like deposit, associated with a periapical radiolucent lesion, was a result of the body's fight for healing, producing unusual radiopacity.

Conclusion

The presence of the calculus-like deposit in a fan shape at the root surface represented dystrophic calcification as a manifestation of the attempt to heal. In the present case, apicoectomy and tissue biopsy for histological evaluation were fundamental for the correct diagnosis.

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Root canal is critical area for biofilm development.

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Extraradicular biofilm on the surface of the root may cause persistent periapical lesions.

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Uncommon radiopaque image association with endodontic periapical lesions was related.

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Persistent periapical lesions associate with extraradicular biofilm represents a challenge for Endodontic treatment.

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Only surgical resection was capable to repair the injury.

Biofilm model systems for root canal disinfection: a literature review

The aim of this review was to present an overview of laboratory root canal biofilm model systems described in the endodontic literature and to critically appraise the various factors that constitute these models. The electronic databases MEDLINE, Web of Science and EMBASE were searched up to and including December 2016 to identify laboratory studies using endodontic biofilm models. The following search terms were used in various combinations: biofilm, root canal, in vitro, endodontic, bacteria, root canal infection model, colony-forming unit. Only English papers from journals with an impact factor were selected. The records were screened by two reviewers, and full-text articles were assessed according to pre-defined criteria. The following data were extracted from the included studies: the microbial composition of the biofilm, the substrate, growth conditions, validation and quantification. Seventy-seven articles met the inclusion criteria. In the majority (86%) of the studies, a monospecies biofilm was cultured. In two studies, a dual-species biofilm was grown; others cultivated a multispecies biofilm, containing at least three species. Enterococcus faecalis was the most frequently used test species (in 79% of all studies, 92% of the monospecies studies). Four studies used an inoculum derived directly from the oral cavity. Human dentine was the most frequently used substratum (88% of the studies). Incubation times differed considerably, ranging from one to seventy days. The most common quantification method (in 87% of the studies) was bacterial culturing, followed by microscopy techniques. The variation in laboratory root canal biofilm model systems is notable. Because of substantial variation in experimental parameters, it is difficult to compare results between studies. This demonstrates the need for a more standardized approach and a validated endodontic biofilm model.

Biochemical characterization of extracellular polymeric substances from endodontic biofilms

Apical periodontitis is frequently associated with the presence of bacteria biofilm, which has an indisputable impact on the prognosis of endodontic therapy due to the high resistance to adverse environmental conditions, chemicals, and antibiotic therapy that characterize bacteria within biofilm. The biofilm matrix acts as a protective shield over the encased microorganisms. The aim of this investigation was to identify the main biochemical components of biofilm matrix from endodontic mono- and dual-species biofilms. Enterococcus faecalis and Actinomyces naeslundii were cultured as mono- and dual-species biofilms for 14 days. Crude extracellular polymeric substances (EPSs) from biofilm matrices were extracted using chemical and physical methods. High-performance liquid chromatography, gas chromatography, and mass spectrometry were used to determine the carbohydrate, protein, and fatty acid components. Chemical analysis of the biofilm matrices revealed that they were mainly composed of stachyose, maltose, and mannose carbohydrates. The protein profile in all biofilm samples showed abundant oxidoreductases and chaperone proteins and some virulence- associated proteins mainly located in the membrane surface. High percentages of saturated and monounsaturated fatty acids were identified in all biofilm matrices, with a major prevalence of palmitic, stearic, and oleic acids. Based on the results, it was possible to obtain for the first time a general overview of the biochemical profile of endodontic biofilm matrices.

Historical and Contemporary Perspectives on the Microbiological Aspects of Endodontics

The microbiota of the oral cavity plays a significant role in pulpal and periapical diseases. Historically, 100 years ago little was known on microbiota, but after a century of investigations, only now can many of the intimate secrets of microbial growth, expansion, persistence, communal activities, and virulence be revealed. However, with the capabilities of the microbiota for mutation, quorum sensing, and information transference, researchers are hard-pressed to keep up with both the changes and challenges that an amazingly wide range of bacterial species pose for both the scientist and clinician. Fortunately, the development and expansion of a vast array of molecular biological investigative techniques have enabled dentistry and its associated medical fields to attempt to keep pace with the wide and fascinating world of oral microbiology.

Quantitative analysis of apically extruded bacteria following preparation of curved canals with three systems

This study compared the amount of apically extruded bacteria following preparation of curved root canals using two continuously rotating multifile and one reciprocating single-file systems. Mesiobuccal canals from maxillary molars were contaminated with Enterococcus faecalis and divided into three groups according to the instrumentation system: Reciproc (R25 instrument, 25/.08), BT-RaCe (10/.06, 35/.00 and 35/.04), and Mtwo (25/.06, 30/.05 and 35/.04). Apically extruded material was collected by a customized apparatus with 1.5% agarose gel covering the root apex to simulate the periradicular tissues. The extruded material was extracted from the gel and subjected to bacteriological culture for bacterial quantification. The three systems showed a high frequency of bacterial extrusion (>70%). There were no statistically significant differences in the counts of extruded bacteria between groups (P > 0.05). The incidence and amount of apical bacterial extrusion were similar between the three systems. The customized apparatus was effective in collecting apically extruded bacteria.

Factors that cause endodontic failures in general practices in Japan

BACKGROUND

Bacterial biofilms that develop on root surfaces outside apical foramens have been found to be associated with refractory periapical periodontitis. However, several other factors cause endodontic failures apart from extraradicular biofilms. The aim of this study was to identify the factors causing endodontic failures in general practices in Japan.

METHODS

Patients diagnosed as having refractory periapical periodontitis by general practitioners and who requested endodontic treatment at Osaka University Dental Hospital were selected by checking medical records from April 2009 to March 2013. Factors causing endodontic failures were identified.

RESULTS

A total of 103 teeth were selected, and 76 teeth completed root-canal treatment. Tooth extractions were required for 18 teeth after or without endodontic treatment. Six teeth required apicoectomy after endodontic treatment. One tooth needed hemisection. One tooth needed intentional replantation. One tooth needed adhesion and replantation. The main causes of treatment failure were open apices (24 teeth), perforation (18 teeth), and root fracture (13 teeth). In six teeth with open apices that required apicoectomy or extraction, extraradicular biofilms may have been related to endodontic failure.

CONCLUSIONS

Most endodontic cases diagnosed with refractory periapical periodontitis by general practitioners were compromised by any other factors rather than extraradicular biofilms.

Histobacteriologic Conditions of the Apical Root Canal System and Periapical Tissues in Teeth Associated with Sinus Tracts

INTRODUCTION

This histobacteriologic study described the pattern of intraradicular and extraradicular infections in teeth with sinus tracts and chronic apical abscesses.

METHODS

The material comprised biopsy specimens from 24 (8 untreated and 16 treated) roots of teeth associated with apical periodontitis and a sinus tract. Specimens were obtained by periradicular surgery or extraction and were processed for histobacteriologic and histopathologic methods.

RESULTS

Bacteria were found in the apical root canal system of all specimens, in the main root canal (22 teeth) and within ramifications (17 teeth). Four cases showed no extraradicular infection. Extraradicular bacteria occurred as a biofilm attached to the outer root surface in 17 teeth (5 untreated and 12 treated teeth), as actinomycotic colonies in 2 lesions, and as planktonic cells in 2 lesions. Extraradicular calculus formation (mineralized biofilm) was evident in 10 teeth.

CONCLUSIONS

Teeth with chronic apical abscesses and sinus tracts showed a very complex infectious pattern in the apical root canal system and periapical lesion, with a predominance of biofilms.

Analysis of the expression of NLRP3 and AIM2 in periapical lesions with apical periodontitis and microbial analysis outside the apical segment of teeth

OBJECTIVE

To detect the distribution and expression levels of the nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) and the absent in Melanoma 2 (AIM2) inflammasomes in periapical lesions and to analyse the possible microbial stimuli outside of teeth.

DESIGN

The distribution of NLRP3 and AIM2 inflammasomes in sixteen periapical lesions was investigated by immunohistochemistry. Meanwhile, the relative gene expression levels of NLRP3 and AIM2 in sixteen periapical lesions and three health periodontal tissue were quantified by real-time polymerase chain reaction (PCR). Moreover, forty-seven teeth without sinus tracts were obtained in the clinic and included in bacterial analysis using PCR. Then, the mRNA levels of apoptosis-associated speck-like protein (ASC), caspase-1, interleukin-1β (IL-1β), NLRP3 and AIM2 in THP-1-derived macrophages treated with lipopolysaccharides (LPS) of Porphyromonas were also quantified by real-time PCR, and the IL-1β secretion level was investigated using enzyme-linked immunosorbent assay (ELISA).

RESULTS

NLRP3 and AIM2 were positively expressed in periapical lesions and were mainly distributed in inflammatory cells. Most of the samples that demonstrated up-regulation of NLRP3 mRNA also demonstrated up-regulation of caspase-1 mRNA. Microbial analysis revealed that Porphyromonas endodontalis was the most commonly detected species and was detected in 27 of 47 cases (57.4%), followed by Fusobacterium nucleatum (20/47, 42.6%), Porphyromonas gingivalis (19/47, 40.4%), Tannerella forsythia (19/47, 40.4%), Actinomyces sp. (17/47, 36.17%), Treponema denticola (10/47,21.28%), Actinomyces israelii (9/47,19.15%), Prevotella intermedia (6/47, 12.77%), Enterococcus faecalis (1/47,2.13%) and Enterococcus faecium (0/47,0). Furthermore, we found that LPS of P. gingivalis induced THP-1 cells to produce IL-1β and to activate NLRP3 and AIM2 inflammasomes.

CONCLUSIONS

Our results suggest that the NLRP3 and AIM2 proteins play a part in the pathogenesis of periapical periodontitis. Anaerobes, such as P. endodontalis, P. gingivalis, F. nucleatum and T. forsythia, were the main detected microbial stimuli that might activate inflammasomes in periapical tissues.

[The use of self-adapting system files (SAF) for controlling microbial biofilms of root canals in the treatment of apical periodontitis]

The aim of this study was to conduct a clinical and laboratory study and evaluate the effectiveness of endodontic root canal treatment using a self-adapting files system (SAF) in the complex treatment of patients with chronic apical periodontitis. 3% sodium hypochlorite solution was used as irrigation agent in all groups which included 20 patients treated with conventional manual tools, 21 patients receiving treatment with ultrasonic activation of irrigant and 26 patients treated with SAF system. Root canal biofilm structure was studied by scanning electron microscopy (SEM) using a Quantum 3D microscope (USA). Clinical efficiency of the root canal treatment was assessed by complications frequency a year after treatment. SEM revealed the presence of high levels of microbial contamination of dentine tubules in the apical portion of the tooth. In standard method group the percentage of re-treatment and surgery was higher than in the studied groups. Use of SAF irrigation system was associated with a decrease in the number of identified pathogens. However, the study revealed high resistance of Enterococcus spp., Porphyromonas gingivalis, Candida albicans to all types of endodontic treatment, so the improvement of methods of root canal microbial biofilms removing need to be continued.

Microbiome in the Apical Root Canal System of Teeth with Post-Treatment Apical Periodontitis

INTRODUCTION

Bacteria present in the apical root canal system are directly involved with the pathogenesis of post-treatment apical periodontitis. This study used a next-generation sequencing approach to identify the bacterial taxa occurring in cryopulverized apical root samples from root canal-treated teeth with post-treatment disease.

METHODS

Apical root specimens obtained during periradicular surgery of ten adequately treated teeth with persistent apical periodontitis were cryogenically ground. DNA was extracted from the powder and the microbiome was characterized on the basis of the V4 hypervariable region of the 16S rRNA gene by using paired-end sequencing on Illumina MiSeq device.

RESULTS

All samples were positive for the presence of bacterial DNA. Bacterial taxa were mapped to 11 phyla and 103 genera composed by 538 distinct operational taxonomic units (OTUs) at 3% of dissimilarity. Over 85% of the sequences belonged to 4 phyla: Proteobacteria, Firmicutes, Fusobacteria and Actinobacteria. In general, these 4 phyla accounted for approximately 80% of the distinct OTUs found in the apical root samples. Proteobacteria was the most abundant phylum in 6/10 samples. Fourteen genera had representatives identified in all cases. Overall, the genera Fusobacterium and Pseudomonas were the most dominant. Enterococcus was found in 4 cases, always in relatively low abundance.

CONCLUSIONS

This study showed a highly complex bacterial community in the apical root canal system of adequately treated teeth with persistent apical periodontitis. This suggests that this disease is characterized by multispecies bacterial communities and has a heterogeneous etiology, because the community composition largely varied from case to case.

Complex Apical Intraradicular Infection and Extraradicular Mineralized Biofilms as the Cause of Wet Canals and Treatment Failure: Report of 2 Cases

This article describes 2 cases that showed persistent intracanal exudation (wet canal) even after several visits of antimicrobial endodontic treatment. Histologic and histobacteriologic investigation was conducted for determination of the cause. The 2 cases involved teeth with apical periodontitis lesions, which presented persistent exudation refractory to treatment after several visits. In case 1, it was not possible to achieve a dry canal, and surgery had to be performed. In case 2, attempts to dry the canal succeeded and the canal was filled, but follow-up examination showed an enlarged apical periodontitis lesion and extraction was performed. Biopsy specimens consisting of the root apex and apical periodontitis lesion for case 1 and the whole root for case 2 were subjected to histologic and histobacteriologic analyses. Both cases showed complex bacterial infection in the apical root, affecting both the intraradicular space and the outer root surface. Case 1 showed bacterial biofilms in ramifications, on untouched walls, and extending to the external root surface to form a thick and partially mineralized structure with high bacterial density. Different bacterial morphotypes were evidenced. Case 2 had a ledge on the apical canal wall created during instrumentation, which was filled with necrotic debris, filling material, and bacteria. The walls of the apical portion of the canal were covered by a bacterial biofilm, which was continuous with a thick extraradicular biofilm covering the cementum and dentin in resorptive defects. The extraradicular biofilm showed areas of mineralization and was dominated by filamentous bacteria. The 2 cases with wet canals and treatment failure were associated with complex persistent infection in the apical part of the root canal system extending to form thick and partially mineralized biofilm structures (calculus) on the outer apical root surface.

Apically Extruded Sealers: Fate and Influence on Treatment Outcome

INTRODUCTION

This retrospective study evaluated cases of unintentional overfillings for the fate of the extruded sealers and their influence on treatment outcome.

METHODS

One hundred five teeth treated by a single operator and exhibiting overfillings in the postobturation radiograph were included in the study. Seventy-five teeth exhibited apical periodontitis lesions at the time of treatment. Sealers included Pulp Canal Sealer (Sybron Dental, Orange, CA), PCS Extended Working Time-EWT (Sybron Dental), Tubli-Seal (Sybron Endo), Endomethasone (Septodont, Saint-Maur-des-Fossés, France), AH Plus (DeTrey GmbH, Konstanz, Germany), and Apexit (Ivoclar Vivadent, Schaan, Lichtenstein). Recall radiographs were compared with immediate postobturation films for removal of the extruded material and status of the periradicular tissues. Data were grouped as 1-, 2- and >4-year recall and statistically analyzed using the chi-square and Fisher exact tests.

RESULTS

As for the sealers' fate, the only statistically significant differences at the 1-year recall were observed when comparing Tubli-Seal with AH Plus, Apexit, and Endomethasone (P < .05). At both the 2- and 4-year recalls, frequency of complete removal of AH Plus and Apexit was significantly lower when compared with all the other sealers (P < .05). No other significant differences were observed between groups. As for the influence on treatment outcome, there were no statistically significant differences between sealers at all follow-up periods (P > .05). Data from the >4-year recall revealed that 79% of the teeth with apical periodontitis lesions at the time of treatment had healed in comparison with 100% of the teeth with no apical periodontitis (P < .01).

CONCLUSIONS

Not all extruded sealers were predictably removed from the periradicular tissues. Treatment outcome was not significantly affected by the type of extruded sealer. A significantly better outcome was observed for teeth with no lesion in comparison with teeth with apical periodontitis.

Antibacterial TAP-mimic electrospun polymer scaffold: effects on P. gingivalis-infected dentin biofilm

OBJECTIVES

This study sought to investigate, in vitro, the effects of a recently developed triple antibiotic paste (TAP)-mimic polymer nanofibrous scaffold against Porphyromonas gingivalis-infected dentin biofilm.

MATERIALS AND METHODS

Dentin specimens (4 × 4 × 1 mm(3)) were prepared from human canines. The specimens were sterilized, inoculated with P. gingivalis (ATCC 33277), and incubated for 1 week to allow for biofilm formation. Infected dentin specimens were exposed for 3 days to the following treatments: antibiotic-free polydioxanone scaffold (PDS, control), PDS + 25 wt% TAP [25 mg of each antibiotic (metronidazole, ciprofloxacin, and minocycline) per mL of the PDS polymer solution], or a saturated TAP-based solution (50 mg of each antibiotic per mL of saline solution). In order to serve as the negative control, infected dentin specimens were left untreated (bacteria only). To determine the antimicrobial efficacy of the TAP-mimic scaffold, a colony-forming unit (CFU) per milliliter (n = 10/group) measurement was performed. Furthermore, additional specimens (n = 2/group) were prepared to qualitatively study biofilm inhibition via scanning electron microscopy (SEM). Statistics were performed, and significance was set at the 5% level.

RESULTS

Both the TAP-mimic scaffold and the positive control (TAP solution) led to complete bacterial elimination, differing statistically (p < 0.05) from the negative control group (bacteria only). No statistical differences were observed for CFU per milliliter data between antibiotic-free scaffolds (2.7 log10 CFU/mL) and the negative control (5.9 log10 CFU/mL).

CONCLUSIONS

The obtained data revealed significant antimicrobial properties of the novel PDS-based TAP-mimic scaffold against an established P. gingivalis-infected dentin biofilm.

CLINICAL RELEVANCE

Collectively, the data suggest that the proposed nanofibrous scaffold might be used as an alternative to the advocated clinical gold standard (i.e., TAP) for intracanal disinfection prior to regenerative endodontics.