Periapical bacterial plaque in teeth refractory to endodontic treatment

Dental Pathophysiology of Odontogenic Sinusitis: Endodontic Infections

Bacterial odontogenic sinusitis (ODS) arises from maxillary dental issues or oral procedures, and affects at least the maxillary sinuses, with or without other paranasal sinus involvement. It has been historically underreported, in contrast to more recent findings attributing 25-40% of chronic maxillary sinusitis to dental causes. Endodontic infections represent one of the most common causes of ODS. Endodontic factors like root canal infection and microbial proximity to sinus cavities play pivotal roles. Host immunological responses further shape disease severity and progression. This article aims to explore the complexity of endodontic infections that cause ODS, elucidating anatomical, microbial, and immunological aspects.

Identification of keystone taxa in root canals and periapical lesions of post-treatment endodontic infections: Next generation microbiome research

AIM

The aim of this study was to analyse and compare the microbiome present in root canals and periapical lesions of teeth with post-treatment infections, and to identify the presence of keystone taxa in both habitats using next-generation sequencing analysis.

METHODOLOGY

Apices and periapical lesions of patients with post-treatment apical periodontitis were surgically extracted. Specimens were cryo-pulverized, bacterial DNA was extracted, and the V3-V4 hypervariable regions of the 16S rRNA gene were sequenced using the Illumina Miseq platform. Bioinformatic analysis was carried out with Mothur software, whilst diversity indices were obtained using operational taxonomic units (OTUs). The diversity indices were compared with the Kruskal-Wallis test, and community composition differences were explored with Permutational Multivariate Analysis of Variance (PERMANOVA). A bacterial functional study was performed with the Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) analysis. Co-occurrence network analyses were performed using the Sparse Correlations for Compositional data (SparCC). Eigencentrality, clr-based abundance and ubiquitousness were applied to infer keystone taxa. P values <.05 were considered statistically significant.

RESULTS

Thirty-two apices and thirty-nine periapical lesions were sequenced and analysed. A similar alpha-diversity (p < .05) and community composition (p = .91) was observed for apices and lesion samples. The most abundant OTUs identified amongst all samples included Fusobacterium nucleatum, Prevotella loescheii, Streptococcus intermedius, Porphyromonas gingivalis, Parvimonas micra, Synergistetes bacterium, Tannerella forsythia and Peptostreptococcus stomatis. The metabolic pathways with >0.81% abundances included membrane transport, genetic information processing and metabolic pathways. F. nucleatum was identified as a keystone taxon as it showed ubiquitousness, an eigenvector centrality value of 0.83 and a clr-based abundance >4.

CONCLUSIONS

The microbiome in apices and periapical lesions of post-treatment endodontic infections showed a similar diversity and taxonomic composition. Co-occurrence network analyses at OTU level identified F. nucleatum as a keystone taxon candidate in these infections.

Predicting early endodontic treatment failure following primary root canal treatment

BACKGROUND

Understanding when and why endodontic treatments fail could help clinicians make prognoses and thus improve treatment outcomes. This study was aimed to assess potential predictors of early endodontic treatment failure. We explored factors contributing to the failure of initial root canal treatment were explored, with a specific emphasis on evaluating the influence of the time elapsed since the initial treatment.

METHODS

This retrospective cohort study enrolled 1262 patients who sought endodontic treatment at our department and 175 patients were included for analysis. Potential causes of endodontic treatment failure were investigated, such as inadequate obturation quality, inadequate coronal status, the presence of additional untreated canals, anatomical complexity, instrument separation, iatrogenic perforation, cracks, and endodontic-periodontal lesions. The patients were divided into "short-term" and "long-term" groups depending on the time that had passed since the initial treatment (i.e., < 5 and > 10 years, respectively). The causes of failure in the short-term and long-term group were analyzed and compared using logistic regression analyses. Subgroup analysis was performed according to the number of years since the initial treatment in the short-term group to further investigate the association between the time and cause of failure (i.e., < 1, 2, 3, and 4 years, respectively).

RESULTS

Untreated additional canals were present in 21.7% of all cases, and in 36.9 and 6.4% of cases in the short-term and long-term groups, respectively. Multivariable analysis showed that the presence of untreated additional canals was significantly associated with short-term compared to long-term failure. Untreated additional canals were also associated with endodontic failure within 1, 2, 3, and 4 years.

CONCLUSIONS

The presence of untreated additional canals was a predictor of endodontic failure within 5 years following initial root canal treatment. To optimize long-term prognosis, it is important to detect and treat all root canals during the initial treatment.

Enterococcus faecalis in secondary apical periodontitis: Mechanisms of bacterial survival and disease persistence

Enterococcus faecalis is a commensal bacterium commonly found in the human gastrointestinal tract. However, in individuals with compromised immune systems, the pathogen can lead to severe illness. This opportunistic pathogen is associated with secondary apical diseases and is adept at resisting antibiotics and other forms of treatment because of its numerous virulence factors. Enterococcus faecalis is capable of disrupting the normal functions of immune cells, thereby hindering the body's ability to eradicate the infection. However, intensive research is needed in further understanding the adverse immunomodulatory effects of E. faecalis. Potential strategies specific for eradicating E. faecalis have proven beneficial in the treatment of persistent secondary apical periodontitis.

Microbiome in paired root apices and periapical lesions and its association with clinical signs in persistent apical periodontitis using next-generation sequencing

AIM

To assess and compare the microbiome of paired root apices and periapical lesions from cases with failed endodontic treatment and to associate the microbiome and bacterial metabolic pathways in both sites with asymptomatic apical periodontitis (AAP) and symptomatic apical periodontitis (SAP), using next-generation sequencing (NGS).

METHODOLOGY

Matched root apices and periapical lesions of patients with failed root canal treatments were surgically extracted. Specimens were cryopulverized, bacterial DNA was extracted and the V3-V4 hypervariable regions of the 16 S rRNA gene were amplified and sequenced using the Illumina Miseq platform. Diversity and community composition were studied in the paired samples, as well as in AAP and SAP cases. Diversity indices were compared in each case by means of the Wilcoxon matched-pairs signed rank and Mann-Whitney U tests. Differences in the community composition were explored with multivariate statistical analysis and Linear discriminant analysis Effect Size (LEfSe). Bacterial functional study was performed through the Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) analysis.

RESULTS

Twenty-one paired apices and lesions were successfully sequenced and analysed, identifying a total of 21 phyla and 600 genera. A higher alpha-diversity was observed in the periapical lesions, although no global differences in the community composition between the two sites were found (p = .87), the most prevalent genera being Fusobacterium, Porphyromonas and Streptococcus. Prevotella, Clostridiales_vadinBB60_group, Bosea, Phreatobacter, Afipia and Xanthobacteriaceae_unclassified were enriched in SAP samples, while Pseudopropionibacterium, Campylobacter and Peptoniphilus were significantly more abundant in AAP cases (p < .05). Metabolic pathways involved in the amino acid metabolism or degradation and flagellum assembly were more abundant in SAP samples, whereas glucose metabolism-related pathways were associated with AAP.

CONCLUSIONS

The bacterial community composition was similar in the apices and periapical lesions. The microbiome was different in AAP and SAP samples, gram-negative bacteria showing higher relative abundances in SAP cases. An association was observed between amino acid degradation and flagellum assembly pathways, and the development of tenderness to percussion or palpation.

Surgical endodontic treatment of maxillary incisors: Case report

This study aims to highlight the possibility of an effective endodontic surgical surgery when nonsurgical treatment of the right maxillary anterior teeth has failed. One year after the apicoectomy, the periapical lesion has completely healed, new bone has formed, and the patient is symptom-free.

Present Status and Future Directions - Surgical Endodontics

Endodontic surgery encompasses several procedures for the treatment of teeth with a history of failed root canal treatment, such as root-end surgery, crown- and root resections, surgical perforation repair, and intentional replantation. Endodontic microsurgery is the evolution of the traditional apicoectomy techniques and incorporates high magnification, ultrasonic root-end preparation and root-end filling with biocompatible filling materials. Modern endodontic surgery uses the dental operating microscope, incorporates cone-beam computed tomography (CBCT) for preoperative diagnosis and treatment planning, and has adopted piezoelectric approaches to osteotomy and root manipulation. Crown- and root resection techniques have benefitted from the same technological advances. This review focuses on the current state of root-end surgery by comparing the techniques and materials applied during endodontic microsurgery to the most widely used earlier methods and materials. The most recent additions to the clinical protocol and technical improvements are discussed, and an outlook on future directions is given. While non-surgical retreatment remains the first choice to address most cases with a history of endodontic failure, modern endodontic microsurgery has become a predictable and minimally invasive alternative for the retention of natural teeth.

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.

Current Status of Phage Therapy against Infectious Diseases and Potential Application beyond Infectious Diseases

Intestinal microbiota plays a key role in regulating the pathogenesis of human disease and maintaining health. Many diseases, mainly induced by bacteria, are on the rise due to the emergence of antibiotic-resistant strains. Intestinal microorganisms include organisms such as bacteria, viruses, and fungi. They play an important role in maintaining human health. Among these microorganisms, phages are the main members of intestinal viromes. In particular, the viral fraction, composed essentially of phages, affects homeostasis by exerting selective pressure on bacterial communities living in the intestinal tract. In recent years, with the widespread use and even abuse of antibacterial drugs, more and more drug-resistant bacteria have been found, and they show a trend of high drug resistance and multidrug resistance. Therefore, it has also become increasingly difficult to treat serious bacterial infections. Phages, a natural antibacterial agent with strong specificity and rapid proliferation, have come back to the field of vision of clinicians and scholars. In this study, the current state of research on intestinal phages was discussed, with an exploration of the impact of phage therapy against infectious diseases, as well as potential application beyond infectious diseases.

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.

A qualitative and semiquantitative SEM study of the morphology of the biofilm on root surfaces of human teeth with endodontic-periodontal lesions

Over the last decades, scanning electron microscopy (SEM) proved to be invaluable for ultrastructural investigation, allowing imaging of the overall appearance and/or specific features of oral biofilms, e.g., microbial colonies and individual cells, glycocalyx, the presence of inorganic products. The aim of this study was the observation and evaluation of the morphology of the biofilm of endodontic-periodontal lesions (EPL) with a modified protocol involving a simplified histologic sample preparation and a low-vacuum SEM examination method. Twenty-one teeth with endodontic-periodontal involvement, extracted for periodontal reasons, were carefully washed with saline, underwent fixation in modified Karnovsky solution and were dehydrated in alcohol series. Samples were examined under low-vacuum SEM. Radicular surfaces were evaluated qualitatively and semiquantitatively for several characteristics, including the presence of bacterial types, the biofilm morphology and the content of root resorptions. Radicular surfaces were divided in four conventional zones Surfaces were evaluated for several characteristics: Presence of bacterial types, biofilm morphology, presence of root resorptions. High-quality images, relevant for endodontic-periodontal biofilms were collected. Continuous, established biofilm was found on all examined surfaces, its detection varying from 19% of the samples on the wall of cemental cone to 52.3% on the radicular surface of the periodontal pocket. Observed microorganisms included cocci, rods an filaments. Spirils and motile bacteria were only accidentally found. SEM investigation of surfaces involved in EPL revealed less surfaces covered by mature biofilm (in only 28.5% of the samples in the ‘transition zone’), especially rods and filaments associated with cemental resorptions and calculus. Biofilm elements were better represented in periodontal pockets than in other zones of EPL (detected in up to 81% of the samples). A strong correlation between mature biofilm and the presence of cocci appears on all investigated zones (P<0.01). Microbiota appeared to be morphologically similar in apical and periodontal areas, especially in old EPL.

Antimicrobial action of NeoMTA Plus on mono- and dual-species biofilms of Enterococcus faecalis and Candida albicans: An in vitro study

OBJECTIVE

To evaluate the antimicrobial action of NeoMTA Plus on mono- and dual-species biofilms of Enterococcus faecalis and Candida albicans.

MATERIAL AND METHODS

A total of 171 sterile dentin blocks, measuring 4 mm × 4 mm × 1 mm, were incubated in media containing E. faecalis (3.1 × 10⁸ cells/mL) and/or C. albicans (1 × 10⁷ cells/mL) for 2 d. These blocks were randomly divided into three groups: the control (no treatment with biomaterials), MTA (treated with an MTA sample with width and thickness same as those of the dentin block after the material was set), and NeoMTA Plus (treated with NeoMTA Plus in a fashion similar to the treatment of the MTA group) groups. The biomaterials remained in contact with the biofilms for 24 h. Quantitative analyses of the number of colony-forming units (CFUs) and metabolic activity (XTT), were performed. Furthermore, qualitative analysis of biofilm structure was performed by scanning electron microscopy. Data were statistically analyzed considering a significance level of 5%.

RESULTS

XTT and the number of CFUs were similar among the groups (p > 0.05). The type of biofilm (mono- or dual-species) or the biomaterial used (MTA or NeoMTA Plus) did not affect the results. Biofilm structure exhibited a robust architecture composed of yeast and bacterial cell multilayers and was homogeneous among the groups.

CONCLUSION

NeoMTA Plus was not effective against mono- and dual-species biofilms of E. faecalis and C. albicans. Further research investigating biofilm removal methods including those involving the use of biomaterials with antiseptics and other supporting therapies is warranted.

Selective Curettage: A Conservative Microsurgical Approach to Treating Large and Complicated Lesions

Endodontic microsurgery is a predictable and successful procedure when using techniques that have been developed over the past several years. One of the steps during surgery involves curettage of the entire lesion. However, there are cases in which the lesion has advanced to invade anatomic structures like the nasal fossa, maxillary sinus, mandibular canal, neighboring vital teeth, or through and through to the palate. These lesions make endodontic microsurgery difficult for the operator to execute and have inherent risks to the patient. Selective curettage is a conservative approach to treat such cases by removing approximately 50%-70% of the granulomatous tissue while avoiding complications and damage to the neighboring structures. Three-dimensional cone-beam computed tomographic imaging, 2-dimensional periapical radiographs, and clinical follow-ups of the selective curettage lesions showed complete or incomplete (scar tissue) healing in all cases with no untoward results.

Endodontic Periapical Lesion: An Overview on the Etiology, Diagnosis and Current Treatment Modalities

Nonsurgical and surgical endodontic treatments have a high success rate in the treatment and prevention of apical periodontitis when carried out according to standard and accepted clinical principles. Nevertheless, endodontic periapical lesions remain in some cases, and further treatment should be considered when apical periodontitis persists. Although several treatment modalities have been proposed for endodontically treated teeth with persistent apical periodontitis, there is a need for less invasive methods with more predictable outcomes. The advantages and shortcomings of existing approaches for the diagnosis and treatment of endodontic periradicular lesions are discussed in this review.

Evaluation of surface integrity of root end cavities prepared using conventional and piezoelectric devices: A scanning electron microscopy study

Introduction

An array of factors control the success of endodontic surgery. One of them is the technique used to prepare the root end cavities which is conventionally being done with burs. In past decades, ultrasonic instruments have been introduced for the same. Studies comparing these instruments on root surface integrity are scarce. Thus, an in-vitro Scanning Electron Microscopy study was designed to evaluate the surface integrity of root end cavities prepared using conventional and piezoelectric devices.

Methodology

Twelve single-rooted human intact mandibular premolar teeth were endodontically treated and included in the study. They were divided into two groups. In the first group, 3 mm root-end cavities were prepared using conventional retro preparation burs and in the second group, 3 mm root-end cavities were prepared using piezoelectric retro-tips. The specimens were coded for blind evaluation and analysed under scanning electron microscope at 100x, 500x and 1000x magnification for smear layer and debris. Gutmann's scoring criteria was followed to score the specimens. Statistical analysis was carried out using Shapiro Wilk test and the independent sample t-test was used to check mean differences between variables.

Results

It was noted that significant statistical differences existed in mean debris and smear layer scores (p< 0.001) between the two groups. In the piezoelectric group, significantly lower debris layer and smear layer was found, compared to the conventional bur group.

Conclusion

Root-end cavities prepared using piezo retrotips produced cleaner, well-centered and more conservative surface with minimal debris & smear layer, compared to root-end cavities prepared using conventional burs.

Effect of immediate periodontal surgical treatment on periodontal healing in combined endodontic-periodontal lesions with communication-A randomized clinical trial

BACKGROUND AND OBJECTIVE

Management of combined endodontic-periodontal lesions needs more clinical investigations. The aim of this prospective randomized clinical trial was to evaluate the effect oftime interval between the non-surgical endodontic treatment (ET) and open flap debridement (OFD) on periodontal healing in combined endodontic periodontal lesions with apical communication.

METHODS

Forty patients were randomly allocated to two treatment protocols. Group 1(immediate periodontal surgery): OFD was performed at 21 days of initiation of ET and SRP, and Group 2(delayed periodontal surgery): OFD was performed after 3 months of initiation of ET and SRP. The primary parameters included probing pocket depth (PPD), relative attachment level (RAL) and bleeding on probing (BOP) and tooth mobility (TM).

RESULTS

Significantly more reduction in PPD, TM and gain in RAL was observed in Group 1 at 3 months of OFD. (P < 0.05) Whereas at 6 months follow up of OFD (6 and 9 months of ET in Group1 and Group 2, respectively), intergroup analysis showed statistically comparable reduction in BOP (%), PPD, TM and gain in RAL (P > 0.05) in both the groups.

CONCLUSION

Immediate periodontal surgery may not affect the outcome of the treatment of combined endo-perio lesions with apical communication.

Novel Endodontic Disinfection Approach Using Catalytic Nanoparticles

INTRODUCTION

The aim of this study was to test a new disinfection technology using biomimetic iron oxide nanoparticles (IO-NPs) with peroxidaselike activity to enhance antibacterial activity on root canal surfaces and in dentinal tubules.

METHODS

The canal surfaces and dentinal tubules of single-rooted intact extracted teeth were infected by growing Enterococcus faecalis biofilms for 3 weeks. The samples were divided into 6 treatment groups: (1) phosphate-buffered saline (PBS) (negative control), (2) 3% hydrogen peroxide (H₂O₂) (test control), (3) IO-NPs (0.5 mg/mL) (test control), (4) IO-NPs (0.5 mg/mL) + 3% H₂O₂, (5) 3% sodium hypochlorite (positive control), and (6) 2% chlorhexidine (positive control). Environmental scanning electron microscopy coupled with energy-dispersive spectroscopy was used to confirm IO-NPs binding to the canal surface after a single treatment. Specimens were labeled with fluorescent staining for live/dead cells, and confocal laser scanning microscopy was used for the quantification of dead bacteria relative to the negative control (PBS).

RESULTS

Both biofilm formation and dentinal tubule infection were successfully recapitulated using the in vitro model. IO-NPs were capable of binding to the infected canal surfaces despite a single, short-term (5-minute) treatment. IO-NP activation of H₂O₂ killed significantly more E. faecalis present on the canal surfaces and at different depths of dentinal tubules when compared with all other experimental groups (P < .05-.0005).

CONCLUSIONS

The results reveal the potential to exploit nanocatalysts with enzymelike activity as a potent alternative approach for the treatment of endodontic infections.

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.

Frequency of bacetrial content finding in persistant periapical lesions

Objectives

To determine the percentage of persistant apical lesions positive for bacterial nucleic acids, to detect microorganisms difficult to cultivate in persistant apical lesions by PCR and relate them to endodontic failure, clinical symptoms and diabetes mellitus.

Materials and methods

The samples of persistent apical lesions were collected during apicoectomy. Bacterial ubiquitous primer 16S rRNA was used to detect 16S ribosomal RNA in 36 samples. A species–specific PCR was performed with primers targeted to the bacterial 16S rRNA genes of Prevotella Nigrescens, Pseudoramibacter alactolyticus, and Propionobacterium propionicum.

Results

Six samples (16.67%) were positive for bacterial ribosomal RNA. Pseudoramibacter alactolyticus was detected in three samples. Propionibacterium propionicum and Prevotella nigrescens were detected in one sample each. The prevalence of infection of such lesions with P. intermedia, P. propionicum and P. alactolyticus is low.

Conslusion

The study we conducted gave insufficient data about extraradicular infection and its connection with diabetes mellitus and clinical symptoms.

Conclusions

Apical lesions persisting after endodontic treatment could harbor microorganisms other than Actinomyces and Propionicum species.

Actinomyces israelii in radicular cysts: a molecular study

OBJECTIVE

To investigate whether the microscopic filamentous aggregates observed in radicular cysts are associated with the molecular identification of Actinomyces israelii. Moreover, to verify whether this bacterium can be detected in radicular cyst specimens not presenting aggregates.

STUDY DESIGN

Microscopic colonies suggestive of Actinomyces were found in 8 out of 279 radicular cyst samples (case group). The case and control groups (n = 12; samples without filamentous colonies) were submitted to the semi-nested polymerase chain reaction to test the presence of A israelii. DNA sequencing was performed to validate polymerase chain reaction results.

RESULTS

Two and 3 samples in the case and control groups, respectively, did not present a functional genomic DNA template and were excluded from the study. A israelii was identified in all samples of the case group and in 3 out of 9 samples of the control group.

CONCLUSIONS

Although A israelii is more commonly identified in radicular cysts presenting filamentous aggregates, it also appears to be detected in radicular cysts without this microscopic finding.

Controversies in Endodontics

Diseases of the dental pulp often have an infectious origin, and treatments are aimed to control infections of the root canal system. Endodontic treatment principles originally evolved on the basis of trial and error, and only in recent decades have scientific methods been adopted to support clinical strategies. Yet, relevant research on the disease processes, their diagnoses, and efficient treatment are rare in the endodontic literature. Hence, the advancement of biologically based knowledge significant to clinical endodontics has been slow. Therefore, many differences of opinion still prevail in this field of dentistry. This review highlights and analyzes the background of some of the more heavily debated issues in recent years. Specifically, it deals with disagreements regarding the clinical management of pulpal exposures by caries in the adult dentition, definitions of success and failure of endodontic therapy, and causes of and measures to control infections of the root canal system. Clearly, a most apparent gap in the published endodontic literature is the lack of randomized clinical trials that address the more significant controversial matters relating to the management of pulpal wounds, medication, and the number of appointments required for the treatment of infected root canals. However, trials in endodontics require extremely long follow-up periods if valid conclusions are to be generated. Therefore, it is not to be expected that there will be rapid solutions to these issues in the foreseeable future.

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.

Biofilm in endodontics: A review

Endodontic disease is a biofilm-mediated infection, and primary aim in the management of endodontic disease is the elimination of bacterial biofilm from the root canal system. The most common endodontic infection is caused by the surface-associated growth of microorganisms. It is important to apply the biofilm concept to endodontic microbiology to understand the pathogenic potential of the root canal microbiota as well as to form the basis for new approaches for disinfection. It is foremost to understand how the biofilm formed by root canal bacteria resists endodontic treatment measures. Bacterial etiology has been confirmed for common oral diseases such as caries and periodontal and endodontic infections. Bacteria causing these diseases are organized in biofilm structures, which are complex microbial communities composed of a great variety of bacteria with different ecological requirements and pathogenic potential. The biofilm community not only gives bacteria effective protection against the host's defense system but also makes them more resistant to a variety of disinfecting agents used as oral hygiene products or in the treatment of infections. Successful treatment of these diseases depends on biofilm removal as well as effective killing of biofilm bacteria. So, the fundamental to maintain oral health and prevent dental caries, gingivitis, and periodontitis is to control the oral biofilms. From these aspects, the formation of biofilms carries particular clinical significance because not only host defense mechanisms but also therapeutic efforts including chemical and mechanical antimicrobial treatment measures have the most difficult task of dealing with organisms that are gathered in a biofilm. The aim of this article was to review the mechanisms of biofilms’ formation, their roles in pulpal and periapical pathosis, the different types of biofilms, the factors influencing biofilm formation, the mechanisms of their antimicrobial resistance, techniques to identify biofilms.

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

INTRODUCTION

This article describes 3 cases that presented persistent symptoms after appropriate endodontic treatment. Histopathologic and histobacteriologic investigation were conducted for determination of the cause.

METHODS

Three cases are reported that presented with persistent symptoms after endodontic retreatment (cases 1 and 2) or treatment (case 3). Periapical surgery was indicated and performed in these cases. The biopsy specimens, consisting of root apices and the apical periodontitis lesions, were subjected to histopathologic and histobacteriologic analyses.

RESULTS

Case 1 was an apical cyst with necrotic debris, heavily colonized by ramifying bacteria, in the lumen. No bacteria were found in the apical root canal system. Case 2 was a granuloma displaying numerous bacterial aggregations through the inflammatory tissue. Infection was also present in the dentinal tubules at the apical root canal. Case 3 was a cyst with bacterial colonies floating in its lumen; bacterial biofilms were also seen on the external apical root surface, filling a large lateral canal and other apical ramifications, and between layers of cementum detached from the root surface. No bacteria were detected in the main root canal.

CONCLUSIONS

Different forms of extraradicular infection were associated with symptoms in these cases, leading to short-term endodontic failure only solved by periapical surgery.

Microbial invasion of dentinal tubules: a literature review and a new perspective

Various features of endodontic microbiology have been investigated using various methods. The aim of the present study was to review the existing literature on endodontic microbiology in dentinal tubules, and to present the features of two cases with endodontic pathology. An electronic search was performed with a search string created ad hoc. Ex vivo and in vitro studies were included, recording the method of detection and characteristics of analyzed teeth. Twenty studies fulfilled the inclusion criteria. Seven of them were in vitro laboratory studies on teeth inoculated after extraction, while 13 were ex vivo studies on extracted, infected teeth. Endodontic bacteria were detected in dentinal tubules, both as single units and as biofilm aggregates. Two similar in vitro cases presented here corroborate the latter findings. A number of techniques have been utilized to observe bacteria in the dentinal tubule ecosystem. Dentinal tubules are favorable niches for microbial survival, either in the form of monomicrobial or polymicrobial communities.

Management of a large periapical lesion using Biodentine(™) as retrograde restoration with eighteen months evident follow up

Injury to anterior teeth is a common event. It requires a treatment approach that assures the complete biologic healing and functional restoration of the tooth or teeth involved. A cystic lesion, which is unable to heal nonsurgically, heals well with surgical intervention and use of mineral trioxide aggregate (MTA) as retrograde filling has been reported in literature. Another material with largely improved handling properties; Biodentine^™ (Septodont, St. Maurdes Fossés, France) was introduced in 2011. It is a calcium silicate based material and manufacturers claim that it can be used for crown and root dentin repair treatment, repair of perforations or resorptions, apexification, and root end fillings. This article presents a case report of surgical management of a large cystic lesion using Biodentine^™ as retrograde filling material which has not been reported in literature so far. Eighteen months radiographic follow-up exhibited completely healed cystic lesion.

Analysis of the secondary endodontic lesions focusing on the extraradicular microorganisms: an overview

The present study aimed at reviewing the literature on extraradicular infections of endodontically treated teeth, summarizing the main hypotheses on etiopathogenesis and describing the most suitable techniques to identify the composition of pathogenic extraradicular microorganisms. Medline database was searched using the keywords "Apical biofilm," "extraradicular infection," "secondary endodontic lesion," "endodontic retreatment," "biofilm" either alone or combined with AND. A further hand search was performed on the main endodontic journals. The most frequent bacterial species identified in different studies and with different techniques may vary considerably. Although the presence of some species of microorganisms seems to be determinant, the true origin of extraradicular infection is still undetermined. The literature analysis showed marked differences in methodology, materials, aims, and techniques adopted, which led to highly heterogeneous outcomes. The picture emerging from this review is that extraradicular infection is likely a multifactorial disease that requires further systematic investigation using standardized techniques.

Microbiota associated with infections of the jaws

The microbial infections involving the craniofacial skeleton, particularly maxilla and mandible, have direct relationship with the dental biofilm, with predominance of obligate anaerobes. In some patients, these infections may spread to bone marrow or facial soft tissues, producing severe and life-threatening septic conditions. In such cases, local treatment associated with systemic antimicrobials should be used in order to eradicate the sources of contamination. This paper discuss the possibility of spread of these infections and their clinical implications for dentistry, as well as their etiology and aspects related to microbial virulence and pathogenesis.