Cellulose fibers from endodontic paper points as an etiological factor in postendodontic periapical granulomas and cysts

Evaluation of Injectable Hyaluronic Acid-Based Hydrogels for Endodontic Tissue Regeneration

Dental pulp tissue engineering (TE) endeavors to regenerate dentin/pulp complex by combining a suitable supporting matrix, stem cells, and biochemical stimuli. Such procedures foresee a matrix that can be easily introduced into the root canal system (RCS) and tightly adhere to dentin walls to assure the dentin surface’s proper colonization with progenitor cells capable of restoring the dentin/pulp complex. Herein was investigated an injectable self-setting hyaluronic acid-based (HA) hydrogel system, formed by aldehyde-modified (a-HA) with hydrazide-modified (ADH), enriched with platelet lysate (PL), for endodontic regeneration. The hydrogels’ working (wT) and setting (sT) times, the adhesion to the dentine walls, the hydrogel’s microstructure, and the delivery of human dental pulp cells (DPCs) were studied in vitro. Hydrogels incorporating PL showed a suitable wT and sT and a porous microstructure. The tensile tests showed that the breaking point occurs after 4.3106 ± 1.8677 mm deformation, while in the indentation test after 1.4056 ± 0.3065 mm deformation. Both breaking points occur in the hydrogel extension. The HA/PL hydrogels exhibited supportive properties and promoted cell migration toward dentin surfaces in vitro. Overall, these results support using PL-laden HA injectable hydrogels (HA/PL) as a biomaterial for DPCs encapsulation, thereby displaying great clinical potential towards endodontic regenerative therapies.

Microbial Association with Genus Actinomyces in Primary and Secondary Endodontic Lesions, Review

The main reason for root canal treatment failure is the persistence of microorganisms after therapy, or the recontamination of the root canal system due to an inadequate seal. In the mouth, Actinomyces spp. constitute a significant part of the normal flora, which is indicative of their ability to adhere to oral tissue and resist cleansing mechanisms, such as salivary flow. This review, performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA), aims to clarify the prevalence of microbial genera that are associated with the genus Actinomyces in primary and secondary endodontic infections (primary outcome), and to identify the most prevalent species of the Actinomyces genus in endodontic lesions (secondary outcome). A total of 11 studies were included in the qualitative and quantitative analysis, and a total of 331 samples were analyzed. Bacteria of the genus Actinomyces were found in 58 samples, and 46 bacterial genera were detected in association with bacteria of the genus Actinomyces. Bacteria of the genus Streptococcus and Propionibacterium were those most frequently associated with Actinomyces in the endodontic lesions considered, and Actinomyces israelii was the most frequently involved species.

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.

Distinguishing structural features between Crohn's disease and gastrointestinal luminal tuberculosis using Mueller matrix derived parameters

Recently, the incidence of inflammatory bowel diseases, especially the Crohn's disease (CD) and gastrointestinal luminal tuberculosis (ITB), has grown rapidly worldwide. Currently there is no general gold standard to distinguish between CD and ITB tissues, which both have tuberculosis and surrounding fibrous structures. Mueller matrix imaging technique is suitable for describing the location, density and distribution behavior of such fibrous structures. In this study, we apply the Mueller matrix microscopic imaging to the CD and ITB tissue samples. The 2D Mueller matrix images of the CD and ITB tissue slices are measured using the Mueller matrix microscope developed in our previous study, then the Mueller matrix polar decomposition and Mueller matrix transformation parameters are calculated. To evaluate the distribution features of the fibrous structures surrounding the tuberculosis areas more quantitatively and precisely, we analyze the retardance related Mueller matrix derived parameters, which show clear different distribution behaviors between the CD and ITB tissues, using the Tamura image processing method. It is demonstrated that the Mueller matrix derived parameters can reveal the structural features of tuberculosis areas and be used as quantitative indicators to distinguish between CD and ITB tissues, which may be useful for the clinical diagnosis.

Paper points revisited: risk of cellulose fibre shedding during canal length confirmation

AIM

To compare the degree of fibre shedding by six brands of endodontic paper point when used for the paper point technique (PPT) of working length confirmation.

METHODOLOGY

An in vitro model simulating the clinical use of paper points in PPT was used to assess the degree of fibre shedding of six brands of size 20, .02 taper paper point. Whilst observing the artificial terminal foramen with polarized light microscopy, the number of fibres shed directly (point inserted 1 mm beyond the terminal foramen) and indirectly (point inserted to length then a gutta-percha point inserted) was assessed. The degree of direct fibre shedding as a function of brand was analysed with Fisher's exact test and multiple pairwise comparisons. Indirect fibre shedding was analysed with Kruskal-Wallis and Wilcoxon rank-sum tests.

RESULTS

All brands shed fibres both directly and indirectly, with a significant influence of brand on the proportion of fibres shed directly (P < 0.0306) and on the mean number of fibres shed indirectly (P < 0.0001). Post hoc analysis demonstrated a similar hierarchy of point integrity for both tests with Classic (UnoDent, Witham, UK) shedding significantly more than other brands and SS White (Gloucester, UK) and Antaeos^® (VDW, Munich, Germany) shedding the least.

CONCLUSION

All brands of paper point may shed cellulose fibres both directly and indirectly with a significant influence of brand on the degree of fibre shedding. Further work should be undertaken to develop biocompatible absorbent dental points.

Epidemiologic evaluation of the outcomes of orthograde endodontic retreatment

INTRODUCTION

Teeth undergoing initial endodontic therapy have a very high survival rate. Some teeth that continue to show signs of pathosis after the initial therapy will require nonsurgical (orthograde) retreatment. Outcome assessment of endodontic retreatment is crucial for appropriate case selection and treatment planning. However, reports on outcomes of orthograde endodontic retreatment performed by endodontists are limited in number, and the reported data vary. In this study, outcomes of orthograde endodontic retreatment performed on 4744 teeth were assessed during a period of 5 years.

METHODS

Data were obtained from retreatments that were performed by endodontists participating in the Delta Dental Insurance plan that insures approximately 15 million individuals in the USA.

RESULTS

Overall, 89% of teeth were retained in the oral cavity 5 years after the endodontic retreatment. Four percent of all teeth underwent apical surgery that occurred mostly within 2 years from completion of orthograde retreatment. Eleven percent of teeth were extracted at the end of the 5-year observation period.

CONCLUSIONS

It appears that orthograde endodontic retreatment yields high incidence of tooth retention after 5 years.

A big role for the very small--understanding the endodontic microbial flora

Apical periodontitis, an inflammatory process around the apex of a tooth root, is primarily a sequel to microbial infection of the pulp space. The microbial flora is composed of a restricted group of the total oral flora, selected by environmental pressures of anaerobiosis, nutrition and competition with other species and inhabits the root canal as a biofilm of coaggregated communities in an extracellular matrix. The untreated infected canal is generally composed of a polymicrobial mix with approximately equal proportions of Gram-positive and Gram-negative species, dominated by obligate anaerobes. The type of microbial flora in the root-filled tooth with persistent apical periodontitis has very different characteristics. These infections are characterized by one or just a few species, predominantly Gram-positive micro-organisms with an equal distribution of facultative and obligate anaerobes. Enterococcus faecalis has been a conspicuous finding in most studies. Because the primary aetiological problem is infection, endodontic treatment is directed at control and elimination of the root canal flora by working in a sterile way. Based on current knowledge, the best available method for obtaining clean, microbe-free root canals is by instrumentation with antimicrobial irrigation reinforced by an intracanal dressing with calcium hydroxide.

Foreign body gingival lesions: distribution, morphology, identification by X-ray energy dispersive analysis and possible origin of foreign material

BACKGROUND

Foreign material may cause and aggravate gingival lesions. This is rarely considered clinically. The lesions are resistant to frequently protracted conventional therapy. The foreign material is often inconspicuous and easily overlooked by the pathologist.

METHODS

85 cases of gingival lesions containing foreign material were investigated by conventional and polarization light microscopy, focusing on the morphology and optical characteristics of the foreign substance. Supplemented with the results of X-ray energy dispersive analysis the foreign material was compared with commonly used dental materials.

RESULTS

The foreign material was most frequently compatible with amalgam. Inconspicuous crystals, often revealed only by polarization microscopy, were most commonly compatible with abrasives, particularly corundum and silicates, and mostly occurred together with amalgam dust.

CONCLUSIONS

Iatrogenic introduction of dental materials during dental procedures explains most foreign body gingival lesions which could be reduced or avoided by prophylactic measures. Pathologists should meticulously scrutinize gingival biopsies routinely applying polarization microscopy.

On the causes of persistent apical periodontitis: a review

Apical periodontitis is a chronic inflammatory disorder of periradicular tissues caused by aetiological agents of endodontic origin. Persistent apical periodontitis occurs when root canal treatment of apical periodontitis has not adequately eliminated intraradicular infection. Problems that lead to persistent apical periodontitis include: inadequate aseptic control, poor access cavity design, missed canals, inadequate instrumentation, debridement and leaking temporary or permanent restorations. Even when the most stringent procedures are followed, apical periodontitis may still persist as asymptomatic radiolucencies, because of the complexity of the root canal system formed by the main and accessory canals, their ramifications and anastomoses where residual infection can persist. Further, there are extraradicular factors -- located within the inflamed periapical tissue -- that can interfere with post-treatment healing of apical periodontitis. The causes of apical periodontitis persisting after root canal treatment have not been well characterized. During the 1990s, a series of investigations have shown that there are six biological factors that lead to asymptomatic radiolucencies persisting after root canal treatment. These are: (i) intraradicular infection persisting in the complex apical root canal system; (ii) extraradicular infection, generally in the form of periapical actinomycosis; (iii) extruded root canal filling or other exogenous materials that cause a foreign body reaction; (iv) accumulation of endogenous cholesterol crystals that irritate periapical tissues; (v) true cystic lesions, and (vi) scar tissue healing of the lesion. This article provides a comprehensive overview of the causative factors of non-resolving periapical lesions that are seen as asymptomatic radiolucencies post-treatment.

The management of periapical lesions in endodontically treated teeth

When root canal therapy is done according to accepted clinical principles and under aseptic conditions, the success rate is generally high. However, it has also been reported that 16% to 64.5% of endodontically treated teeth are associated with periapical radiolucent lesions. There are great variations among clinicians when suggesting treatment of these failed endodontic cases. This article will discuss factors influencing treatment decisions on these particular cases, and the pros and cons of nonsurgical retreatment versus surgical retreatment. The advancement of modern endodontic microsurgery will also be discussed.

Detection of a residual foreign body during root canal treatment

A 25-yr old female with a 12-month history of orofacial trauma was referred to us with acute pain with positive percussion of the left mandibular first premolar and swelling in the left-posterior mandibular area. The diagnosis was pulpal necrosis with acute apical abscess. Both preoperative and length determination radiographs revealed a semi-opaque area on the root of the first premolar that was later identified as a residual fragment of windshield left in the soft tissues. Thorough medical record, clinical and radiographic examination may be helpful in the detection of foreign bodies in the orofacial region.

Do procedural errors cause endodontic treatment failure?

BACKGROUND

This article reviews the effect of endodontic procedural errors, such as underfilling, overfilling, root perforations and separated instruments, on the outcome of endodontic therapy.

TYPES OF STUDIES REVIEWED

Filling the root canal more than 2 millimeters from the radiographic apex (underfilling) or beyond the radiographic apex (overfilling), perforations of the root canal system and instrument separation are possible complications of endodontic therapy. Although these procedural errors may have different causes, they all may affect the outcome of treatment.

RESULTS

Endodontic procedural errors are not the direct cause of treatment failure; rather, the presence of pathogens in the incompletely treated or untreated root canal system is the primary cause of periradicular pathosis. Procedural errors typically are due to several factors. Among them is a lack of understanding of the root canal anatomy, the principles of mechanical instrumentation and tissue wound healing.

CLINICAL IMPLICATIONS

Procedural errors impede endodontic therapy, thus increasing the risk of treatment failure, especially in teeth with necrotic pulps and periradicular lesions. However, procedural errors often are preventable.

Pathogenesis of apical periodontitis and the causes of endodontic failures

Apical periodontitis is a sequel to endodontic infection and manifests itself as the host defense response to microbial challenge emanating from the root canal system. It is viewed as a dynamic encounter between microbial factors and host defenses at the interface between infected radicular pulp and periodontal ligament that results in local inflammation, resorption of hard tissues, destruction of other periapical tissues, and eventual formation of various histopathological categories of apical periodontitis, commonly referred to as periapical lesions. The treatment of apical periodontitis, as a disease of root canal infection, consists of eradicating microbes or substantially reducing the microbial load from the root canal and preventing re-infection by orthograde root filling. The treatment has a remarkably high degree of success. Nevertheless, endodontic treatment can fail. Most failures occur when treatment procedures, mostly of a technical nature, have not reached a satisfactory standard for the control and elimination of infection. Even when the highest standards and the most careful procedures are followed, failures still occur. This is because there are root canal regions that cannot be cleaned and obturated with existing equipments, materials, and techniques, and thus, infection can persist. In very rare cases, there are also factors located within the inflamed periapical tissue that can interfere with post-treatment healing of the lesion. The data on the biological causes of endodontic failures are recent and scattered in various journals. This communication is meant to provide a comprehensive overview of the etio-pathogenesis of apical periodontitis and the causes of failed endodontic treatments that can be visualized in radiographs as asymptomatic post-treatment periapical radiolucencies.

Endodontic retreatment of an autotransplanted lower first premolar: a case report

A 24-year-old female with no contributory medical history had been treated by orthodontic alignment and transplantation of the lower left first premolar to the upper left first premolar site to correct for congenitally missing upper premolars. Subsequently, the transplanted premolar was treated by conventional endodontics and apical surgery for persistent periapical periodontitis over a span of 12 years. A combination of conventional endodontic retreatment and periapical surgery resulted in periapical healing. This case outlines the need for careful preoperative case assessment.

The periapical space--a dynamic interface

The ultimate aim of endodontic treatment is to encourage the healing of apical periodontitis, or to prevent it from occurring if it was not present prior to treatment. Apical periodontitis is a general term used to describe an inflammatory response to irritation caused by the contents of a root canal system and it has several distinct forms. The most common is a granuloma but this can develop into other disease entities such as an abscess, a periapical pocket cyst or a true cyst, all of which present as radiolucencies. However, periapical radiolucencies may also be caused by extra-radicular infections, foreign body reactions and periapical scars, or they may be due to other tumours and cysts that have not originated from pulp disease. Practitioners must recognise and understand the different pathological entities and the dynamic interactions that occur in the periapical tissues in order to correctly diagnose and treat these conditions.

Mechanisms involved in the resistance of Enterococcus faecalis to calcium hydroxide

AIM

This study sought to clarify the mechanisms that enable E. faecalis to survive the high pH of calcium hydroxide.

METHODOLOGY

E. faecalis strain JH2-2 was exposed to sublethal concentrations of calcium hydroxide, with and without various pretreatments. Blocking agents were added to determine the role of stress-induced protein synthesis and the cell wall-associated proton pump.

RESULTS

E. faecalis was resistant to calcium hydroxide at a pH of 11.1, but not pH 11.5. Pre-treatment with calcium hydroxide pH 10.3 induced no tolerance to further exposure at pH 11.5. No difference in cell survival was observed when protein synthesis was blocked during stress induction, however, addition of a proton pump inhibitor resulted in a dramatic reduction of cell viability of E. faecalis in calcium hydroxide.

CONCLUSIONS

Survival of E. faecalis in calcium hydroxide appears to be unrelated to stress induced protein synthesis, but a functioning proton pump is critical for survival of E. faecalis at high pH.

A new bacterial species associated with failed endodontic treatment: identification and description of Actinomyces radicidentis

OBJECTIVE

This report describes 2 endodontic patients who had persistent signs and symptoms after conventional root canal treatment. The aim of this study was to determine what microorganisms were present in the root canals of the teeth with failed endodontic therapy.

STUDY DESIGN

After removal of the root fillings, the canals were sampled by advanced microbiological techniques and the isolates were characterized by various tests.

RESULTS

Bacteria, which grew in pure cultures, were isolated in each case. The bacteria were similar to each other and were classified as Actinomyces on the basis of phylogenic and phenotypic evidence. The bacteria were different from others within the genus, thus warranting designation as a new species, Actinomyces radicidentis.

CONCLUSIONS

The 2 cases of endodontic failure were infected with A radicidentis, a new Actinomyces species. This bacterium joins a restricted group of other microorganisms that have been associated with failure of root canal treatment.

Aetiology of root canal treatment failure: why well-treated teeth can fail

LITERATURE REVIEW

Root canal treatment usually fails when the treatment is carried out inadequately. However, there are some cases in which the treatment has followed the highest standards yet still results in failure. In most of the cases, the endodontic failure results from persistent or secondary intraradicular infection. Extraradicular infections may also be implicated in the failure of some cases. In addition, it has been claimed that a few cases can fail because of intrinsic or extrinsic nonmicrobial factors. The purpose of this paper is to discuss the aetiology of the failure of root canal treatment, particularly in cases of well-treated root canals. Indications for the treatment of endodontic failures are also discussed.

Comparison of clinical and histologic diagnoses in periapical lesions

OBJECTIVE

To determine the frequency with which histopathologic examination of periapical biopsy specimens contributed information not anticipated clinically.

STUDY DESIGN

Clinical and histopathologic information from 805 sequentially submitted periapical biopsy specimens over a 2-year period was compared. Clinical data included endodontic status, age and sex of patient, location of lesion, and submitting clinician. Histopathologic diagnoses were categorized as 1) sequelae of pulpal necrosis (SPN), 2) complicated SPN (CSPN) with infection or antral involvement, or 3) periapical lesions unrelated to pulpal necrosis (PLUPN).

RESULTS

Of the 805 cases, 788 (97.9%) were SPN, 9 (1.1%) were CSPN, and 8 (1%) were PLUPN, representing a range of locally aggressive but benign lesions and 1 malignancy. Comparison of clinical and histologic diagnoses indicated that the clinical interpretation was inaccurate in 4.1% of cases (suggesting SPN in PLUPN cases or PLUPN in SPN cases). In another 0.9% of cases, the histologic analysis (indicating CSPN) contributed additional information to the clinical diagnosis.

CONCLUSIONS

A histopathologic examination contributed clinically relevant information in 5.0% of submitted cases. General extrapolation of this figure is not possible. Theoretical considerations, which could positively or negatively bias this figure, are discussed.

Persistent periapical radiolucencies of root-filled human teeth, failed endodontic treatments, and periapical scars

OBJECTIVE

This report describes 6 cases that demonstrate persistent periapical radiolucent lesions after conventional root canal treatment.

STUDY DESIGN

Six teeth that had conventional root canal treatment or re-treatment with nonresolving periapical radiolucencies underwent periapical surgery. Biopsies were obtained and analyzed descriptively by correlative light and transmission electron microscopy for general features and microbial findings.

RESULTS

Three findings were identified: periapical lesions with persisting infection in the apical root canal system (2 cases); a cyst (1 case); and periapical healing by scar tissue formation (2 cases).

CONCLUSIONS

These results confirm previous observations that associated factors in the failure of endodontic treatment include persistent intraradicular infection and periapical cysts. In addition, unresolved periapical radiolucencies may occasionally be due to healing by scar tissue, which may be mistaken as a sign of failed endodontic treatment.

Cholesterol as an aetiological agent in endodontic failures--a review

Presence of cholesterol clefts in apical periodontitis lesions is a common histopathological observation. However, a potential aetiological association of cholesterol crystals to non-resolving apical periodontitis lesions after endodontic treatment has been suggested only recently. This article is an attempt to explain the biological basis for the inability of body cells to eliminate the local accumulation of cholesterol crystals, and to consolidate available clinical and experimental data in support of the view that massive accumulation of cholesterol crystals in inflamed periapical tissues can interfere with the periapical healing after conventional root canal treatment. As the irritating cholesterol crystals and certain other aetiological agents of failed endodontic treatment exist outside the root canal system, it is concluded that re-treatment alone, of such cases, is unlikely to resolve the factors that sustain the lesion. Apical surgery is indicated for successful management of such cases.

Long-term retention of a paper point in the periapical tissues: a case report

A case is reported of a 15 mm paper point found in the periapical area of a maxillary right central incisor during endodontic surgery for an unresolved periapical radiolucency. The paper point had been present for between five and nine years. Histopathological examination showed the presence of chronically inflamed fibrous connective tissue with a number of foreign body giant cells and focal collections of chronic inflammatory cells. SEM comparison of the specimen with a similarly treated fresh paper point showed no indication of degradation of the paper point by host defense cells.

Legume-associated residual cyst

This report describes three unique cases of residual cyst (RC) which were characterized by large legume implants. To determine whether these represented a distinctive RC subset or if implanted materials have general importance in RC pathogenesis, a retrospective comparison of these cases and 37 further RCs with 40 control periapical cysts was performed. The frequency of foreign material implantation and the associated histopathologic features were assessed. No significant differences were noted suggesting that foreign implantations do not have an etiologically significant association with RCs and that the legume-associated RCs represent a unique subgroup. The relationship of the legume-associated RCs to the category of lesions variously termed giant cell hyaline angiopathy, oral pulse granuloma or hyaline ring granuloma is discussed.