Apical root canal microbiome associated with primary and posttreatment apical periodontitis: A systematic review

BACKGROUND

Microorganisms colonizing the apical root canal system are conceivably the ones directly involved with the causation and maintenance of apical periodontitis.

OBJECTIVES

This article systematically reviews the reports on the microbiome occurring exclusively at the apical root canal of teeth with primary and posttreatment apical periodontitis.

METHODS

The electronic databases PubMed, Embase, Web of Science, Science Direct, and Proquest were searched up to August 2023. Clinical studies using culture and molecular microbiology methods to identify the microbial taxa present exclusively in the apical root canal segment of infected teeth with apical periodontitis were included. Studies were critically assessed using the Joanna Briggs Institute Critical Prevalence Assessment Checklist.

RESULTS

From 2277 articles initially detected, 52 were selected for full reading and 21 were eventually included in this review. Of these, molecular methods were used in 19 and culture in 2 studies. Ten studies evaluated primary infections, 8 evaluated posttreatment infections, and 3 included both. Cryopulverization of the apical root specimens was conducted in 11 studies. All studies evaluated the prevalence and diversity of bacteria, and only one also reported on fungi. Overall, the most frequent/abundant bacterial taxa found in the apical canal of primary infections were Pseudoramibacter alactolyticus, Olsenella uli, Fusobacterium species, Streptococcus species, Porphyromonas endodontalis, Prevotella species, Actinomyces species, Parvimonas micra, Treponema denticola, Synergistetes species, and an as-yet uncharacterized taxon. In posttreatment infections, the most prevalent/abundant bacterial taxa included species of Streptococcus, Enterococcus, Fusobacterium, Actinomyces, Pseudoramibacter, Pseudomonas, and Propionibacterium. At the phylum level, Firmicutes was the most represented. The average apical bacterial load ranged from 105 to 106 in primary infections and from 103 to 104 in posttreatment infections.

DISCUSSION

Microbial diversity in the apical part of the root canal system was examined encompassing data from both primary and posttreatment infections. Heterogeneity amongst the studies, especially in sample collection and microbial identification methods, is an important limitation that prevented a meta-analysis.

CONCLUSIONS

There is a pronounced bacterial diversity in the infected apical canal, with a high interindividual variability. Different microbiome compositions at the species/genus level are observed according to the infection type.

REGISTRATION

PROSPERO CRD42021275886.

Correlation Between Proinflammatory Cytokine Expression and Clinical Data in Apical Granuloma

INTRODUCTION

This study was intended to evaluate the expression of inflammatory cytokines commonly secreted by CD4+ T cells (IL-2, IL-5, IL-17, TGF-β, TNF-α, and IFN-γ) in apical granulomas and correlate with the clinical conditions and time elapsed since root canal treatment.

METHODS

Eighteen biopsy specimens obtained by periradicular surgery of teeth with post-treatment apical periodontitis and diagnosed as apical granuloma were available from the oral pathology laboratory. Silanized slides containing paraffin sections were used for immunohistochemical reactions. Images were analyzed by using an optical microscopy and each slide was subdivided into 5 fields at high magnification.

RESULTS

IFN-γ and TGF-β were the cytokines with the highest expression levels. There were statistically significant differences when comparing IL-2 and IFN-γ (P < .05), and IL-2 and TGF-β (P < .05). Comparison between the detected cytokines and clinical data and time of treatment demonstrated significant correlation (P < .05) between lower expression of IL-2 and the presence of painful symptoms, absence of sinus tract, and treatments performed more than 4 years before. It was also possible to observe a significant correlation between lower expression of IL-5 and treatments performed less than 4 years before (P < .05).

CONCLUSION

IFN-γ and TGF-β were highly expressed in apical granulomas. However, only IL-2 and IL-5 levels were associated with clinical data and time since previous root canal treatment.

Impact of root canal preparation using two single-file systems on the intra-radicular microbiome of teeth with primary apical periodontitis

OBJECTIVES

This study aimed to describe the effects of two single-file systems on the diversity of the endodontic microbiome of teeth with primary asymptomatic apical periodontitis.

MATERIALS AND METHODS

The root canals from single-rooted teeth with apical periodontitis were prepared using either the Reciproc Blue (RB) or the XP-endo Shaper (XPS) instrument system. The latter was followed by a supplementary step with the XP-endo Finisher (XPF) instrument. For irrigation, 5.25% sodium hypochlorite was used. Root canal samples were taken at the baseline (S1), after preparation (S2), and after the supplementary step (S3). DNA was extracted and subjected to high-throughput sequencing using the MiSeq Illumina platform.

RESULTS

Samples from 10 teeth from the RB and 7 from the XPS group were subjected to DNA sequencing. Initial samples differed significantly from post-preparation samples in bacterial diversity, with no significant difference when comparing the two instrument systems. The most dominant phyla in S2 were Bacteroidetes, Proteobacteria, Firmicutes, Fusobacteria, and Actinobacteria. The same phyla were found to dominate baseline samples and samples taken after using XPF, but with differences in the ranking of the most dominant ones. At the genus level, the most dominant genera identified after RB instrumentation were Bacteroidaceae [G-1], Fusobacterium, and Staphylococcus, while the most dominant genera after XPS instrumentation were Fusobacterium and Porphyromonas. These genera were also dominant in the initial samples.

CONCLUSIONS

Both treatment protocols had measurable effects on the root canal microbial diversity, with no significant differences between them. Most of the dominant taxa involved in the primary infection and probably in the aetiology of apical periodontitis were eliminated or substantially reduced.

CLINICAL RELEVANCE

The most dominant taxa that persisted after instrumentation were Fusobacterium, Porphyromonas, Staphylococcus, and Bacteroidaceae [G-1].

Bacteriologic Conditions of the Apical Root Canal System of Teeth with and without Posttreatment Apical Periodontitis: A Correlative Multianalytical Approach

INTRODUCTION

This study used a correlative multianalytical approach to investigate the bacteriologic conditions in the apical root canal system of treated teeth with or without apical periodontitis and their correlation with the technical quality of the previous root canal obturation and the presence and volume of apical periodontitis lesions.

METHODS

Root apexes were obtained from recently extracted root canal-treated teeth with (n = 23) and without (n = 22) apical periodontitis lesions as demonstrated by cone-beam computed tomographic examination. The root apexes were sectioned and subjected to micro-computed tomographic (micro-CT) scanning. The specimens were cryopulverized, and DNA extracted from the powder was used as a template in real-time polymerase chain reaction assays to quantify total bacteria and members of the Streptococcus genus and Actinobacteria phylum. The bacteriologic findings were compared between the 2 groups and also evaluated for associations with cone-beam computed tomographic and micro-computed tomographic data.

RESULTS

Bacteria were detected in all apical canal samples except 1. The mean counts of total bacteria, streptococci, and actinobacteria did not differ significantly between teeth with or without apical periodontitis (P > .05). Streptococcus levels were significantly lower by 80% in the apical canals of teeth with small lesions compared with those without lesions (P < .05). The limit of filling >2 mm short was significantly associated with more total bacterial counts compared with canals filled 0-2 mm short (P < .05). An adequate coronal restoration was significantly associated with lesser counts of Streptococcus (P < .05).

CONCLUSIONS

Comparable bacterial loads were observed in the apical canal system of treated teeth with and without apical periodontitis, suggesting that factors other than only the total bacterial levels may also influence the development and progression of apical periodontitis. Bacteria were found in the apical canal in virtually all cases with a high prevalence of streptococci and actinobacteria. Streptococci counts were significantly higher in the apical canal of teeth with inadequate restorations and teeth with no lesions. Underfilled canals showed higher bacterial counts.

Factors influencing the outcome of nonsurgical root canal treatment and retreatment: A retrospective study

This study assessed the influence of diverse variables on the outcome of nonsurgical root canal treatment/retreatment. In general, 304 teeth from 218 patients were treated/retreated and the outcome evaluated by the periapical index (PAI). Teeth with apical periodontitis lesions that have not completely healed were classified as success or failure based on lenient and rigid criteria, respectively. Findings were evaluated using a logistic regression analysis. The overall success rates were 74% and 82% using the PAI-rigid and lenient success criteria, respectively. Specifically for treatment, the success rates were 73% (rigid) and 82% (lenient), while for retreatment they were 78% (rigid) and 83% (lenient). The treatment outcome was negatively affected by overextension, presence of preoperative lesion, lesion size >10 mm, and higher number of treatment visits (with no intracanal medication). Regarding retreatment, the chance of success was greater for teeth with adequate coronal restorations.

Intracanal removal and apical extrusion of filling material after retreatment using rotary or reciprocating instruments: A new approach using human cadavers

AIM

This study compared intracanal removal of filling as well as the frequency and volume of extruded material after retreatment with either HyFlex or Reciproc instruments in mandibular teeth from cadavers.

METHODOLOGY

The root canals of 14 pairs of contralateral single-rooted teeth in mandibles of cadavers were instrumented with Reciproc R40 and filled using lateral compaction. The mandibles were scanned in a micro-computed tomographic (micro-CT) device before and after retreatment procedures. The contralateral teeth were assigned to two groups (n = 14) according to the retreatment protocol using either HyFlex or Reciproc instrument systems. In the HyFlex group, the HyFlex Remover instrument was worked 3 mm short of the working length (WL), followed by HyFlex CM 40.04 and 50.04 at the WL. In the Reciproc group, the R50 instrument was worked up at the coronal two thirds, followed by two more cycles until the WL was reached. Pre- and post-operative micro-CT images were analysed for extrusion and intracanal removal of filling material.

RESULTS

After retreatment, extrusion of filling material occurred in 11 (78%) and 14 (100%) teeth from HyFlex and Reciproc groups respectively (p > .05). A similar volume of extruded material was observed after retreatment with both systems (p > .05). A significant decrease in the intracanal filling volume was verified after retreatment with both tested systems (p < .05). However, residual filling material was found in all root canals, regardless of the system. The amount of filling material removed (HyFlex = 80.8%; Reciproc = 65.9%) and the operation time was similar between systems (p > .05).

CONCLUSIONS

A high frequency of filling material extrusion was observed after retreatment with the two systems in a cadaver model, with no significant difference between them. Both protocols obtained similar efficacy in filling material removal procedures, although none completely cleaned the canals.

Multipopulation evaluation of the internal morphology of mandibular first premolars from different South American countries. A micro-computed tomography study

OBJECTIVE

To evaluate and compare several anatomical parameters of mandibular first premolars from individuals from different Latin American countries using micro-computed tomography.

DESIGN

Five hundred extracted mandibular first premolars from Brazilian, Argentinian, Chilean, Colombian, and Ecuadorian individuals were scanned using micro-computed tomography (n = 100 teeth/country). Root canal configurations were classified according to established parameters. Analyses also included: canal volume and surface area, structure model index, distances from the apical foramen to the root apex or the cementoenamel junction, major/minor apical canal diameters, canal orifice shape, and prevalence of ramifications.

RESULTS

A single root was the most common anatomy in all countries (range, 97%-100%). Vertucci's type-I canal was the most frequent configuration (range, 36%-66%), followed by C-shaped and type-V canals. The oval-shaped canal orifice was the most predominant in all countries (range, 34%-58%), followed by the circular shape (range, 16%-47%). C-shaped canals occurred in all subpopulations (range, 14%-26%), always associated with radicular grooves. Ranges for canal ramifications were as follows: accessory canals, 36%-73%; lateral canals, 4%-12%; and apical delta, 4%-14% of the teeth. Many anatomic parameters differed significantly between countries (P < .05).

CONCLUSIONS

Vertucci's types-I and -V, and C-shaped canals were the most prevalent configurations in the subpopulations investigated. Accessory canals and several complex anatomies were found, with some significantly different frequencies between countries.

Shaping ability of BlueShaper, TruNatomy, DC Taper and HyFlex EDM in long oval canals: An ex vivo study

AIM

This study evaluated and compared the shaping ability of four rotary instrument systems in long-oval root canals using microcomputed tomographic (micro-CT) evaluation. Currently, there is no data available on the canal shaping abilities of BlueShaper and DC Taper instruments.

METHODOLOGY

Sixty-four single-rooted mandibular premolars were matched based on similar root canal morphologic features as determined by (micro-CT) and randomly assigned to 1 of 4 experimental groups (n = 16) according to the instrument system used: BlueShaper, TruNatomy, DC Taper and HyFlex EDM One File. Changes in the root canal surface and volume, remaining dentine thickness, and number of prepared areas were assessed.

RESULTS

No significant differences were found amongst the four instrument systems for the parameters evaluated (p > .05). There was a significant reduction in the number of unprepared areas and the remaining dentine thickness after each increase in size of the instruments tested (p < .05).

CONCLUSIONS

The four instrument systems perform similarly in long oval root canals. Although none could prepare all canal walls, larger preparations incorporated significantly more surfaces in the final shape.

Influence of sealer type on treatment outcome of teeth with apical periodontitis: a systematic review

BACKGROUND

The purpose of this article was to Evaluate the influence of sealer on the outcome of non-surgical endodontic treatment or retreatment of permanent teeth with apical periodontitis (PROSPERO registration: CRD42020205951).

METHODOLOGY

A systematic review of original clinical studies was carried out following PRISMA guidelines to answer whether the type of sealer used in endodontic treatment or retreatment influences the repair of apical periodontitis determined by clinical and radiographic parameters. Electronic searches were performed in PubMed, Embase, Web of Science, Scopus, and the Cochrane Library database, until May 2023. Gray literature and a hand search of reference lists were also performed. The risk of bias was assessed using Cochrane RoB2 for randomized trials and the Newcastle-Ottawa Scale (NOS) for prospective and retrospective cohort and case-control studies.

RESULTS

Among 1046 studies, a total of 819 were selected by title and abstract, resulting in 23 for full-text review. In total, 11 studies met the inclusion criteria (1467 patients/teeth with apical periodontitis). The quality assessment using RoB2 included five randomized control trials, of which four had medium risk and one had a low risk of bias. According to the NOS scale, five studies were classified as low risk and one study was considered as medium risk of bias. The sealer type and obturation techniques varied, and the mean follow-up time was 3.7 years. Most studies used two-dimensional radiographic criteria to assess the treatment outcome sealers and not cements. Eight studies did not find significant differences when comparing cements. The healing rates ranged from 56.7% to 90%.

CONCLUSIONS

The results of this review support that the current endodontic sealers do not seem to influence the treatment outcome of permanent teeth with apical periodontitis. Although the studies had medium and low risk of bias, the results should be interpreted with caution. More randomized studies of long-term outcomes comparing filling materials are needed to strengthen this claim and allow for a meta-analysis.

Disinfection and Shaping of Vertucci Class II Root Canals after Preparation with Two Instrument Systems and Supplementary Ultrasonic Activation of Sodium Hypochlorite

INTRODUCTION

This study compared disinfection and shaping after root canal preparation with either XP-endo Shaper or TruNatomy instrument systems, supplemented by ultrasonic activation of sodium hypochlorite (NaOCl) with either stainless-steel (SS) or nickel-titanium (NiTi) inserts.

METHODS

Mesial roots from mandibular molars with Vertucci class II configuration were divided into 2 groups (n = 24) based on anatomically paired micro-computed tomography (micro-CT) analyses. Pre and postpreparation micro-CT scans were obtained to evaluate the shaping performance. The canals were contaminated with a mixed bacterial culture for 30 days and then subjected to preparation with either XP-endo Shaper or TruNatomy instruments using NaOCl irrigation. Supplementary ultrasonic activation of NaOCl was conducted using either an SS (TruNatomy group) or NiTi (XP-endo Shaper group) insert. Bacteriological samples were taken from the canals before preparation (S1), after preparation (S2), and after the supplementary approach (S3). Bacterial reduction was evaluated using a quantitative real-time polymerase chain reaction.

RESULTS

Preparation with both instrument systems significantly reduced bacterial counts (P < .01). After preparation, 36% (TruNatomy) and 35% (XP-endo Shaper) were negative for bacteria. These values increased to 59% and 65% after ultrasonic activation with the SS and NiTi inserts, respectively. The quantitative data in S2 showed that XP-endo Shaper promoted a significantly higher bacterial reduction than TruNatomy (P < .05). No significant intragroup differences were observed after ultrasonic activation (P > .05), probably because the SS insert promoted a significantly higher S2-to-S3 reduction than the NiTi insert (P < .01). Micro-CT analysis revealed no significant differences in the unprepared areas between the groups (P > .05).

CONCLUSIONS

The XP-endo Shaper caused a significantly higher bacterial reduction than TruNatomy in Vertucci class II canals. Better antibacterial results after ultrasonic activation were observed for the SS ultrasonic inserts than for the NiTi inserts.

Post-treatment apical periodontitis associated with a missed root canal in a maxillary lateral incisor with two roots: A case report

Missed canals can be a common cause of persistent intraradicular infection and post-treatment apical periodontitis. This article reports on a rare case of a maxillary lateral incisor with two roots exhibiting symptomatic post-treatment apical periodontitis regardless of a radiographically adequate root canal treatment. The second root, which was only revealed by cone-beam computed tomography, had passed unnoticed during the first treatment, and its missed canal was the most likely cause of symptoms and treatment failure. Reintervention including the proper management of the extra root canal and retreatment of the main canal resulted in the resolution of symptoms and periradicular tissue healing. This case report reinforces the need for three-dimensional radiographic diagnosis to search for the cause of post-treatment disease and guide the decision-making process for proper management.

Influence of brushing motions on the shaping of oval canals by rotary and reciprocating instruments

OBJECTIVE

The effects of brushing on shaping with three different instruments were assessed in oval canals.

DESIGN

Mandibular incisors were assigned to 6 groups (n = 12/group) according to the system, each one with or without brushing: Reciproc Blue, VDW.Rotate, and Race EVO. Micro-computed tomography was performed before and after preparation.

RESULTS

Brushing strokes caused no increase in canal volume, surface area, and structure model index independently of the system (p > 0.05), except for RaCe EVO in the full canal surface area (p < 0.05). Brushing did not increase the prepared areas (p > 0.05), except for Reciproc in the apical canal (p < 0.05). Reciproc with no brushing exhibited less pericervical dentin than with brushing (p < 0.05), while RaCe EVO with brushing resulted in less remaining dentin (p < 0.05).

CONCLUSIONS

The brushing motion had no effects on the overall shaping performance of the 3 instruments tested. An exception was the increase in prepared surface area in the apical canal segment when the Reciproc instrument was used with brushing strokes.

Histologic features of external cervical resorption affecting impacted maxillary canines. Report of two cases

Reports on the histopathologic features of external cervical resorption (ECR) in unerupted teeth are scarce. This article reports on 2 maxillary impacted canines from different patients that showed ECR lesions and were surgically removed and histologically evaluated. Case 1 showed symptoms associated with oral communication of the dental follicle and pulpal exposure. Radiographs and cone-beam computed tomographic imaging showed that resorption affected a large part of the root and the crown. Case 2 was asymptomatic, and the resorption cavity was restricted to the tooth crown. Both teeth were extracted and subjected to histologic processing and analysis. In case number 1, the coronal pulp was necrotic and infected, showing areas of exposure to the resorption channels. The apical pulp was vital and uninflamed. The pulp space was surrounded by a continuous pericanalar resorption-resistant sheet. Part of the resorbed area of dentin was occupied by inflamed granulation tissue. More apically, a network of trabecular bone was present in the resorbed area. In case number 2, the pulp around the resorbed area was uninflamed and vital. A large fraction of the lost dentin was replaced by trabecular bone, closely adapted to the irregularly resorbed dentin surface, and no inflammatory cells. Our findings indicate that impacted teeth with ECR may remain asymptomatic until associated with infection. Histologic features of resorption in impacted teeth were similar to those in erupted teeth. In the case associated with infection, the resorbed area was occupied by inflamed tissue and newly formed bone. In the case with no infection, the resorption area was filled with bone undergoing a remodeling process.

Microbial Community Profiling Using Terminal Restriction Fragment Length Polymorphism (T-RFLP) and Denaturing Gradient Gel Electrophoresis (DGGE)

In their natural environments, microorganisms usually live in organized communities. Profiling analysis of microbial communities has recently assumed special relevance as it allows a thorough understanding of the diversity of the microbiota, its behavior over time, and the establishment of patterns associated with health and disease. The application of molecular biology approaches holds the advantage of including culture-difficult and as-yet-uncultivated phylotypes in the profiles, providing a more comprehensive picture of the microbial community. This chapter focuses on two particular techniques, namely terminal restriction fragment length polymorphism (T-RFLP) and denaturing gradient gel electrophoresis (DGGE), both of which have been widely used in environmental studies and have been recently successfully used by the authors in the study of the oral microbial communities associated with conditions of health and disease.

Successful regenerative endodontic treatment in a tooth with incomplete root apex and posttreatment apical periodontitis: A case report

This case report describes the procedure and outcome of regenerative endodontic treatment (RET) in a tooth with incomplete root apex and posttreatment apical periodontitis. A 44-year-old patient was referred to the endodontist because of a periapical lesion on tooth #21 and a recent episode of acute periapical abscess. On clinical and radiographic examination, this tooth presented with tenderness to percussion and palpation, periapical radiolucent lesion, external apical resorption, and incomplete apex formation. After coronal access, the filling material was removed, and the canal was gently prepared with hand files, using 1% NaOCl as the main irrigant followed by final irrigation with 17% EDTA, activated with XP-endo Finisher (FKG Dentaire, La Chaux-de-Fonds, Switzerland). The root canal was filled with a double antibiotic paste with ciprofloxacin and metronidazole (1:1). After three weeks, RET was performed by stimulating bleeding into the canal, and when a clot was formed, a bioceramic (EndoSequence BC Sealer, Brasseler USA, Savannah, GA) plug was placed on it, followed by coronal restoration. The tooth remained asymptomatic since RET was concluded. Clinical and radiographic follow-ups showed complete repair of the apical periodontitis lesion and the absence of symptoms after eight months. This satisfactory outcome was confirmed after 34 months.

Key words:Bioceramic material; ciprofloxacin; metronidazole; persistent apical periodontitis; regenerative endodontic treatment.

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.

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.

Dens invaginatus: clinical implications and antimicrobial endodontic treatment considerations

Dens invaginatus or dens in dente is a developmental dental anomaly resulting from an invagination of the enamel organ into the dental papilla during odontogenesis. Radiographically, it is usually seen as a radiolucent invagination surrounded by a radiopaque area (enamel) limited to the tooth crown or extending into the root. Because the invagination is opened to the oral cavity, it can retain saliva, food remnants, and bacteria. In conditions that the enamel lining of the invagination is naturally absent or lost due to caries, bacterial cells and products can diffuse from the invagination through the dentin tubules to reach the pulp and cause disease. Management of teeth with dens invaginatus include preventive sealing or filling of the invagination, or, if the pulp is affected, therapeutical options include vital pulp therapy, nonsurgical root canal treatment, apexification or regenerative endodontic procedures, periradicular surgery, intentional replantation, or extraction. It is recommended that the invagination be always approached, regardless of the type of dens invaginatus. The root canal should be treated whenever the pulp is irreversibly inflamed or necrotic. Endodontic management of teeth with dens invaginatus is often tricky because of its anatomical complexity, and special and customized strategies should be devised. This review discusses the endodontic implications of this anomaly and the current treatment recommendations based on anatomic, pathologic, and technologic considerations.

Planned Apical Preparation Using Cone-Beam Computed Tomographic Measures: A Micro-Computed Tomographic Proof of Concept in Human Cadavers

INTRODUCTION

This study assessed the amount of unprepared surface areas at the apical 4-mm segment of the root canal after a planned preparation based on cone-beam computed tomography (CBCT) measurements.

METHODS

Eighteen posterior mandible segments were obtained from cadavers and scanned using CBCT and micro-computed tomographic (micro-CT) imaging. CBCT images were used to measure the largest initial canal diameter from 29 root canals of premolars at 1, 2, 3, and 4 mm short of the apical foramen. Each measurement was used to select a master apical instrument with size/taper that was 1 diameter larger to prepare the apical 4 mm of each particular root canal. A post-preparation micro-CT scan was obtained, and the unprepared canal areas were calculated.

RESULTS

A very high amount of surface areas over the apical 4 mm of the root canal was included in the final preparation (mean >90%). The unprepared areas ranged from as low as 3.7% to a maximum of 14.6% (mean and median, 9.2% and 9.1%, respectively).

CONCLUSIONS

The proposed planned apical root canal preparation resulted in optimized root canal shaping with a substantial amount of prepared surface areas. The protocol used also resulted in a conservative canal enlargement using final instruments that were 1 size larger than the initial largest canal diameter.

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.

Bacterial Invasion of Pulp Blood Vessels in Teeth with Symptomatic Irreversible Pulpitis

INTRODUCTION

This study described the degenerative changes and infection patterns of the pulp tissue associated with symptomatic irreversible pulpitis.

METHODS

The material consisted of 32 extracted teeth with untreated deep caries that were clinically and histologically diagnosed with irreversible pulpitis and were part of the histopathologic collection of 1 of the authors. The controls consisted of intact teeth with normal uninflamed pulps and teeth with reversible pulpitis. Teeth were processed for histopathologic and histobacteriologic analyses.

RESULTS

All teeth with irreversible pulpitis showed areas of severe acute inflammation, necrosis, microabscesses, and bacterial infection in the pulp chamber. These areas were surrounded by a chronic inflammatory infiltrate, and, at the distance, the pulp tissue was often uninflamed. Bacteria were also observed in the areas surrounding the necrotic foci, both as scattered cells through the extravascular space and at varying numbers within the blood vessel lumen. The number of bacteria and the density of the intravascular bacterial aggregations varied considerably. In one third of the cases, bacteria occurred in the lumen of venules in areas at a considerable distance from the necrotic focus in the coronal third of the root. No intravascular bacteria were noted in the middle and apical segments of the canal. No bacteria were found in the pulps of any of the control specimens.

CONCLUSIONS

Bacterial invasion and colonization of necrotic areas were observed in the pulp of all teeth with caries exposure and symptomatic irreversible pulpitis. Bacterial penetration of blood vessels occurred in all cases, suggesting that this may be an important mechanism of spread of bacterial infection through the pulp tissue in an endodontic infection.

PRILE 2021 guidelines for reporting laboratory studies in Endodontology: explanation and elaboration

Guidance to authors is needed to prevent their waste of talent, time and resources in writing manuscripts that will never be published in the highest-quality journals. Laboratory studies are probably the most common type of endodontic research projects because they make up the majority of manuscripts submitted for publication. Unfortunately, most of these manuscripts fail the peer-review process, primarily due to critical flaws in the reporting of the methods and results. Here, in order to guide authors, the Preferred Reporting Items for study Designs in Endodontology (PRIDE) team developed new reporting guidelines for laboratory-based studies: the Preferred Reporting Items for Laboratory studies in Endodontology (PRILE) 2021 guidelines. The PRILE 2021 guidelines were developed exclusively for the area of Endodontology by integrating and adapting the modified CONSORT checklist of items for reporting in vitro studies of dental materials and the Clinical and Laboratory Images in Publications (CLIP) principles. The process of developing the PRILE 2021 guidelines followed the recommendations of the Guidance for Developers of Health Research Reporting Guidelines. The aim of the current document is to provide authors with an explanation for each of the items in the PRILE 2021 checklist and flowchart with examples from the literature, and to provide advice from peer-reviewers and editors about how to solve each problem in manuscripts prior to their peer-review. The Preferred Reporting Items for study Designs in Endodontology (PRIDE) website (http://pride-endodonticguidelines.org/prile/) provides a link to the PRILE 2021 explanation and elaboration document as well as to the checklist and flowchart.

PRILE 2021 guidelines for reporting laboratory studies in Endodontology: A consensus-based development

Reproducible, skilfully conducted and unbiased laboratory studies provide new knowledge, which can inform clinical research and eventually translate into better patient care. To help researchers improve the quality and reproducibility of their research prior to a publication peer-review, this paper describes the process that was followed during the development of the Preferred Reporting Items for Laboratory studies in Endodontology (PRILE) 2021 guidelines and which used a well-documented consensus-based methodology. A steering committee was created with eight individuals (PM, RO, OP, IR, JS, EP, JJ and SP), plus the project leaders (PD, VN). The steering committee prepared an initial checklist by combining and adapting items from the modified Consolidated Statement of Reporting Trials checklist for reporting in vitro studies of dental materials and the Clinical and Laboratory Images in Publications principles as well as adding several new items. The steering committee then formed a PRILE Delphi Group (PDG) and PRILE Online Meeting Group (POMG) to provide expert advice and feedback on the initial draft checklist and flowchart. The members of the PDG participated in an online Delphi process to achieve consensus on the items within the PRILE 2021 checklist and the accompanying flowchart for clarity and suitability. The PRILE checklist and flowchart developed by the online Delphi process were discussed further by the POMG. This online meeting was conducted on 12 February 2021 via the Zoom platform. Following this meeting, the steering committee developed a final version of the PRILE 2021 guidelines and flowchart, which was piloted by several authors when writing up a laboratory study for publication. Authors are encouraged to use the PRILE 2021 guidelines and flowchart to improve the clarity, completeness and quality of reports describing laboratory studies in Endodontology. The PRILE 2021 checklist and flowchart are freely available and downloadable from the Preferred Reporting Items for study Designs in Endodontology website (http://pride-endodonticguidelines.org/prile/).

Clinical and radiographic outcome of the root canal treatment of infected teeth with associated sinus tract: A retrospective study

This retrospective study evaluated the outcome of the endodontic treatment/retreatment of teeth with intraoral sinus tracts. Seventy-two teeth from 70 individuals were included. One operator treated all teeth over about 20 years. Time for the sinus tract to heal was recorded. Treatment outcome was evaluated after at least 1 year and classified as healed, healing or diseased. The overall healed rate of periradicular lesions was 73.6% (74.1% for treatment and 72.2% for retreatment). In 6 (8.3%) teeth, lesions were healing. Thirteen teeth (18.1%) exhibited persistent disease. In 68/72 (94.4%) cases, the sinus tract healed in less than 1 month. No preoperative/intraoperative variable affected the outcome (P > 0.05). Missing restorations had a negative impact (P < 0.05). Healing of both the sinus tract quickly after treatment and the periradicular lesion later were usually achieved. Closure of the sinus tract in the first month was a good predictor of lesion healing.

Micro-computed tomographic evaluation of root canal morphology in mandibular first premolars from a Colombian population

Dental anatomy can vary significantly between different populations from different countries. Dental anatomical variations are of great interest to the dental professional, especially to endodontists, since they can influence the outcome of endodontic treatment. The purpose of the present study was to describe the anatomical variations of the root canal in mandibular first premolars in a population from Colombia, using micro-computed tomography. Fifty mandibular first premolars were scanned on a SkyScan 1174 and the microcomputed tomographic images were reconstructed. Anatomy was assessed using three-dimensional models. The parameters used were: Vertucci's classification, area and volume, perimeter, circularity, and major and minor diameter at 1, 2 and 3 mm from the apical foramen. According to the Vertucci's classification, teeth were classified as: types I (40%), V (24%), VII (4%) and III (4%), with 28% not classifiable. C-shaped canals were found in 1.8% of the sample. Mean evaluations at 1, 2, 3 mm of the foramen were as follows, respectively: perimeter 1.07 ± 0.57, 1.27 ± 0.78 and 1.57 ± 0.84 mm; circularity 0.59 ± 0.19, 0.57 ± 0.20 and 0.56 ± 0.22; maximum diameter 0.41 ± 0.23, 0.48 ± 0.33 and 0.60 ± 0.37 mm; minimum diameter 0.24 ± 0.10, 0.26 0.11 and 0.21 ± 0.13 mm. Mean total area and volume were 61.27 ± 16.47 mm2 and 12.47 ± 4.95 mm3, respectively. There was wide anatomical variation in mandibular first premolars from Colombian individuals, reinforcing the need for proper anatomical knowledge to establish more effective strategies for endodontic treatment.

Accuracy of Microcomputed Tomography in Detecting Dentinal Cracks: A Correlative Study with Scanning Electron and Operative Microscopy

The aim of the study was to evaluate the accuracy of microcomputed tomography (mCT) to detect dentinal cracks when compared with scanning electron microscopy (SEM) and operating microscopy (OM). Different conditions of pixel size (10 or 17 μm), sample moisture (dry/moist), and transillumination (with/without) were evaluated. Additionally, the influence of the dentinal defect width on its detection was analyzed. The root canals of human mandibular incisors were prepared with the Reciproc R40 instrument (VDW, Munich, Germany). The roots were sectioned 5 and 10 mm from the apex, and mCT scans of middle and apical segments were performed at two pixel sizes: 10 μm and 17 μm, under dry and moist conditions (groups: 10dry, 10moist, 17dry, and 17moist). The operating microscope was used with and without transillumination (groups: OMTrans and OM). Findings showed that accuracy was moderate for the 10dry, 10moist, and OMTrans groups, poor for OM and very poor for 17dry and 17moist. The thickness of the dentin crack significantly influenced its detection by mCT using the resolution of 10 μm in both dry and wet conditions (P = .002), 17 μm in the dry condition (P = .002), and by the operating microscope using transillumination (P = .009). Some cracks visualized in SEM were not detected by mCT and an operating microscope. Not only the mCT resolution but also the sample moisture condition and the dentinal crack width can significantly influence its detection.

Influence of a High-fat Diet in the Progression of Apical Periodontitis

INTRODUCTION

This study evaluated the effects of a high-fat diet (HFD) on the progression of apical periodontitis (AP) in rats.

METHODS

Eight-week old Wistar rats (N = 24) were included in this study. Half of the animals received an HFD and the other half a control diet (CD). AP lesions were induced 8 weeks later by creating pulp exposure of the mandibular left first molars. The animal's body mass was verified on a weekly basis. After 21 and 40 days, the animals were sacrificed. Blood was collected for biochemical tests, and the liver was removed for hepatic triglycerides analysis. The left hemimandibles were removed, radiographed, and then prepared for histologic evaluation. The right hemimandibles (region near molars) were removed for bone mineral density analysis by dual-energy X-ray absorptiometry.

RESULTS

Radiographs showed that AP lesions were significantly larger in the HFD group compared with the CD group (P < .05). Histologic analysis confirmed that the AP lesions were larger and revealed a more severe inflammatory infiltrate in the HFD group. Bone mineral density was reduced in the HFD group compared with the CD groups (P < .05). The HFD resulted in a significant increase in body mass (P < .05), liver mass (P < .05), relative liver mass (P < .05), and hepatic triglycerides (P < .05). The levels of triglycerides and very-low-density lipoprotein were significantly higher in the 40-day HFD group compared with the 21-day HFD and 21- and 40-day CD groups (P < .05).

CONCLUSIONS

Findings suggest that an HFD can influence the progression and severity of AP.

Disinfecting and Shaping Type I C-shaped Root Canals: A Correlative Micro-computed Tomographic and Molecular Microbiology Study

INTRODUCTION

This ex vivo study compared the disinfection and shaping abilities of 2 preparation protocols in C-shaped canals.

METHODS

Mandibular second molars with type I C-shaped canals were pair matched based on micro-computed tomographic (micro-CT) analysis and distributed into 2 groups. The canals were contaminated with a mixed bacterial culture and prepared using 2 protocols, both with 2.5% sodium hypochlorite irrigation: XP-endo Shaper (FKG Dentaire, La Chaux-de-Fonds, Switzerland) supplemented with XP-endo Finisher (FKG Dentaire) (XP-E) and BioRaCe (FKG Dentaire) supplemented with a Hedström file (Dentsply/Sirona, Tulsa, OK) (BR-Hed). Micro-CT scans and intracanal bacteriologic samples were taken before (scan #1 and sample 1) and after preparation (scan #2 and sample 2) and after the supplementary step (scan #3 and sample 3). Canal shaping was evaluated by micro-CT imaging, and disinfection was assessed by quantitative polymerase chain reaction.

RESULTS

Micro-CT data from the XP-E (n = 21) and BR-Hed (n = 23) protocols revealed no significant differences between groups regarding shaping parameters (canal volume, surface area, structure model index, and prepared walls) after preparation and after the supplementary step (P > .05). All these parameters significantly increased after each preparation step (P < .05), except for structure model index changes after the XP-endo Finisher (P > .05). Bacteriologic data from the XP-E (n = 21) and BR-Hed (n = 22) groups showed that 14 (66.7%) and 10 (45.5%) S2 samples still had detectable bacteria, respectively. The corresponding figures for supplementary steps with the XP-endo Finisher and Hedström file were 11 (52.4%) and 10 (45.5%), respectively. Bacterial counts in sample 1 significantly decreased in samples 2 and 3 in both groups (P < .01). Intragroup comparison between sample 2 and sample 3 showed a 66% reduction in counts after using the Hedström file and 18% after using the XP-endo Finisher (P > .05 for both groups). The quantitative bacterial reduction was not different between groups (P > .05).

CONCLUSIONS

The XP-endo Shaper and BioRaCe systems have similar disinfecting and shaping abilities in C-shaped canals. Supplementary steps with the Hedström file and the XP-endo Finisher were similarly effective in improving shaping, but this was not sufficient to enhance disinfection. About half of the cases, in both groups, still harbored detectable amounts of bacteria.

Disinfection and outcome of root canal treatment using single-file or multifile systems and Ca(OH)2 medication

This clinical study reports on the antibacterial effects and outcome of endodontic treatment using either a single-file or a multifile system, associated with calcium hydroxide interappointment medication. The root canals of single-rooted teeth with apical periodontitis were treated by using either Reciproc or BioRaCe instrument systems, 2.5% NaOCl irrigation, and calcium hydroxide medication. Bacteriological samples taken before preparation and immediately before obturation were evaluated for total bacterial counts by quantitative real-time polymerase chain reaction (qPCR). Patients were followed up and the treatment outcome was assessed by clinical and radiographic criteria. Decreasing lesions were classified as success in a lenient criterion or failure in a rigid one. Bacteria were detected in all initial samples (47 cases) and were significantly reduced after treatment in both groups (p<0.001). In the Reciproc and BioRaCe groups, 7/25 (28%) and 11/22 (50%) root canals yielded negative qPCR results before obturation, respectively (p>0.05). Quantitative bacterial reduction was similar between groups (p>0.05). The success rate in the BioRaCe group was 95.5% and 77% in the loose and rigid criterion, respectively. In the Reciproc group, corresponding figures were 88% and 76%. Differences in outcome were not significant (p>0.05). No diseased case showed negative qPCR results for bacteria. A difference of >1 Log10 counts was observed between healed and diseased cases. Root canal treatments of teeth with apical periodontitis using a single-file or a multifile system for preparation, associated with NaOCl irrigation and calcium hydroxide interappointment medication, showed similar antibacterial effectiveness and success rate.

Supplementing filling material removal with XP-Endo Finisher R or R1-Clearsonic ultrasonic insert during retreatment of oval canals from contralateral teeth

This study compared the efficacy of XP-Endo Finisher R and R1-Clearsonic insert in removing filling material remnants from oval canals. Twelve pairs of contralateral premolars were treated and subsequently retreated with Reciproc 50. A supplementary procedure with XP-Endo Finisher R or R1-Clearsonic was performed. Micro-computed tomography was used to quantify the filling material volume in the full canal and apical segment lengths. Intragroup analyses revealed significant reduction of filling material after both procedures, not only in the full canal but also in the apical segment (P < 0.05). The amount of filling material removed with XP-Endo Finisher R and R1-Clearsonic was 47.9% and 52.2% in the apical segment (P > 0.05), and 82.1% and 64.6% in the full canal (P < 0.05). None of the instruments was effective in completely removing the filling material from the apical canal, but better results were obtained with XP-Endo Finisher R in the total canal length.

Unusual Location of Dens Invaginatus Causing a Difficult-to-Diagnose Pulpal Involvement

This article reports on an unusual case of dens invaginatus in a maxillary third molar that was causing severe symptoms of irreversible pulpitis. This malformation was not clinically or radiographically identified, and the occurrence of referred pain made the early identification of the responsible tooth difficult. Determination of the tooth that was the source of symptoms was only possible after an observation period and fast aggravation of the pathologic process to cause pulp necrosis and extreme tenderness to percussion. The diagnosis of dens invaginatus was made only after extraction and sectioning. Histopathologic and histobacteriologic features of this case are illustrated.

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.

Pulp and dentine responses to selective caries excavation: A histological and histobacteriological human study

OBJECTIVE

The present study investigated the histobacteriological condition of human carious dentine, and the histological response of dental pulps after selective caries excavation to firm dentine and cavity restoration with adhesive procedures.

METHODS

Twelve vital teeth with medium/deep occlusal caries from 12 patients were scheduled for extraction. The patients gave consent to have caries removed selectively and the cavity restored with adhesive procedures prior to extraction. Caries excavation was achieved using burs and sharp hand excavators until "leathery" or "firm" dentine was encountered. After extraction, the teeth were completely-demineralised, processed for light microscopy, serial-sectioned and stained with haematoxylin and eosin staining for histological examination of dentine characteristics and pulpal responses. Additional sections were stained with Taylor-modified Brown and Brenn technique for histobacteriological examination of bacteria infiltration of the dentinal tubules and dental pulp.

RESULTS

The 12 teeth showed varying degrees of tertiary dentine formation. Chronic inflammatory cell infiltrates were identified in the pulp of all specimens and appeared as scattered inflammatory cells or exiguous localised accumulations. Capillaries were heavily congested with erythrocytes and polymorphonuclear leukocytes. A large amount of stainable bacteria was observed in the dentine subjacent to the cavity floor in all specimens.

CONCLUSIONS

The present study demonstrated that "leathery" or "firm" carious dentine is infected. The remnant bacteria in the dentine provoked subclinical pulpal inflammation over the entire evaluation period. The presence of potentially-arrested caries does not necessarily mean that bacterial infection is absent or under control.

CLINICAL SIGNIFICANCE

Knowledge on the pulpal response to active caries and the inflammatory responses associated with bacteria ingress into dentine is paramount in helping clinicians make an informed, rational choice based on biologically-robust principles.

Bacteriologic status of non-cavitated proximal enamel caries lesions. A histologic and histobacteriologic study

OBJECTIVES

This histologic and histobacteriologic study evaluated non-cavitated interproximal white spot lesions in human teeth for the 1) presence and morphology of bacterial aggregations at the enamel-dentinal junction (EDJ), and 2) reactions in the subjacent pulp tissue.

METHODS

The material comprised 16 third molars diagnosed with early interproximal caries lesions obtained consecutively in a single clinical practice. Four third molars with clinically intact proximal surfaces served as controls. Caries activity was categorized as active or arrested. Teeth were prepared for histologic and histobacteriologic analyses.

RESULTS

Control teeth exhibited normal tissue conditions with no bacteria. Macroscopic discoloration of the superficial dentin occurred in 14/16 teeth with early caries lesions. Bacterial aggregations resembling biofilms were observed in 10/16 teeth (six with active and four with arrested lesions). Bacterial cells were observed superficially in some of the underlying dentinal tubules, while in a few cases a deeper penetration was evident. Pathologic changes of varying degrees were observed in the pulps of all 16 teeth, regardless of the caries activity (active or arrested). Pulp reactions varied from disruption of the odontoblast layer, with loss of odontoblasts, to formation of tertiary dentin.

CONCLUSIONS

Bacterial biofilms associated with white-spot caries lesions may traverse the enamel and reach the underlying dentin in both active and arrested lesions. In all teeth with early lesions, the pulps showed changes in response to the very superficial biofilm challenge.

CLINICAL SIGNIFICANCE

In non-cavitated, active or arrested, enamel caries lesions, bacteria traverse the enamel and may establish structured biofilms at the enamel-dentinal junction, causing early pulp changes. These new findings may stimulate clinicians to rethink the rationale for treatment methods that are based on the assumption that bacteria are absent in white-spot lesions.

An Unusual Case of a Large Periapical Cyst Mimicking a Nasopalatine Duct Cyst

This article reports on the management of a large median symmetrical lesion of the anterior palate, which was clinically and radiographically diagnosed as an infected nasopalatine duct cyst. However, histopathology demonstrated it to be a radicular cyst of endodontic origin.

Atypically grown large periradicular cyst affecting adjacent teeth and leading to confounding diagnosis of non-endodontic pathology

This article reports a case of a large osteolytic lesion in the mandible, mostly associated with the apices of the premolars, and suspected as having a non-endodontic origin because the 2 premolars responded positively to the cold sensibility test. The distal border of the lesion reached the mesial root of the first molar, which also had a small lesion in its distal aspect. Cone-beam computed tomography revealed that the large lesion communicated with the small molar lesion. Because the large lesion was suspected as having a non-endodontic origin, surgery was scheduled for enucleation and biopsy. The molar was root canal-retreated, and the 2 premolars treated. Histologic analysis of the premolar pulps showed vitality but advanced degenerative changes. The lesion was histologically diagnosed as an inflammatory periradicular cyst, which originated in the first molar and had an atypical growth to the premolar area. Follow-up revealed that the affected area healed uneventfully.

Searching for Helicobacter pylori and Chlamydia pneumoniae in primary endodontic infections

Objectives: The purpose of this study was to search samples from primary endodontic infections for the presence of two common human bacterial pathogens -Helicobacter pylori and Chlamydia pneumoniae

Methods: Genomic DNA isolated from samples taken from 25 root canals of teeth with asymptomatic (chronic) apical periodontitis and 25 aspirates from acute apical abscess was initially amplified by the multiple displacement amplification approach and then used as template in species-specific polymerase chain reaction (PCR) for detection of H. pylori and C. pneumoniae. Results: All clinical samples were positive for the presence of bacterial DNA. However, no clinical sample was positive for either H. pylori or C. pneumoniae

Conclusions: Neither H. pylori nor C. pneumoniae were found in samples from primary endodontic infections. These findings suggest that these species are not candidate endodontic pathogens and that the necrotic root canal does not serve as a reservoir for these human pathogens in healthy patients. (Eur J Dent 2012;6:158-162)

Vital pulp therapy: histopathology and histobacteriology-based guidelines to treat teeth with deep caries and pulp exposure

OBJECTIVES

Vital pulp therapy (VPT) encompasses distinct treatment modalities for deep caries that approximate the pulp chamber in vital teeth. Confusion exists in the literature in terms of the indication and rationale for each VPT approach. The objectives of the present study are to elucidate the indications for VPT and to present a set of histopathology and histobacteriology-based guidelines for VPT in teeth with deep caries.

METHODS

Two hundred and sixty-four carious, unrestored and VPT-treated human teeth, which were extracted for reasons not related to the present study. The teeth were processed for histological and histobacteriological examination. Other 757 clinical cases that received different VPT procedures were followed-up to identify success rates, with the longest observational period of 30 years.

RESULTS

Follow-up of the clinical cases indicated that direct pulp capping was successful in 73.2%, partial pulpotomy in 96.4% and full pulpotomy in 77.8% of the cases. Histological and histobacteriological examination showed a localised inflammatory response that commonly occurred in the subjacent pulp tissue as soon as the enamel was penetrated by caries. If the softened and infected dentine were completely excavated, without pulp exposure, and the cavity restored with an adequate restoration, pulp inflammation frequently subsided. In teeth showing pulp exposure, the extent of bacterial penetration varied and areas of infection presented severe pulp inflammation, including micro-abscesses. However, the pulp tissue apical to the infected/inflamed area was usually uninflamed and normal. Guidelines based on the present histopathological, histobacteriological and clinical findings are proposed for VPT and mainly involve direct examination of dentine and the exposed pulp tissue under deep caries for decision-making, and require strict asepsis during procedures.

CONCLUSIONS

Vital pulp therapy following the guidelines proposed in the present article has the potential to improve the outcome of the conservative treatment of mature teeth with deep caries and in some occasions may be an alternative to pulpectomy.

CLINICAL SIGNIFICANCE

A guideline for VPT in the treatment of deep caries is proposed, focusing on direct observation of dentine and the exposed pulp tissue under deep caries. Stringent aseptic techniques are mandatory for VPT procedures to be successful.

Influence of solvent and a supplementary step with a finishing instrument on filling material removal from canals connected by an isthmus

AIM

To evaluate the effectiveness of a solvent (eucalyptol) in improving filling material removal from canals connected by isthmuses, and the additional cleaning effect of a finishing instrument.

METHODOLOGY

The mesial canals from 32 mandibular molars (Vertucci's type II morphology) were instrumented and filled with the single-cone technique using Reciproc R25 gutta-percha points (VDW, Munich, Germany) combined with Sealer 26 (Dentsply, Petrópolis, RJ, Brazil). Each root was then subjected to retreatment using the Mtwo instrument system (VDW), with or without a solvent (n = 16 per group). The volume of filling material in the canals was assessed by micro-computed tomographic (micro-CT) scans taken before and after retreatment. Canals with remnants of filling material received a supplementary procedure with the XP-endo Finisher R instrument (FKG Dentaire, La Chaux-de-Fonds, Switzerland), with or without eucalyptol, and another micro-CT scan was taken. All retreatment procedures were performed inside a cabinet under a controlled temperature (37 °C). Filling material removal was evaluated in the 5-mm apical canal system for the canal+isthmus space or the isthmus alone. Statistical analyses were performed to compare the removal of filling material with and without eucalyptol, and after a supplementary approach with XP-endo Finisher R. The level of significance was set at 5% for all statistical tests (P < 0.05).

RESULTS

The amount of filling material removed from the canal+isthmus with Mtwo instruments was 83.2% when no solvent was used and 83.8% using the solvent (P > 0.05). When the isthmus area was evaluated separately, most specimens were associated with a reduction in the filling material, with no significant difference between the groups with or without using a solvent (P > 0.05). The supplementary step with XP-endo Finisher R significantly improved removal of filling material from both canal and isthmus area (P < 0.05), regardless of the use of a solvent (P > 0.05).

CONCLUSION

The use of eucalyptol did not improve filling material removal from Vertucci's type II molar mesial canals and isthmuses. XP-endo Finisher R significantly enhanced removal of filling material from the canals and isthmuses.