Prognosis of root canal treatment in teeth with preoperative apical periodontitis: a study with cone‐beam computed tomography and digital periapical radiography

The trend of radiographic healing after root canal treatment in teeth with apical periodontitis based on cone-beam computed tomography: A 4-year longitudinal study

OBJECTIVES

The aim of this study was to observe the radiographic healing of periapical lesions after root canal treatment via volumetric measurements based on cone-beam computed tomography (CBCT) over 4 years.

METHODS

In total, 162 single-root teeth from patients with chronic periapical periodontitis who underwent primary root canal treatment were included in this retrospective study. Follow-up visits were scheduled at 1, 2, and 4 years after treatment. The volume of radiolucency at pretreatment and follow-up were measured, and the radiographic outcomes were classified into 4 categories: absence, reduction, uncertain or enlargement. Reduction or enlargement was considered when the volumetric change in radiolucency was 20 % or more.

RESULTS

During the 4-year follow-up period, 128 teeth were reviewed at least once, including 3 extracted teeth. Of the remaining 125 teeth, the volume of radiolucency was reduced in 116 teeth (90.6 %), uncertain in 5, and enlarged in 4 teeth during 1 to 4 years after treatment. Among the 43 teeth with reduced radiolucency at 1 year after treatment, 42 (97.7 %) had continuing reduced lesions at 4 years. In the 2 teeth with enlarged radiolucency at 1 year, the volume of radiolucency doubled at 4 years. Cox regression analysis revealed that the preoperative radiolucency size was a risk factor for persistent periapical radiolucency.

CONCLUSIONS

The efficacy of root canal treatment for apical periodontitis was predictable. When the radiolucency changed by 20 % or more in volume on CBCT scans at 1 year after treatment, reversal of the radiographic healing tendency was rare.

CLINICAL SIGNIFICANCE

The volumetric changes in radiolucency on CBCT could reflect trends in the healing process and may foster early clinical decision-making.

Expert consensus on difficulty assessment of endodontic therapy

Endodontic diseases are a kind of chronic infectious oral disease. Common endodontic treatment concepts are based on the removal of inflamed or necrotic pulp tissue and the replacement by gutta-percha. However, it is very essential for endodontic treatment to debride the root canal system and prevent the root canal system from bacterial reinfection after root canal therapy (RCT). Recent research, encompassing bacterial etiology and advanced imaging techniques, contributes to our understanding of the root canal system's anatomy intricacies and the technique sensitivity of RCT. Success in RCT hinges on factors like patients, infection severity, root canal anatomy, and treatment techniques. Therefore, improving disease management is a key issue to combat endodontic diseases and cure periapical lesions. The clinical difficulty assessment system of RCT is established based on patient conditions, tooth conditions, root canal configuration, and root canal needing retreatment, and emphasizes pre-treatment risk assessment for optimal outcomes. The findings suggest that the presence of risk factors may correlate with the challenge of achieving the high standard required for RCT. These insights contribute not only to improve education but also aid practitioners in treatment planning and referral decision-making within the field of endodontics.

The association of endodontic prognostic factors with the presence of periapical lesion, its volume, and bone characteristics in endodontically treated molars: a cross-sectional study

BACKGROUND

This study intended to evaluate the association between several endodontic prognostic factors with the presence of periapical lesions (PLs), their volume, and bone characteristics including cortical bone destruction (CBD) and buccal plate bone height (BPBH) in root-filled molar teeth using cone-beam computed tomography.

METHODS

A collection of 143 scans of endodontically treated maxillary/mandibular first or second molars recorded over 8 years, were obtained from a specialized radiology center. Data on prognostic factors including tooth number, gender, jaw type, the status and number of missed canals, obturation length, restoration type, presence of a separated instrument, presence of a post or screw in the canals, and presence of perforation were collected. The assessed outcomes included PL presence, PL volume, CBD, and BPBH. The association between prognostic factors and outcomes was evaluated using multiple logistic regression models with adjusted covariates and multifactorial ANOVA at a significance level of 0.05.

RESULTS

A total of 282 molars from 82 women and 50 men with a mean age of 40.6 ± 12.27 were included. Among those, 139 teeth presented PL with a mean volume of 18.68 mm3. CBD was prevalent in 137 teeth and the mean BPBH appeared to be 9.45 mm. The presence of a missed canal (OR = 10.022, P < .05), underfilled canal (OR = 3.725, P < .05), overfilled canal (OR = 15.859, P = .018), and perforation (OR = 15.261, P = .013) was significantly associated with PLs. None of the prognostic factors could considerably contribute to the CBD (P > .05). The presence of a missed canal was positively associated with the PL volume (P < .05). Similarly, missed canals (P < .05), perforation (P < .05), and separated instruments (P = .004) were associated with a significantly reduced BPBH.

CONCLUSIONS

Overfillings, perforations, missed canals, and underfillings were identified as remarkable predictors of PL, arranged in descending order of their respective impact. The only factor capable of significantly increasing the PL volume was the missed canal. In brief, obturation length errors, perforations, missed canals, and separated instruments were robustly correlated with endodontic failure, which highlights the importance of mitigating the potential for errors by following the fundamentals of endodontics.

Effectiveness of root canal filling materials and techniques for treatment of apical periodontitis: A systematic review

BACKGROUND

Apical periodontitis (AP) is an inflammatory disease of the apical periodontium as sequelae of pulp death. It is managed by disinfection and filling of the root canal space.

OBJECTIVES

The aim of this systematic review was to investigate whether obturation techniques and materials used for root canal filling led to the management of AP.

METHODS

A systematic review protocol was written following the preferred reporting items for systematic reviews and meta-analyses (PRISMA) checklist and registered on the international prospective register of systematic reviews (PROSPERO; CRD42021260275) including two populations, interventions, comparisons, outcomes and time (PICOT) for the research questions querying the effectiveness of obturation techniques (PICOT 1) and materials (PICOT 2) for the management of AP. Electronic searches were conducted on PubMed, ScienceDirect, Scopus and Embase search engines. Searches on International Endodontic Journal, Journal of Endodontics, Clinical Oral Investigations, Journal of Dental Research and Journal of Dentistry websites were also conducted, until May 2021. Both primary (tooth survival) and secondary outcomes were evaluated. The risk of bias was assessed by Cochrane RoB2 for the randomized and ROBINS-I for the nonrandomized trials.

RESULTS

The search strategy identified 1652 studies, with 1600 excluded on the title and abstract screening, leaving 52 studies for full-text screening. In total, 10 studies met the inclusion criteria. The obturation technique and materials used did not affect the outcome of AP. Vertical compaction resulted in faster resolution of periapical lesions. The oral health-related quality of life of patients treated with lateral condensation exhibited poorer outcomes compared with single matched cone after 6 months of recall.

DISCUSSION

The inclusion and exclusion criteria used for this systematic review enabled the capture of all the literature available on the effect of obturation techniques and materials on the outcome of AP. The data were heterogenous, and a number of articles investigating obturation techniques had no information on the materials and techniques used as they looked at the quality of fill.

CONCLUSIONS

Included studies did not find any difference between different procedures (PICOT 1) and materials (PICOT 2). The risk of bias was high, thus the findings should be interpreted with caution.

REGISTRATION

PROSPERO registration number: CRD42021260275.

The effect of periapical lesion size on the success rate of different endodontic treatments: a systematic review and meta-analysis

INTRODUCTION

This systematic review evaluated the effect of periapical lesion (PL) size on the success rate of different endodontic treatments, including root canal treatment (RCT), non-surgical retreatment (NSR), and apical surgery (AS).

METHODS

Cohorts and randomized controlled trials investigating the outcomes of endodontic treatment of permanent teeth with PL and its size were identified electronically through Web of Science, MEDLINE, Scopus, and Embase databases. Two reviewers independently conducted the study selection, data extraction, and critical appraisal process. The quality of the included studies was evaluated using the Newcastle-Ottawa Scale and the 11-item Critical Appraisal Skills Program checklist for randomized controlled trials. The success rates of the endodontic treatments (small lesions and large lesions) were estimated using the rate ratios (RRs) with an associated 95% confidence interval (CI).

RESULTS

Out of 44 included studies, 42 were cohort, and 2 were randomized controlled trials. Thirty-two studies had poor quality. For the meta-analysis, five studies in RCT, 4 in NSR, and 3 in AS were considered. The RR of the endodontic treatment success in PLs was 1.04 in RCT (95% CI, 0.99-1.07), 1.11 in NSR (95% CI, 0.99-1.24), and 1.06 in AS (95% CI, 0.97-1.16). Only sub-group analysis of long-term follow-up of RCT showed a significantly higher success rate in small lesions than in large lesions.

CONCLUSIONS

Considering the quality of studies and variation in outcomes and size classification, our meta-analysis demonstrated that the PL size had no significant effect on the success rate of different endodontic treatments.

PROBE 2023 guidelines for reporting observational studies in endodontics: Explanation and elaboration

Observational studies play a critical role in evaluating the prevalence and incidence of conditions or diseases in populations as well as in defining the benefits and potential hazards of health-related interventions. There are currently no reporting guidelines for observational studies in the field of Endodontics. The Preferred Reporting Items for study Designs in Endodontology (PRIDE) team has developed and published new reporting guidelines for observational-based studies called the 'Preferred Reporting items for OBservational studies in Endodontics (PROBE) 2023' guidelines. The PROBE 2023 guidelines were developed exclusively for the speciality of Endodontics by integrating and adapting the 'STrengthening the Reporting of OBservational studies in Epidemiology (STROBE)' checklist and the 'Clinical and Laboratory Images in Publications (CLIP)' principles. The recommendations of the Guidance for Developers of Health Research Reporting Guidelines were adhered to throughout the process of developing the guidelines. The purpose of this document is to serve as a guide for authors by providing an explanation for each of the items in the PROBE 2023 checklist along with relevant examples from the literature. The document also offers advice to authors on how they can address each item in their manuscript before submission to a journal. The PROBE 2023 checklist is freely accessible and downloadable from the PRIDE website (http://pride-endodonticguidelines.org/probe/).

Tomographic, microbiological and histological characterization of secondary apical periodontitis: case series

This case series included a tomographic, microbiological, and histopathological description of 15 secondary apical periodontitis (SAP) lesions obtained by apical microsurgery performed in 10 patients to better understand the etiology and pathogenesis of SAP. Preoperative tomographic analyses were performed through Cone beam computerized tomography - Periapical index (CBCT-PAI), and apical microsurgeries were then carried out. The removed apices were used for microbial culturing and for molecular identification using PCR for the detection of 5 strict anaerobic bacteria (P. gingivalis, P. intermedia, P. nigrescens, T. forsythia, and T.denticola) and 3 viruses Herpes simplex viruses (HSV), Cytomegalovirus (CMG) and Epstein-Barr Virus (EBV) by nested PCR. The removed apical lesions were histologically described. Univariate statistical analyses were performed by using STATA MP/16 (StataCorp LLC, College Station, TX, United States). CBCT-PAI analyses revealed PAI 4 and PAI 5 score lesions that involved cortical plate destruction. Eight SAPs were positive by culture, while nine SAP lesions were positive by PCR. Fusobacterium species were the most frequently cultured organisms in 7 SAP lesions, followed by D. pneumosintes in 3. In contrast, by single PCR, T. forsythia and P. nigrescens were detected in 5 lesions, T. denticola in 4 lesions, and P. gingivalis in 2 lesions. Twelve periapical lesions were granulomas, and the remaining three SAP lesions were radicular cysts. In conclusion, this case series study revealed that secondary apical lesions presented tomographic involvement of PAI 3 to 5, and that most SAP lesions were apical granulomas containing anaerobic and facultative microorganisms.

The Changes in Size of Periapical Lesions after Root Canal Treatments Assessed by Digital Periapical Radiography and Cone-Beam Computed Tomography: A 2-Years Prospective Clinical Study

Background and Objectives: There is limited information regarding comparison of long-term dynamics of periapical bone destruction estimated by digital periapical radiography (DPR) and by cone-beam computed tomography (CBCT). This study aimed to compare the radiographically assessed periapical changes of endodontically treated teeth over 2 years of follow-up and to analyse disagreements in periapical lesion size estimates around the same roots using DPR and CBCT. Materials and Methods: A total of 176 endodontically treated teeth, of 128 patients with apical periodontitis, were assessed by DPR and CBCT, at baseline and after 2 years. All periapical radiolucencies were categorised by severity (S0, S1, S2, S3) concerning their size. Descriptive statistics were used to report distribution of the radiolucencies at baseline and at follow-up, and their size transitions over 2 years. Site-specific comparison of the radiolucencies identified by two methods was performed using Z test and Pearson’s chi-square test. Results: majority of the detected radiolucencies were scored as S0: 65% and 68% at baseline; 89% and 83% at follow-up, by DPR and CBCT, respectively. Site-specific score comparison showed that disagreements comprised 18% and 20% of the total number of radiolucencies detected by DPR and CBCT, respectively. There were more disagreements between DPR and CBCT within categories S1 and S2 + S3 compared to S0: at baseline, they comprised 17–33% and after two years 62–95% of all detected radiolucencies within the category. 65% of non-matching score transitions over two years occurred between S0 and S1. The CBCT-based evaluation resulted in negative treatment outcomes for 10 more root canals than the DPR-based result. Conclusions: Most remarkable disagreement between DPR and CBCT recordings was observed within the radiolucency categories S2 and S3. However, the diagnostic accuracy of both radiographic methods was questionable as it resulted in a high proportion of non-matching S0-S1 lesion transitions over 2 years.

EDTA Combined with C-Pilot Files and Microultrasound for Root Canal Calcification: Dredging Effect and Safety Analysis

Objective

This paper discussed the dredging effect and safety of ethylenediaminetetraacetic acid (EDTA) combined with C-pilot files and microultrasound (mUS) on root canal calcification.

Methods

From October 2021 to January 2022, 132 patients with calcified root canals treated in our hospital were selected as the research subjects. Among them, 64 cases who received EDTA combined with C-pilot Files and mUS plus ultrasonic instruments to dredge calcified root canals were regarded as the research group (RG), and another 68 cases given ultrasonic instruments plus C-pilot files were regarded as the control group (CG). The root canal dredging time was recorded, and the dredging success rate and total success rate of different tooth positions and calcification sites were compared between groups. The clinical efficacy was assessed 6 months after treatment. Pain severity was evaluated by the Pain Intensity Numerical Rating Scale (PI-NRS) before (T0), during (T1), and after treatment (T2). Finally, the incidence of adverse reactions within one week after treatment was counted.

Results

RG was observed with statistically higher success rates of root canal dredging in different tooth positions and calcified sites than CG (P < 0.05). Besides, the total effective rate of treatment was 92.19% in RG, which was also higher compared with CG, while the root canal dredging time in RG was shorter than that in CG (P < 0.05). Increased NRS scores were found in both groups at T1, and the score in RG was significantly lower compared with that in CG. At T2, both groups showed a lower PI-NRS score than T1 but higher than T0, and the score at T2 was also lower in RG as compared to CG (P < 0.05). Moreover, the reduced incidence of adverse reactions were observed in RG compared with CG (P < 0.05).

Conclusions

EDTA combined with C-pilot files and mUS can effectively improve the dredging success rate of root canals obstructed by calcification, shorten the dredging time, and improve patient comfort, which is an effective method for clinical dredging of calcification obstructed root canals.

Macrophages in periapical lesions: Potential roles and future directions

Periapical lesions are infectious diseases that occur in the apical region of teeth. They result in the destruction of alveolar bone and are usually accompanied by swelling, pain, and possible systemic impacts. A complex interaction between pathogens and the host immune system determines the development, progression, and outcome of periapical lesions. The lesions, if not treated promptly, may cause resorption of bone tissue, destruction of the periodontal ligament, and loss of the affected teeth, all of which can severely worsen the quality of life of patients, often at considerable economic cost to both patients and medical organizations. Macrophages are a group of heterogeneous cells that have many roles in the development of infections, destruction and reconstruction of bone tissues, and microbe–host interactions. However, the differential and comprehensive polarization of macrophages complicates the understanding of the regulatory mechanism of periapical lesion progression. This report provides a comprehensive review of recent advances in our knowledge of the potential role of macrophages in determining the turnover of human periapical lesions. For example, macrophage differentiation might indicate whether the lesions are stable or progressing while the extent of bacteria invasion could regulate the differentiation and function of macrophages involved in the periapical lesion. In addition, alternative strategies for the treatment of apical periodontitis are discussed.

Is the quality of root canal filling obtained by cone-beam computed tomography associated with periapical lesions? A systematic review and meta-analysis

AIM

To evaluate the influence of root canal filling quality on periapical lesion status using cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

The bibliographic search was conducted in electronic databases of PubMed, Embase, Scopus, and Web of Science without restrictions related to the year of publication and language. Inclusion criteria were prospective or retrospective cohort studies that followed periapical pathosis for, at least, 1 year. Three reviewers independently evaluated the eligibility for inclusion, extracted data, and assessed the risk of bias. The quality of the studies was based on the Newcastle-Ottawa Scale. This meta-analysis was performed to evaluate the quality of treatment by the homogeneity and apical extension of the filling.

RESULTS

Of the 1179 studies initially recovered, six cohort studies were included, out of which four were considered with a low risk of bias. The results showed that the absence of gaps in the filling reduced the chance of unhealed periapical lesions by 2.39 times (RR = 2.39; 95% CI: 1.62-3.53; p < 0.00001; I² = 55%). An apical filling extension of 0-2 mm below the apex also contributed significantly to the absence of unhealed periapical lesions (RR = 1.49; 95% CI: 1.15-1.94; p = 0.003; I² = 2%).

CONCLUSION

The homogeneity and apical extension of the filling influenced the presence of unhealed periapical lesions in endodontically treated teeth evaluated using CBCT.

CLINICAL RELEVANCE

Apical extension of the filling ranging between 0 and 2 mm short of the apical foramen and the homogeneity of the filling without gaps are directly related to the success rate of root canal treatment.

Ultrasound-Activated Nanodroplet Disruption of the Enterococcus faecalis Biofilm in Dental Root Canal

Conventional methods used to control bacterial biofilm infection in root canals have poor efficacy, causing repeated and chronic infections, which pose a great challenge to clinical treatment. Microbubbles, due to their small size and ultrasound (US)-enhanced cavitation effects, have attracted considerable clinical attention. They possess the potential for therapeutic application in restricted spaces. We address the above problem with a strategy for the restricted space of root canals. Herein, phase-change nanodroplets (P-NDs) exposed to US are combined with common antibacterial drugs to disrupt a 7 day Enterococcus faecalis biofilm in an in vitro human tooth model. Specifically, the preparation of P-NDs is based on secondary cavitation. Their average particle size is ∼144 nm, and the stability is favorable. The clearance effect for the biofilm is notable (the disruption rate of P-NDs + US is 63.1%, P < 0.01), while the effect of an antibacterial in conjunction with 2% chlorhexidine (Chx) is significant (the antibiofilm rate of P-NDs@2% Chx + US is 96.2%, P < 0.001). Furthermore, biocompatibility testing on human periodontal ligament fibroblasts demonstrated that P-NDs are safe. In summary, the strategy that we have proposed is suitable for the removal of biofilms in root canals. Notably, it also has great potential for application in the treatment of bacterial infections in restricted spaces.

Vertical root fractures in root treated teeth-current status and future trends

Vertical root fracture (VRF) is a common reason for the extraction of root filled teeth. The accurate diagnosis of VRF may be challenging due to the absence of clinical signs, whilst conventional radiographic assessment is often inconclusive. However, an understanding of the aetiology of VRFs, and more importantly, the key predisposing factors, is crucial in identifying teeth that may be susceptible. Thorough clinical examination with magnification and co-axial lighting is essential in identifying VRFs, and although CBCT is unable to reliably detect VRFs per se, the pattern of bone loss typically associated with VRF can be fully appreciated, and therefore, increases the probability of correct diagnosis and management. The prevalence of VRFs in root filled teeth is significantly greater than in teeth with vital pulps, demonstrating that the combination of loss of structural integrity, presence of pre-existing fractures and biochemical effects of loss of vitality, are highly relevant. Careful assessment of the occlusal scheme, presence of deflective contacts and identification of parafunctional habits is imperative in both preventing and managing VRFs. Furthermore, anatomical factors such as root canal morphology, may predispose certain teeth to VRF. The influence of access cavity design and root canal instrumentation protocols should be considered although the impact of these on the fracture resistance of root filled teeth is not clearly validated. The post-endodontic restoration of root filled teeth should be expedient and considerate to the residual tooth structure. Posts should be placed 'passively' and excessive 'post-space' preparation should be avoided. This narrative review aims to present the aetiology, potential predisposing factors, histopathology, diagnosis and management of VRF and present perspectives for future research. Currently, there are limited options other than extraction for the management of VRF, although root resection may be considered in multi-rooted teeth. Innovative techniques to 'repair' VRFs using both orthograde and surgical approaches require further research and validation. The prevention of VRFs is critical; identifying susceptible teeth, utilizing conservative endodontic procedures, together with expedient and appropriate post-endodontic restorative procedures is paramount to reducing the incidence of terminal VRFs.

Outcomes of Primary Root Canal Therapy: An updated Systematic Review of Longitudinal Clinical Studies Published between 2003 and 2020

Background

A comprehensive effort to evaluate outcomes of primary root canal therapy (RCT) between 1966 and 2002 was published by Ng et al. (2007, International Endodontic Journal, 40, 921; 2008, International Endodontic Journal, 41, 6). Changes in endodontic materials and treatment methods warrant an updated analysis of outcomes.

Objectives

This study aimed to (1) quantify the success rates of primary RCT published between 2003 and 2020; and (2) investigate the influence of some characteristics known/suspected to be associated with treatment outcomes.

Methods

An electronic search was performed in the following databases (01‐01‐2003 to 12‐31‐2020): Pubmed, Embase, CINHAL, Cochrane and Web of Science. Included study designs were longitudinal clinical studies (randomized control trials, cohort studies, retrospective observational studies). Studies with at least twelve‐months of post‐operative review and success rates based on clinical and radiographic criteria were analysed. The terms ‘strict’ (complete resolution of periapical lesion) or ‘loose’ (reduction in size of existing periapical lesion) were used to describe the outcome criteria. Weighted, pooled success rates were calculated. Random effects meta‐regression models were used to investigate potential sources of statistical heterogeneity. The Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach was used to evaluate for quality assessment of the included studies.

Results

Forty‐two studies were included in the review. Meta‐analyses showed that the weighted pooled success rates were estimated to be 92.6% (95% CI: 90.5%–94.8%) under ‘loose criteria’ and 82.0% (95% CI: 79.3%–84.8%) under ‘strict’ criteria. The most significant areas of study heterogeneity were year of publication and qualification of operator. The majority (64.29%) of studies were considered to be of low quality of evidence.

Discussion

Biological factors continue to have the most significant impact on RCT outcomes. The technological method of instrumentation had no significant effect. The quality of evidence was based primarily on study design and only randomized control trials were considered to be ‘high’ quality of evidence.

Conclusions

The reported success rates show improvement over time. Weighted success rates for studies with a minimum of four‐years follow‐up had better outcomes, compared to those with less than four years, when ‘strict criteria’ were used.

Registration

PROSPERO database (CRD42021226311).

Application of computer-assisted dynamic navigation in complex root canal treatments: Report of two cases of calcified canals

Root canal treatment and non-vital bleaching of teeth with pulp canal obliteration may represent a complex challenge to the clinician. This report describes the usefulness of the computer-assisted dynamic navigation system for the root canal treatment of two cases of teeth with a history of traumatic injury, extensively obliterated root canals and crown discoloration. Clinical and cone-beam computed tomographic evaluations were completed prior to procedures and 12 months after treatment. Both cases were treated using a computer-assisted dynamic navigation system coupled to a high-speed handpiece in order to establish the location and orientation of the partially obliterated canal and endodontic access route planning. The system allowed an accurate localisation of the root canal with a conservative access cavity. At the 12-month recall examination, the patients continue to be symptom-free, with a normal appearance of the mucogingival complex, adequate restoration of the tooth colour and intact periapical structures.

Present status and future directions - Minimal endodontic access cavities

In the last decades, the move of Medicine towards minimally invasive treatments is notorious and scientifically grounded. As Dentistry naturally follows its footsteps, minimal access preparation also became a trend topic in the endodontic field. This procedure aims to maximize preservation of dentine tissue, backed up by the idea that this is an effective way to reduce the incidence of post-treatment tooth fracture. However, with the assessment of the body of evidence on this topic, it is possible to observe some key-points (a) the demand for nomenclature standardization, (b) the requirement of specific tools such as ultra-flexible instruments, visual magnification, superior illumination, and three-dimensional imaging technology, (c) minimally invasive treatment does not seem to affect orifice location and mechanical preparation when using adequate armamentarium, but it (d) may impair adequate canal cleaning, disinfection, and filling procedures, and also (e) it displays contradictory results regarding the ability to increase the tooth strengthen compared to the traditional access cavity. In spite of that, it is undeniable that methodological flaws of some benchtop studies using extracted teeth may be responsible for the conflicting data, thus triggering the need for more sophisticated devices/facilities and specifically designed research in an attempt to make it clear the role of the access size/design on long-term teeth survival. Moreover, it is inevitable that a clinical approach like minimal endodontic access cavities that demands complex tools and skilled and experienced operators bring to the fore doubts on its educational impact mainly when confronted with the conflicting scientific output, ultimately provoking a cost-benefit analysis of its implementation as a routine technique. In addition, this review discusses the ongoing scientific and clinical status of minimally invasive access cavities aiming to input an in-depth and unbiased view over the rationale behind them, uncovering not only the related conceptual and scientific flaws, but also outlining future directions for research and clinical practices. The conclusions attempt to skip from passionate disputes highlighting the current body of evidence as weak and incomplete to guide decision making, demanding the development of a close-to-in-situ laboratory model or a large and well-controlled clinical trial to solve this matter.

Microbiological Aspects of Root Canal Infections and Disinfection Strategies: An Update Review on the Current Knowledge and Challenges

The oral cavity is the habitat of several hundreds of microbial taxa that have evolved to coexist in multispecies communities in this unique ecosystem. By contrast, the internal tissue of the tooth, i.e., the dental pulp, is a physiologically sterile connective tissue in which any microbial invasion is a pathological sign. It results in inflammation of the pulp tissue and eventually to pulp death and spread of inflammation/infection to the periradicular tissues. Over the past few decades, substantial emphasis has been placed on understanding the pathobiology of root canal infections, including the microbial composition, biofilm biology and host responses to infections. To develop clinically effective treatment regimens as well as preventive therapies, such extensive understanding is necessary. Rather surprisingly, despite the definitive realization that root canal infections are biofilm mediated, clinical strategies have been focused more on preparing canals to radiographically impeccable levels, while much is left desired on the debridement of these complex root canal systems. Hence, solely focusing on "canal shaping" largely misses the point of endodontic treatment as the current understanding of the microbial aetiopathogenesis of apical periodontitis calls for the emphasis to be placed on "canal cleaning" and chemo-mechanical disinfection. In this review, we dissect in great detail, the current knowledge on the root canal microbiome, both in terms of its composition and functional characteristics. We also describe the challenges in root canal disinfection and the novel strategies that attempt to address this challenge. Finally, we provide some critical pointers for areas of future research, which will serve as an important area for consideration in Frontiers in Oral Health.

Detection of Dental Apical Lesions Using CNNs on Periapical Radiograph

Apical lesions, the general term for chronic infectious diseases, are very common dental diseases in modern life, and are caused by various factors. The current prevailing endodontic treatment makes use of X-ray photography taken from patients where the lesion area is marked manually, which is therefore time consuming. Additionally, for some images the significant details might not be recognizable due to the different shooting angles or doses. To make the diagnosis process shorter and efficient, repetitive tasks should be performed automatically to allow the dentists to focus more on the technical and medical diagnosis, such as treatment, tooth cleaning, or medical communication. To realize the automatic diagnosis, this article proposes and establishes a lesion area analysis model based on convolutional neural networks (CNN). For establishing a standardized database for clinical application, the Institutional Review Board (IRB) with application number 202002030B0 has been approved with the database established by dentists who provided the practical clinical data. In this study, the image data is preprocessed by a Gaussian high-pass filter. Then, an iterative thresholding is applied to slice the X-ray image into several individual tooth sample images. The collection of individual tooth images that comprises the image database are used as input into the CNN migration learning model for training. Seventy percent (70%) of the image database is used for training and validating the model while the remaining 30% is used for testing and estimating the accuracy of the model. The practical diagnosis accuracy of the proposed CNN model is 92.5%. The proposed model successfully facilitated the automatic diagnosis of the apical lesion.

Plasma Rich in Growth Factors in the Treatment of Endodontic Periapical Lesions in Adult Patients: A Narrative Review

Platelet concentrates have been widely used in regenerative medicine, including endodontics. The aim of this manuscript was to assess critically the efficacy of PRF in the treatment of endodontic periapical lesions in adult patients on the basis of the literature. The PICO approach was used to properly develop literature search strategies. The PubMed database was analyzed with the keywords: "((PRP) OR (PRF) OR (PRGF) OR (CGF)) AND (endodontic) AND ((treatment) OR (therapy))". After screening of 155 results, 14 articles were included in this review. Different types of platelet concentrates are able to stimulate the processes of proliferation and differentiation of mesenchymal stem cells. Platelet rich fibrin (PRF) releases growth factors for at least 7 days at the application site. Growth factors and released cytokines stimulate the activity of osteoblasts. Moreover, the release of growth factors accelerates tissue regeneration by increasing the migration of fibroblasts. It was not possible to assess the efficacy of PRF supplementation in the treatment of endodontic periapical lesions in permanent, mature teeth with closed apexes, due to the lack of well-designed scientific research. Further studies are needed to analyze the effect of PRF on the healing processes in the periapical region.

Prognostic validity of the Periapical and Endodontic Status Scale for the radiographically assessed 2-year treatment outcomes in teeth with apical periodontitis: a prospective clinical study

Background

Endodontic treatment planning and treatment success evaluation are largely based on radiographic assessment of anatomical and treatment-related parameters of teeth with apical periodontitis (AP). This prospective clinical study aimed to assess radiographically the 2-year endodontic treatment outcomes for teeth with AP, and to evaluate prognostic validity of Periapical and Endodontic Status Scale (PESS).

Methods

A total of 128 patients, representing 176 teeth with AP were examined by cone-beam computed tomography at baseline and at 24 months after endodontic treatment. Treatment outcome was evaluated using estimates of periapical radiolucency and the relationship between anatomical structures and location. The strength of the associations between these and treatment-related parameters was tested by logistic regression analysis. PESS sensitivity and specificity were calculated for every treatment risk group (low, moderate, high) of teeth.

Results

One hundred and fifty-seven teeth, representing 350 root canals had a positive treatment outcome, while 19 teeth, representing 53 root canals had a negative treatment outcome at 24 months. The probability of negative outcome was 25 times higher in the moderate/high-risk group than in the mild-risk group of teeth (OR = 25.1; 95%CI [12.2–51.5]). Pre-treatment complications and retreatment cases with radiolucency were associated with negative outcomes (OR = 35.9; 95%CI [12.6–102.4]; OR = 26.437; 95%CI [10.9–64.1], respectively). PESS sensitivity and specificity was over 80% in all risk groups except for high risk group, due to very low number of cases.

Conclusions

Endodontic treatment outcome depends on the severity of periapical changes. The presence of complications and retreatment cases with periapical lesions are associated with negative treatment outcome. The PESS is a valid instrument to predict outcome of teeth with low-moderate treatment risk of AP.

Evaluation of the accuracy values of cone-beam CT regarding apical periodontitis: a systematic review and meta-analysis

Specialists need to know how accurate and effective each radiographic procedure is, and which ones can provide better images for bone resorption around the apical periodontitis. Therefore, the researcher decided to conduct the present study with the aim of evaluate the accuracy values of cone-beam CT regarding apical periodontitis. The PubMed, Embase, ISI, Scopus, and Medicine have been used to search articles over the last 15 years between 2005 and December 2020. Meta-analysis data with 95% confidence interval (CI), Random effect model, and restricted maximum-likelihood methods were calculated. Random effects were used to deal with potential heterogeneity and I² showed heterogeneity. I² values above 50% signified moderate-to-high heterogeneity. The meta-analysis has been evaluated with the statistical software Stata/MP v.16 (The fastest version of Stata). One hundred and fifty-eight studies were selected to review the abstracts, six papers met these crucial criteria to do a systematic review and meta-analysis. Sensitivity and specificity of digital periapical radiography was 50% (ES 0.50; 95% CI 0.05, 0.95) and 83% (ES 0.83; 95% CI 0.52, 1.15), respectively. Sensitivity and specificity of cone-beam computed tomographic was 95% (ES 0.95; 95% CI 0.80, 1.00) and 90% (ES 0.90; 95% CI 0.78, 1.03), respectively. In conclusion, CBCT imaging reports values with excellent accuracy vs digital periapical radiography.

Use of mind maps in dental education: An activity performed in a preclinical endodontic course

PURPOSE/OBJECTIVES

(1) to assess the ability of dental students to use mind maps to express the relationships of endodontic theory and technique; (2) to explore features illustrated from the highest- and lowest-graded mind maps; and (3) to evaluate improvements in successive mind maps from the same student.

METHODS

A total of 31 second-year students were asked to configure a mind map on root canal cleaning-shaping and then 18 weeks later develop a second mind map on root canal obturation. Faculty visually analyzed the mind maps using a qualitative approach: a multilayered process of thematic analysis. Codes and themes were generated to investigate if students were able to express appropriate and evidence-based ideas on the topics (accuracy of relationships and depth of information presented). Two of the highest- and 2 of the lowest-graded mind maps for each activity were directly compared. Improvement by the same student from the first to second mind map was also evaluated based on trend/style and creativity.

RESULTS

The majority of the students accurately expressed the scientific basis for root canal cleaning-shaping and obturation. The highest-graded mind maps displayed the biomedical and humanistic conceptions of critical thinking. In comparing the second mind map to the first, nearly 50% of the students incorporated more detail and artistic expression in the second map.

CONCLUSIONS

using mind maps in dental education can benefit students with different learning styles and help the instructor to identify the level of conceptualization that the student had developed about a topic.

Current status on minimal access cavity preparations: a critical analysis and a proposal for a universal nomenclature

In the last decade, several access cavity designs involveing minimal removal of tooth tissue have been described for gaining entry to pulp chambers during root canal treatment. The premise behind this concept assumes that maximum preservation of as much of the pulp chamber roof as possible during access preparation would maintain the fracture resistance of teeth following root canal treatment. However, the smaller the access cavity, the more difficult it may be to visualize and debride the pulp chamber as well as locate, shape, clean and fill the canals. At the same time, a small access cavity may increase the risk of iatrogenic complications as a result of poor visibility, which may have an impact on treatment outcome. This study aimed to critically analyse the literature on minimal access cavity preparations, propose new nomenclature based on self-explanatory abbreviations and highlight the areas in which more research is required. The search was conducted without restrictions using specifics terms and descriptors in four databases. A complementary screening of the references within the selected studies, as well as a manual search in the highest impact journals in endodontics, namely International Endodontic Journal and Journal of Endodontics, was also performed. The initial search retrieved 1831 publications. The titles and abstracts of these papers were reviewed, and the full text of 94 studies was assessed. Finally, a total of 28 studies were identified as evaluating the influence of minimally invasive access cavity designs on the fracture resistance of teeth and on the different stages of root canal treatment (orifice location, canal shaping, canal cleaning, canal filling and retreatment). Overall, the studies had major methodological drawbacks and reported inadequate and/or inconclusive results on the utility of minimally invasive access preparations. Furthermore, they offered limited scientific evidence to support the use of minimally invasive access cavities to improve the outcome of root canal treatment and retreatment; they also provided little evidence that they preserved the fracture resistance of root filled teeth to a greater extent than traditional access cavity preparations. It was concluded that at present, there is a lack of supporting evidence for the introduction of minimally invasive access cavity preparation into routine clinical practice and/or training of undergraduate and postgraduate students.

Outcome of Root Canal Treatments Provided by Endodontic Postgraduate Students. A Retrospective Study

The aim of this study was to assess the preoperative, intraoperative, and postoperative factors that influenced complete periapical healing in teeth that underwent primary root canal treatment (RCT), in patients treated by postgraduate students in endodontics. Factors were retrieved and compared with the periapical status during the follow-up visit. Healing was considered as the absence of clinical and radiological symptoms. Variables significantly associated by the chi-squared test were included in a logistic regression model (LRM). Preoperative factors associated with healing were: American Society of Anesthesiology (ASA) status (p = 0.01); the absence of preoperative pain (p = 0.04); positive response to pulp tests; when the RCT cause was caries, pain, abscess, or sinus tract; probing depth <4 mm; the absence of mobility; absence or <4 mm periapical lesion (p < 0.01). In the LRM, the factors included were: absence or <4 mm periapical lesion; probing depths <4 mm; RCT caused by caries, pain, abscess, or sinus tract; the tooth was not a bridge abutment. Postoperative factors were: teeth with direct restoration; teeth that did not act as a support for a fixed prosthetic restoration; the favorable condition of the coronal restoration (p < 0.01). In the LRM, only the status of the coronal restoration was included. Preoperative conditions and the adequate fit of the coronal restoration influenced the outcome of RCT.

Management of odontogenic sinusitis: multidisciplinary consensus statement

BACKGROUND

Odontogenic sinusitis (ODS) can present a therapeutic dilemma because multiple treatment strategies have been reported. ODS review articles have been published, but they have lacked multidisciplinary collaboration and an evidence-based methodology. The purpose of this article was to perform an evidence-based review of ODS management options, and develop a multidisciplinary consensus statement on ODS management options.

METHODS

An evidence-based review of dental and medical literature on ODS management was performed using PubMed, EMBASE, and Cochrane Review Databases up to December 2019. Exclusion criteria included non-English-language articles, case series with fewer than 10 patients, fungal sinusitis, and studies that did not report treatment success rates. Because aggregate levels of evidence for recommendations were no higher than level C, a clinical consensus statement was conducted using a modified Delphi method.

RESULTS

Sixteen articles met inclusion criteria for the evidence-based review on the following ODS management options: dental treatment alone or combined with ESS for various dental pathologies, and endoscopic sinus surgery (ESS) alone for dental implant-related ODS. Strong consensus was achieved for 9 of the 10 clinical statements, the strongest being the use of shared decision-making for selecting management strategies. No consensus was reached for determining the extent of ESS necessary for uncomplicated ODS.

CONCLUSION

Strong consensus was reached that ODS management should involve shared decision-making between the otolaryngologist, dental provider, and patient, where the benefits and risks of dental treatment and ESS are discussed. Higher-quality studies are necessary to develop evidence-based treatment recommendations for ODS.

Sealing Ability of Endodontic Cements: An In Vitro Study

The root canal system must be obturated using a hermetic seal to prevent the penetration of microorganisms and bacterial toxins into the endodontic system. The principles of adhesive dentistry have been increasingly used in endodontics. In fact, resin-based sealers are increasingly used. The objective of this study was to evaluate, in vitro, the sealing ability of resin cement in comparison with calcium hydroxide-based cement. Materials and Methods. Eighty root canals were prepared with the Tilos system and were randomly divided into four groups according to the filling material. The best combination was evaluated on the basis of its sealing ability. The dye infiltration degree was evaluated using both a stereomicroscope after diaphanization and the dye rise test. Results. A significant difference was observed between the four obturation systems with regard to the number of infiltrated walls (p=0.014) and the infiltration depth (p=0.025). The group of teeth obturated with EndoREZ® and EndoREZ® gutta cones differ significantly from the group obturated with EndoREZ® cement and gutta-percha cones in terms of apical sealing (p=0.011). A significant difference was also observed between the group of teeth obturated using EndoREZ® gutta cones and EndoREZ® cement and the group of teeth obturated with EndoREZ® cement (p=0.026). Conclusion. When used with EndoREZ® gutta cones, EndoREZ® cement showed the best sealing ability, particularly in the apical region. When used with gutta-percha cones, Acroseal and EndoREZ® cements exhibited similar sealing abilities.

Reproducibilidad en el diagnóstico imagenológico de periodontitis apical a partir de CBCT

Objetivo: esta investigación evaluó la reproducibilidad en el diagnóstico imagenológico de PA en dientes del maxilar superior a partir de 60 CBCT tomadas en una institución clínica en una ciudad intermedia en Colombia. Métodos: el estudio fue realizado por dos observadores previamente calibrados de CBCT del maxilar superior que contenían dientes permanentes con ápice cerrado, correspondientes a adultos mayores de 18 años de edad. La presencia o ausencia de periodontitis apical se analizó utilizando el índice CBCT PAI. La información registrada fue relacionada con variables de interés. Resultados: la reproducibilidad entre los evaluadores fue sustancial o perfecta. La prevalencia de periodontitis apical encontrada fue del 21,6%, en los dientes con tratamiento de endodoncia 12,4% y en los dientes sin tratamiento endodóntico 9,2%. Conclusiones: la tomografía CBCT proporciona al clínico información que permite una mayor claridad en la fase de diagnóstico. Los dientes con la mayor prevalencia de PA fueron el primer molar y el primer premolar superior izquierdo respectivamente.

Prevalence of apical periodontitis and its association with previous root canal treatment, root canal filling length and type of coronal restoration - a cross-sectional study

AIM

To analyse the prevalence of periapical lesions and their association with previous root canal treatment, root canal filling length and type of coronal restoration using in vivo cone-beam computed tomographic (CBCT) assessment.

METHODOLOGY

A global sample of 20 836 teeth, with a combined total of 27 046 roots, from 1160 patients, was analysed via CBCT assessment in eight health centres. Each tooth was evaluated by one out of five examiners after having performed a defined calibration procedure on the basis of 319 teeth. Intra- and inter-rater reliability tests were performed. Each tooth was classified according the tooth number, presence/absence of periapical lesions, presence/absence of previous root canal treatment, length of root canal filling (short, good or overfilling) and type of coronal restoration. The z-test for proportions was used to analyse differences between tooth subgroups, and an odds ratio was determined in order to analyse the association between treatment status and periapical lesions. A P < 0.05 was considered significant.

RESULTS

At a tooth level, the overall prevalence of periapical lesions in the sample was 10.4%. Maxillary teeth were associated with a significantly larger percentage of lesions (13.1%), whilst maxillary first molars had the greater proportion of lesions (21.2%). The prevalence of periapical lesions was significantly larger in root filled teeth (55.5%), short root canal fillings (72.7%) and in teeth restored with crowns (46.1%). At a root level, the mesiobuccal roots of both maxillary first molars had a tendency for a larger percentage of periapical lesions.

CONCLUSION

History of root canal treatment, root canal filling length and type of coronal restoration influenced the presence of periapical lesions. Molars were more commonly associated with periapical lesions on root filled teeth, particularly those with short root fillings and those with crowns.