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Background/Aim. Maxillary first molars are one of the most challenging teeth for endodontic therapy. There are certain disparities in the number of roots and canals and canal interrelationships within the same root, particularly those with fused roots. The aim of the study was to assess ex vivo features of roots, root canals, and canal walls in maxillary first molars with fused roots. Methods. Out of the total of 366 maxillary first molars, 64 extracted maxillary first molars with fused roots were included in the study using cone-beam computed tomographic and microscopic examining. Tooth dimensions at the level of pulp chamber floor, number, location and distance between orifices, number and canal morphology, canal wall thickness, and features of apical foramina were examined and measured. Results. The incidence of maxillary first molars with root fusion was 17.5%, of which 60.0% was palatal fused to distobuccal root. At the level of the pulp chamber floor, the bucco-palatal dimension was significantly larger at 10.4 mm than M-D with 7.0 mm. Four canal orifices were detected in 65.6%, with the shortest distance of 1.95 mm between MB1 and MB2. In fused roots, two or three canals most frequently correlated strongly with the number of major apical foramina. No fusion of canals was found in fused roots. The thinnest canal wall in the mesiobuccal and distobuccal fused root was mesial with 1.25 mm, and distal with 1.31 mm, while for the palatal root, the thinnest was the palatal wall with 1.97 mm. Two or three large apex foramina were registered with a significant correlation with the number of canals in the fused root. Conclusion. The most frequent type of fusion was between the palatal and distobuccal roots. Bucco-palatal dimension at the level of the pulp chamber floor was significantly larger than the mesiodistal, with the shortest inter-orifice distance between the MB1 and MB2 orifice. The number of canals was either two or three, coinciding with the number of major apical foramina. There was no fusion of the canals in fused roots. The thinnest canal wall was either mesial or distal.

Introduction. Postoperative sensitivity in restorative dentistry can be related to preparation trauma, dentin adhesives’ ability to seal open dentinal tubules, deformation of restorations under occlusal stresses and microleakage. Objective. The study assessed possible reduction in postoperative sensitivity with low shrinkage compared to conventional composites using different bonding agents and the influence of the operator skill on the incidence of postoperative sensitivity. Methods. Nine hundred and sixty permanent premolars and molars with primary carious lesions from patients 21 to 40 years old were used. Cavities 2 to 3 mm deep and with margins in enamel were prepared by four operators. Two operators had five years (A and B) and two had over 20 years (C and D) of clinical experience. Teeth were divided into eight groups each contained 120 restorations: (1) Els®+James-2 (original formula), (2) Els®+James-2 (new formula), (3) Els®+Excite, (4) InTenSe®+James-2 (original formula), (5) InTenSe®+James-2 (new formula), (6) InTenSe®+Excite, (7) Tetric Ceram®+Excite, and (8) Point 4®+OptiBond Solo Plus. At 14 days postoperatively, two independent operators, who did not take part in the clinical procedure, assessed postoperative teeth sensitivity using special questionnaires. Data were analyzed using non-parametric chi-square, Mann-Whitney and ANOVA tests. Results. Group 8 showed significantly higher score than the other groups. Less postoperative sensitivity was reported with two low-shrinkage composites (groups 2, 3, and 5) but with no significant difference. There was no statistical difference between groups 1, 2, 3, 4, 5, 6 and 7. Operator A had the highest postoperative sensitivity score compared to the other three. Conclusion. Conventional composite material Point 4® with its bonding agent caused significantly more postoperative sensitivity than low shrinkage composites combined with different adhesives. Operator skill influenced the incidence of postoperative sensitivity. [Projekat Ministarstva nauke Republike Srbije, br. 1454042]

Introduction: More detailed acquaintance with specialist endodontic literature and treating complicated endodontic cases have revealed that the palatal root canal in maxillary first molars has different features from generally accepted simplicity. Aim: The aim of this study was to investigate the number, orientation and shape of the curvature of the palatal root canal in maxillary first molars, characteristics that may have great influence on the procedure and outcome of endodontic therapy. Materials and methods: Material consisted of 100 left and 100 right extracted human first maxillary molars. Extended access cavity was prepared, and canal orifices were detected using an endodontic probe. K-flex file no 15 or 20 was then introduced into the palatal root canal until the tip appeared at the apical foramen. The tooth was radiographed from buccal-oral (clinical) and mesial-distal (proximal) aspect under standardized conditions. On magnified images, the number and character of canal, orientation and shape of the curvature were determined. Results: One palatal root canal was found in each of 200 teeth. From the clinical projection, 60% of the palatal canals appeared curved and from the proximal 93.5% (p

Introduction. The first maxillary molar is a tooth with three roots, and mesiobuccal one is with the most complex canal morphology. Factors influencing variations of its morphology are numerous, and may significantly complicate endodontic treatment. Objective. The objective was to investigate the number, configuration and curvature orientation of the mesiobuccal root canals in the maxillary first molars. Methods. The study was conducted on 200 mesiobuccal (MB) roots of extracted first molars in human subjects using radiography. In each canal Flexofile was introduced until reaching the apical foramen and the root was then radiographed in series from two projections. Number of root canals (MB1, MB2 and MB3), configuration according to Vertucci classification, and the orientation of the curvature were established. Relevant statistical parameters and the significance of differences were computed (p

Endodontic treatment of the teeth with severe root canal curvatures has become one of the greatest problems in clinical practice. Recently, new instruments and techniques have been introduced in the endodontic procedure. The aim of this study was, on the basis of clinical practice, to show the possibilities of the endodontic treatment in the teeth with severely curved root canals, after dependable decision about endodontic instruments and techniques. This article presents a complete endodontic procedure in two teeth with different curvature shape of the root canal in patients that were treated at the Department of Restorative Dentistry and Endodontics, School of Dentistry, Belgrade. Coronal to apical 'crown down' technique was used for the root canal preparation with hand NiTi ProTaper instruments with progressive multicone design. The main reasons for choosing manual technique were complexity, shape of presented curvatures and better tactile sensation control of canal instruments in order to avoid possible mistakes and complications. Clinical X-rays of the teeth with permanent obturation clearly showed that extremes of the root canal morphology could be successfully solved by the right choice of all factors during endodontic procedure.

Background: It is not yet clear how different irrigation protocols and intracanal laser irradiation effects bioceramic sealers. In this vitro study, we aimed to evaluate the dislocation resistance of a bioceramic root canal sealer after different laser-assisted disinfection protocols and irrigants., Methods: Sixty extracted human straight single-canal teeth were instrumented, and randomly divided into five experimental groups (n=10) according to the disinfection protocol used: group 1, conventional needle irrigation (CI) with sodium hypochlorite (NaOCl)+ethylenediaminotetraacetic acid (EDTA)+NaOCl; group 2, Photon initiated photoacoustic streaming (PIPS) of NaOCl+EDTA+NaOCl; group 3, NaOCl+EDTA+diode laser; group 4, NaOCl+EDTA+photodynamic therapy (PDT); group 5, CI with NaOCl+EDTA+Chlorhexidine (CHX); and control group without any treatment. The root canals were filled with a bioceramic root canal sealer (BioRoot RCS) using the single-cone filling technique. After three weeks of storage, the samples from each canal thirds were transversely sectioned and the push-out test was performed., Results: The PIPS group showed the lowest dislocation resistance values in the coronal third (p>0.05), and no difference was observed among the other groups (p<0.05). The dislocation resistance in the middle and apical thirds was the highest in the diode laser group (p<0.05)., Conclusion: Final root canal irradiation with diode laser led to improved dislocation resistance of the bioceramic sealer. PDT did not adversely affect the dislocation resistance of BioRoot RCS. The PIPS reduced the dislocation resistance values in the coronal third, but not in the middle and apical thirds., Competing Interests: Declaration of Competing Interest The authors have stated explicitly that there are no conflicts of interest in connection with this article., (Copyright © 2022. Published by Elsevier B.V.)

Introduction: This study aimed to summarize data on apical periodontitis (AP) and nonsurgical root canal treatment (NSRCT) prevalence and risk factors related to age, gender, and quality of restorative and endodontic treatment in the general population from cross-sectional studies published between 2012 and 2020., Methods: An electronic search was performed in the following databases: Web of Science, Scopus, and PubMed. The conducted literature search covered studies published between 2012 and 2020, without restrictions on language. The STROBE and NOS tools were used for quality assessment of the included studies., Results: Sixteen articles were included in the review. In total, 200,041 teeth were examined. On average, 6.3% of teeth had AP, and 7.4% had NSRCT. Forty-one percent of RCT teeth had AP, and 3.5% of untreated teeth had AP. Female patients were less prone to AP in endodontically treated teeth only, compared with male patients (P < .001). Variable stratification of age subgroups among included studies prevented us from conducting a meta-analysis. An increase in AP frequency was found in teeth with inadequate restorative and endodontic treatment (P < .001 and P < .001, respectively). Because of high heterogeneity, these results should be taken with caution., Conclusions: There is an increased AP prevalence in the adult general population compared with data from 2012 (6.3% versus 5.4%) in both endodontically treated (41.3% versus 35.9%) and untreated teeth (3.5% versus 2.1%). In addition, AP developed less frequently in female patients with endodontically treated teeth and in teeth with inadequate compared with adequate restorative and endodontic treatment., (Copyright © 2020 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Objectives: This study aimed to investigate whether Epstein-Barr virus (EBV) positive periapical lesions exhibited higher mRNA levels of Notch signalling molecules (Notch2 and Jagged1), bone resorption regulators (receptor activator of nuclear factor kappa-β ligand (RANKL) and osteoprotegerin (OPG)), and proinflammatory cytokines (tumour necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β) and IL-6) compared to EBV negative lesions. Additionally, the potential correlation between investigated molecules in periapical lesions was analyzed. Materials and methods: Sixty-four apical periodontitis lesions were obtained subsequent to standard apicoectomy procedure. The presence of EBV was determined using nested PCR. Based on the presence of EBV all periapical lesions were divided into two groups, 29 EBV positive and 35 EBV negative lesions. A reverse transcriptase real-time PCR was used to determine mRNA levels of Notch2, Jagged1, RANKL, OPG, TNF-α, IL-1β and IL-6. Results: Significantly higher mRNA levels of Notch2, Jagged1, RANKL and IL-1β were observed in EBV positive compared to EBV negative lesions. Significant positive correlation was present between Notch2 and Jagged1, Jagged1 and RANKL, and IL-β and TNF-α in EBV positive periapical lesions. Conclusions: Notch signalling pathway may be involved in alveolar bone resorption in apical periodontitis lesions infected by EBV.

Apical periodontitis represents a chronic inflammatory process within periapical tissues, mostly caused by etiological agents of endodontic origin. Progressive bone resorption in the periapical region represents the hallmark of apical periodontitis and occurs as the consequence of interplay between polymicrobial infections and host response. The Notch signaling pathway is an evolutionary conserved cell-signaling system that plays an important role in a variety of cell functions including proliferation, differentiation and apoptosis. In recent years its involvement in bone homeostasis has attracted a significant consideration. We hypothesized that Notch signaling pathway, which has a complex interplay with proinflammatory cytokines and bone resorption regulators, contributes to alveolar bone resorption via increased Notch receptors on immune cell surface and stimulates Notch receptor intracellular domain (NICD) translocation into the nucleus. The potential benefit of medications aimed to down-regulate these pathways in apical periodontitis treatment remains to be assessed., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Introduction: The exact mechanisms of periapical bone resorption have not been fully elucidated. This study aimed to analyze the expression of Notch signaling molecules (Notch2, Jagged1, and Hey1) and proinflammatory cytokines (tumor necrosis factor alpha [TNF-α], interleukin [IL]-1β, and IL-6) in human apical periodontitis lesions with different receptor activator of nuclear factor kappa B ligand (RANKL)/osteoprotegerin (OPG) ratios and determine their potential correlation., Methods: The study group consisted of 50 periapical lesions collected in conjunction with apicoectomy. The relative gene expression of the investigated molecules (Notch2, Jagged1, Hey1, RANKL, OPG, TNF-α, IL-1β, and IL-6) in all tissue samples was analyzed using reverse transcriptase real-time polymerase chain reaction. The Student t test, Mann-Whitney U test, and Spearman correlation were used for statistical analysis., Results: Based on the RANKL/OPG ratio, periapical lesions were either RANKL predominant (RANKL > OPG, n = 33) or OPG predominant (RANKL < OPG, n = 17). Symptomatic lesions occurred more frequently in RANKL-predominant compared with OPG-predominant lesions (24 vs 7, P = .029). Notch2, Jagged1, Hey1, and TNF-α were significantly overexpressed in lesions with predominant RANKL compared with lesions with predominant OPG (P = .001, P = .001, P = .027, and P = .016, respectively). Significant correlations were observed between the investigated genes in periapical lesions., Conclusions: Notch signaling appeared to be activated in periapical inflammation. An increase in Notch2, Jagged1, Hey1, and TNF-α expression in RANKL-predominant periapical lesions corroborates their joined involvement in extensive periapical bone resorption., (Copyright © 2018 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: Varicella zoster virus (VZV) and subsequent herpes zoster (HZ) infection have been proposed as a causative agent of periapical pathoses and root resorption. This review aimed to identify, synthesize, and present a critical analysis of the available data on the association among VZV, subsequent HZ infection, and the development of periapical pathoses and root resorption and to analyze the level of evidence of available studies., Methods: The literature search covered MEDLINE, Science Citation Index Expanded, and Scopus. A qualitative critical appraisal of the included articles was performed., Results: The electronic database search yielded 66 hits from PubMed, 73 hits from Web of Science, and 107 from Scopus. Seven case reports and 3 cross-sectional studies were included in the final review. When summarized, in 7 patients with a history of a previous HZ attack and with no other apparent cause, 23 teeth were diagnosed with apical periodontitis, 8 teeth with internal and 1 tooth with external root resorption. The cross-sectional studies investigated the presence of VZV DNA in samples of acute apical abscess. The VZV DNA was found only in 2 of 65 samples., Conclusions: All studies included in this systematic review had a low level of evidence (4 and 5). Still, the potential role of VZV in the etiopathogenesis of periapical pathoses and root resorption cannot be ruled out. Future investigations should be directed toward the analysis of VZV pathologic effects on pulp blood vessels, which might cause local ischemia and tissue necrosis., (Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Objective: The aim of this study was to assess the presence of herpesviruses and periodontopathic bacteria and to establish their potential association with pericoronitis., Materials and Methods: Fifty samples obtained with paper points (30 from pericoronitis and 20 controls) were subjected to polymerase chain reaction (PCR) analysis. A single-stage and nested PCR assays were used to detect herpesviruses: human cytomegalovirus (HCMV) and Epstein-Barr virus (EBV) and six periodontopathic anaerobic bacteria: Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Parvimonas micra, Treponema denticola, and Tannarella forsythia., Results: Pericoronitis samples harbored HCMV and EBV at significantly higher rates than the control group (70 vs. 40 % and 46.7 vs. 15 %, P = 0.035, P = 0.021, respectively). P. micra and T. forsythia (66.7 vs. 0 %, and 40 vs. 10 %, P = 0.001, P = 0.021, respectively) were significantly more common in pericoronitis compared to the control group. Multivariate logistic regression analysis showed that the presence of T. forsythia was associated with pericoronitis development (OR 7.3, 95 % CI, 1.2-43.2, P = 0.028)., Conclusion: The occurrence of HCVM and EBV extends our previous knowledge on microbiota in pericoronitis. These PCR-based findings demonstrated that bacterial and viral DNA occurred concomitantly in pericoronitis samples. T. forsythia appeared to be significantly associated with pericoronitis development in the examined sample., Clinical Relevance: Herpesviral-bacterial co-infections might exacerbate the progression of pericoronitis.

Chronic inflammatory processes in periapical tissues caused by etiological agents of endodontic origin lead to apical periodontitis. Apart from bacteria, two herpesviruses, Epstein-Barr virus (EBV) and Human cytomegalovirus (HCMV) are recognized as putative pathogens in apical periodontitis. Although previous reports suggest the involvement of EBV in the pathogenesis of apical periodontitis, its exact role in periapical bone resorption has not yet been fully elucidated. We hypothesize that EBV infection in apical periodontitis is capable of inducing periapical bone resorption via stimulation of reactive oxygen species (ROS) overproduction. Increased levels of ROS induce expression of receptor activator of nuclear factor kappa B (NF-κB) ligand (RANKL). RANKL binding to receptor activator of nuclear factor κB (RANK) present on the surface of preosteoclasts induces their maturation and activation which consequently leads to bone resorption. The potential benefit of antiviral and antioxidant-based therapies in periapical bone resorption treatment remains to be assessed., (Copyright © 2016 Elsevier Ltd. All rights reserved.)