Vertical root fractures in endodontically treated teeth: diagnostic signs and clinical management

Developing evidence-based clinical imaging guidelines for the diagnosis of vertically fractured teeth

OBJECTIVES

This study aimed to develop an evidence-based clinical imaging guideline for teeth suspected with vertical root fractures.

METHODS

An adaptation methodology based on the Korean Clinical Imaging Guidelines (K-CIG) was used in the guideline development process. After searching for guidelines using major databases such as Ovid-Medline, Elsevier-Embase, National Guideline Clearinghouse, and Guideline International Network, as well as domestic databases such as KoreaMed, KMbase, and KoMGI, two reviewers analyzed the retrieved articles. The retrieved articles were included in this review using well-established inclusion criteria.

RESULTS

Twenty articles were identified through an online search, of which three were selected for guideline development. Based on these three guidelines, this study developed specific recommendations concerning the optimal imaging modality for diagnosing teeth suspected of vertical root fractures.

CONCLUSIONS

Periapical radiography is the preferred method for assessing teeth with mastication-related pain and suspected vertical root fractures. However, if intraoral radiographs do not provide sufficient information about root fractures, a small FOV CBCT may be considered. However, the use of CBCT in endodontically treated teeth is significantly constrained by the presence of artificial shading.

Factors associated with the outcome of root canal treatment-A cohort study conducted in a private practice

AIM

To investigate the association of various pre-, intra- and post-operative factors on root canal treatment outcome.

METHODOLOGY

In this cohort study, primary or secondary root canal treatment of mature permanent teeth was performed by a single endodontist in a private practice over 13 years, and followed 1-4 years after treatment. Treatment details and clinical and radiographic data were collected. The proportion of successfully treated teeth and roots based on strict radiographic (periapical index (PAI) ≤2) and clinical criteria (absence of pain, swelling or sinus tract) was estimated. To evaluate joint associations of prognostic factors and treatment success probability, 44 pre, intra- and post-operative factors were investigated using bivariate associations, and a multiple logistic regression model was fitted using Generalized Estimating Equations.

RESULTS

1259 teeth (2445 roots, 3149 canals) were assessed with a recall rate of 91%. The proportion of successfully treated teeth was 79.9% [95% confidence interval 77.7-82.1]. Eleven prognostic factors were identified that significantly reduced the odds ratio (OR) for treatment success at tooth level. Six were preoperative: injury history (OR = 0.05[0.01-0.24]), root PAI (OR = 0.29[0.20-0.42], 0.21[0.13-0.34] and 0.22[0.12-0.42] for PAI = 3, 4 and 5, respectively, against PAI = 1), lesion diameter (OR = 0.30[0.21-0.43] and 0.24[0.16-0.37] for diameters of 1-5 mm and ≥6 mm, respectively, against no lesion), tooth type (OR = 0.51[0.27-0.97] and OR = 0.45[0.24-0.83] for premolars and molars, respectively, against incisors or canines), tenderness to periapical palpation (OR = 0.64[0.43-0.94]) and two canals per root (OR = 0.67[0.54-0.83]). Four factors were intraoperative: root filling of unsatisfactory quality (OR = 0.18[0.08-0.40]) or extending beyond or shorter than 2 mm from the apex (OR = 0.44[0.26-0.75] and 0.62[0.40-0.97] respectively), resin sealer (OR = 0.58[0.39-0.87] against bioceramic sealer) and single visit treatment (OR = 0.40[0.21-0.75] against multiple visits). One factor was post-operative: defective coronal restoration (OR = 0.35[0.21-0.56]).

CONCLUSION

The following factors were associated with unsuccessful root canal treatment: (i) history of injury, apical periodontitis with increased severity (larger lesion, higher PAI, tenderness to periapical palpation), or complicated anatomic conditions (premolar or molar, two canals in a single root); (ii) technically suboptimal root filling (of unsatisfactory quality or not ending within 2 mm of radiographic apex) performed in a single-visit, or use of resin sealer instead of novel bioceramic sealer; (iii) suboptimal quality coronal restoration.

Radiographic Criteria for Differential Diagnosis Between Vertical Root Fracture and Apical Periodontitis in Single-Rooted Endodontically Treated Premolars Using Cone-Beam Computed Tomography

INTRODUCTION

This study explores the differences between the patterns of bone defects associated with vertical root fracture (VRF) and apical periodontitis (AP) in single-rooted endodontically treated premolars (SRETPs) based on cone-beam computed tomography (CBCT) data.

METHODS

Eighty-four SRETPs were extracted and categorized into the VRF and AP groups. On preoperative CBCT images, the location of bone defects according to the root thirds in buccolingual and mesiodistal directions across the study groups were compared.

RESULTS

The majority of bone defects in the VRF group were longitudinal and combined, involving more than one root thirds in buccolingual and mesiodistal directions simultaneously. A uniform approach to comparing bone defects using the sites of periradicular area with bone loss as a comparison unit was developed. In the VRF group, bone loss sites in the middle and coronal thirds were detected more often and were located mainly buccolingually compared with the AP group (P < .001).

CONCLUSION

Bone defects in the middle or middle and coronal root thirds in the buccolingual direction may be potential radiographic signs useful in differentiating between VRF and AP in SRETPs. The introduction of the uniform approach to assessment of bone loss patterns will give practitioners a single simple tool and improve the quality of endodontic treatment.

Prevalence of Vertical Root Fractures in a University Endodontics Program versus a Private Endodontics Office

Introduction

Vertical root fractures (VRFs) typically have a poor prognosis with an extraction or occasionally root amputation as the preferred treatment. VRFs have been considered an epidemic, motivating changes in the access openings, as well as in the preparation and disinfection protocols of endodontic treatment. Hence, we aimed to evaluate the prevalence of VRFs by tracking cases in both a University Endodontic Program (UEP) and a private endodontics practice (PP). We also evaluated changes in prevalence during COVID-19 along with the alterations in the frequency of cases diagnosed by clinical and radiographic signs which were later confirmed by direct visualization compared to those in which the suspicion was based on clinical and radiographic signs alone.

Methods and Materials

This retrospective study looked at the prevalence of VRF in patient records at UEP and a PP. Data for the pre-COVID-19 and COVID-19 time periods were extracted from patient records and referral letters then compared. Data for suspected and confirmed prevalence were compared.

Results

The UEP group included 21,156 patients while the PP group comprised 7,209 patients. The prevalence of VRFs in the former cohort was 1.80%, while 2.62% of the latter cohort exhibited VRFs with a combined total of 2.01%. The combined total prevalence of VRFs pre-COVID-19 was 1.72%, increasing from 2.1% to 3.82% during COVID-19 (p < 0.0001). The same applied to suspected cases for both clinical settings. The increase in confirmed cases between the two periods was statistically significant for the UEP group (p=0.0202) but it was insignificant for the PP group (p=0.0721).

Conclusion

The combined prevalence for VRFs was 2.01% for all years denying the claim that VRF is a pandemic phenomenon. COVID-19 period saw almost a double increase in the prevalence of VRF compared to pre-COVID-19 era. This was consequently associated with a significant increase in the number of suspected VRF cases.

The effect of sealer type and obturation technique on the fracture resistance of endodontically treated roots

OBJECTIVE

This study evaluated the effect of sealer type with various obturation techniques on the fracture resistance of root filled teeth.

MATERIALS AND METHODS

Eighty mandibular premolars were collected, and root canals of 70 of them were prepared by Mtwo system up to 40/04. Thirty teeth were obturated using TotalFill BC sealer, and 30 using AH Plus sealer, with one of the obturation techniques (N = 10), namely cold lateral compaction (CLC), warm vertical compaction (WVC), and single cone (SC). Ten teeth were left without obturation as a positive control, and the other 10 teeth were not prepared serving as a negative control. Teeth were stored for 3 weeks, and the crowns were separated and the roots were subjected to fracture test using a universal testing machine.

RESULTS

Data was analyzed by ANOVA followed by Tukey's test. Fracture resistance of the TotalFill groups was significantly higher than the AH Plus groups in each obturation technique, and SC had the highest fracture resistance regardless of sealer used (P < 0.05). Obturation of the root canal by TotaFill BC sealer increased the calcium/phosphorous ratio in the dentin of the root.

CONCLUSIONS

Obturation with TotalFill BC sealer improved the fracture resistance of the roots more than AH Plus sealer, and obturation with SC resulted in higher fracture resistance than CLC and WVC.

CLINICAL RELEVANCE

Obturation of the root canal with Bioceramic sealer with single cone obturation technique could reduce the incidence of vertical root fracture.

Comparison of Dentin Microstructure and Its Correlation to the Direction of Fracture Line in Mandibular Molars of Young and Older Individuals: In Vitro Study

INTRODUCTION

The aim of the study was to assess the presence and extent of sclerotic dentin and to study its impact on the direction of fracture lines in extracted mandibular first molars of young (20-44 years) and older age groups (45 and older).

METHODS

Extracted permanent mandibular first molars were collected along with the related demographic details. A total of 40 teeth were included in this study, 20 each from young age group (YA group) (20-44 years) and older age group (OA group) (45-70 years). All molars were decoronated, and the sectioned mesial roots were embedded in acrylic blocks. They were subjected to vertical force in a universal testing machine. Fractured roots were then examined under the stereomicroscope at ×8 magnification to determine the direction and pattern of the fracture line. The roots were then sectioned and evaluated at ×10 and ×20 magnification to assess the dentin microstructure and its correlation with the direction of the fracture line. Statistical analysis was done by using χ2 test (P < .05).

RESULTS

A greater incidence and degree of sclerotic dentin were found in the OA group as compared with the YA group, which was statistically significant. The sclerotic dentin was distributed predominantly mesiodistally and the fracture line propagated buccolingually in both young and older groups, which was statistically significant (P < .05).

CONCLUSIONS

The presence of sclerotic dentin mesiodistally may impede crack propagation in this direction for both young and older age groups, causing the fracture line to extend buccolingually in coronal third of the root.

Influence of voxel size and filter type on detecting vertical root fracture using cone-beam computed tomography

Vertical root fractures (VRFs) can start at any level of the root and progress longitudinally to the coronal attachment. This study aimed to investigate the effects of different exposure parameters used when obtaining CBCT scans in detecting simulated VRFs. Hence, 80 intact human mandibular single-rooted pre-molar teeth without root fractures were included in the study. No statistically significant difference was found between the filters in terms of VRF detection in the group with the roots with only root canal filling (Groups 1 and 5); however, 100 voxels were found to be more successful in terms of VRF detection than other voxel sizes. Results of this study suggest that using lower voxel sizes leads to an accurate diagnosis of vertical root fracture, in addition, our results revealed that using AR filters did not improve the diagnostic accuracy in detecting VRFs.

Anatomical complexities affecting root canal preparation: a narrative review

A fundamental aspect of the Endodontic field is the knowledge of root canal anatomy. Using a variety of techniques, the internal and external anatomy of teeth have been extensively investigated throughout the past century. Recent improvements in three-dimensional computed tomography have enabled more detailed evaluations of root canal morphology in both clinical and laboratory settings. Essentially, researches have unveiled that the root canal constitutes a complex system, comprising not only the main root canal but also lateral components, including isthmuses, fins, accessory canals and apical ramifications. Undoubtedly, this intricate morphology poses a significant challenge when it comes to the process of shaping, cleaning and disinfecting the root canal system. This article aims to explore the anatomical aspects of the root canal system that impact the chemomechanical procedures.

Prior Restorative Procedures to Endodontic Treatment

Tooth loss due to fracture and the failure of endodontic treatment (ET) are common situations in teeth with extensive tissue destruction. This is due to the fragility of the remaining dental structure and the difficulty in sealing cavities, which is sometimes associated with the violation of the supracrestal insertion tissue. The previous restoration of marginal ridges or cusps with composite resin (CR) restores their fracture resistance, due to the adhesive characteristics of the restorative material, while also protecting the quality of endodontic treatment through better sealing. However, the protocol adopted in teeth requiring endodontic treatment involves performing the restorative procedure only after the endodontic procedures. The objective of this study was to report a case in which restoration of marginal ridges and/or cusps was performed prior to endodontic treatment, focusing on maintaining the tooth in function without dental fracture. The restoration was performed with an inverted operative sequence before the endodontic treatment. There was a violation of the supracrestal insertion tissue, requiring crown lengthening surgery (CLS) prior to the restorative procedure. Clinical and radiographic evaluations were performed postoperatively at seven days, three, six, and nine months, and five years. Tooth function was maintained without dental fractures or restoration loss. Periradicular space healing occurred with the disappearance of the lesion. Performing the restorative procedure prior to endodontic treatment in teeth with extensive coronal destruction is an alternative technique that facilitates clinical procedures, reduces the likelihood of dental loss due to fracture, and promotes endodontic treatment success.

Biomechanical perspectives on dentine cracks and fractures: Implications in their clinical management

OBJECTIVES

The present review discussed the biomechanical properties of cracks and fractures in crown and root dentine and attempted to explain why cracked teeth and vertical root fractures are so frequent despite the existence of multiple crack toughening mechanisms in dentine. The implications of this knowledge were used to justify how these defects are managed clinically.

DATA, SOURCES AND STUDY SELECTION

Literature search was conducted on PubMed, Web of Science, and Scopus for a narrative review on fracture mechanics of crown and root dentine as well as the clinical management of cracked teeth and teeth with vertical root fracture.

CONCLUSIONS

Although dentine is tougher and less brittle than enamel, it's facture toughness is considerably lower than most ductile metals. Because the initiation toughness of dentine is very low, cracks initiate from incipient damage under low stress While crack toughening mechanisms exist that enable dentine to resist crack extension, these mechanisms are often inadequate for protecting dentine from crack propagation that ultimately leads to catastrophic failure. Additional factors such as ageing also reduces the resistance of dentine to crack growth. Because dentine cracks are eventually filled with bacteria biofilms upon exposure to oral fluids, they enable rapid bacteria ingress into the dental pulp via open dentinal tubules. To date, treatment options for cracked teeth are limited. While most teeth with vertical root fracture are recommended for extraction, new strategies have been reported that appeared to achieve short-term success in preserving these teeth.

CLINICAL SIGNIFICANCE

Current strategies for the management for dentine cracks and fractures are limited and their long-term effectiveness remain uncertain. Understanding the characteristics, toughening mechanism and weakening factors of tooth cracks is helpful in designing better treatment.

Detecting Vertical Root Fractures Using Modified Methylene Blue Dye: A Preliminary In Vitro Study

Diagnostically, vertical root fractures (VRFs) can be a frustrating experience for the dentist. Misdiagnosis could result in significant time and effort losses involved in erroneously intervening endodontically and/or periodontally. Certainly, diagnosing VRFs is often very difficult, and diagnoses based on speculations have led to the extraction of many salvageable teeth. This study was conducted in the radiology unit of College of Dentistry, Prince Sattam bin Abdulaziz University, between December 2021 and June 2022 to evaluate the ability to detect VRFs following the use of a novel radio-opaque dye using periapical radiographs (PARs) and cone-beam computed tomography (CBCT). After carefully inducing VRFs on extracted, single-rooted, virgin premolars (n = 26), they were assigned to control (n = 2) and experimental groups (n = 24). The fracture site of the tooth in the control group received methylene blue dye, whereas the experimental group received a novel dye. Two differently angled PARs were obtained for all the teeth, followed by a CBCT image. Three blinded investigators participated in scoring a Likert scale form with a set of questions. Inter-/intra-examiner reliability showed excellent consistency using Cronbach's alpha test. The Z-test revealed CBCT and PAR to be equally adept at detecting VRFs, with the mean values showing no statistically significant differences. The extent of the VRFs and dye penetration were significantly better when angled radiographs and axial view CBCT were evaluated. Within the limitations of this study, the dye tested showed promising initial results as an aid in radiographically detecting VRFs. The use of such minimally invasive methods is critically needed for diagnosing and managing VRFs. However, further testing should be performed prior to its clinical use.

Detection of vertical root fractures by cone-beam computed tomography based on deep learning

OBJECTIVES

This study aims to evaluate the performance of ResNet models in the detection of in vitro and in vivo vertical root fractures (VRF) in Cone-beam Computed Tomography (CBCT) images.

METHODS

A CBCT image dataset consisting of 28 teeth (14 intact and 14 teeth with VRF, 1641 slices) from 14 patients, and another dataset containing 60 teeth (30 intact and 30 teeth with VRF, 3665 slices) from an in vitro model were used for the establishment of VRFconvolutional neural network (CNN) models. The most popular CNN architecture ResNet with different layers was fine-tuned for the detection of VRF. Sensitivity, specificity, accuracy, PPV (positive predictive value), NPV (negative predictive value), and AUC (the area under the receiver operating characteristic curve) of the VRF slices classified by the CNN in the test set were compared. Two oral and maxillofacial radiologists independently reviewed all the CBCT images of the test set, and intraclass correlation coefficients (ICCs) were calculated to assess the interobserver agreement for the oral maxillofacial radiologists.

RESULTS

The AUC of the models on the patient data were: 0.827(ResNet-18), 0.929(ResNet-50), and 0.882(ResNet-101). The AUC of the models on the mixed data get improved as:0.927(ResNet-18), 0.936(ResNet-50), and 0.893(ResNet-101). The maximum AUC were: 0.929 (0.908-0.950, 95% CI) and 0.936 (0.924-0.948, 95% CI) for the patient data and mixed data from ResNet-50, which is comparable to the AUC (0.937 and 0.950) for patient data and (0.915 and 0.935) for the mixed data obtained from the two oral and maxillofacial radiologists, respectively.

CONCLUSIONS

Deep-learning models showed high accuracy in the detection of VRF using CBCT images. The data obtained from the in vitro VRF model increases the data scale, which is beneficial to the training of deep-learning models.

The Effect of Bioceramic HiFlow and EndoSequence Bioceramic Sealers on Increasing the Fracture Resistance of Endodontically Treated Teeth: An In Vitro Study

Background/purpose Root fractures after endodontic treatment are a serious complication, and it often causes tooth loss, several studies have found a correlation between root canal preparation and filling, and the possibility of root fracture. Therefore, this study aimed to evaluate the root fracture resistance of the endodontically treated mandibular premolars after preparing and filling by EndoSequence Bioceramic (BC), EndoSequence BC HiFlow, and AH Plus (AHP). Materials and methods The study sample consisted of 75 single-rooted and single-canal mandibular premolars, they were randomly distributed into five groups: Group I: root canals preparation and fillings with AHP sealer; Group II: root canals preparation and fillings with EndoSequence BC sealer; Group III: root canals preparation and fillings with BC HiFlow sealer; Group IV (Negative Control): without root canals preparation; and Group V (Positive Control): canals preparation without root canals filling. A glide path was established by #10 hand K-file, then the crowns were cut, and the canals were prepared and filled. All teeth were restored with glass ionomer cement and kept in an incubator at 37°C for a week. All samples were placed within acrylic bases and a vertical force was applied using a Testometric machine and the fracture resistance force was recorded. Results EndoSequence BC and BC HiFlow groups showed slightly better fracture resistance (494.440, 496.960 N respectively) than AHP group (492.680 N). However, no statistically significant difference was found between the two groups (P-value >0.05). The greatest mean fracture force was observed in the positive control group (736.040 N) with statistically significant difference between the other groups (P-value <0.01) and the least mean fracture force was shown in the negative control group (318.040 N) with statistically significant difference between the other groups (P-value <0.01). Conclusion Based on this in vitro study, the use of EndoSequence BC, BC HiFlow, and AHP enhanced the fracture resistance in root-filled single-rooted premolar teeth. While, the application of EndoSequence BC, BC HiFlow, and AHP did not increase the fracture resistance of roots compared to that of unprepared root canals.

Finite element and in vitro study on biomechanical behavior of endodontically treated premolars restored with direct or indirect composite restorations

Objectives of the study were to investigate biomechanical properties of severely compromised premolars restored with composite restorations using finite element analysis (FEA), and in vitro fracture resistance test. A 3-D model of an endodontically treated premolar was created in Solidworks. Different composite restorations were modelled (direct restoration-DR; endo-crown-EC; post, core, and crown-C) with two different supporting tissues: periodontal ligament/alveolar bone (B), and polymethyl methacrylate (PMMA). Models were two-point axially loaded occlusally (850 N). Von Mises stresses and strains were calculated. The same groups were further tested for static fracture resistance in vitro (n = 5, 6.0 mm-diameter ball indenter, vertical load). Fracture resistance data were statistically analyzed (p < 0.050). The highest stresses and strains in all FEA models were observed on occlusal and vestibular cervical surfaces, corresponding to fracture propagation demonstrated in vitro. C showed the lowest stress in dentin, while EC showed lower stresses and strains in crown cement. B models demonstrated larger high stress areas in the root than PMMA models. No significant differences in fracture resistance (N) were observed between groups (DR: 747.7 ± 164.0, EC: 867.3 ± 108.1, C: 866.9 ± 126.3; p = 0.307). More conservative restorations seem a feasible alternative for endodontically treated premolars to conventional post-core-crown.

CBCT Patterns of Bone Loss and Clinical Predictors for the Diagnosis of Cracked Teeth and Teeth with Vertical Root Fracture

AIM

This study aimed to identify clinical and radiographic characteristics of teeth with longitudinal fractures to assist in the diagnosis and differentiation between cracked teeth and teeth with vertical root fracture (VRF).

METHODS

Ninety-five patients (95 teeth) diagnosed with a longitudinal fracture (only cracked teeth or VRF) through clinical visualization of the fracture line were included in this study. Clinical and radiographic data were collected from the patients' record to identify the characteristics associated with each condition. Fifty-four patients (54 teeth) had full radiographic [periapical radiograph (PA) and cone-beam computed tomography scan (CBCT)] and clinical findings (probing depths and clinical images of the fracture line). PA and CBCT images were evaluated by two independent examiners to identify the different patterns of bone loss associated with these teeth (no defect, angular defect, J-shaped defect, combined defect). Cohen Kappa analysis was used to compare the results between the two examiners and between the findings of the PA and the CBCT. Pearson's chi-square analysis, fisher exact test, and Adjusted Bonferroni post Hoc testing were used to establish an association between the type and extension of the longitudinal fracture with the probing depth, the CBCT pattern of bony defects, and the presence/absence of the buccal plate. Also, to compare the clinical and radiographic characteristics of cracked teeth and teeth with VRF (P<0.05).

RESULTS

CBCT images had 4.4 times the odds of detecting bony defects suggestive of longitudinal fractures compared to PA. Teeth with VRF were more associated with indirect restorations, deep probing (>6mm), absence of the cortical plate and a J-shaped defect on the CBCT (P<0.05). Cracked teeth, on the other hand, were associated with direct restorations, shallow probing (<6mm), intact cortical plate, and the presence of an angular defect on the CBCT (P<0.001). There was a significant correlation between a radicular extension of the fracture line and deep probing, as well as J-shaped defects (P<0.05).

CONCLUSION

Patterns of bone loss on the CBCT can likely differentiate between cracked teeth and teeth with VRF. The presence of an angular defect may suggest the presence of a crack in the tooth prior to intervention. J-shaped defects, deep probing (>6mm), and loss of the cortical plate are likely suggestive of VRF.

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.

Management of a radiopaque foreign body associated with a lower first premolar: A case report

Operator mishaps significantly affects root canal treatment outcome. However, several factors affect root canal anatomy of teeth. Therefore, knowledge of teeth anatomy and the use of advanced technologies like cone-beam computed tomography (CBCT), magnification, and illumination are crucial for better diagnostic purposes and to avoid any procedural errors. In this case report, we present a case of a 32-year-old male patient with a radiopaque foreign body associated with a lower first premolar tooth and how do the use of advanced technologies could affect the treatment outcome.

Angiogenesis during coronal pulp regeneration using rat dental pulp cells: Neovascularization in rat molars in vivo and proangiogenic dental pulp cell-endothelial cell interactions in vitro

Background/purpose

Angiogenesis is considered a crucial event for dental pulp regeneration. The purpose of this study was to demonstrate neovascularization during coronal pulp regeneration in rat molars using rat dental pulp cells (rDPCs) and to examine whether rDPC-endothelial cell interactions promote proangiogenic capacity in vitro.

Materials and methods

Maxillary first molars of Wistar rats (n = 42) were pulpotomized and rDPCs isolated from incisors were implanted with a porous poly (l-lactic acid) (PLLA) scaffold and hydrogel (Matrigel). After 3, 7, and 14 days, coronal pulp tissues were examined histologically and by nestin and CD146 immunohistochemistry. rDPCs and rat dermal microvascular endothelial cells (rDMECs) were cocultured for 4 days and vascular endothelial growth factor (VEGF) synthesis and angiogenic factor gene expression were determined by enzyme-linked immunosorbent assays and real-time polymerase chain reaction, respectively. Effects of cocultured medium on tube formation by rDMECs were also evaluated.

Results

Implantation of rDPC/PLLA/Matrigel induced coronal pulp regeneration with dentin bridge formation and arrangement of nestin-positive odontoblast-like cells at 14 days. PLLA/Matrigel without rDPCs did not induce pulp regeneration. CD146-positive blood vessels increased in density in the remaining pulp tissues at 3 and 7 days, and in the regenerated pulp tissue at 14 days. rDPC/DMEC coculture significantly promoted VEGF secretion and mRNA expression of nuclear factor-kappa B, angiogenic chemokine CXCL1, and chemokine receptor CXCR1. Cocultured medium significantly promoted tube formation.

Conclusion

Coronal pulp regeneration with rDPC/PLLA/Matrigel was accompanied by neovascularization. rDPC-rDMEC interactions may promote angiogenic activity represented by proangiogenic factor upregulation and tube formation in vitro.

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.

Periodontal Manifestations in Vertical Root Fractured Teeth

Vertical root fractures are more commonly encountered following endodontic treatment and in teeth without endodontic treatment, with habits like bruxism and eating coarse, hard food. The teeth most predisposed to fracture are the premolars of the maxilla and mandible, the mesial roots and mesiobuccal roots of the mandibular molars, maxillary molars and the mandibular incisors. Timely identification of cracked teeth and fractures is the key since it permits a conservative and preventive approach. Delay in diagnosis and treatment will result in the involvement of the underlying periodontium, causing periodontal pockets, abscess formation, and bone loss, thereby further complicating the outcome. Appropriate diagnosis, education, and counseling of the patient by the dentist and coronal restoration following root canal treatment are mandatory to prevent the loss of teeth in patients. The prognosis of multirooted teeth is more favorable. Affected single-rooted teeth may, however, require immediate extraction. MEDLINE database and Scopus search (www.scopus.com) were performed using the key words “vertical root fracture” or “longitudinal root fracture.” Text book chapters were manually checked.

Effect of different intracanal medicaments on the fracture resistance of the human root

Background:

The effect of different intracanal medicaments on root fracture resistance has not been thoroughly investigated in the short and long term. To assess the effect of calcium hydroxide (CH), CH combined with Chlorhexidine (CHX), double antibiotic paste (DAP), and simvastatin as intracanal medicaments on the fracture resistance of the human root. One hundred and twenty single-rooted mandibular premolars which were extracted for periodontal reasons were collected for this in vitro study.

Materials and Methods:

This was an in vitro study. All teeth were decoronated. Root canals were prepared by the Pro taper system, and %2.5 NaOCl was used for irrigation. The smear layer was removed using %5.25 NaOCl and 17% ethylenediaminetetraacetic acid each for 3 min. The samples were randomly divided into five groups based on the medicament: (1) CH (2) CH + CHX (3) Simvastatin (4) DAP (5) Control group. All specimens in each group were incubated for 1 week (Subgroup A) and 1 month (Subgroup B). Then, medicaments were removed and filled with gutta-percha and AH26 sealer. All samples were tested for fracture resistance. The data were statistically evaluated with the SPSS software 17. ANOVA and Mann–Whitney U and Wilcoxon tests were used for the analysis of the data. P = 0.05 was considered statistically significant.

Results:

Although CH and CH + CHX increased the fracture resistance in a 1-week period, there was no significant difference between the groups after 1 month.

Conclusion:

Under the limitations of this study, CH and CH + CHX, DAP and simvastatin do not have a negative effect on root fracture resistance when used as intracanal medicaments for <1 month.

Vertical Root Fracture in Non-Endodontically and Endodontically Treated Teeth: Current Understanding and Future Challenge

A vertical root fracture (VRF) is a complex complication that usually leads to tooth extraction. The aim of this article is to review the prevalence, demography, distribution, diagnostic methods, etiology and predisposing factors, clinical features, radiographic characteristics and treatment strategies of VRFs in non-endodontically treated teeth (VRFNETT) and endodontically treated teeth (VRFETT). Search terms for each subject related to VRFNETT and VRFETT were entered into MEDLINE, PubMed and Google Scholar. Systematic reviews, retrospective cohort studies, demographic research, clinical studies, case reports and case series were reviewed. Most of the VRFs were found in patients older than 40 years old. Older populations were discovered in the non-endodontically treated VRF group when compared to the endodontically treated VRF group. Male patients were found at a greater prevalence than females in the non-endodontically treated VRF group. The initial occurrence of a VRF may accompany radiolucent lines within the root canal, unusual space between the canal wall and intracanal material, a widening of the PDL space along the periradicular surfaces, angular bony destruction, step-like bone defects, V-shaped diffuse bone defects, or root resorptions corresponding to the fracture line before the clear separation of the fractured fragment. The indicative clinical and radiographic signs of VRF included a coronally positioned sinus tract, deep-narrow periodontal defects, the displacement of a fractured fragment, periradicular radiolucent halos and the widening of the root canal space. Interestingly, VRFNETT are more often observed in the Chinese population. Some patients with multiple VRFs were observed, suggesting possible predisposing factors in genetics and tooth development. The management of a VRF usually involves a multidisciplinary approach. The common distribution and features of VRFNETT and VRFETT were elucidated to facilitate recognition and diagnosis. Besides extraction, variable therapeutic schemes, such as the repair of the VRF, root amputation and others reported in earlier literature, are available. A long-term prognosis study of the various therapeutic strategies is needed.

A critical analysis of research methods and experimental models to study dentinal microcracks

The purpose of this narrative review was to discuss the scientific milestones that led to the current understanding of the root dentinal microcrack phenomenon based on the interplay between the usage of micro-computed tomography (micro-CT) as an analytical tool alongside a close-to-mouth experimental model. In 2009, reports on the development of dentinal microcracks in extracted teeth after root canal preparation triggered an awareness of the potential for vertical root fractures (VRFs) of endodontically treated teeth could be developed from defects created by the mechanical stress of nickel-titanium preparation systems on dentine. This assumption was taken for granted, even though no cause-effect relationship had been scientifically demonstrated. Since then, several studies using the sectioning method with extracted teeth have been published and the large discrepancy amongst their outcomes soon become evident. Moreover, the high frequency of reported dentinal microcracks largely contrasted with the clinical incidence of VRFs, raising doubts on their methodological reliability. Using micro-CT technology, it was demonstrated by several studies that, in extracted teeth, dentinal defects already existed before the endodontic procedures, indicating that the initial reports framed a non-existing cause-effect relationship between canal preparation and dentinal microcracks. Although these new findings contributed to a better comprehension of this phenomenon, the misconception that microcracks were the starting point for VRFs was only surpassed with a new in situ approach using fresh cadavers. Surprisingly, microcracks were not identified in sound teeth. As a conclusion, dentinal microcracks in extracted teeth can be considered a non-natural occurrence observed only in a laboratory set-up as a consequence of dehydration and storage conditions. Thus, dentinal microcracks shall not be considered as the starting point for VRFs as they do not manifest in non-extracted teeth. Identifying dentinal microcracks as a laboratory phenomenon highlights the impact of recent scientific developments to disclaim the clinical relevance of laboratory-obtained outcomes.

A novel insertion design of fiber materials for the adhesive reattachment in vertically fractured teeth

Objective

This ex vivo study aimed to evaluate the strengthening effect of different ferrule and reattachment designs with fiber and adhesive materials on vertically fractured teeth.

Methods

Ninety extracted single-root premolars were instrumented and divided into nine groups (two control groups and seven experimental groups; n = 10). The negative control (NC) group comprised of intact teeth, while the positive control (PC) group comprised of root canal-treated teeth. The roots of the teeth in the experimental groups were vertically fractured into two equal fragments. The fragments were reattached with one of the followings: 4-methacryloxyethyl trimellitate anhydride/methacrylate-tri-n-butyl borane (4-META/MMA-TBB) resin, 4-META/MMA-TBB + quartz fiber post, 4-META/MMA-TBB + glass fiber bundles, 4-META/MMA-TBB + quartz fiber post + 1 mm ferrule, 4-META/MMA-TBB + glass fiber bundles + 1 mm ferrule, 4-META/MMA-TBB + quartz fiber post + 2 mm ferrule, and 4-META/MMA-TBB + glass fiber bundles + 2 mm ferrule. The core build-ups were made with composite resin. The specimens were subjected to compressive loading until failure occurred. Mean load necessary to fracture each sample and the fracture types of these samples were recorded.

Results

The highest mean fracture load was recorded in the NC group (1,036.7 N), which was not significantly higher than the PC group (989.66 N) (p > 0.05). The roots reattached with quartz fiber post demonstrated significantly less fracture strength (871.9 N) as compared to the other test and control groups (p < 0.05). There was no significant difference between the PC group and reattached fragments with different ferrule designs in terms of fracture resistance (p > 0.05).

Conclusions

The customized fiber bundles may be more suitable for reattachment of vertically fractured teeth than the rigid fiber posts. For reattachment procedures, the ferrule design may be preferred to increase the fracture strength of vertically fractured teeth.

Residual Dentin Thickness in Bifurcated Maxillary Premolars after Cervical Preflaring Preparation: A CBCT Analysis

Objective:

This study evaluated the residual dentin thickness (RDT) of maxillary premolars after the use of different cervical preflaring (PF) drills by using cone-beam computed tomography (CBCT).

Methods:

Eighty bifurcated maxillary premolars were accessed and randomly divided into 5 groups (n=16). PF was performed with Gates-Glidden #1, #2, and #3 (group 1), Largo #1 and #2 (group 2), and LA Axxess #20/.06 (group 3), #35/.06 (group 4), and #45/.06 (group 5). CBCT images were acquired before (preoperative) and after (postoperative) PF. Initial and final cervical dentin thickness was measured at the buccal, palatal, mesial, and distal aspects, 0.5 mm coronally to the furcation, on both buccal and palatal roots, using CBCT’s image analysis software. The percentage of removed dentin after PF preparation was also calculated. Data were analyzed using ANOVA followed by Tukey’s test at a significance level of P < 0.05.

Results:

No statistically significant differences were found among the groups for preoperative or postoperative RDT (P > 0.05). LA Axxess #20/.06 (group 3) removed significantly less cervical dentin at all root canal aspects on both buccal and palatal roots. The mesial aspect of the buccal root and distal aspect of the palatal root were significantly reduced after the use of LA Axxess #45/.06 (group 5) and Largo #1 and #2 drills (group 2), respectively (P < 0.05).

Conclusion:

PF in bifurcated maxillary premolars should be performed with LA Axxess instrument #20/.06. The use of Gates-Glidden #1, #2, and #3, Largo #1 and #2, and LA Axxess #45/.06 drills should be done with caution.

An Update on Root Canal Preparation Techniques and How to Avoid Procedural Errors in Endodontics

Background:

Effective root canal treatment involves cleaning and shaping root canals using a range of instrumentation procedures and techniques. The aim of this review was to provide an update on root canal hand instrumentation techniques and how to overcome iatrogenic errors.

Methods:

A comprehensive search was carried out using multiple databases, PubMed, Medline, Google scholar, and Scopus, to identify relevant studies addressing the objective of this study and to summarize the current evidence to readers. Keywords, i.e., endodontics, root canal preparation, hand instrumentation, techniques and procedural errors, as well as, MeSH terms, i.e. “endodontics”, “instrumentation”, “root canal preparation” were used to conduct our comprehensive search.

Results:

The hybrid technique is a commonly-used approach that combines the benefits of both the crown-down and step-back techniques and was reported to be one of the best techniques to produce an optimal root canal preparation outcome. Hand-instrument manipulation using the balanced forced technique is also favoured as it rapidly and safely permits removal of canal contents allowing irrigants and medications to reach deep inside canal spaces.

Conclusion:

The use of hand files is still recommended for initial canal negotiation and preparation and is essential for the correction of procedural errors. This study provided an update on several hand instrumentation techniques commonly used in endodontics. The correct and safe application of these techniques can prevent iatrogenic procedural errors from occurring which optimizes the quality of treatment outcome.

Effectiveness of photon-initiated photoacoustic streaming in root canal models with different diameters or tapers

Background

This study aimed to compare the use of photon-initiated photoacoustic streaming (PIPS) and conventional needle irrigation (CNI) in conjunction with different concentrations of sodium hypochlorite (NaOCl) to remove Enterococcus faecalis (E. faecalis) suspended bacteria and biofilms from root canal systems with different diameters or tapers.

Methods

Artificial root canal samples (n = 480) were randomly divided into three groups (n = 160/group). The canals were prepared to fit file sizes #10/.02, #25/.02, or #25/.06. The size #10/.02 group was incubated for seven days. The size #25/.02 or #25/.06 group was incubated for 2 days. A stable biological model of E. faecalis infection was established. The root canals were washed with distilled water or with 1%, 2%, or 5.25% NaOCl combined with CNI or PIPS. Bacterial suspensions and biofilms were assessed using an ATP assay kit and fluorescence microscopy. Image-Pro Plus was used to analyse the average fluorescence intensity to determine the most suitable root canal irrigation solution.

Results

In the CNI and PIPS groups, the ATP value of the 5.25% NaOCl subgroup was the lowest, followed by that of the 2% and 1% NaOCl subgroups. The ATP value of the distilled water subgroup was the highest (P < 0.05). When the root canal taper was 0.02, the ATP value of the #10/.02 + PIPS group was significantly lower than that of the #25/.02 + CNI group (P < 0.05). The average fluorescence intensity of the #10/.02 + PIPS group was lower than that of the #25/.02 + CNI group (P < 0.05). When the apical diameter was #25, the ATP value of the 0.02 taper in the PIPS group was lower than that of the 0.06 taper in the CNI group (P < 0.05), and the average fluorescence intensity of the 0.02 taper + PIPS group was lower than that of the 0.06 taper + CNI group (P < 0.05). PIPS combined with 2% and 5.25% NaOCl effectively improved the long-term antibacterial effect after irrigation and re-culture for 6 h.

Conclusions

Compared with CNI, PIPS has greater ability to remove bacteria in root canals with a small preparation diameter and a small taper. PIPS with 2% and 5.25% NaOCl exhibited superior antibacterial and bacteriostatic effects.

Comparative Evaluation of Dentinal Microcrack Formation before and after Root Canal Preparation Using Rotary, Reciprocating, and Adaptive Instruments at Different Working Lengths-A Micro-computed Tomographic Study

INTRODUCTION

This study aimed to compare root dentinal microcrack formation after root canal shaping using rotary, reciprocating, and adaptive instruments at different working lengths using micro-computed tomographic imaging.

METHODS

One hundred eighty extracted mature mandibular molar mesial roots with 2 separate canals were selected. The mesial roots were resected at the cementoenamel junction and randomly divided into 4 groups (n = 45) based on the nickel-titanium file system used: ProTaper Universal (Dentsply Maillefer, Ballaigues, Switzerland), ProTaper Gold (Dentsply Maillefer), Twisted File Adaptive (SybronEndo, Orange, CA), and Reciproc Blue (VDW, Munich, Germany). Each of the 4 groups were then subdivided into 3 groups (n = 15) depending on the working length used for root canal preparation (ie, instrumentation 1 mm short, flush, and 1 mm beyond the major apical foramen). The roots were imaged with micro-computed tomographic scanning before and after root canal preparation. The cross-sectional images generated were screened to detect the presence of new microcracks.

RESULTS

The ProTaper Universal system significantly increased the number of postinstrumentation microcracks at all working lengths (P ≤ .05). No significant increase (P > .05) in postinstrumentation microcracks was observed in the ProTaper Gold, Twisted File Adaptive, or Reciproc Blue groups.

CONCLUSIONS

Rotary instrumentation induced a higher number of dentinal microcracks compared with reciprocating and adaptive instruments. Instrumentation at different working lengths did not significantly influence the formation of dentinal microcracks.

Performance of Bioceramic-based Root Filling Material with Artifact Reduction Properties in the Detection of Vertical Root Fractures Using Cone-beam Computed Tomography

Introduction:

In Cone-beam Computed Tomography (CBCT) images, metallic artifacts by root filling materials reduce the quality of images. It seems that bioceramic sealers produce fewer artifacts than gutta-percha. In this situation, the possibility of VRF detection could increase, and therefore, flap and exploratory surgery would not be needed. The purpose of this study was to evaluate the performance of a bioceramic-based root filling material in the detection of Vertical Root Fractures (VRF) in CBCT imaging.

Materials and Methods:

This study was conducted at the dental school from March to August 2019, and 100 healthy human mandibular premolar teeth were obtained and randomly divided into two equal groups. The teeth were filled with either AH26 and gutta-percha or bioceramic root filling materials. VRF was induced on half of the decoronated teeth in each group using a Global Testing Machine, and the others were considered control. CBCT imaging was performed by the Cranex 3D machine. Comparisons of the 2 groups were made using the Mann-Whitney test.

Results:

There was a significant difference between the two groups of bioceramic and gutta-percha in the measured indices, including sensitivity (P=0.017), specificity (P=0.018), positive predictive value (P=0.018), negative predictive value (P=0.018), and accuracy (P=0.011). The Area Under Curve (AUC) also showed a significant difference between the two groups (P=0.011). According to Kappa test results, no significant difference was obtained between the findings of the two observers.

Conclusion:

Different root filling materials showed a different extent of artifact in CBCT images. Bioceramic root filling material induces fewer artifacts in CBCT images, and the diagnostic value of VRF in CBCT images in the root canals filled with it is greater than those filled with AH26 and gutta-percha.

Cemental tear: An overlooked finding associated with rapid periodontal destruction. A case series

Cemental tear is defined as cementum fragment completely or partially detached from the root surface, and it has been associated with localized rapid periodontal breakdown. Although history of trauma and/or attrition may be risk factors, the etiopathology of cemental tear remains unknown. This case series aims to discuss the clinical, radiographic and histopathologic features of cemental tears to aid clinicians in making differential diagnosis. Three teeth from three patients presenting a periradicular lesion underwent an exploratory surgery to determine the cause and provide treatment. Soft and hard tissue biopsies were obtained from each lesion and forwarded for histopathologic evaluation. Two patients received a guided tissue regeneration (GTR) procedure, which allowed the tooth to be retained. One patient received an extraction with simultaneous guided bone regeneration (GBR) due to a hopeless prognosis of the tooth. The results after histopathologic evaluation yielded a final diagnosis of cemental tear for all three patients. Cemental tears may be overlooked, and therefore, they should be included in the differential diagnosis of periapical periodontitis, endodontic-periodontal lesion and vertical root fracture (VRF).

Shrinkage Strains in the Dentin of Endodontically Treated Teeth with Water Loss

INTRODUCTION

Dehydration has been considered as a potential contributor to vertical root fractures (VRFs) after root canal treatment (RCT). A loss of water could cause embrittlement of dentin and detrimental shrinkage strains. Senior patients have the highest risk of VRF. In this study, we characterized the spatial distribution in shrinkage of tooth roots with respect to donor age and prior RCT.

METHODS

Single-rooted human teeth with and without prior RCT were collected from young (age <25 years) and old (age >60 years) adults. Transverse slices were sectioned from the apical, middle, and coronal thirds of the roots, and digital image correlation was used to evaluate shrinkage during free convection. Crack initiation and growth analysis was performed via optical microscopy, and bound water in dentin was characterized by Raman spectroscopy.

RESULTS

The rate of shrinkage was significantly higher (p ≤ .05) in the apical third than in the middle and coronal thirds of all teeth regardless of donor age. The highest shrinkage strain occurred in the apical third of old donor teeth with prior RCT. In addition, the RCT-treated old teeth suffered the highest percentage of water loss with dehydration. Cracks initiated from the root surface and extended toward the canal with loss of water and shrinkage.

CONCLUSIONS

The apical third undergoes significantly larger shrinkage strains with dehydration than the remainder of the root. Prior RCT exacerbates the extent of shrinkage, particularly in the teeth of seniors and after clinical function, which could increase the propensity for VRF.

The effect of taper and apical preparation size on fracture resistance of roots

This study investigated the effect of taper and apical preparation size on the fracture resistance of roots. 84 mandibular incisor teeth were selected. Groups (n = 12): uninstrumented (control group), 25/0.04, 25/0.06, 25/0.08, 30/0.04, 30/0.06 and 30/0.08. K3XF files (Kerr Endodontics, Orange, CA) were used for canal preparation. Fracture resistance was tested using a Universal test machine. For statistical analysis, the level of significance was P ≤ 0.05, and one-way anova and post hoc LSD tests were used. The control group showed the highest fracture resistance (P < 0.05). No significant difference was found between 25/0.04 and 25/0.06; 25/0.06 and 25/0.08; 30/0.04 and 30/0.06; 30/0.06 and 30/0.08; 25/0.04 and 30/0.04; 25/0.06 and 30/0.06; and 25/0.08 and 30/0.08 (P > 0.05). Significant differences were found between 25/0.04 and 25/0.08; 30/0.04 and 30/0.08; and 25/0.08 and 30/0.04 (P < 0.05). In conclusion, the clinical selection of larger tapers can cause a higher risk of fracture.

Detection of Dentinal Microcracks in Radicular Dentin after Shaping with XP-endo Shaper, Neoendo Flex Files, and Hero Shaper Using Scanning Electron Microscope: An In Vitro Study

The study aimed to compare the extent of dentinal microcracks in the radicular dentin using hand K files and various types of rotary nickel-titanium (NiTi) file systems. Forty mandibular incisor teeth (human) were grouped for the study. The root apices were closed, and the canals were straight (<5°). The samples were divided into four groups (n = 10). Group 1-Hand K file system (SybronEndo, SA), Group 2-XP-endo Shaper (FKG Dentaire, La Chaux-de-Fonds, Switzerland), Groups 3-Neoendoflex file (Neoendo, Orikam, India), and Group 4-Hero Shaper files (Micro-Mega, Becacon, France). Sectioning was done at 3, 6, and 9 mm from the apex, perpendicular to the long axis using a diamond disc under water coolant. The cut samples were then observed through a scanning electron microscope at ×50 enlargement. The control group showed no microcracks except one sample in the coronal third, which was less significant. The difference in the amount of crack detected on comparing the different groups was significant. In the experimental groups, XP-endo Shaper group showed significantly less number of cracks than the Neoendo flex, and Hero Shaper groups. Within the limitations of this study, all the system, except hand K files, produced remarkable dentinal microcracks. Least cracks were seen in canals instrumented with XP-endo Shaper. It can also be noted that single file system causes less number of microcracks.

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.

Differences in the corono-apical location of sinus tracts and buccal cortical bone defects between vertically root-fractured and non-root-fractured teeth based on periradicular microsurgery

This retrospective study aimed to investigate whether the corono-apical location of sinus tracts differs according to the presence/location of vertical root fracture (VRF) in microsurgically treated root-filled teeth. The cases included were (1) anterior and premolar teeth without a preoperative diagnosis of VRF, (2) those with a periodontal probing depth of ≤3 mm, and (3) those for which preoperative cone-beam computed tomography (CBCT) scans and intraoperative video records were available. VRF was diagnosed intraoperatively. The locations of buccal cortical bone defects and fracture lines were categorized on video images, and the corono-apical sinus tract locations were determined by superimposing video images onto volume-rendered CBCT images. Eleven of the 78 teeth investigated had VRF, and there was no significant difference in the incidence of sinus tracts between vertically fractured and non-fractured teeth (Mann-Whitney U-test, P > 0.05). The location of the sinus tract was significantly more coronal in vertically fractured than in non-fractured teeth (Mann-Whitney U-test, P < 0.0001). The location of sinus tracts was high correlated with cortical bone defects (Spearman's correlation, P < 0.0001). In microsurgically treated anterior and premolar teeth with a normal probing depth, sinus tracts were located more coronally in vertically fractured than in non-fractured teeth, and were highly correlated with the location of cortical bone defects.

Analysis of clinical associated factors of vertical root fracture cases found in endodontic surgery

BACKGROUND/PURPOSE

Early diagnosis of vertical root fracture (VRF) has been a great challenge. Since there is no single specific etiology identified, prevention of VRFs in endodontically treated teeth is quite difficult. The study aimed to evaluate the clinical associated factors of VRFs.

MATERIALS AND METHODS

A retrospective observational study of medical charts was conducted in the Department of Endodontics of Taipei Medical University Hospital in Taiwan from January 2012 to July 2018. Logistic regression model was performed to determine the association between VRF and its clinical associated factors, inclusive of the tooth characteristics (age, gender and tooth type) and iatrogenic risk factors (history of root canal treatment, restoration and post).

RESULTS

A total of 359 teeth were included in the study. The prevalence of VRF on a tooth basis was 18.7%. The result showed that age of more than 50 years (adjusted OR = 3.20, 95% CI: 1.81-5.64, p < 0.001) had significant higher risk of VRFs than those of less than 50 years. The subjects of molars (adjusted OR = 4.31; 95%CI = 2.24-8.27; P value < 0.001) and premolars (adjusted OR = 2.61; 95%CI = 1.16-5.86; P value = 0.021) had significant higher risk of VRFs than those of incisors. However, other variables such as gender, history of root canal treatment, restoration and post had no significant association with the VRF.

CONCLUSION

Age and tooth type are significant clinical associated factors of VRF. In the presence of these factors as well as predominant diagnostic factors, clinical practitioners should be aware of the possible diagnosis of VRFs.

The Effect of Silver, Zinc Oxide, and Titanium Dioxide Nanoparticles Used as Final Irrigation Solutions on the Fracture Resistance of Root-Filled Teeth

Aim

This study was conducted to evaluate the effect of three nanoparticle solutions used as final root canal irrigants on the fracture resistance of endodontically treated roots.

Materials and Methods

Sixty intact single-rooted premolar teeth were used after removing the crowns below the cementum–enamel junction to standardize the length of the remaining roots to 13 mm. After instrumenting the roots using ProTaper Universal rotary instruments up to size F4, the roots were randomly divided into six groups (n=10) according to the final irrigating solutions: Group 1: normal saline; Group 2: 2% chlorhexidine (CHX); Group 3: 17% EDTA+2.5% NaOCl; Group 4: 17% EDTA+0.1% silver nanoparticle (SNP) solution; Group 5: 17% EDTA+0.1% titanium dioxide nanoparticle (TNP) solution; Group 6: 17% EDTA+0.1% zinc oxide nanoparticle (ZNP) solution. After filling the root canals with gutta-percha and AH Plus sealer, the fracture resistance (FR) values were measured. The data were subjected to the one-way analysis of variance and the Tamhane post hoc test (p=0.05).

Results

EDTA + NaOCl had the lowest FR value, followed by normal saline and CHX (p values < 0.05). No significant difference was found between the FR of roots irrigated with CHX and normal saline (p > 0.05). The application of nanoparticles (SNP, TNP, and ZNP) was associated with a significantly greater FR than that of other irrigation solutions (p values < 0.05).

Conclusion

The final irrigation of root canals with nanoparticles enhanced the fracture resistance of the endodontically treated roots. The lowest FR value was observed for NaOCl.

Digital subtraction radiography in detection of vertical root fractures: accuracy evaluation for root canal filling, fracture orientation and width variables. An ex-vivo study

OBJECTIVE

Ex-vivo evaluation of the detectability of vertical root fractures (VRFs) using digital subtraction radiography (DSR) and conventional digital periapical radiography (CDPR); investigation of the effect of root canal filling, x-ray angulation, and thickness of the VRF in the diagnostic accuracy.

MATERIALS AND METHODS

Sixty root canals were mechanically prepared and radiographed either with a gutta-percha root canal filling or without, at 0^o and ± 10^o. VRFs were introduced with a universal testing machine. The width and angulation of the fracture line with the radiographic beam were calculated. DSR was performed comparing radiographs obtained prior to and after the VRF induction. Five examiners evaluated the resultant images and analysis was performed using receiver operator characteristic (ROC) statistics and binary logistic regression tests.

RESULTS

No significant differences in sensitivity, specificity, and the areas under the ROC curves (AUC) between the CDPR and DSR were detected (p > 0.05), except for root canal filled teeth where the AUC for DSR was higher (p < 0.05). Using DSR, a VRF was 1.3 times more likely to be diagnosed [95% confidence intervals (CI): 1.045-1.59; p = 0.018]. A correct diagnosis was 2.399 times more likely to occur in non-filled teeth regardless of the radiographic technique (95% CI 1.940-2.965; p = 0). The regression coefficients were positive for width and negative for angle.

CONCLUSIONS

DSR showed a better diagnostic accuracy of VRFs compared with CDPR, in single root canal filled teeth. The angulation, the width, and the presence of a root canal filling affected the diagnostic potential.

CLINICAL RELEVANCE

DSR is a cost- and time-effective imaging technique that could contribute in early diagnosis of VRFs.

Effect of Super-Bond C&B and self-adhesive dual-cured resin cement on the fracture resistance of roots with vertical root fracture

Background. Vertical root fracture might occur during root canal preparation, obturation, post procedures or endodontic treatment.

Methods. Fifty-four single-rooted human teeth were decoronated to obtain a standardized length. The root canals were enlarged up to #50 and obturated with gutta-percha and root canal sealer. Eighteen teeth were used as a control group, and vertical root fracture was induced in the remaining teeth. The samples were randomly divided into three groups, as follows: control group (without vertical root fracture), Super-Bond C&B group (fragments were attached with Super-Bond C&B), and self-adhesive dual-cured resin cement group (fragments were attached with self-adhesive dual-cured resin cement). Each specimen was subjected to a fracture resistance test, and data were statistically analyzed using chi-squared test, one-way ANOVA and post hoc Tukey tests (P=0.05).

Results. The fracture resistance values of the control and Super-Bond C&B groups were higher than those of the self-adhesive dual-cured resin cement group (P<0.05). However, there were no significant differences between the control and Super-Bond C&B groups (P>0.05).

Conclusion. Within the limitations of the present study, Super-Bond C&B was beneficial in obtaining higher fracture resistance in endodontically treated roots with vertical root fracture.

Endodontically treated posterior teeth restored with or without crown restorations: A 5-year retrospective study of survival rates from fracture

AIM

The aim of the present study was to investigate survival rates from fracture of endodontically treated posterior teeth (ETT) restored with or without crowns with recall periods of up to 5 years.

METHODS

ETT with single-unit crown or resin composite restorations were studied based on the inclusion criteria. Restoration, tooth structure loss, adjacent teeth, fracture, and restorability were recorded. Survival rates from fracture were calculated, and risk factors were identified.

RESULTS

Overall, survival rate of ETT with crowns (92.2%) was significantly higher than resin composites (77.4%) (P < 0.05). ETT with one or two surface loss/es and two adjacent teeth had a high survival rate of 86.9%, which was not significantly different to ETT with crowns (P ≥ 0.05). Restoration and adjacent teeth were identified as significant factors. The majority of fractured ETT with resin composites were restorable, whereas those with crowns were unrestorable. Survival rates from unrestorable fracture were not significantly different between the crown (93.1%) and resin composite (96%) (P ≥ 0.05).

CONCLUSIONS

The survival rate from the fracture of ETT restored with crowns was significantly higher than ETT restored with resin composites, but was not significantly different to ETT with one or two ETT with one or two surface loss/es and two adjacent teeth. ETT restored with resin composites had mostly restorable fracture, whereas ETT with unrestorable fracture were similar between the two restorations.

The detection of vertical root fractures in post-core restored teeth with cone-beam CT: in vivo and ex vivo

OBJECTIVES

To compare the accuracy of cone-beam CT ex vivo and in vivo for the detection of artificially created large and small vertical root fractures in extracted teeth restored with post-core.

METHODS

Individual metal cast post-cores were fixed in the root canals of 50 extracted single-rooted human teeth. In 30 teeth fractures were created by tapping posts with a hammer. The teeth were sterilised in autoclave and embedded into bite-plates made of silicon impression material. Cone-beam CT scanning was performed ex vivo and in vivo . For the in vivo scanning, teeth in sterile plastic bags were inserted into the mouths of volunteers. Then the teeth were sectioned with low-speed saw and the widths of the VRFs were measured microscopically. The teeth were distributed into 2 groups in accordance with the measured fractures' widths: large (wider than 180-250 µm) and small (80-150 µm). Five observers assessed the presence of vertical root fractures on axial CBCT slices. Sensitivity, specificity, accuracy and inter examiner agreement were calculated.

RESULTS

The accuracy of cone-beam CT in vitro for large and small vertical root fractures detection was 0.56 and 0.40 respectively (p = 0.043). The sensitivity values were 0.53 and 0.27 for large and small vertical root fractures, respectively (p = 0.043). The visualisation of fracture lines in vivo was impossible in 90 % of cases, because of low image quality. Inter examiner reliability analysis showed κ values ranging from 0.02 to 0.54.

CONCLUSIONS

Fracture width affected the in vitro detectability of vertical root fractures by cone-beam CT in teeth with metal cast post-cores. The detectability of root fractures in vivo was decreased because of low image quality, making the assessment of sound tooth tissue impossible.

[Algorithm of radiological examination of patients with inflammatory and destructive bone changes in lower molars area]

The study presents the analysis and comparison of orthopantomogram (OPG) and cone-beam computed tomograms (CBCT) of 62 patients with inflammatory-destructive processes of bone in the lower molars area. The analysis resulted in an algorithm of radiological examination of patients with selected pathologies for diagnosis and definition of further treatment tactics.

Effect of object position in the field of view and application of a metal artifact reduction algorithm on the detection of vertical root fractures on cone-beam computed tomography scans: An in vitro study

Purpose

To assess the effects of object position in the field of view (FOV) and application of a metal artifact reduction (MAR) algorithm on the diagnostic accuracy of cone-beam computed tomography (CBCT) for the detection of vertical root fractures (VRFs).

Materials and Methods

Sixty human single-canal premolars received root canal treatment. VRFs were induced in 30 endodontically treated teeth. The teeth were then divided into 4 groups, with 2 groups receiving metal posts and the remaining 2 only having an empty post space. The roots from different groups were mounted in a phantom made of cow rib bone, and CBCT scans were obtained for the 4 different groups. Three observers evaluated the images independently.

Results

The highest frequency of correct diagnoses of VRFs was obtained with the object positioned centrally in the FOV, using the MAR algorithm. Peripheral positioning of the object without the MAR algorithm yielded the highest sensitivity for the first observer (66.7%). For the second and third observers, a central position improved sensitivity, with or without the MAR algorithm. In the presence of metal posts, central positioning of the object in the FOV significantly increased the diagnostic sensitivity and accuracy compared to peripheral positioning.

Conclusion

Diagnostic accuracy was higher with central positioning than with peripheral positioning, irrespective of whether the MAR algorithm was applied. However, the effect of the MAR algorithm was more significant with central positioning than with peripheral positioning of the object in the FOV. The clinical experience and expertise of the observers may serve as a confounder in this respect.

The association between clinical diagnostic factors and the prevalence of vertical root fracture in endodontic surgery

BACKGROUND/PURPOSE

Diagnosis of vertical root fractures (VRFs) can often be challenging due to the similarity of signs and symptoms with other common dental infectious diseases. This study was aimed at evaluating the potential relationship between VRFs and commonly used clinical diagnostic factors.

METHODS

330 root-filled teeth with endodontic failures were subjected to endodontic microsurgery over a six-year period. VRFs were identified in 61 teeth. A randomly age- and sex-matched retrospective case-control study was conducted on a subset of 59 root-filled teeth with VRFs (cases) and 177 root-filled teeth without VRFs (controls). The strength of association between preoperative signs and radiographic findings and VRFs was evaluated using logistic regression model.

RESULTS

Sinus tract, periodontal pocket depth ≥5 mm, periodontal swelling or abscess, and radiological image of J-shaped or "halo" radiolucency were significantly more frequent in cases than in controls (p < 0.05). With regard to logistic regression analysis, J-shaped or "halo" radiolucency demonstrated the greatest association with VRF, followed by periodontal pocket depth ≥5 mm, sinus tract, and periodontal swelling or abscess. Approximately 70% of cases manifested themselves as combinations of at least two of these factors. Teeth having two and three or four of these factors had 3.14 times and 11.64 times higher risks for the presentations of VRFs, respectively (p < 0.001).

CONCLUSION

The major risk for VRFs was represented by those presenting radiological image of J-shaped or "halo" radiolucency, periodontal pocket depth ≥5 mm, sinus tract, and periodontal swelling or abscess simultaneously.