Modeling fracture in multilayered teeth using the finite volume-based phase field method.

The present work, utilizing the finite volume-based phase field method (FV-based PFM), aims to investigate the initiation and propagation of cracks in the second molar of the left mandible under occlusal loading. By reconstructing cone beam computed tomography scans of the patient, the true morphology and internal mesostructure of the entire tooth are implemented into numerical simulations, including both 2D slice models and a realistic 3D model. Weibull functions are introduced to represent the tooth's heterogeneity, enabling the stochastic distribution characteristics of mechanical parameters. The results indicate that stronger heterogeneity leads to greater crack tortuosity, uneven damage distribution, and lower fracture stress. Additionally, different cusp angles (50° and 70°) and pre-existing fissure morphologies (i.e., U-shape, V-shape, IK-shape, I-shape, and IY-shape) also significantly affect the mechanical performance of the tooth. The study reveals that different cusp angles affect the location of crack initiation. Overall, this work demonstrates the utility of the FV-based PFM framework in capturing the complex fracture behavior of teeth, which can contribute to improved clinical treatment and prevention of tooth fractures. The insights gained from this study can inform the design of dental crown restorations and the optimization of cusp inclination and contact during clinical occlusal adjustments.

Effect of Pulp Chamber Access, Instrumentation, Obturation, and Restoration on the Fracture Resistance of Endodontically Treated Canine Teeth in Dogs.

Veterinary studies documenting the effect of endodontic treatment on tooth fracture resistance are scarce. The objective of this ex vivo study was to evaluate the effects of mesial access preparation and restoration, as well as pulp chamber access, instrumentation, obturation, and restoration, on the fracture resistance and characteristics of canine teeth in dogs. Sixty-five dog canine teeth were divided into 4 groups: 1. Standard endodontic treatment through a mesial access only; 2. Treatment as per group 1, adding an incisal access, instrumentation and obturation of the pulp chamber, and restoration of the access; 3. Treatment as per group 2, without pulp chamber obturation or restoration of the incisal access; and 4. Untreated teeth. The fracture resistance and characteristics of each group were documented using axial compression testing, angled 45° disto-occlusal to the long axis of the crown. The maximum force prior to fracture in groups 1, 3, and 4 were not statistically different, demonstrating that restored mesial and incisal accesses with pulp chamber instrumentation did not statistically affect fracture resistance. However, obturated and restored group 2 teeth demonstrated decreased fracture resistance compared to all other groups (P < .001). Additionally, 26.7% of group 1 teeth sustained complicated crown fractures, while 100% of group 2 teeth fractured within the obturation or restorative materials, preventing pulp exposure in these cases. Although the cause and clinical importance of decreased tooth fracture resistance following pulp chamber obturation and restoration remains unknown, it may provide protective value for maintaining a coronal seal in the event of tooth fracture.

Fracture Strength of Tooth Roots Following Canal Preparation by Three Rotary File Systems: An In Vitro Study.

BACKGROUND: Since the beginning of modern endodontics, there have been many concepts, strategies, and techniques for root canal preparation. A mind-boggling variety of files have developed for negotiating and shaping them throughout the years. Today's most secure, most effective, and simplest file system combines the most reliable design elements of the past with the latest technological advances to create the most effective file system. So, the need for the study is to evaluate the fracture strength of tooth roots following canal preparation by three rotary file systems: ProTaper Universal file system (Dentsply, USA), ProTaper Next file system (Dentsply Sirona USA), and Neolix A1 nickel-titanium (NiTi) file system (Orikam Healthcare India Pvt Ltd., New Delhi, India). METHOD: Ninety human mandibular molars were selected for the study. Inclusion criteria include human mandibular first and second molars and teeth removed for routine clinical reasons, and intact apices were selected, excluding cases with root surface caries, root surface fissures, teeth with immature root apex, mesial canal fusion, extremely short roots, thin roots, or curved roots. All teeth were preserved in a solution of 10% neutral buffered formalin for two weeks and then transferred to distilled water for examination. The teeth were randomly divided into three groups. Access cavities were created, and working lengths were determined. Groups 1, 2, and 3 underwent shaping using ProTaper Universal, ProTaper Next, and Neolix A1 (NiTi) file systems, respectively, following guidelines. Canals were irrigated with sodium hypochlorite and ethylenediaminetetraacetic acid (EDTA) and were obturated up to the mid-root region with AH Plus sealer. To facilitate fracture testing, obturation was performed to distribute the load from the spreader to the canal wall. The EndoSequence and Quick-Fill obturation system were utilized to fill the apical half of the canal with gutta-percha material. After obturation, the distal root of each tooth was cut, while the mesial root was securely positioned in a putty material. A universal testing machine was employed for the fracture tests, operating at a cross-head speed of 1 mm/min. The machine was equipped with a D11 hand spreader tip, which was inserted into the root canal to make contact with the gutta-percha. Gradual force was applied to the root canal until a fracture occurred, at which point the force application was stopped. The amount of force required to cause the fracture was measured in newtons. Data were collected and recorded using IBM SPSS Statistics for Windows, Version 17.0 (Released 2008; IBM Corp., Armonk, New York, United States) and then transferred to Microsoft Excel for analysis. Descriptive statistics, mean, and standard deviation were used for continuous data. The fracture resistance of dental roots treated with three types of files was compared using a one-way ANOVA. Graphs were generated using Excel and Word. A significance level of p<0.01 was chosen. RESULT: ANOVA indicated significant differences in mean fracture resistance: Neolix A1 (NiTi) (95.3 N) > NEXT (91.0 N) > universal (86.6 N), with a p-value of 0.004 (<0.001), confirming statistical significance. CONCLUSION: The study concludes that the canal instrumented with Neolix A1 (NiTi) exhibits higher fracture resistance after canal instrumentation compared to ProTaper Next and ProTaper Universal.

Outcomes of root canal treatments with three different sealers for 120 fractured maxillary fourth premolar teeth in small-to medium-sized dogs.

Introduction: Tooth fracture is one of the most common traumatic maxillofacial injuries in dogs and cats. For fractures with pulp exposure occurring in functionally important teeth, the literature indicates that root canal treatment (RCT) is an effective therapy option that may be the remedy of choice before extraction. The most commonly reported fractures in the United States involve canine teeth; however, fractures of the maxillary fourth premolars are more common in Korea, where there are many small-and medium-sized dogs. RCT mechanically and chemically removes pulp tissue and bacteria (cleaning and shaping) from the infected root canal, and obturates the root canal with filling material to restore tooth functionality without inflammation. Various techniques, instruments, and materials used in humans have been modified for application in veterinary dentistry. Methods: This study analyzed the results of RCT of the maxillary fourth premolar in 120 small-and medium-sized dogs (weighing less than 25 kg) using three different sealers (silicone-based sealer, bioceramic sealer, and calcium hydroxide-based sealer) through a simple application of the single-cone technique. Results: The overall success rate of RCT in maxillary fourth premolars was 90.83%, with 8.33% no evidence of failure (NEF) and 0.83% failure. Discussion: There were no significant differences between the three different sealers. Furthermore, preexisting periapical lesion (PAL) was reconfirmed as a factor in reducing the success rate of RCT. In addition, the working length and master apical file of each root were analyzed in our study as a novel reference for endodontic veterinarians.

Factors Influencing Vertical Radicular Fractures in Teeth Supported by Metallic Dental Core: A Scoping Review.

Purpose: The aim of this work is to conduct a literature review to highlight all the parameters involved in sub-prosthetic radicular fractures of teeth supported by metallic dental core. Materials and Methods: The following research was performed among published studies over the last 10 years in two PubMed/Medline and Scopus and supplemented by manual searching within the bibliographies. The search was restricted to publications in English and French. Results: Out of the 1464 articles initially identified, 18 studies met our inclusion criteria and were subsequently included in the literature review. These consisted of eight Finite Element Analysis Studies, two Retrospective Studies and one Randomized Controlled Trial. The results of this review show that radicular fractures are influenced by several variables, including predisposition, with maxillary premolars and mandibular molars being the most commonly affected teeth. Intracanal preparation can induce crack formation, leading to localized high stress concentrations. Increased ferrule height to 2 mm significantly enhances dental fracture resistance. Using high modulus of elasticity alloys results in nearly complete stress transmission to dentin due to their limited deformability and absorption capacity. The highest fracture resistance is achieved when posts are sealed using resin-modified glass-ionomer cement. Longer posts may be preferable to prevent vertical fractures. Additionally, occlusal factors, through repetitive stresses, contribute to crack propagation from surface defects, a phenomenon termed fatigue fracture. Conclusion: These findings have significant implications. Practitioners should be aware of the predisposition of certain teeth, the importance of preserving the ferrule effect, the choice of root post materials, post Cement Material and the role of occlusal forces in managing and preventing vertical root fractures.

The International Association of Dental Traumatology (IADT) and the Academy for Sports Dentistry (ASD) guidelines for prevention of traumatic dental injuries: Part 1: General introduction.

The Guidelines for Prevention of Traumatic Dental Injuries were reviewed and approved by the Board of Directors of the International Association of Dental Traumatology (IADT) and the Academy for Sports Dentistry (ASD).

The International Association of Dental Traumatology (IADT) and the Academy for Sports Dentistry (ASD) guidelines for prevention of traumatic dental injuries: Part 4: Faceshields for the prevention of dental and oral trauma.

The Guidelines for Prevention of Traumatic Dental Injuries were reviewed and approved by the Board of Directors of the International Association of Dental Traumatology (IADT) and the Academy for Sports Dentistry (ASD).

The International Association of Dental Traumatology (IADT) and the Academy for Sports Dentistry (ASD) guidelines for prevention of traumatic dental injuries: Part 5: Secondary prevention of dental injuries.

The Guidelines for Prevention of Traumatic Dental Injuries were reviewed and approved by the Board of Directors of the International Association of Dental Traumatology (IADT) and the Academy for Sports Dentistry (ASD).

The International Association of Dental Traumatology (IADT) and the Academy for Sports Dentistry (ASD) guidelines for prevention of traumatic dental injuries: Part 3: Mouthguards for the prevention of dental and oral trauma.

The Guidelines for Prevention of Traumatic Dental Injuries were reviewed and approved by the Board of Directors of the International Association of Dental Traumatology (IADT) and the Academy for Sports Dentistry (ASD).

The International Association of Dental Traumatology (IADT) and the Academy for Sports Dentistry (ASD) guidelines for prevention of traumatic dental injuries: Part 10: First aid education.

The Guidelines for Prevention of Traumatic Dental Injuries were reviewed and approved by the Board of Directors of the International Association of Dental Traumatology (IADT) and the Academy for Sports Dentistry (ASD).

The International Association of Dental Traumatology (IADT) and the Academy for Sports Dentistry (ASD) guidelines for prevention of traumatic dental injuries: Part 2: Primary prevention of dental trauma across the life course.

The Guidelines for Prevention of Traumatic Dental Injuries were reviewed and approved by the Board of Directors of the International Association of Dental Traumatology (IADT) and the Academy for Sports Dentistry (ASD).

The International Association of Dental Traumatology (IADT) and the Academy for Sports Dentistry (ASD) guidelines for prevention of traumatic dental injuries: Part 6: Education.

The Guidelines for Prevention of Traumatic Dental Injuries were reviewed and approved by the Board of Directors of the International Association of Dental Traumatology (IADT) and the Academy for Sports Dentistry (ASD).

The International Association of Dental Traumatology (IADT) and the Academy for Sports Dentistry (ASD) guidelines for prevention of traumatic dental injuries: Part 8: ToothSOS app.

The Guidelines for Prevention of Traumatic Dental Injuries were reviewed and approved by the Board of Directors of the International Association of Dental Traumatology (IADT) and the Academy for Sports Dentistry (ASD).

Investigation of Anterior Teeth Fractures Among Students Aged Between 8 and 13 Years in Hyderabad, India.

Introduction Trauma involving anterior teeth stands as a prevalent type of dental injury among school-age children, impacting physical, psychological, and social well-being. This study aimed to assess the occurrence of fractures in anterior teeth among school children in Hyderabad and its associated risk factors. Materials and methods This research incorporated a cross-sectional analysis, involving 2046 children in the age group of 8 to 13 years from different schools in Hyderabad City. Alongside clinical evaluations, all participants completed a questionnaire regarding traumatic dental injuries.  Results Results indicated a prevalence rate of 8.5%, notably higher among younger boys. Factors such as lip competence coverage, increased overjet, and malocclusion with maxillary incisor proclination were associated with a heightened risk of such injuries. The peak incidence was observed at age 12, with fractures involving enamel and dentin being the most common type, predominantly affecting the maxillary central incisors. Conclusion The findings emphasize the significance of educational programs aimed at enhancing awareness and understanding of dental injuries among parents, students, and school staff.

Mechanisms of dental injuries in basketball, United States, 2003-2022.

BACKGROUND/AIM: Oral injuries such as oral soft tissue lacerations and contusions can occur in basketball by mechanisms such as running into other players or falling. Given a high enough impact force, dental injuries such as tooth fractures and avulsions can occur. Previous research has studied the different types of oral injuries as well as the mechanisms that cause them. Yet, the mechanisms resulting in dental injuries have remained unexplored. The aims of this study were to investigate the distribution of different oral injuries within each injury mechanism and evaluate which mechanisms were most likely to lead to a dental injury. MATERIALS AND METHODS: This is a retrospective cohort study using the National Electronic Injury Surveillance System (NEISS). Subjects who experienced oral injuries from basketball between January 1, 2003 and December 31, 2022 were included in this study. The independent variable was the injury mechanism. The dependent variable was the dental injury outcome (yes/no). Multivariate logistic regression was used to measure the association between the injury mechanism and the dental injury outcome. A p < .05 was considered statistically significant. RESULTS: This study included 4419 subjects who experienced oral injuries (national estimate, 138,980). Approximately 14.7% of oral injuries were dental injuries. Subjects experiencing collisions with objects such as walls or the basketball hoop (odds ratio (OR), 4.39; p < .001), falls (OR, 3.35; p < .001), or contact with the basketball (OR, 1.77; p = .006) had significantly higher odds of sustaining a dental injury relative to those experiencing contact with another player. CONCLUSIONS: Basketball players experiencing contact to the mouth have high odds of sustaining a dental injury. An understanding of injury mechanisms is important for medical teams to manage these injuries and for coaches to educate athletes on safe and proper playing styles. Furthermore, healthcare providers and basketball staff should encourage athletes to wear mouthguards to reduce the risk of traumatic dental injuries.

Retrospective Assessment of Endodontically Treated Teeth Replaced by Dental Implants.

INTRODUCTION: This study investigated endodontically treated teeth that were replaced by dental implants at the University of North Carolina (UNC) at Chapel Hill School of Dentistry. The primary objective of this study was to determine the reasons leading to the extraction of endodontically treated teeth and their subsequent replacement with dental implants. The secondary objective was to evaluate the proportion of these teeth that, according to experienced endodontists, could have been preserved. METHODS: The UNC-Chapel Hill's dental electronic health records between 2004 and 2019 were probed for implant placement that replaced root canal-treated teeth. Preextraction radiographs and clinical charts were examined to ascertain the primary reason related to the extraction and to compile a profile for each case. In cases in which endodontic failure was the primary reason for extraction, radiographs and clinical findings were evaluated by 2experienced endodontists to assess potential treatment options. RESULTS: Between 2004 and 2019, 29.3% (1564 of 5229) of teeth replaced by dental implants at UNC School of Dentistry had undergone root canal treatment, with the mandibular first molar being the most commonly replaced tooth. The leading reasons for extraction were recurrent caries associated with defective restoration (26.6%), fracture of coronal structure (21.5%), vertical root fracture (20.9%), compromised periodontal condition (13.8%), and endodontic failure (2.4%). Two experienced endodontists evaluated extractions due to endodontic failure and concluded that 61.7% of them could have been candidates for endodontic retreatment. CONCLUSION: Substantial loss of tooth structure was the leading cause of extraction of root canal-treated teeth, followed by vertical root fracture and periodontal disease. Although endodontic failure constituted a minor portion of the reasons for extraction, a considerable number of teeth were extracted due to vertical root fractures following root canal treatment. A significant proportion of the extracted teeth due to endodontic failure could have been considered as potential candidates for endodontic retreatment.

Crown Fragment Reattachment by the Minimal Intervention Approach for Coronal Tooth Fractures: A Case Series.

Dental trauma is the most frequently encountered injury that requires immediate attention. Several procedures are available to manage broken teeth afflicted by trauma but the choice of procedure depends upon structural, functional, and esthetic considerations. The goal is to choose the least invasive, immediate, and simple technique that can meet the patient's expectations. The aim of this case series is to present a minimal intervention approach as a primary treatment option for the reattachment of trauma-induced fractured coronal tooth fragments, to preserve and enhance function, esthetics, and structure.

Computer-Aided Design/Computer-Aided Manufacturing of Customized Abutment for Rehabilitating a Malpositioned Implant Using Digital Flow: A Case Report.

This study presented a rehabilitation option for malpositioned implants; this involved obtaining their position and inclination through intraoral scanning, and producing a customized abutment with CAD/CAM technology. The patient in this case report presented a root fracture in tooth 21 and was subjected to extraction, implant installation, and immediate provisional prosthesis. The implant was installed with a distal inclination due to anatomical limitations. After osseointegration, an intraoral scanning transfer provided a digital model (file extension .stl), which reproduced the implant's position and inclination. Then, the file was sent so that a customized abutment (CAD/CAM) could be manufactured, promoting the final rehabilitation of the case; this allowed for good hygiene, load distribution in the dynamic interocclusal relationship, and favorable esthetics, whereas many would otherwise recommend implant removal. The result presented lower costs, a shorter time frame, and a lower morbidity for the patient.