Biomechanical Evaluation of the Mandibular First Molar After Simulated Occlusal Wear Using 3D Finite Element Analysis

PURPOSE：This study aimed to investigate the biomechanical basis of vertical tooth fracture occurring in the mesial root of the mandibular first molar. METHODS：We used 3D finite elements to analyze the stress distribution and transient displacement of the mandibular first molar after occlusal surface wear and tooth tilt. Based on four degrees of wear within each of the surface wear and tooth tilt groups, eight models were established in addition to the control model. A simulated bite force of 200 N was loaded on the occlusal surface, and nonlinear finite element analysis was used to explore the biomechanical basis of vertical root fracture. RESULTS：When the distal tipping angle of the abrasion plane of the mandibular first molar increased from 5° to 15°, the angle between the instantaneous displacement contours and the long axis of the tooth decreased. Meanwhile, the mesial root was found to suffer the highest stress concentration, and the possibility of longitudinal root fracture was increased. CONCLUSION: By evaluating the biomechanical effect of tooth wear and occlusal loading, we are able to identify some clinical interventions that may prevent vertical tooth fracture.

New-onset haemoptysis and associated lung mass in the setting of dental care avoidance during the COVID-19 pandemic

We present a case of new-onset haemoptysis and associated lung lesion on chest imaging in the setting of the COVID-19 pandemic. This was believed to be due to dental care avoidance after tooth fracture and long-term use of temporary dental filler, with subsequent aspiration and bronchial injury. Our patient underwent bronchoscopy due to persistent haemoptysis with findings of mild traumatic injury. She responded to conservative management with no pharmacologic intervention. With time, there was resolution of symptoms and radiographic improvement of the lung lesion. We include a brief discussion on the influence of the COVID-19 pandemic on healthcare avoidance, complications of tooth fracture and the differential diagnosis of a new solitary lung lesion on chest imaging.

Fundamental mechanics of tooth fracture and wear: implications for humans and other primates

Until recently, there had been little attempt in the literature to identify and quantify the underlying mechanics of tooth durability in terms of materials engineering concepts. In humans and most mammals, teeth must endure a lifetime of sustained occlusal mastication—they have to resist fracture and wear. It is well documented that teeth are resilient, but what are the unique features that make this possible? The present article surveys recent materials engineering research aimed at addressing this fundamental question. Elements that determine the mechanics and micromechanics of tooth fracture and wear are analysed: at the macrostructural level, the geometry of the enamel shell and cuspal configuration; and at the microstructural level, interfacial weakness and property gradients. Inferences concerning dietary history in relation to evolutionary pressures are discussed.

Naturally-occurring tooth wear, tooth fracture, and cranial injuries in large carnivores from Zambia

Determining the incidence and causes of craniodental damage in wild carnivores is often constrained by limited access to specimens with associated ecological data, such as prey type and abundance. We assessed dental condition and cranial injuries in lion, leopard, and spotted hyena in relation to prey and predator populations in Zambia’s Luangwa Valley, where large prey are more abundant and lion and leopard more numerous, and the Greater Kafue Ecosystem, where smaller prey species are more prevalent and lion and leopard less common. In Luangwa, lions had significantly higher rates of tooth fracture, and blunt trauma injuries attributable to prey-handling, compared to Kafue lions. In contrast, leopards in both regions had similar rates of tooth wear and breakage. Overall, lions showed a significantly higher tooth fracture rate than leopards on a per tooth basis. Spotted hyenas had the highest rates of tooth wear and fracture among all three carnivores, and greatly exceeded previously recorded rates based on historical samples. Despite larger numbers of lion and leopard in Luangwa, there was no difference in incidence of intraspecific injuries between regions. These results are consistent with a greater abundance of large prey species, especially buffalo, in the diets of Luangwa lions, and previous work showing a reliance on smaller prey species in Kafue throughout the large carnivore guild.

A Multidisciplinary Approach to the Management of inadequate clinical crown of Maxillary Central incisor: A Clinical Report

Introduction: Anterior tooth fracture is the most commonly presenting clinical condition during routine dental practise. Restoration of such tooth is challenging task due to fracture position and amount of remaining coronal tooth structure. Tooth fracture at or below the gingival level usually have a poor prognosis. Treatment options for such clinical conditions range from tooth extraction to prosthodontic rehabilitation with surgical crown lengthening and/or orthodontic extrusion. This clinical report describes a multidisciplinary approach for management of such cases by the orthodontic forced eruption and clinical crown lengthening followed by the final restoration with indirect resin customized post core and crown.

PENATALAKSANAAN FRAKTUR ELLIS KELAS III 11 DENGAN PULPEKTOMI DAN RESTORASI MAHKOTA PASAK

A 19-year-old male patient came to Unud Hospital with a complaint that his upper right front tooth was broken. The patient's right front toothaches when he consumes cold food or drinks and bleeds every morning. Pain still exists even if food or cold drinks are removed. Complaints felt since 7 months ago. The tooth now feels pain but is not as severe as the initial tooth fracture. Patients have consumed mefenamic acid to reduce pain. The tooth has never been treated by a dentist. The patient is now treated with pulpectomy accompanied by a fused to metal porcelain jacket crown restoration with a cast post-core. After controlling for one week after treatment, the desired result is the loss of subjective and objective complaints in the patient.

Injury Prevention, Safety Education and Violence in Relation to the Risk of Tooth Fracture among Korean Adolescents

This study aimed to determine the injury prevention-, safety education-, and violence-related factors pertaining to tooth fracture experience (TFE) in Korean adolescents. We used data from the 14th Korea Youth Risk Behavior Survey (KYRBS) in 2018. The 60,040 participants were selected using a complex sampling design from middle and high schools. The participants completed a self-administered questionnaire. The explanatory variables, including school safety education and violence, were assessed in relation to prevention of traumatic injuries. Complex-samples multivariable logistic regression models were applied to explain the factors related to TFE over the past 12 months. The overall prevalence of TFE was 11.4%. Risk factors related to tooth fractures were not wearing a seatbelt on an express bus, not wearing helmets while riding motorcycles and bicycles, clinical treatment due to injuries at school, injuries associated with earphone/smartphones use, and lack of school safety education such as danger evacuation training. The top risk factor was injuries associated with earphone/smartphone usage, followed by lack of familiarity with school safety education. Thus, to prevent tooth fractures among adolescents, schools should strengthen their safety education, including education regarding mobile device usage, and wearing a seatbelt and wearing a helmet. Care should be taken to manage facilities around the school and to prevent injury related to tooth fracture. Further studies on various risk factors related to tooth fractures are warranted.

Health-Risk Behavior-, Mental Health-, and Physical Exercise-Related Risk Factors for Tooth Fractures in Korean Adolescents

We aimed to determine factors related to tooth fracture experience in Korean adolescents. This study used data from the 14th Korea Youth Risk Behavior Survey in 2018, a cross-sectional web-based survey of health-risk behaviors among a representative sample of Korean middle- and high-school students aged 12–17 years. A total of 60,040 participants were selected using a complex sampling design of the survey from 400 middle schools and 400 high schools. They answered a self-administered questionnaire survey in classrooms. Explanatory variables included those pertaining to health-risk behaviors, mental health, and physical exercise. Complex-sample multivariable logistic regression models were applied to identify factors related to tooth fracture experience in the past 12 months. The overall prevalence of dental fracture experience was 11.4%. Risk factors related to tooth fractures in Korean adolescents were unhealthy behaviors such as alcohol and tobacco consumption; mental health problems including stress, depression, and suicidal ideation; and intensive physical exercise. The major risk factor related to tooth fractures was depression. To prevent tooth fractures among adolescents, schools should strengthen mental health education, encourage mouthguard use during intensive physical exercise, and develop school environments to prevent orofacial injuries. Further studies on various risk factors related to tooth fractures are warranted.