Influence of bone definition and finite element parameters in bone and dental implants stress: A literature review

This article belongs to the Special Issue New Trends in Bioengineering in Osseointegration and Dental Implants.Bone plays an important role in dental implant treatment success. The goal of this literature review is to analyze the influence of bone definition and finite element parameters on stress in dental implants and bone in numerical studies. A search was conducted of Pubmed, Science Direct and LILACS, and two independent reviewers performed the data extraction. The quality of the selected studies was assessed using the Cochrane Handbook tool for clinical trials. Seventeen studies were included. Titanium was the most commonly-used material in dental implants. The magnitude of the applied loads varied from 15 to 300 N with a mean of 182 N. Complete osseointegration was the most common boundary condition. Evidence from this review suggests that bone is commonly defined as an isotropic material, despite being an anisotropic tissue, and that it is analyzed as a ductile material, instead of as a fragile material. In addition, and in view of the data analyzed in this review, it can be concluded that there is no standardization for conducting finite element studies in the field of dentistry. Convergence criteria are only detailed in two of the studies included in this review, although they are a key factor in obtaining accurate results in numerical studies. It is therefore necessary to implement a methodology that indicates which parameters a numerical simulation must include, as well as how the results should be analyzed

Análisis del comportamiento mecánico del conjunto implante dental-prótesis ubicado en huesos con distintas densidades ante cargas fisiológicas

Los implantes dentales son unos dispositivos médicos destinados a ser los sustitutos de un diente perdido o ausente. Hacen la función de una raíz artificial y están fabricados de materiales biocompatibles como el titanio, que favorece una adecuada osteointegración implante - hueso. Hoy en día son muchas las personas que utilizan implantes dentales, pero existen casos en los que las personas rechazan los implantes. Este fenómeno puede deberse a numerosas causas, una de ellas, y la clave del estudio del proyecto, la densidad ósea.En este proyecto se estudia el comportamiento mecánico de un implante dental frente a cuatro densidades óseas distintas. Se analizan las zonas del implante y, principalmente, del hueso donde aparecen concentraciones de tensiones y se propondrán mejoras de diseño del implante para reducir estas concentraciones de tensiones.Además, también se realiza un estudio de mercado de los tipos de implantes dentales existentes. Para la realización del estudio se han creado modelos 3D y se ha realizado el ensamblaje de los mismos. A los modelos se les han asignado unas propiedades y condiciones de contorno que simulan un caso real de un implante frente a un hueso. Tras este análisis se han obtenido los resultados de tensiones del implante y del hueso con cada una de las cuatro densidades.En el análisis de los resultados de tensiones se observa una mayor vulnerabilidad en las zonas de la rosca del orficio del hueso, donde los valores de tensiones son mayores. En el implante las zonas más vulnerables son las zonas del pilar, justo por encima del implante, y la parte de la rosca, donde las tensiones superan el límite elástico del material. Por último, cabe destacar que el estudio realizado puede servir de ayuda para posteriores proyectos, ya que a día de hoy, no existe casi literatura relacionada con los análisis de implantes dentales frente a distintas densidades óseas.<br /

Efecto del tipo de comportamiento de hueso en la biomecánica de implantes dentales

Los implantes dentales son un tratamiento cada vez más común para reemplazar la pérdida de dientes o sustituir aquéllos en mal estado. Una parte crucial a la hora de tener éxito colocando un implante es la osteointegración, que hace referencia a la integración hueso-implante.El objetivo del presente estudio es analizar un conjunto implante-prótesis ante cargas fisiológicas con el objetivo de encontrar diferencias en su comportamiento modelando el hueso como un material elástico-lineal y como un material ortótropo. Para la realización del estudio se ha diseñado el conjunto implante-prótesis en 3D, se le han aplicado los materiales correspondientes a cada parte, habiendo utilizado Ti6Al4V para el implante dental, una aleación cobalto-cromo para la corona y dando propiedades al hueso, tanto isótropas como anisótropas, habiendo utilizado 4 orientaciones diferentes para el caso ortótropo. Se ha seguido la norma ISO 14801 a la hora de colocar las condiciones de contorno y las cargas a las que está sometido el conjunto. Mediante el cálculo de elementos finitos se han obtenido las tensiones a las que está sometido el conjunto y se han analizado.Las conclusiones encontradas son que existe una clara diferencia en el comportamiento óseo entre el modelo elástico-lineal y el modelo ortótropo, siendo las tensiones del modelo ortótropo entre un 9 y un 19% menores que en el caso elástico-lineal; y que esta diferencia en el comportamiento óseo no tiene apenas relevancia en el comportamiento del implante dental.<br /

Long-Term Fatigue and Its Probability of Failure Applied to Dental Implants

It is well known that dental implants have a high success rate but even so, there are a lot of factors that can cause dental implants failure. Fatigue is very sensitive to many variables involved in this phenomenon. This paper takes a close look at fatigue analysis and explains a new method to study fatigue from a probabilistic point of view, based on a cumulative damage model and probabilistic finite elements, with the goal of obtaining the expected life and the probability of failure. Two different dental implants were analysed. The model simulated a load of 178 N applied with an angle of 0°, 15°, and 20° and a force of 489 N with the same angles. Von Mises stress distribution was evaluated and once the methodology proposed here was used, the statistic of the fatigue life and the probability cumulative function were obtained. This function allows us to relate each cycle life with its probability of failure. Cylindrical implant has a worst behaviour under the same loading force compared to the conical implant analysed here. Methodology employed in the present study provides very accuracy results because all possible uncertainties have been taken in mind from the beginning

Long-term fatigue and its probability of failure applied to dental implants

It is well known that dental implants have a high success rate but even so, there are a lot of factors that can cause dental implants failure. Fatigue is very sensitive to many variables involved in this phenomenon. This paper takes a close look at fatigue analysis and explains a new method to study fatigue from a probabilistic point of view, based on a cumulative damage model and probabilistic finite elements, with the goal of obtaining the expected life and the probability of failure. Two different dental implants were analysed. The model simulated a load of 178¿N applied with an angle of 0°, 15°, and 20° and a force of 489¿N with the same angles. Von Mises stress distribution was evaluated and once the methodology proposed here was used, the statistic of the fatigue life and the probability cumulative function were obtained. This function allows us to relate each cycle life with its probability of failure. Cylindrical implant has a worst behaviour under the same loading force compared to the conical implant analysed here. Methodology employed in the present study provides very accuracy results because all possible uncertainties have been taken in mind from the beginning

Dental Implants Fatigue as a Possible Failure of Implantologic Treatment: The Importance of Randomness in Fatigue Behaviour

Objective. To show how random variables concern fatigue behaviour by a probabilistic finite element method. Methods. Uncertainties on material properties due to the existence of defects that cause material elastic constant are not the same in the whole dental implant the dimensions of the structural element and load history have a decisive influence on the fatigue process and therefore on the life of a dental implant. In order to measure these uncertainties, we used a method based on Markoff chains, Bogdanoff and Kozin cumulative damage model, and probabilistic finite elements method. Results. The results have been obtained by conventional and probabilistic methods. Mathematical models obtained the same result regarding fatigue life; however, the probabilistic model obtained a greater mean life but with more information because of the cumulative probability function. Conclusions. The present paper introduces an improved procedure to study fatigue behaviour in order to know statistics of the fatigue life (mean and variance) and its probability of failure (fatigue life versus probability of failure)

A Validation Employing Convolutional Neural Network for the Radiographic Detection of Absence or Presence of Teeth

Dental radiography plays an important role in clinical diagnosis, treatment and making decisions. In recent years, efforts have been made on developing techniques to detect objects in images. The aim of this study was to detect the absence or presence of teeth using an effective convolutional neural network, which reduces calculation times and has success rates greater than 95%. A total of 8000 dental panoramic images were collected. Each image and each tooth was categorized, independently and manually, by two experts with more than three years of experience in general dentistry. The neural network used consists of two main layers: object detection and classification, which is the support of the previous one. A Matterport Mask RCNN was employed in the object detection. A ResNet (Atrous Convolution) was employed in the classification layer. The neural model achieved a total loss of 0.76% (accuracy of 99.24%). The architecture used in the present study returned an almost perfect accuracy in detecting teeth on images from different devices and different pathologies and ages

Implant Treatment in Atrophic Maxilla by Titanium Hybrid-Plates: A Finite Element Study to Evaluate the Biomechanical Behavior of Plates

A severely atrophied maxilla presents serious limitations for rehabilitation with osseointegrated implants. This study evaluated the biomechanical and long-term behavior of titanium hybrid-plates in atrophic maxilla rehabilitation with finite elements and probabilistic methodology. A three-dimensional finite element model based on a real clinical case was built to simulate an entirely edentulous maxilla with four plates. Each plate was deformed to become accustomed to the maxilla&rsquo;s curvature. An axial force of 100 N was applied in the area where the prosthesis was adjusted in each plate. The von Mises stresses were obtained on the plates and principal stresses on maxilla. The difference in stress between the right and left HENGG-1 plates was 3%, while between the two HENGG-2 plates it was 2%, where HENGG means Highly Efficient No Graft Gear. A mean maximum value of 80 MPa in the plates&rsquo; region was obtained, which is a lower value than bone resorption stress. A probability cumulative function was computed. Mean fatigue life was 1,819,235 cycles. According to the results of this study, it was possible to conclude that this technique based on titanium hybrid-plates can be considered a viable alternative for atrophic maxilla rehabilitation, although more studies are necessary to corroborate the clinical results

Influence of Bone Definition and Finite Element Parameters in Bone and Dental Implants Stress: A Literature Review

Bone plays an important role in dental implant treatment success. The goal of this literature review is to analyze the influence of bone definition and finite element parameters on stress in dental implants and bone in numerical studies. A search was conducted of Pubmed, Science Direct and LILACS, and two independent reviewers performed the data extraction. The quality of the selected studies was assessed using the Cochrane Handbook tool for clinical trials. Seventeen studies were included. Titanium was the most commonly-used material in dental implants. The magnitude of the applied loads varied from 15 to 300 N with a mean of 182 N. Complete osseointegration was the most common boundary condition. Evidence from this review suggests that bone is commonly defined as an isotropic material, despite being an anisotropic tissue, and that it is analyzed as a ductile material, instead of as a fragile material. In addition, and in view of the data analyzed in this review, it can be concluded that there is no standardization for conducting finite element studies in the field of dentistry. Convergence criteria are only detailed in two of the studies included in this review, although they are a key factor in obtaining accurate results in numerical studies. It is therefore necessary to implement a methodology that indicates which parameters a numerical simulation must include, as well as how the results should be analyzed

Dental Images Recognition Technology and Applications: A Literature Review

Neural networks are increasingly being used in the field of dentistry. The aim of this literature review was to visualize the state of the art of artificial intelligence in dental applications, such as the detection of teeth, caries, filled teeth, crown, prosthesis, dental implants and endodontic treatment. A search was conducted in PubMed, the Institute of Electrical and Electronics Engineers (IEEE) Xplore and arXiv.org. Data extraction was performed independently by two reviewers. Eighteen studies were included. The variable teeth was the most analyzed (n = 9), followed by caries (n = 7). No studies detecting dental implants and filled teeth were found. Only two studies investigated endodontic applications. Panoramic radiographies were the most common image employed (n = 5), followed by periapical images (n = 3). Near-infrared light transillumination images were employed in two studies and bitewing and computed tomography (CT) were employed in one study. The included articles used a wide variety of neuronal networks to detect the described variables. In addition, the database used also had a great heterogeneity in the number of images. A standardized methodology should be used in order to increase the compatibility and robustness between studies because of the heterogeneity in the image database, type, neural architecture and results