The Biomechanics of Lip-Bumper Appliances. A Finite Elements Analysis Approach

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Innovative approach for the in vitro research on biomedical scaffolds designed and customized with CAD-CAM technology

Studies on biomaterials involve assays aimed to assess the interactions between the biomaterial and the cells seeded on its surface. However, the morphology of biomaterials is heterogeneous and it could be tricky to standardize the results among different biomaterials and the classic plastic plates. In this light, we decided to create, by means of computer-aided design (CAD) technology, a standardized sample model, with equal shape and sizes, able to fit into a classic shape of a 96-wells tissue culture plate (TCP)

Use of Machine Learning to Investigate the Quantitative Checklist for Autism in Toddlers (Q-CHAT) towards Early Autism Screening.

In the past two decades, several screening instruments were developed to detect toddlers who may be autistic both in clinical and unselected samples. Among others, the Quantitative CHecklist for Autism in Toddlers (Q-CHAT) is a quantitative and normally distributed measure of autistic traits that demonstrates good psychometric properties in different settings and cultures. Recently, machine learning (ML) has been applied to behavioral science to improve the classification performance of autism screening and diagnostic tools, but mainly in children, adolescents, and adults. In this study, we used ML to investigate the accuracy and reliability of the Q-CHAT in discriminating young autistic children from those without. Five different ML algorithms (random forest (RF), naïve Bayes (NB), support vector machine (SVM), logistic regression (LR), and K-nearest neighbors (KNN)) were applied to investigate the complete set of Q-CHAT items. Our results showed that ML achieved an overall accuracy of 90%, and the SVM was the most effective, being able to classify autism with 95% accuracy. Furthermore, using the SVM-recursive feature elimination (RFE) approach, we selected a subset of 14 items ensuring 91% accuracy, while 83% accuracy was obtained from the 3 best discriminating items in common to ours and the previously reported Q-CHAT-10. This evidence confirms the high performance and cross-cultural validity of the Q-CHAT, and supports the application of ML to create shorter and faster versions of the instrument, maintaining high classification accuracy, to be used as a quick, easy, and high-performance tool in primary-care settings

Non-linear Viscoelastic Finite Element Analysis of the Effect of the Length of Glass Fiber Posts on the Biomechanical Behaviour of Directly Restored Incisors and Surrounding Alveolar Bone

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Implant-to-bone force transmission: a pilot study for in vivo strain gauge measurement technique

The experimental determination of local bone deformations due to implant loading would allow for a better understanding of the biomechanical behavior of the bone-implant-prosthesis system as well as the influence of uneven force distribution on the onset of implant complications. The present study aimed at describing an innovative in vivo strain gauge measurement technique to evaluate implant-to-bone force transmission, assessing whether and how oral implants can transfer occlusal forces through maxillary bones. In vivo force measurements were performed in the maxillary premolar region of a male patient who had previously received a successful osseointegrated titanium implant. Three linear mini-strain gauges were bonded onto three different buccal cortical bone locations (i.e. coronal, middle, apical) and connected to strain measuring hardware and software. A customized screw-retained abutment was manufactured to allow for vertical and horizontal loading tests. As to the vertical load test, the patient was instructed to bite on a load cell applying his maximum occlusal force for 20 s and then recovering for 10 s to restore the bone unstrained state; the test was repeated 20 times consecutively. As regards the horizontal load test, the implant was subjected to a total of 20 load applications with force intensities of 5 and 10 kg. During the tests, the recorded signals were plotted in real time on a graph as a function of time by means of a strain analysis software. The described strain gauge measurement technique proved to be effective in recording the forces transmitted from osseointegrated implants to the cortical bone. Horizontal loads caused higher deformations of cortical bone than vertical biting forces; in both situations, the deformation induced by the force transferred from the implant to the bone progressively decreased from the coronal to the apical third of the alveolar ridge. At approximately 9 mm from the implant neck, the effect of occlusal force transmission through osseointegrated titanium implants was negligible if compared to the apical region

The effect of ferrule height on stress distribution within a tooth restored with fibre posts and ceramic crown: A finite element analysis

Objectives. To evaluate via finite element analysis the effect of different ferrule heights on stress distribution within each part of a maxillary first premolar (MFP) restored with adhesively luted glass fiber-reinforced resin (GFRR) posts and a ceramic crown. Methods. The solid models consisted of MFP, periodontal ligament and the corresponding alveolar bone process. Four models were created representing different degrees of coronal tissue loss (0 mm, 1 mm, 2 mm and 3 mm of ferrule height). First set of computing runs was performed for in vivo FE-model validation purposes. In the second part, a 200-N force was applied on the buccal cusp directed at 45° to the longitudinal axis of the tooth. Principal stresses values and distribution were recorded within root, abutment, posts, crown and related adhesive interfaces. Results. All FE-models showed similar stress distribution within roots, with highest stress present in the chamfer area. In composite abutments higher stress was observed when no ferrule was present compared to ferruled FE-models. Stress distribution within crown and GFRR posts did not differ among the models. Stress values at the adhesive interfaces decreased with increasing ferrule height. Significance. The stress state at abutment-crown and post-root interfaces was very close to their strength, when ferrule was not present. Similarly, higher ferrule produced more favorable stress distribution at post-abutment and abutment-root interfaces. Endodontically treated teeth with higher ferrule exhibit lower stress at adhesive interfaces that may be expected to lower the probability of clinical failur