When restoring teeth, a higher restoring success rate can be achieved by using posts with an elastic modulus similar to that of dentin and a core, with equal or higher strength, such as glass fiber posts. Moreover, the failure mode for these post systems will allow for further repair. SUMMARY AimsThis work studied how prefabricated intraradicular post material affects the mechanical performance of restored teeth. The effect of using two different materials (glass fiber and stainless steel) with significantly different elastic moduli was studied. Methods 48Operative Dentistry distributions confirmed a worse mechanical performance on teeth restored using stainless steel posts, with a high stress concentration due to the significant difference between the elastic moduli of the steel and the surrounding materials. ConclusionWithin the limitations of this study, post systems, where the elastic modulus of the post is similar to that of dentin and core, have a better biomechanical performance.

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1This paper presents the results of a descriptive survey on human grasps. Sixty-four videos 2 were selected to represent tasks performed in activities of daily living (ADL) main areas 3 (personal care, meal preparation, eating, housekeeping, etc.). Elementary grasps were 4 identified for each hand, and the grasp type (from a 9-type classification), the hands involved, 5 and the duration were registered for each case. The results show that most commonly used 6 grasps are: pinch, non-prehensile, cylindrical, lateral pinch and lumbrical. The presence of 7

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A three-dimensional scalable biomechanical model of the four fingers of the hand to evaluate power grip is proposed. The model has been validated by means of reproducing an experiment in which the subjects exerted the maximal voluntary grasping force over cylinders of different diameters. The model is used to simulate the cylinder grip for two hand sizes and for five different handle diameters. The reduction of the muscle forces using different handle diameters has been studied. The model can be applied to the design and evaluation of handles for power grip and to the study of power grasp for normal and abnormal hands.

Numerous research works have studied the effect of post-design parameters on the mechanical behaviour of restored teeth without reaching any clear conclusions. Previous works by the authors ascertained the effect of material and post-dimensions for non-crowned restored teeth. The aim of this work was to study the effect of post-material and diameter for crowned teeth. First, an experimental fracture strength test was performed on eighteen extracted human maxillary central incisors. Teeth were decoronated, treated endodontically and restored (nine with glass fibre posts and nine with stainless steel posts). Several post-diameters were used. The final crown restoration was carried out using a reinforced glass-ceramic material. Failure loads were recorded and results were compared using the one-way anova. Secondly, the finite element technique was used to model the restored teeth and to compare the estimated stress distributions. The addition of the crown did not affect the strength of the restoration to any significant extent and post-diameter did not influence the biomechanical performance of either of the post-systems. The crown acts as a protector, thus eliminating the influence of the post-diameter that was found previously when using stainless steel posts, but it does not completely rule out the possibility of a root fracture. Significantly, lower failure loads were found experimentally for teeth restored with stainless steel posts. The stress distributions predicted by the model corroborated these findings and allowed the authors to propose the use of glass fibre posts as a more robust restorative technique.

Starting from our general critical-state theory, which includes the effects of both flux-line cutting and flux pinning, we develop a numerical method for finding the magnetic response of type-II superconductors subjected to parallel magnetic fields that change in both magnitude and orientation. We describe model calculations of the time-evolving magnetic profiles when the direction of an applied magnetic field of fixed magnitude oscillates with large amplitude, and we compare our results with related experiments by Cave and LeBlanc. We also report model calculations for the ac behavior when the sample is subjected to a dc bias field and a large-amplitude ac field at various angles (0°, 45°, and 90°) relative to this field.