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Aims and Objectives: Dimension of dental implant is an important parameter which has a considerable impact on the biomechanical load transfer characters and its prognosis. Excessive stress in the bone-implant interface may result in the failure of the implant. The aim of this study was to evaluate the impact of implant diameter and length on neighboring tissues around the implant. The results of the study will help in developing a scientific methodology to select appropriate implant diameter and length. Materials and Methods: In this study, tapered implants of different diameter and length were numerically analyzed using bone-implant models developed from computed tomography generated images of mandible with osseointegrated implants. The impact of various diameters on stress distribution was examined using implants with a length of 13 mm and diameters of 3.5 mm, 4.3 mm and 5.0 mm. Implants with a diameter of 4.3 mm and lengths of 10 mm, 13 mm, 16 mm was developed to examine the impact of various implant length. All materials were assumed to be linearly elastic and isotropic. Masticatory load was applied in a natural direction, oblique to the occlusal plane. The Statistical Package for the Social Sciences software package was used for statistical analysis. Results: Maximum von Mises stresses were located around the implant neck. It was demonstrated that there was statistically significant decrease in von Mises stress as the implant diameter increased. Conclusion: Within the limitations of this study there was statistically significant decrease in von Mises stress as the implant diameter increased. [ABSTRACT FROM AUTHOR]

Biomechanics comprises all kinds of interactions between tissues and organs of the body and the forces acting on them. Biomechanics comprises the response of the biologic tissues to the applied loads. Aims and objectives: Attempt has been made to understand the basics of biomechanics with a view on finite-element stress distribution analysis in three situations namely: 1. To compare the stress distribution in a single implant with the narrow ceramic occlusal table and wide ceramic occlusal table. 2. To compare the stress distribution in two implants supporting a three-unit bridge, one model with implants placed parallel to each other and the other with one implant placed in angular position to the other. 3. To compare the difference in the stress distribution in six implants and four implants supporting mandibular over- denture. Materials and Methods: The three-dimensional (3-D) finite-element mesh model was modeled with the standard dimension of the implant with 11-mm long and 4-mm wide using the software package `NISA'. Results and Discussion: The design, number and placement of implants play an important role. Summary and Conclusion: The basic principles of biomechanics must be respected. [ABSTRACT FROM AUTHOR]

The current study describes the vacuum system of ILSF storage ring. The design uses the stainless steel vacuum chambers with a continuing keyhole profile all around the storage ring. The NEG cartridge and Ion pumps which are installed in the antechamber will pump all the vacuum sectors. Using Monte-Carlo simulation proved that the machine could reach an average pressure of 1 nTorr after the commissioning phase, which could guarantee a vacuum life time of about 13 h. The general layout of the vacuum system and the construction steps for the vacuum chambers will also be elaborated on. Several discrete photon absorbers which are designed in three types will absorb all the synchrotron radiations. For the heat load study, a simulation with Synrad is performed to calculate the power distribution on the absorber surfaces. Then the result is used to calculate the stress and strain on the absorbers by Finite Element Analysis (FEA). [ABSTRACT FROM AUTHOR]