Implant Platform Switching: Biomechanical Approach Using Two-Dimensional Finite Element Analysis

In implant therapy, a peri-implant bone resorption has been noticed mainly in the first year after prosthesis insertion. This bone remodeling can sometimes jeopardize the outcome of the treatment, especially in areas in which short implants are used and also in aesthetic cases. To avoid this occurrence, the use of platform switching (PS) has been used. This study aimed to evaluate the biomechanical concept of PS with relation to stress distribution using two-dimensional finite element analysis. A regular matching diameter connection of abutment-implant (regular platform group [RPG]) and a PS connection (PS group [PSG]) were simulated by 2 two-dimensional finite element models that reproduced a 2-piece implant system with peri-implant bone tissue. A regular implant (prosthetic platform of 4.1 mm) and a wide implant (prosthetic platform of 5.0 mm) were used to represent the RPG and PSG, respectively, in which a regular prosthetic component of 4.1 mm was connected to represent the crown. A load of 100 N was applied on the models using ANSYS software. The RPG spreads the stress over a wider area in the peri-implant bone tissue (159 MPa) and the implant (1610 MPa), whereas the PSG seems to diminish the stress distribution on bone tissue (34 MPa) and implant (649 MPa). Within the limitation of the study, the PS presented better biomechanical behavior in relation to stress distribution on the implant but especially in the bone tissue (80% less). However, in the crown and retention screw, an increase in stress concentration was observed.

Utilizing the CORBA platform in the construction of a highly immersive virtual environment

This article presents the implementation of a distributed system of virtual reality, through the integration of services offered by the CORBA platform (Common Object Request Broker Architecture) and by the environment of development of 3D graphic applications in real time, the WorldToolkit, of Sense8. The developed application for the validation of this integration is that of a virtual city, with an emphasis on its traffic ways, vehicles (movable objects) and buildings (immovable objects). In this virtual world, several users can interact, each one controlling his/her own car. Since the modelling of the application took into consideration the criteria and principles of the Transport Engineering, the aim is to use it in the planning, project and construction of traffic ways for vehicles. The system was structured according to the approach client/server utilizing multicast communication among the participating nodes. The chosen implementation for the CORBA was the Iona's ORBIX software. The performance results obtained are presented and discussed in the end.

Marine Protected Areas in Brazil: An ecological approach regarding the large marine ecosystems

The objective of this study was to address the importance of implementing Coastal and Marine Protected Areas in Brazil and to examine their distribution, based on the delimitation of Large Marine Ecosystems. Out of a total of 336 protected areas identified in Brazilian coastal and marine areas, the North Platform has the largest protected area, but the ecosystem with the largest number of protected area, predominantly sustainable areas, was the East Coast followed by the South Platform. One of the reasons the eastern coast of Brazil to have more protected areas is the fact that there is a largest amount of coral reefs. Additionally there was political opportunities for the creation of protected areas for sustainable use. The coastal region of Brazil has achieved the goal proposed by the Seventh Conference of the Parties to the Convention on Biological Diversity - 7, but only then through the category V of the International Union for Conservation of Nature, which is not the best efficient means of conserving resources. The goal for marine conservation shows only the area above the recommended under protection in North Platform. The Marine portion of the East Coast and the South Platform has few protected areas, regardless of category management. We consider the coastal region the range of 12 nautical miles from baselines determined in accordance with the United Nations Convention on the Law of the Sea. As for the number of strategies permitted by law and used for the conservation of coastal and marine systems, coastal systems show a higher number when compared with the marine system. We suggest that the Brazilian government should specify strategies for the protection of marine systems and expand the protected areas of all Large Marine Ecosystems. © 2013 Elsevier Ltd.