Avaliação do comportamento de parafusos de retenção de próteses implanto suportadas : conexão hexágono interno

• Autor(a) principal: Souza, Elbio Costa
• Data de Publicação: 2015
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da PUC_RS
• Texto Completo: http://tede2.pucrs.br/tede2/handle/tede/6241
• topic: ODONTOLOGIA; IMPLANTODONTIA; MATERIAIS DENTÁRIOS; PRÓTESE DENTÁRIA; CIENCIAS DA SAUDE::ODONTOLOGIA

This study aimed to evaluate "in vitro" possible changes on prosthetic retaining screws on implants with platform external hexagon, this because the loosening this component is very common in clinical dentistry practice. Were assessed screws of UCLA's pillars of titanium Neodent® brand and 3i BIOMET® and of titanium with surface treated with tungsten carbide Neodent® brand. Two techniques of utilization of the screws were compared, the technique I, recommended by the manufacturer with only the definitive torque, and the technique II , utilized in broad scale in Brazil where multiple torques are applied in the same screw simulating the clinical steps, up to definitive installation. The initial weight of all the screws (T0) was registered, in the screws of technique I, it was given definitive torque (32N.cm to Neodent® and 20N.cm to 3i BIOMET®) submitted to mechanical cycling and the final weight (TF) registered. In the screws of technique II have been applied opening and closing cycles, and their weights registered (T1, T2 and T3) before applying the definitive torque and mechanical cycling after the final weight has been registered (TF). The morphologies and the surface compositions of the screws were evaluated using SEM and EDS at each time. The results showed significant weight loss in the three screws groups, of technique I (p< 0.005 for uncoated Neodent®, p = 0.001 for coated Neodent® and p < 0.001 to 3i BIOMET®) and on one step of the uncoated Neodent® group and two steps of the other two groups of technique II (p <0.001 for all groups), and comparing the final weight of the screws of the two techniques, only the uncoated Neodent® screws of the technique I, showed significantly higher values than the screws, of the technique II (p = 0.021 for uncoated Neodent®, p = 0.089 for coated Neodent® and p = 0.095 to 3i BIOMET®), as well as SEM showed less permanent deformation for the technique I of these screws. EDS showed no major changes in the surface compositions. Therefore, the use of the definitive screw only at time of final torque would not necessarily minimize problems regarding to the loosening the retaining screws of implant supported prostheses.