ABSTRACT
Natural teeth possess fibbers, which are the periodontal ligaments, and whose function is to neutralise the masticatory forces transmitted to the bone. The majority of dental implants is not able to reduce this force. One implant design of the IMZ system (Interpore International) incorporates an intramobile resilient element (IMC) of polioximethylene resin between the implant and the prosthesis. According to its proponent, this IMC element imitates the function of the periodontal ligament and the natural movement inherent to the tooth. IMZ also produces a titanium IME identical to the first, and a third type made of titanium and polioximethylene resin with a different geometry. The Finite Element Method (FEM) is an approximate solution technique for mathematical models which seek to represent the mechanical behaviour of bodies, here the prosthetic structure, subjected to loads and their support. In the present work, axisymmetric elements were employed, since they exhibit geometrical symmetry about the central axis, with non-axisymmetric loads. The objective of the present work was to simulate the mechanical behaviour of a system composed of prosthesis-implant-bone support under masticatory forces. Studies have shown such forces to be in the range 113-190 N, reaching 100 N in the incisors region and 500 N in the molar region. Based on this information, it was decided to test and compare the three IME of the IMZ system applying 500 N loads in the vertical direction, which is considered to be the principal 722direction of the forces of the posterior teeth. In another study, a 173 N load was applied at a 30° angle, as an average load for the anterior teeth. For vertical and inclined loads, there was not a significant difference in the stress transmission to the bone although some differences appear on the stress concentration in the retaining screw.
