Ortomicrotribômetro

Abstract

This work consisted of the conception and development of an orthomicrotribometer, integral module of a microtribometer that, together with the developed methodology, makes it possible to characterize the tribology of orthodontic appliance. The orthomicrotribometer consists of a portico, positioning systems, application, control and monitoring of efforts systems, reciprocating movement system and position monitoring system. It allows parameterized tests in order to represent what happens in the mouth, with also representative movements, that is, at low speeds and large amplitudes, using orthodontic components as sample, bracket and wire, immersed in artificial saliva. To validate the equipment and the proposed methodology, tests were conducted varying the normal force (0.5; 1.0 and 1.5 N), frequency (0.1; 0.5 and 1.0 Hz) and the environment (dry and immersed in artificial saliva). The coefficient of friction and the wear rate data were quantified in order to study the motion, the reactions and interactions between bracket and wire. Through a computational resource, named triboscopy, which enables quick visual identification of changes in coefficient of friction that occur either during the test or in a specific position in the sample, along with Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and Optical Microscopy (OM) analyses, it was possible to characterize the effects of variations imposed on the tribo-system. The analyses indicate that both the increase of the normal force and the frequency induced the reduction of the friction coefficient. The wear rate decreased with increasing the normal force and increased with increasing frequency. The mechanism that governs the behavior of the tribe-system is the formation of tribe-layers, and in the tests with artificial saliva is the lubrication that it exerts on the contact between the two surfaces that determines the behavior. The experimental strategy, conception and development of the orthomicrotribometer, biological and mechanical representative parameterization, as well as its validation through the methodology development allowing the tribological characterization of orthodontic appliance, evidence that the developed orthomicrotribometer is a versatile equipment that allows different configurations of orthodontic components in an representative environment of the oral cavity as well as being a powerful tool in the development of new materials for wires and brackets.