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| Author(s): |
Ricardo Alexandre Zavanelli
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Piracicaba, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Faculdade de Odontologia de Piracicaba |
| Defense date: | 1999-09-04 |
| Examining board members: |
Guilherme Elias Pessanha Henriques;
Itamar Ferreira;
Mauro Antonio de Arruda Nóbilo
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| Advisor: | Guilherme Elias Pessanha Henriques |
| Abstract | |
The fatigue is responsible for 90% of metallic component failures during service. This phenomenon is closely related to superficial alteration and it occurs during cyclic stress application. Removable partial dentures (RPDs) are affected by fatigue due to cyclic mechanism of the masticatory system and the frequent insertion and removal. Because of unique and favorable properties, titanium and its alloys have been used in manufacturing crowns and bridges. However, it has been shown that preventive agents with fluoride probably affect titanium alloy surfaces. The aim of this study was to evaluate compare and analise the fatigue life of commercially pure titanium and Ti-6Al-4V alloy in different media (without media, artificial saliva and fluoride artificial saliva). For each alloy, thrirty dumb-bell rods 2.3 mm in diameter were.cast in Rematitan-System (Rematitan-Dentaurum IP. Winkelstroeter KG-Germany). The fatigue strength test was carried out with an universal testing machine (MTS- Materials Testing System - Test Star II), using a load 30 % lower than the calculated yield strength at a 0.2% offset. After failure, the number of cycles were recorded and the fracture surfaces were examined with a scanning electron microscope (S.E.M.). The mean values indicated that Ti-6Al-4V alloy achieved 21,269.50 cycles against 19,151.60 cycles for the c.p. titanium, and, when the solutions were present, the number of cycles was drastically reduced, probably due to pits caused by superficial reactions, as showed in S.E.M. analyses. It was observed that: Ti-6Al-4V alloy had the highest mean values of fatigue strenght, however, there were no siglificant differences as regards c.p. titanium. free-standing the presence or absence of media; the solutions reduced fatigue strength for both alloys, with statistically significant differences to specimens tested without the solutions; the fluoride solution was the most harmful agent, but there were no significant differences between fluoride solution and artificial saliva (AU) | |