Search

Objectives: To evaluate the effects of the abutment material and the connection type on the implant-abutment connection rigidity. Methods: The study evaluated eighteen implants with three different types of connections: external-hexagon, tri-channel, and conical connection. Half of the implants were connected to titanium abutments, and the other half to zirconia abutments, forming six study groups (n=3). The implants were submitted to 1,200,000 load cycles with a force amplitude of 90 N. During load application, the implant-abutment connection rigidity was determined in each cycle. The values obtained were analyzed with the two-way ANOVA test according to the abutment and connection types. Results: Rigidity tended to increase during loading cycles. The abutment material did not influence rigidity (p=0.883). The external-hexagon connection presented lower rigidity than the internal connections, with statistically significant differences (p=0.013). Conclusions: The abutment material does not influence the implant-abutment connection’s rigidity. The external-hexagon connection proved to be less rigid and stable than the internal connections.

Objective: Titanium is the most commonly used material to manufacture dental implants and abutments. Recently, zirconia abutments have been manufactured with better aesthetic properties. However, zirconia abutments are harder than titanium implants; therefore, they could wear the implant surface. Therefore, this article aims to describe a sphere-plane system that can be used to assess the wear that different abutment materials cause in the titanium of dental implants when submitted to cyclic loading. This method can be used to simulate the oral cavity, where the abutment (sphere) applies loads onto the implant (titanium plane). The spheres were made of different materials (titanium and zirconia), and the specimens were loaded for 4,000,000 cycles. The scar size and area on titanium planes were measured with stereoscopic images and analysed through profilometry. Results: The wear of titanium planes was similar when tested against zirconia or titanium spheres. The sphereplane system is a method that can be used to evaluate and quantify the wear of the titanium of dental implants, and compared with methods that use real implants, this system is simpler and less expensive. This method could facilitate further research to evaluate the wear of titanium against different materials and under different testing conditions.

Dissertação de Mestrado Conjunto Europeu em Tribologia de Superficies e Interfaces apresentada à Faculdade de Ciências e Tecnologia As ligas de titânio têm sido utilizadas em várias aplicações desde a indústria aeroespacial e automóvel e também como materiais para aplicações biomédicas (por exemplo, usados como implantes) devido à sua alta resistência ao desgaste e corrosão. A liga de Titânio Ti6Al4V, também conhecido como Grau 5, tem sido usada com sucesso em aplicações de engenharia biomédica (por exemplo, implantes dentários ou articulações de joelho) devido a ter excelentes características mecânicas e biocompatibilidade com características adequadas de corrosão.Como o Ti6Al4V é utilizado em aplicações especializadas, por ter a opção de construção e controle geométricos de certos parâmetros como a porosidade, muitas vezes é possível produzir uma liga como um produto impresso em 3D, que reduz a matéria-prima utilizada, mas também reduz o tempo de produção desde a fabricação até o acabamento.Comparando duas amostras de Ti6Al4V, uma produzida usando manufatura subtrativa convencional (usinagem) e outra produzida usando processo de manufatura aditiva - FSL (Fusão Seletiva por Laser). Eles foram testados em termos eletroquímicos pelo método de polarização potenciodinâmica, seguido por monitorização do potencial em circuito aberto antes, após e durante um teste tribológico contra uma esfera de Zircónio enquanto submerso em saliva artificial (para reproduzir o ambiente da cavidade bocal) sujeito a cargas de 3, 5 e 7 N.O potencial do elétrodo de trabalho foi monitorizado utilizando a técnica de Potencial de Circuito Aberto em condições simples de repouso e com início do teste tribológico (deslizamento alternativo de configuração bola-plano) para diferentes cargas e número de ciclos e frequência constante. Curvas de polarização, representando a densidade de corrente (A / cm2) vs. Potencial (V vs. SCE) foram obtidas e a resistência à corrosão foi comparada e discutida, seguida de uma avaliação de COF e desgaste. Titanium alloys have been utilized in various applications from Aerospace and Automobiles to their use as biomedical materials (eg. used as an implant) which is due to their high resistance of the combined wear and corrosion which could otherwise be detrimental to the lifetime of the product. Ti6Al4V, also known as Grade 5 Titanium alloy commercially, has been successfully used in biotechnology applications (e.g. cavity implants or knee joints) due to having best of both worlds (excellent mechanical characteristics and biocompatibility with suitable tribo-corrosion characteristics). Since Ti6Al4V is used in specialized applications, by having the choice to play with the geometrical construction and control, of certain parameters like porosity, it is often tempting to produce such alloy as a 3D printed product, which not only reduces raw material used but also reduces the lead time from manufacturing to finishing. Comparing two samples of Ti6Al4V, one produced using conventional subtractive manufacturing (machining) and another produced using additive manufacturing process - Selective Laser Melting (SLM). They were tested for electrochemically by Potentiodynamic Polarization Method, followed by Open Circuit Potential (OCP) monitoring before, after and during a tribological test against a Zirconia counter body while being submerged in artificial saliva (to mimic a dental implant) per load (3, 5 and 7 N) per sample.The potential of the working electrode was monitored using the Open Circuit Potential (OCP) technique under simple resting conditions and with tribometer input (reciprocating sliding of ball-on-flat configuration) for different loads for the same number of cycles and frequency. Polarization curves, representing the current density (A/cm2) vs. potential (V vs. SCE) were obtained and the corrosion resistance was compared and discussed followed by an evaluation of COF and wear. Outro - Erasmus Mundus