It can be concluded that LCT and THT were associated with higher bond strengths to intraradicular dentine than CWCT. However, LCT was associated with more empty voids than the other techniques.
The mechanical aspects of tightening screws over implants are important to ensure a successful prosthetic rehabilitation. Screw loosening is a common problem that can be avoided with passive adaptation of the components and an increased tensile force developed in the screw, a preload. Objective: This in vitro study evaluated the effect on preload of a carbon lubricant deposited on the surface of titanium alloy prosthetic screws: conventional Ti6Al4V and surface enhanced. Material and methods: Conventional titanium alloy prosthetic (n = 7) and carbon coating surface enhanced screws(n = 7) were compared. Each prosthetic screw supporting a metallic UCLA over an implant was tightened with the manufacturer’s recommended torque of 32 N.cm. The removal torque values, recorded for ten consecutive cycles of tightening and removal, were used to estimate the preload. Implant blocks were then sectioned and the interfaces were observed by light microscopy. Results: The lowest removal torque, and consequently the highest preload values, was achieved for the lubricated group in most cycles. The contacts between threads were located at the coronal aspect of all observed screw mating threads. Conclusion: Data indicate that the lower coefficient of friction of a carbon lubricant can generate higher preload. The machining precision observed produced the adaptation and regular contact interfaces.
Dedico esta pesquisa primeiramente a Deus, pois sem Ele, nada seria possível e não estaríamos agora reunidos, desfrutando, juntos, destes momentos valiosos e de grande importância científica! Dedico, sem hesitar, a mim mesma, Juliane Nhata, pois só Eu sei das dificuldades encontradas durante a execução dessa dissertação. Quantas foram às portas fechadas encontradas, os conflitos vivenciados e os-não‖ recebidos. Aos meus pais, Osir Pedro Nhata e Maria Szychta Nhata, os maiores e melhores-Orientadores‖, pelo esforço, apoio, dedicação e compreensão nos momentos de fraqueza e turbulência. Vocês me ensinaram a descobrir o valor da persistência e da responsabilidade, indispensáveis para a construção e conquista do meu projeto de vida. Vocês são os meus maiores mestres! Obrigada por tudo! Aos meus amados irmãos Giovani Nhata e Tiago Valentim Nhata e demais familiares por terem acreditado e fornecido condições para que eu concluísse mais uma etapa desta vida.
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