Relation between implant/abutment vertical misfit and torque loss of abutment screws

This study investigated whether there is a direct correlation between the level of vertical misfit at the abutment/implant interface and torque losses (detorque) in abutment screws. A work model was obtained from a metal matrix with five 3.75 x 9 mm external hex implants with standard platform (4.1 mm). Four frameworks were waxed using UCLA type abutments and one-piece cast in commercially pure titanium. The misfit was analyzed with a comparator microscope after 20 Ncm torque. The highest value of misfit observed per abutment was used. The torque required to loose the screw was evaluated using a digital torque meter. The torque loss values, measured by the torque meter, were assumed as percentage of initial torque (100%) given to abutment screws. Pearson's correlation (α=0.05) between the misfit values (29.08 ± 8.78 µm) and the percentage of detorque (50.71 ± 11.37%) showed no statistically significant correlation (p=0.295). Within the limitations of this study, it may be concluded that great vertical misfits dot not necessarily implies in higher detorque values.Este trabalho teve como objetivo correlacionar o nível de desajuste vertical pilar/implante a perda do torque aplicado (destorque). Um modelo de trabalho foi obtido a partir de uma matriz metálica com cinco implantes tipo hexágono externo (Titamax, Neodent, Curitiba, Brasil) com plataforma regular (4,1 mm). Sobre esta matriz, quatro infra-estruturas foram enceradas utilizando pilares tipo UCLA e fundidas em monobloco com titânio comercialmente puro (Tritan grau I, Dentaurum, Alemanha). Os desajustes foram analisados com um microscópio óptico comparador (Mytutoyo, Japão) após torque de 20 Ncm. O maior valor de desajuste observado por pilar foi utilizado. O valor do torque de desaperto, avaliado com um torquímetro digital (TQ-680, Instrutherm, Brasil), foi calculado em porcentagem do valor do torque inicial (100%) dado aos parafusos protéticos. O teste de correlação de Pearson (p