Effect of different torque levels on the implant/abutment interface using castable “UCLA” abutments

ABSTRACT

The abutment/implant interface has been reported as a significant factor on tensile transfer, adverse biological responses or prosthetic restoration complications. The abutment/implant junction success is directly related to pre-load attained during torque application. The purpose of this work was to assess the vertical fit/misfit degree on abutment/implant interface, when castable “UCLA” type abutments are used on fixed prosthesis process on implants, after different torque levels applications. Four three-unit fixed prosthesis were manufactured by the same laboratory. Torque was applied on the same framework using initially a 10 Ncm (T1) and later, a 20 Ncm torque level (T2) with a screwdriver hand Torquimeter. Trough scanning electronic microscope (SEM), it was obtained two photographs corresponding to mesial and distal regions of each prosthesis unit, summing 24 assessed regions to each applied torque value. After submitting the results to statistical analyses Paired T-Test (p<0.05), a significant difference was seen between the average vertical fit/misfit degree T1 = 23.53mm ± 20.20; T2 = 9.01m ± 11.69 (p=0.000). The misfit degree decrease when applied manufacturers recommended torques, could decrease mechanical (loosening or fracture of the screw) complications.