Avaliação de desajuste vertical de infraestruturas protéticas sobre implantes confeccionadas em liga de Co-Cr e Ni-Cr e soldagem TIG

Abstract

A common failure observed in cases of total dentures on implants is vertical misfit. This is due of bad adaptation between components and corresponds from the base of the prosthetic cylinder to the abutment or bottom base of the abutment to an implant base, reflected in poor biomechanical behavior beyond other consequences. Thus, the aim of this study was to evaluate quantitatively the vertical misfit of mini-abutments cylinders of prosthetic framework on implant in CoCr alloys and NiCr alloys before and after TIG welding. Fifty frameworks - composed of two prosthetic cylinders –of cobalt-chromium alloys(CoCr) and nickel chrome alloy (NiCr) were divided into 5 groups (n = 10): control group (GC), with pre-made cylinders, with 0.85 mm thickness; test groups: CoCr1.5, CoCr2, Nicro1.5 and NiCr2, with cylinders 1.5 and 2.0 mm thickness, respectively. Rectified the cylinders of test groups and then took all 50 infrastructures inscanning electron microscope (SEM) to measure the vertical misfits before soldering. Afterward, were to execute the TIG welding and again the infrastructures were taken to SEM. Data were analyzed by the Shapiro-Wilk test, Kruskal Wallis, Mann-Whitney test, Wilcoxon test and T-test, considering significant p<0.05 values. The results showed that both the thickness of the cylinder before welding (p <.0001) and after welding (p = .005) and the type of alloy before welding (p <.0001) and after welding (p = .0313) influenced the vertical misfit. The results showed statistically significant difference between GC and test groups (p<.001) and between test groups CoCr1.5 with NiCr1.5 (p=.0459) and NiCr1.5 and NiCr2 (p=.0490) before to welding. After welding, there was no statistically significant difference between the test groups, but there was difference between GC and CoCr2 (p=.0051) and GC and NiCr2 (p=.0095). Finally, in the analysis between the groups before and after welding, there was a statistically significant difference for GC (p<.0001) and NiCr2 (p= .0005). Considering the parameters and techniques used, it can be concluded that both the type of alloy and the thickness of the cylinder influenced the vertical misfit, and the casting process seems to have corroborated more negative than the welding process with the obtained results, since before soldering all the test groups presented differences in relation to the GC and before and after the weld only two groups presented statistical difference.