[Comparative clinical and laboratory study of the force loss generated by NiTi closed coil springs].

The purpose in this study was to compare the force decay of laboratory and clinical NiTi closed coil springs. Specimens were 30 NiTi coil springs (clinical) and 15 (laboratory in artificial saliva 36.6 ºC) springs were tested by dynamometer to evaluate force loos at different intervals: 1, 2 and 3 months of use. Data (gF) were analyzed statistically using. Clinical and laboratory data were compared to evaluate effect of the oral environment on force loss. It was observed a significant force loss of NiTi springs. NiTi springs showed force loss (13.2%) at 28 days of clinical use, with a further significant loss from 4-12 weeks (~21%); force levels remained steady thereafter. Were not statistically different in clinical and laboratory force loss data. Space was closed at an average rate of 1 mm/month.