Redu？？o da for？a de reten？？o e abertura de grampos a barra em "I" de Roach e sua correla？？o

the purpose of this research was to determine the retention drop of i-bar clasps, their possible opening during mechanical cycling and their correlation. two co-cr alloys were used and the design of clasps were: short-thin; short-thick; long-thin; long-thick. clasps were also partially covered or not with resin. measurements were made at the initial stage and after 20 thousand cycles. the results led to the following conclusions: the alloys presented similar retention drop; opening of the several types of clasps were similar, but retention drop was minor on long-thin clasp and major on short-thick ones; resin did not influence the opening of clasps but increased retention drop; correlation between retention drop and opening of clasps was not significant.