  In this work we focus our attention in the inconsistency that appears when
the Semi-Exact Foldy-Wouthuysen transformation for the Dirac field interacting
with space-time torsion field is performed. In order to solve this problem, we
present a new involution operator that makes possible to perform the exact
transformation when torsion field is present. Such operator has a structure,
well known in the literature, composed of the product of an operator that acts
in the matrices space and another one that acts in the function space. We also
present the bound state of this theory and discuss the possible experimental
analysis.
