  The effects of a type of regularization for finite temperatures on the
estoration of chiral and axial symmetries are investigated within the SU(3)
Nambu-Jona-Lasinio model. The regularization consists in using an infinite
cutoff in the integrals that are convergent at finite temperature, a procedure
that allows one to take into account the effects of high momentum quarks at
high temperatures. It is found that the critical temperature for the phase
transition is closer to lattice results than the one obtained with the
conventional regularization, and the restoration of chiral and axial
symmetries, signaled by the behavior of several observables, occurs
simultaneously and at a higher temperature. The restoration of the axial
symmetry appears as a natural consequence of the full recovering of the chiral
symmetry that was dynamically broken. By using an additional ansatz that
simulates instanton suppression effects, by means of a convenient temperature
dependence of the anomaly coefficient, we found that the restoration of U(2)
symmetry is shifted to lower values, but the dominant effect at high
temperatures comes from the new regularization that enhances the decrease of
quark condensates, especially in the strange sector.
