  There are two effects of extra matter fields on the Lorentzian traversable
wormhole. The ``primary effect'' says that the extra matter can afford to be a
part of source or whole source of the wormhole when the wormhole is being
formed. Thus the matter does not affect the stability of wormhole and the
wormhole is still safe. If the extra matter is extotic, it can be the whole
part of the source of the wormhole.
  The ``auxiliary effect'' is that the extra matter plays the role of the
additional matter to the stably-existed wormhole by the other exotic matter.
This additional matter will change the geometry of wormhole enough to prevent
from forming the wormhole by backreaction. In the minimally coupled massless
scalar field case, the self-consistent solution was found. The backreaction of
the scalar field can dominate the exotic matter part so that it will hinder the
formation of the wormhole.
