Construction and enlargement of dilatonic wormholes by impulsive   radiation
  The dynamical behavior of traversable wormholes and black holes under impulsive radiation is studied in an exactly soluble dilaton gravity model. Simple solutions are presented where a traversable wormhole is constructed from a black hole, or the throat of a wormhole is stably enlarged or reduced. These solutions illustrate the basic operating principles needed to construct similar analytic solutions in full Einstein gravity. 
Hiroko Koyama, Sean A. Hayward and Sung-Won Kim