Using all letters

                                                                            desensitize

                                                                           desensitized

                                                                           desensitizes

                                                                            sensitized

                                                                          The other words:

                                                                              denizen

                                                                             denizens

                                                                              dizzied

                                                                              dizzies

                                                                             dizziest

                                                                             dizziness

                                                                               seize

                                                                              seized

                                                                              seizes

                                                                              seizins

                                                                             sensitize

                                                                            sensitizes

                                                                               sized

                                                                               sizes

                                                                              siziest

                                                                             siziness

                                                                              sneeze

                                                                              sneezed

                                                                              sneezes

                                                                             sneeziest

                                                                              tizzies

                                                                              tzetze

                                                                              tzetzes

                                                                              tzitzis

                                                                               zeins

                                                                               zeiss

                                                                              zested

                                                                             zestiest

                                                                               zests

                                                                               zitis