Reoxidized nitrided oxide is compared with nitrided oxides and dry SiO2 for radiation-induced interface-state generation (DELTA-D(itm)) and midgap voltage shifts (DELTA-V(mg)). The suppression of DELTA-D(itm) observed with heavy nitridation or reoxidation is explained in terms of the trapped-hole recombination model together with the shifting of the location of the trapped positive charge away from the Si interface. This model can also explain the effect of nitrogen annealing on nitrided oxides.