A study of tooth deterioration in specimens of recent mammals was conducted. The condition of several series of bat (<i>Artibeus jamaicensis</i>) skulls was monitored during field procedures, laboratory processing, and with controlled microenvironments that simulated temperature and relative humidity in permanent storage areas of many research collections. By monitoring the incidence of tooth cracking, particularly in canines and second premolars, it was determined that moisture changes and content were major factors in tooth stability. Moisture changes during washing procedures greatly accelerated cracking. Teeth subjected to relative humidities below 50% tended to be more fragile and susceptible to damage; below 40%, deterioration increased substantially because of desiccation.