Dry heat involves equipment such as ovens and flame which can be used to sterilize through the oxidation of organic material. This form of high heat will not be useful for all situations as it takes a long time to be effective. Moist heat such as steam under pressure is actually hotter than the boiling water that produces it. This moist heat is useful for many situations in the clinical setting as it achieves the same effectiveness as dry heat in a shorter time and at a lower temperature. Moist heat is the basis of the autoclave which combines this moist heat with high pressure. Remember that autoclaving is the only way to assure the destruction of endospores. Moist heat denatures proteins, which halts microbe metabolism and causes death. Dry heat dehydrates microbial cells, and the absence of water then inhibits metabolism. However, the loss of water can also stabilize some proteins present in microbes, and in these cases the object being treated must be exposed to the dry heat for a longer time so that the proteins are denatured.
