A moisture barrier on the injured area slows down the evaporation of moisture naturally present in the skin. As wounds heal in a moist environment they heal without scab or crust formation. Even tea bag and water compresses are found to be more effective than no treatment. Use of a dressing significantly reduces nipple pain and the amount of eschar on the surface of the nipple. (Ziemer)
However when damaged nipples are treated with the still commonly recommended application of air drying and hair dryers, the fissured areas produce scabs, which the baby often loosens while breastfeeding. The nipple then bleeds again and grows another scab. This pattern can go on until healing is complete, causing the mother a very uncomfortable time.
In the early 70s it was established that a moist, scab free, environment enhanced the movement of cells across the wound surface and facilitated healing (Rovee 1972). Current wound treatment methods employ the use of moisture to aid healing. A moist environment is critical for epithelisation, the proliferation and migration of epithelial cells across the surface of a wound during healing. (Bolton 2000) Oils including vitamin E oil do not facilitate wound healing. All oils stay on the surface of the skin and may offer some temporary relief. Dry or cracked skin does not lack oil, it lacks moisture.
It is impossible to add moisture to the skin from an outside source (this process must happen from within). By helping the skin to prevent evaporation, the skin can retain more of its own natural moisture.
However for the mother with damaged nipples the most pressing issue may not be the time it will take for her nipples to heal but how quickly she can get relief from her pain.