Among the newest skin-rejuvenating treatments are those that do not destroy outer tissue as they work their way down to stimulatecollagengrowth in the dermis. The two such noninvasive procedures now in use deliver controlled energy to the skin in slightly different ways. For both, the process is gradual and the softening of wrinkles occurs over time. They also spare patients long recoveries and downtime. Increasingly, doctors are starting to combine these nonablative procedures with chemical peels, microdermabrasion and even laser resurfacing.