Background and Objective: Deep heating or denaturation of collagen has been reported to be necessary for nonablative skin rejuvenation. The purpose of this study was to examine whether thermally damaged collagen is an indispensable factor to increase the amount of collagen in vivo. Epidermal and dermal responses to infrared light therapy using a Titan source were examined with the aim of correlating histological and clinical responses in human and amelanotic mouse skin.

Study Design/Materials and Methods: Ten, 20, or 30 J/[cm.sup.2] infrared light were irradiated on the human subject's skin (thigh), while 5, 10, 20, or 30 J/[cm.sup.2] were used on amelanotic mouse skin. Biopsies were ...