A study published in the International Journal of Dermatology (2011;50:1075-1082) evaluated skin rejuvenation effects of trichloroacetic acid (TCA) and phenol peels in photoaged hairless mice. Photoaged skin exhibits deep coarse wrinkles, dryness, telangiectasia, skin atrophy, and hyperpigmentation. Three types of chemical peels are currently used: superficial type, penetrates and damages the papillary dermis (TCA 10%–30%); medium type, penetrates and damages the upper reticular dermis (TCA 50%); deep type, penetrates and damages the lower reticular dermis (phenol, Baker-Gordon peel formula). The mechanism by which peels improve photoaged properties of skin is not fully understood.
In this study, 18 mice were progressively photoaged with UVB light. The mice were than distributed into 5 groups: group 1 (n=4), TCA 30%; group 2 (n=4), TCA 50%; group 3 (n=3), phenol (Baker-Gordon peel formula, modified); group 4 (n=4), photoaged controls; and group 5 (n=3), non–UV-exposed controls. On days 7, 14, 28, and 60 after peeling, the mice underwent 4-mm punch biopsies. Although TCA 50% and phenol peels had more significant improvement than TCA 30% (P<.05), an increase in dermal thickness, collagen fibers, and elastic fibers was found in all peel groups compared to controls. These increases were maintained for 60 days.
What’s the issue?
Although dermatologists have been using chemical peels to treat fine wrinkles and lines, hyperpigmentation, and decreased skin elasticity for a long time, the exact mechanism of action is unknown. This study showed increased dermal thickness, collagen fibers, and elastic fibers on histologic evaluation, which in turn improves deep and coarse wrinkles as well as skin thickness. Although medium and deep peels (TCA 50% and phenol, respectively) improved these qualities more than a superficial peel (TCA 30%), I prefer superficial to medium-depth peels due to patient comfort and safety. Have you noticed a big difference in results between deep and medium peels?