When a Trichloroacetic Acid (TCA) peel results in full frost, what layer of the skin has been reached?

When a Trichloroacetic Acid (TCA) peel results in full frost, it indicates that the peel has effectively reached the upper reticular dermis. The phenomenon known as "frosting" occurs as a result of the chemical reaction between the TCA and the proteins in the skin, leading to the formation of a white, frost-like appearance. This reaction suggests that adequate penetration and damage have occurred in the skin layers, specifically within the upper reticular dermis, which is part of the middle layer of the skin.

The upper reticular dermis contains collagen and elastin fibers that provide strength and elasticity to the skin. When TCA is applied to the skin at the correct concentration and exposure time, it disrupts the epidermis and superficial dermis, penetrating deeper to treat various skin concerns effectively. This depth of action is essential for the intended results of improved skin texture, tone, and the reduction of fine lines or wrinkles.

Other layers mentioned, such as the stratum corneum, contain dead skin cells and would not result in frosting since they don't respond to TCA in the same way. The basal layer is part of the epidermis where new skin cells are generated, but it does not account for the