anatomy of the skin

Silicones do work on various types of scars. They are the only proven effective OTC products available. This treatment, commonly referred to as ‘The Golden Standard in Scar Treatment’ is non-invasive and easy to use. But how do they work?

Various theories circulate on the mechanism of silicone scar sheets and gels. Some state that the scar improving effects are due to pressure administered by the sheets. Others say that the reduced elevation and redness of scars are the result of a static electric field created by the silicones.

But there’s no evidence these assumptions are right. Also theories on improved oxygen supply, or an increased blood flow as a result of administering silicones have not been proven. Hydration does seem to play a major role but there’s more to it than simply moisturizing scar tissue.

According to various experts it is occlusion which is the key to the efficacy of silicone scar treatment. To understand we have to take a closer look at the water retaining function of the skin.

Healthy skin conserves water and functions as a barrier to microbial infection. The outermost layer of the skin (stratum corneum) normally contains water and is responsible for water conservation, but its function is disrupted when the skin is damaged.

“After a full-thickness wound, transepidermal water loss (TEWL) is increased and can take longer than 1 year to recover to basal levels. In addition, this water loss (TEWL) is greater with hypertrophic scars and keloids than with atrophic scars or normal skin [1].”

Water loss caused by skin injury leads to dehydration of the tissue which, on its turn, is thought to stimulate the production of small proteins (cytokines). These proteins are theorized to lead to changes in the skin (dermis) and increased scar tissue creation (collagen production) by cells that play a major role in wound healing (fibroblasts).

Although application of silicone sheeting to skin causes hydration of the stratum corneum, the extent of hydration is less than that produced by a plastic film, and the increase in hydration compared with normal skin decreases after repeated treatment [2].

These results have been interpreted to suggest that the semi-occlusive nature of silicone gel sheeting improves scars by providing adequate but not excessive hydration [2]. A plausible explanation for the mechanism of action of silicone-based products, therefore, is that occlusion causes a decrease in TEWL and normalizes the hydration  state of keratinocytes, which then signal dermal fibroblasts to downregulate extracellular matrix production.[3]

Or in other, less technical words, silicone sheeting is thought to provide the exact right amount of occlusion which restores the water balance in the skin and scar tissue. Certain processes in the scar tissue are more balanced out which results in less abnormal scar tissue creation.

[1] Suetake T, Sasai S, Zhen YX, Ohi T, Tagami H (1996) Functional analyses of the stratum corneum in scars: Sequential studies after injury and comparison among keloids, hypertrophic scars, and atrophic scars. Arch Dermatol 132:1453–1458

[2]Suetake T, Sasai S, Zhen YX, Tagami H (2000) Effects of silicone gel sheet on the stratum corneum hydration. Br J Plast Surg 53:503–507

[3] Evolution of Silicone Therapy and Mechanism of Action in Scar Management Thomas A. Mustoe. Aesth Plast Surg (2008) 32:82–92