Dow Corning on Silicone
Performance-enhancing Materials Appropriate for Health Care Innovation
Hypertrophic scars and keloids are fibrotic conditions that result in an over-deposition of collagen in the skin. They can be caused by minor cutaneous perturbations such as ear piercing or acne, or by traumatic injuries such as burns. Visually, these scars are raised reddish nodules that can cause pruritus, pain, restricted movement, and cosmetic disfigurement. The principal difference distinguishing keloid from hypertrophic scarring is that a keloid progressively invades the surrounding healthy tissue. In contrast, a hypertrophic scar only increases in dimension by pushing out its margins; there is no expansion into the surrounding tissue. Whether the scar is hypertrophic or keloid, the scar tissue rarely extends deep into the dermis.
It is well documented in published literature that various factors including ethnic background, hormonal status and injury location can contribute to a heightened incidence of scarring. Keloids are more prevalent in individuals with darker skin pigmentation, with an incidence of 4.5 - 16% in African and Hispanic populations. Of note, data from the National University of Singapore indicates that keloids are three (3) times more common in Chinese patients than among Caucasian patients. Another study in the published literature suggests that Chinese are slightly more prone to keloids than the darker-skinned Indians and Malays. Hypertrophic scars are more common and occur with equal frequency in all racial groups.
The average age of onset for keloids has been estimated to be approximately 22 years for both men and women. Others report a higher incidence in young women relative to age matched males, which may reflect a higher frequency of ear lobe piercing among women. Specific body sites that are more prone to scarring are areas with oil-secreting sebaceous glands or areas of increased skin tension. They include the shoulders, upper back, upper arms, chest, ears, cheeks and neck. Hypertrophic scars can regress over time, whereas spontaneous regression of keloids is rare.
Overall Benefits of Silicone
Among qualified materials used in health care applications, silicones are clearly recognized for their biocompatibility. Additionally, silicone chemistry offers a broad range of performance characteristics that make materials suitable for use in many types of processes and applications, ranging from multifunctional excipients and active pharmaceutical ingredients to medical device components.
Silicone Solutions for Scars
A variety of techniques have been utilized to prevent, as well as treat, abnormal scars. The standards for preventing and treating abnormal scars are therapies using silicone gel sheeting and intralesional corticosteroids. Clinical studies have proven that silicone gel sheeting is safe, and is superior to polyethylene, polyurethane and other occlusive dressings. Although less studied, formulations of silicone fluids have also demonstrated efficacy on minor hypertrophic scars. Whether this beneficial response is due in part to silicone-induced skin hydration is at present unknown.
A number of other treatment modalities have also been explored (e.g. topical or intralesional steroid applications, ultrasound, cryotherapy, compression therapy, radiotherapy, and laser therapy), but few have been supported by controlled clinical studies. Surgical excision can result in recurrence, as the new surgical wound is prone to the same mechanical, immunological and biochemical forces as the original scar. In general, hypertrophic scars appear to be more responsive to treatment than keloids.
* Information Source: Dow Corning®