Effect Of Silicone Gel Research Articles

A prospective, randomized, placebo controlled, double blind study of silicone gel in prevention of hypertrophic scar at donor site of skin grafting

Background:Hypertrophic scarring at donor site of skin grafting is prevalent among Asians. The effectiveness of silicone gel in scar prevention may influence the surgeons and patients regarding its routine use during the postoperative period.Aims and Objectives:To study the efficacy of silicone gel in prevention of hypertrophic scars at donor site of skin grafting.Design:Prospective randomized placebo controlled double blind study.Setting:The study was conducted in the department of Plastic Surgery, Sri Venkateswara Institute of Medical Sciences (SVIMS) University, Tirupati, Andhra Pradesh, India from June 2007 to June 2009. Patients were recruited during follow-up in the OPD.Materials and Methods:The susceptibility to scar development varied among patients; therefore, donor site scars were divided into upper half and lower half. Two types of coded gel prepared by an independent pharmacist were used on either half. Thus, selection and assessment biases and confounders were eliminated.Results:100 scars in 50 patients were randomized into two arms, 50 control and 50 silicone gel. The median age was 25.5 years and there were 30 men (60%) and 20 women (40%). Thirty-seven patients (74%) had good compliance. The overall incidence of donor site hypertrophic scar was 94% (47 out of 50). At the second month postoperatively, the silicone gel scars were scored lower when compared with the control scars. The differences were statistically significant in all parameters, including pigmentation (P = 0.001), Vascularity (P = 0.010), pliability (P = 0.001), and height (P = 0.010).Conclusion:The effect of silicone gel in prevention of hypertrophic scar development in donor site scars is promising. Success of silicone gel in its prophylactic role will create its routine use in all types of surgery to minimize the formation of hypertrophic scars in the early postoperative period.

The effects of topically applied silicone gel and its silver derivative on the prevention of hypertrophic scarring in two rabbit ear-scarring models

Topically applied silicone gel is an effective treatment in the management of hypertrophic scars. This early study of silicone gel predates other well-controlled scientific studies that demonstrate these findings. Our well-established rabbit ear scarring model creates 7 mm punch wounds down to the bare cartilage, including the removal of the perichondrium. In this study, we employ a new model that creates 10 mm punch wounds that leaves the perichondrium intact. Both the 7 mm and new 10 mm scar models were used to study the effectiveness of silicone gel and silicone gel silver respectively on hypertrophy and the inhibition of scar formation. All samples were harvested at post-wounding day 35 for histological analysis. Silicone gel significantly reduced scar area (p=0.005), scar elevation index (p=0.03), and epidermal area (p=0.016). Silicone gel silver significantly reduced scar elevation index (p=0.004). The new 10 mm scar model resulted in more hypertrophic scarring than the typical, 7 mm wound scar model (p=0.0001). In conclusion, silicone gel and its silver derivative are effective in preventing hypertrophic scarring and scar models that leave the perichondrium intact causes scars with more hypertrophy.

Effects of silicone gel on burn scars

Aim To study the efficacy of silicone gel applied to hypertrophic burn scars, in reducing scar interference with normal function and improving cosmesis. Methods A randomised, double-blind, placebo-controlled trial involving 38 people with hypertrophic burn scars. Each scar was divided into two segments; silicone gel sheet was applied randomly to one of the two and placebo to the other. Participants were seen again after 1 and 4 months. Their data and wound characteristics were collected using the Vancouver scar scale. Results The median age of participants was 22 years (1.5–60 years) and 16 were male; 4 did not attend follow-up and were excluded from the study. There were no significant differences in baseline characteristics. Although after 1 month all scar scale measures were lower in treated areas, only the vascularity scale was significantly different between the two areas. After 4 months, all scale measures were significantly lower in the silicone gel group than in the control group, except for the pain score. Conclusion Silicone gel is an effective treatment for hypertrophic burn scars.

A Randomized, Placebo-Controlled, Double-Blind, Prospective Clinical Trial of Silicone Gel in Prevention of Hypertrophic Scar Development in Median Sternotomy Wound

Hypertrophic scarring caused by sternotomy is prevalent among Asians. The effectiveness of silicone gel in scar prevention may influence the decision of surgeons and patients regarding its routine use during the postoperative period. The authors conducted a randomized, placebo-controlled, double-blind, prospective clinical trial. The susceptibility to scar development varied among patients; therefore, sternal wounds were divided into the upper half and the lower half. Two types of coded gel prepared by an independent pharmacist were used on either half. Thus, selection and assessment biases and confounders were eliminated. One hundred wounds in 50 patients were randomized into two arms, 50 control and 50 silicone gels. The median age was 61 years and there were 34 men and 16 women. Ethnic distribution was 28 Malays, 18 Chinese, and four Indians. No side effect caused by the silicone gel was noted. Ninety-eight percent of patients had moderate to good compliance. The incidence of sternotomy scar was 94 percent. At the third month postoperatively, the silicone gel wounds were scored lower when compared with the control wounds. The differences were statistically significant in all parameters, including pigmentation (p = 0.02), vascularity (p = 0.001), pliability (p = 0.001), height (p = 0.001), pain (p = 0.001), and itchiness (p = 0.02). The effect of silicone gel in prevention of hypertrophic scar development in sternotomy wounds is promising. There are no side effects and patients' compliance is satisfactory. This study may popularize the use of silicone gel in all types of surgery to minimize the formation of hypertrophic scars in the early postoperative period.

The Effect of Silicone Gel on Basic Fibroblast Growth Factor Levels in Fibroblast Cell Culture

Topical silicone gel has shown promise in the treatment of hypertrophic and keloid scars. However, its mechanism of action remains undetermined. To investigate whether the presence of silicone alters the secretion of basic fibroblast growth factor (bFGF), a key cytokine involved in the scar formation process. Serum-free fibroblast cell cultures were established from normal, keloid, and fetal skin, which heals without scarring, and exposed to silicone gel. Serial cell counts were performed, and supernatants were collected for bFGF quantification by enzyme-linked immunosorbent assay at 4, 24, 72, and 120 hours. Growth curves were similar and no statistically significant differences in population doubling times were observed between treated and untreated specimens. Statistically significant differences in bFGF levels between treated and untreated normal fibroblasts were observed at 24, 72, and 120 hours after cell culture initiation. Differences in bFGF levels between treated and untreated fetal fibroblasts that approached statistical significance were observed at 72 and 120 hours. These results suggest that silicone gel is responsible for increased bFGF levels in normal and fetal dermal fibroblasts. We postulate that silicone gel treats and prevents hypertrophic scar tissue, which contains histologically normal fibroblasts, by modulating expression of growth factors such as bFGF. Our data support the hypothesis that substances that favorably influence wound healing do so by correcting a deficiency or overabundance of the growth factors that orchestrate the tissue repair process.

The effect of silicone-gel on the immune response.

Silicone materials have been used in medical applications for at least 30 years. Despite this long history of use the question whether silicones can mediate an immunological reaction that may be detrimental to the host remains unanswered. Most studies on the biocompatability of silicones conclude that silicones are chemically stable compounds, which however are often capable of eliciting a benign chronic inflammatory response. Recently, our laboratory has conducted a series of animal experiments aimed at determining the immunological adjuvancy potential of silicone-gel taken from commercial breast implants. Our previous studies have indicated that silicone-gel is a potent humoral (antibody) adjuvant. Our present studies have found that silicone-gel is capable of eliciting auto-antibodies to rat thyroglobulin and bovine collagen II. However this immune response did not produce any histological evidence of thyroiditis or arthritis. Theories to explain why silicone-gel behaves as an adjuvant are discussed along with discussion of the hypothesis on the desirability of replacing silicone-gel with a more hydrophilic material in bioimplants.

Short-Term Effect of Silicone Gel on Peripheral Nerves

The effect of silicone gel on the peripheral nerve was studied in Sprague-Dawley rats. Silicone gel was placed either extraneurally (N = 36) adjacent to or injected directly in the sciatic nerve (N = 20). Nerve histology was studied every 2 weeks over a 20-week period. Extraneural silicone gel elicited an intense inflammatory response characterized initially by predominantly histiocytes with a few eosinophils, lymphocytes, and foreign-body giant cells. The cellular response peaked at 4 weeks, after which time collagen deposition increased and the thickness of the cellular infiltrate surrounding the gel decreased. The gel was temporarily contained by the inflammatory response, but throughout the time course of the study, gel migration and breakup into smaller droplets occurred. Each droplet appeared to initiate the inflammation-fibrosis cycle anew. Perineural fibrosis was marked by 20 weeks, but there was no penetration of the epineurium by the gel. Intraneurally injected silicone gel also caused a delayed, but similar inflammatory response, eventually followed by fibrosis surrounding the gel. Intraneural gel tended to remain in larger droplets and did not migrate over the duration of this study. No direct evidence of gel toxicity to peripheral nerves was observed in either the extraneural or intraneural gel groups despite the initial intense inflammatory response and subsequent fibrosis.