## 4 Discussion
While the adhesive component of the wound dressings in Allevyn provides a silicone-based seal and Biatain uses non-silicone-based adhesion, both types of wound dressing have an occlusive character and lead to a moist skin environment overall. Mepilex, on the other hand, uses the company's own Safetac(r) technology. This is a special form of silicone adhesion that is very well tolerated by the underlying skin, but is more suitable for wounds that do not exude as heavily, which might also account for the measured lower-TEWL and moisture values. Synthetic skin substitutes are used for various forms of severe skin damage. These can be traumatic or post-operative in nature, occurring after major burns, and are also used in the treatment of chronic, poorly healing wounds. They are designed to replace the extracellular matrix of the body's own skin, so that the wound healing process in the affected areas of the body is facilitated and better cosmetic and functional resultscan be achieved [37]. The skin substitutes examined in the present study are of different compositions. While Biobrane and Xenoderm re-synthesize parts of the skin derived from pigs, Epigard and Suprathel are synthetically produced preparations. Suprathel consists of polylactic acid, polycaprolactone and trimethylene carbonate, while Epigard consists of a polymer foam layer coated with a silicone-based, water-repellent layer. Although there are clear differences between the preparations in terms of skin-substitute composition, none of the preparations showed significantly higher TEWL values in the present study, either on the second day of the study or in comparison with the control group, which supports the hypothesis that these dressings could counteract excessive accumulation of humidity in, and evaporation from, the underlying skin, and thus replace some of the protective properties of skin in this respect (skin substitute). Overall, the skin substitutes examined are less occlusive in nature compared to other wound dressings examined. Although one of the objectives is also to create a moist wound environment for skin regeneration [38], it is not as moist as in the case of foam wound dressings, for example. Scar plasters are characterized by their supportive nature. They exert traction on the underlying skin so that wound healing is supported. They also promote collagen formation and restructuring, control inflammation, and influence the water balance [39]. Most scar plasters are semi-occlusive-to-occlusive in nature, and silicone-based. They increase the hydration of the stratum corneum and thus prevent the formation of hypertrophic scars [40]. In the present study, significantly increased TEWL and skin-hydration values were achieved for all scar patches on the second day of the study. Cica care achieved the highest mean daily differences in the study. Tegaderm, belonging to the wound-dressing category of transparent wound dressings, showed the second-highest mean daily difference values in the study. As previously mentioned, they are semipermeable in nature and are therefore intended to maintain a certain degree of permeability. Nevertheless, they have a primarily occlusive effect and collect fluids underneath the wound dressing, in the form of exudates or sweat, for example [35]. The findings thus match the intended wound-dressing properties. All dressings that showed significant TEWL differences between the control condition and the measurement condition were self-adherent. With regard to the increase in TEWL, the extent of occlusion of the wound dressing appears to play a significant role. If it is desirable for the clinical setting to create a wound healing environment that is as self-contained as possible, a self-adhesive preparation should be used. Non-self-adhesive dressings did not achieve such high TEWL values. While the findings with regard to skin moisture were not quite as distinct, the comparison of adhesive versus non-adhesive preparations did reveal a noticeable difference.