THE FEATURES OF THE FACE SKIN CONSTRUCTION THAT INFLUENCE ON THE FORMATION OF CICATRICAL TISSUES DURING SUGICAL INTERVENTIONS

Abstract

Formation of pathological scars of maxillofacial localization after surgery is a significant and widespread problem of modern surgical stomatology and maxillofacial surgery. A significant percentage of patients who needs planned and urgent surgical interventions cause rapid development of reconstructive-restorative surgery of the maxillofacial region. The analysis of domestic and foreign literary sources was devoted to the peculiarities of the structure of the skin of the head and neck and the optimization of the skin incisions of this localization. Functional features of human skin depend on the mechanical properties of the dermis, which provides elasticity and resistance to stretching. Changes in the biomechanics of the dermis occur during aging, excessive insolation, scarring, and fibrosis. In addition, mechanical changes in the extracellular matrix of the skin affect the activity and phenotype of the fibroblasts, which adapt the stiffness of the cytoskeleton. Extracellular matrix stiffness defines and maintains cell identity and influences the proliferation, differentiation, migration and expression of skin cells. The extracellular matrix has been regarded for a long time as a structure with simple architectonics. But, due to modern research, it is known that this complex formation is highly specialized. The different classes of macromolecules that make up the extracellular matrix determine its biological functions. For example, collagen proteins are responsible for the tensile strength of tissues, proteoglycans and glycosaminoglycan are important for hydration and compression resistance, and glycoproteins such as laminas facilitate cell attachment. The largest structures of the extracellular matrix are elastin fibers, which are mainly localized in tissues subject to high mechanical stress, such as skin, lungs, or arteries. These structures represent a very complex organization whose core consists of elastin surrounded by a mantle of microfibrils. Collagen proteins in the dermis contain mainly type I collagen (85% - 90%) with smaller amounts of type III collagen (10% - 15%). Skin fibroblasts synthesize individual collagen type I and III polypeptide chains as precursor molecules, called procollagens. During the formation of insoluble collagen fibrils, specific proteases break down the carboxy- and amino-terminal domains, forming pN-collagen (procollagen from which the carboxy-terminal domain propeptide is cleaved) and pC-collagen (procollagen, from which the amino-terminal propeptide is cleaved). Because type I and III procollagen, pN-collagen and pC-collagen are precursors of mature collagen molecules, their level usually reflects the level of collagen biosynthesis. Collagens and elastin contain highly abundant fibrils, each of which is repeated in a sequence enriched in the conformation of polyproline II, cross-linked, insoluble in assembly and resistant to the most photolytic enzymes. The monomeric block of type I collagen consists of two extended chains α1 and one chain α2, twisted together into a triple helix. The direction of collagen and elastin fibers, according to biomechanical studies, has a significant effect on the enlargement of the wound on the head skin and the tension when closing its edges. The overwhelming reduction of tension and accordingly the improvement of reparative processes in the skin occur when the incision lines correspond to the so-called "golden spiral". Conclusion. Thus, the analysis of domestic and foreign literature sources indicates the relevance of the selected topics, the need for further studies on the biomechanical and histological substantiation of incisions, which are due to the peculiarities of the structure of the skin in the head and neck to create optimal conditions for reparative regeneration.

Keywords

• pathological scars, elastin, collagen, maxillofacial localization.