Wrinkle

A wrinkle, also known as a rhytide, is a fold, ridge or crease in the skin or on fabric. Skin wrinkles typically appear as a result of aging processes such as glycation, habitual sleeping positions, loss of body mass, or temporarily, as the result of prolonged immersion in water. Age wrinkling in the skin is promoted by habitual facial expressions, aging, sun damage, smoking, poor hydration, and various other factors.

Development of facial wrinkles is a kind of fibrosis of the skin. Misrepair-accumulation aging theory suggests that wrinkles develop from incorrect repairs of injured elastic fibers and collagen fibers. Repeated extensions and compressions of the skin cause repeated injuries of extracellular fibers in derma. During the repairing process, some of the broken elastic fibers and collagen fibers are not regenerated and restored but replaced by altered fibers. When an elastic fiber is broken in an extended state, it may be replaced by a “long” collagen fiber. Accumulation of “long” collagen fibers makes part of the skin looser and stiffer, and as a consequence, a big fold of skin appears. When a “long” collagen is broken in a compressed state, it may be replaced by a “short” collagen fiber. The “shorter” collagen fibers will restrict the extension of "longer" fibers, and make the “long” fibers in a folding state permanently. A small fold, namely a permanent wrinkle, then appears.

Although the exact mode of action of tretinoin is unknown, current evidence suggests that tretinoin decreases cohesiveness of follicular epithelial cells. Additionally, tretinoin stimulates mitotic activity and increased turnover of follicular epithelial cells. Tretinoin is better known by the brand name Retin-A.

Glycosaminoglycans (GAGs) are produced by the body to maintain structural integrity in tissues and to maintain fluid balance. Hyaluronic acid is a type of GAG that promotes collagen synthesis, repair, and hydration. GAGs serve as a natural moisturizer and lubricant between epidermal cells to inhibit the production of matrix metalloproteinases (MMPs). Topical glycosaminoglycans supplements can help to provide temporary restoration of enzyme balance to slow or prevent matrix breakdown and consequent onset of wrinkle formation.

Dermal fillers are injectable products frequently used to correct wrinkles, and other depressions in the skin. They are often a kind of soft tissue designed to enable injection into the skin for purposes of improving the appearance. The most common products are based on hyaluronic acid and calcium hydroxylapatite.

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