Nowadays, in the arsenal of modern dermatocosmetology, there is a fairly wide range of methods of correcting various aesthetic skin imperfections - chemical peelings, mechanical dermabrasion, laser treatment, microdermabrasion, contour plastic, and others. Nevertheless, new directions and technologies in the beauty industry are constantly evolving and improving.
This trend is particularly typical for hardware methods, especially for laser medicine. The use of lasers, first in dermatology and then in cosmetics, has had an impressive time. More than 25 years have passed since one of the newest methods of laser treatment - selective photothermolysis - appeared. The pioneers of this direction, the Americans RR Anderson and JA Parrish, determined the fate of fractional lasers in medicine and made them indispensable for the treatment of such aesthetic skin imperfections as capillary hemangiomas. Port wine stains, hypertrichosis, tattoos, rosacea, pigment disorders, photoaging, wrinkles, etc.
Modern techniques for skin reshaping
We live in a time when more people are living into old age than ever before. And since many of them are still active, the fight against aging skin is one of the most important problems in aesthetic medicine.
Plastic surgery can rejuvenate the shape of the face by removing excess skin. At the same time, however, the skin remains altered through time (age-related aging) or external factors (light aging). It is also important that most patients want to look younger without surgery.
In this case, what method should be used to influence the skin and what should be done inside it in order to really rejuvenate it?
All methods with which the appearance of the skin can be improved are combined in one principle: They have a traumatic effect on the skin and trigger fibrosis, which leads to tension and compression.
Currently, dermatocosmetology uses three main types of remodeling effects on the skin, including:
- chemical stimulation - chemical peelings with acids (trichloroacetic acid, glycolic acid, etc. );
- mechanical stimulation - mechanical dermabrasion, microdermabrasion, mesotherapy, fillers, subcision with needles;
- Thermal stimulation - laser ablation, thermal lifting with lasers and broadband light sources, high frequency lifting, fractionated methods.
Chemical stimulation
Historically, acid peeling (peeling) was the first method of skin rejuvenation. The principle of peeling is a partial (as with superficial peeling) or almost complete (as with medium and deep peeling) destruction of the epidermis, which is harmful to fibroblasts and dermis structures. This damage triggers an inflammatory response (the stronger, the greater the volume of destruction itself), which leads to additional production of collagen in the skin.
However, in order to achieve the desired result, the epidermis must be sacrificed when peeling. Burn experiments have misled many and allegedly "proven" that the epidermis is a self-renewing organ that recovers quickly over the damaged area. In this regard, scrubs became more and more aggressive towards the epidermis (for example, deep phenol peeling) for a period of time, until finally the accumulated problems led specialists to realize the malignancy of this, a method that ultimately leads to the thinning of the skin.
Proponents of deep exfoliation ignored the emerging problems. Their essence was that due to the destruction of the papillae of the dermis and the weakening of nutrition, the epidermis becomes thinner and the number of cells in the prickly layer is significantly reduced in comparison with what was before peeling. A decrease in the barrier function of the stratum corneum leads to a decrease in skin moisture. (This is why almost all patients suffer from severe dryness of the skin after prolonged deep peeling. ) Simultaneously, the introduction of lighter peelings (with trichloroacetic acid and fruit acids) did not fulfill their hopes of effectively tightening the skin.
Mechanical stimulation
Of the methods of mechanical stimulation of involutional changes in the skin, dermabrasion using rotary devices (at a speed of v; rotation of cutters up to 100, 000 rpm) deserves special attention. Modern Schumann-Schreus devices are currently in use (Germany)
The method can only be used in a surgical hospital, as the procedure requires anesthesia, postoperative treatment of the wound surface, a special toilet for the eyes and mouth, as well as devices for patient feeding (due to the fact that the pronounced postoperative edema, which occurs 2-3 days after the procedure, making it difficult to open eyes and mouth).
The method is very effective, but unfortunately mechanical dermabrasion carries a high risk of complications such as:
- persistent postoperative hyperemia;
- the appearance of areas of depigmentation due to the destruction of melanocytes when the cutter penetrates the basement membrane;
- wound surface infection;
- Scars (if the cutter is immersed too deeply into the skin)
All of this has determined the limited application of this method in clinical practice.
thermal stimulation
Ablative redesign
Since the late 1980s, lasers have been used to rejuvenate the skin by removing layers of tissue (ablation) [4]. The precise, traumatic removal of the surface layer of the skin with a carbon dioxide laser stimulates the synthesis of its own collagen in it. The amount increases several times after the procedure. Then it will gradually be reorganized.
The use of a CO2 laser was most effective when it was exposed to a deep thermal effect on all layers of the dermis, which manifested itself externally through the effect of skin tightening. The procedure is known as "laser dermabrasion" or "laser" resurfacing, and in terms of efficiency, there couldn't have been any other method of skin rejuvenation that existed at the time (Fig. 1).
Fig. 1. Scheme of traditional laser skin resurfacing (laser dermabrasion)
However, the CO2 laser also causes a number of complications. In addition, further studies have shown that such a deep effect on the dermis stimulates the formation of fibrous tissue to a greater extent than does collagen that contributes to the synthesis of a new normal [5]. Developed fibrosis can make the skin look unnaturally pale. Collagen synthesized after the treatment is reabsorbed after a few years like any collagen formed at the site of the scar. As a result of the thinningin the epidermis, which is caused by atrophy of the papillary layer of the dermis, fine wrinkles appear on the skin. Due to the weakening of the barrier function of the stratum corneum, the moisture content of the skin decreases and it looks atrophic.
Erbium-aluminum-yttrium-garnet-erbium lasers appeared a little later. Such advantages of an erbium laser as a lower thermal penetration depth (erbium lasers penetrate to a depth of 30 μm, CO2 lasers - up to 150 μm) and (as a result) excited the lower risk of burns and carbonization of the tissue, as well as the relative cheapness (imCompared to carbon dioxide lasers) the attention of many specialists around the world.
However, as experience has been gained with these two types of installations, the opinion has developed among experts that CO2 lasers are more efficient [6]. Despite the negative effects of carbon dioxide laser dermabrasion described above, this procedure remains indispensable for correcting acne scars. In addition, it can be viewed as an alternative to surgical skin tightening - of all the methods of remodeling, only exposure to a CO2 laser can actually have a pronounced effect on collagen contraction with a visible clinical lifting effect.
The problem with all of the methods described above is that they often "sacrifice" the epidermis, that is, cause considerable damage. To rejuvenate your skin and look really young, you need a perfect epidermis with natural properties, papillae of the dermis, good hydration, normal skin tone and elasticity. The epidermis is a very complex, highly specialized organ with a thickness of up to 200 micrometers. This is our only defense against the effects of negative environmental factors. Therefore, whatever we do to rejuvenate the skin, we need to make sure that the underlying normal architecture is never damaged.
This concept contributed to the emergence of non-ablative skin reshaping technology.
Non-ablative remodeling
The most common devices for non-ablative skin remodeling are neodymium (Nd-YAG) and diode lasers as well as broadband light sources (IPL). The principle of their action - selective photothermolysis - consists in the heating and destruction of structures containing a sufficient amount of melanin or oxyhemoglobin. In the skin these are accumulations of melanocytes (lentigo, melasma) or microvessels (telangiectasia). The emitted wavelengths used in non-ablative lasers correspond to the maxima of the absorption spectra of oxyhemoglobin or melanin. The procedure for treatment with non-ablative lasers and IPL is quite safe, the rehabilitation time is minimal, however, such treatment only eliminates pigmentation and vascular problems and cosmetic defects. In this case, there is some thickening of the skin, but the effect achieved is short-lived.
Fractional Skin Remodeling Techniques
The constant search for new, highly effective and at the same time safe methods for skin rejuvenation has led to the emergence of a revolutionary technology - the fractional emission of laser radiation. The proposed skin rejuvenation method has been specifically designed to overcome some of the difficulties noted above. In contrast to "conventional" ablative and non-ablative laser methods, which are intended to achieve uniform thermal damage to the skin at a certain depth, fractional methods allow its selective microscopic thermal damage to be achieved in the form of numerous altered columns and untouched areas around these micro-woundsto leave. Currently, the industry makes two types of fractional lasers: non-ablative and ablative.
The first uses an erbium-doped optical fiber that produces radiation with a wavelength of 1550 nm. The fractional laser forms thousands and tens of thousands of microdamages in the skin in the form of columns - microthermal treatment zones (MLZ) - with a diameter of 70-150mk depth to 1359mcm
As a result, around 15-35 skin will be photocoagulated on the treated area. The chromophore for the laser is water. Coagulation occurs mainly in the lower layers of the epidermis and dermis. The stratum corneum remains intact because it contains a relatively small amount of water and this greatly reduces the risk of infection. Epidermal recovery is rapid due to the small lesion volume and the short migration distance of the keratinocytes. The healing period is accompanied by moderate edema and hyperemia, followed by desquamation, which occurs on April 5-7. Day occurs. The patient practically does not lose any social activity.
This technology - fractional photothermolysis (FF) - is a highly effective method for non-ablative fractional skin reshaping. Course treatment is prescribed to achieve the desired effect. Depending on the clinical situation, it is recommended to perform 3 to 6 procedures with an interval of 4-6 weeks. As with any other method of non-ablative skin reshaping, the end result is only visible 4 to 8 months after the procedure (cumulative effect).
In cases where a more aggressive effect on the skin is required - to correct scars, remove deep wrinkles and excess skin, the method of fractional ablation (FA or fractional deep dermal ablation -FDDA) is used.
The fractional ablation method combines the advantages of a CO2 laser and the fractional principle of laser radiation emission. In contrast to conventional CO2 lasers, which remove the entire skin surface layer by layer, the FA units form a large number of microablative zones (MAL) with a diameter of up to 300 µm at an evaporation depth of 350 to 1800 µm (Fig. 2).
During this process, laser radiation, which penetrates the deep layers of the skin, destroys the upper layer of the epidermis. In terms of efficiency, ablative fractional laser rejuvenation can be compared to plastic surgery. This is how deep the laser beam reappears.
Fig. 2. The principle of operation of the ablative fractionated laser: formation of microablative zones - MAZ (a); Dependence of the MAZ formation depth on the laser radiation power (b)
As in the case of FF, 15 to 35% of the skin of the treated area is actually exposed (in some cases up to 70%). Recovery after the FA procedure is faster than after layer-by-layer ablation. This is due to the fact that, significantly, part of the epidermis and stratum corneum remains intact. Immediately after the procedure, skin bleeding is observed for some time, but this soon stops (Fig. 3 a, b).
Fig. 3. Gradual restoration of the skin using the fractional ablation procedure: view immediately after treatment (a); every other day (b); after 5 days (c); 14 days (d) after an operation
Numerous microbleeds occur in the dermis, causing a complex cascade of changes that lead to the production of new collagen. After the bleeding has stopped, the serous fluid remaining on the surface of the skin must be removed. Its release is observed within 48 hours after the procedure, until complete epithelialization of the microablative zones occurs. During this time, the patient uses special external means for wound healing. Usually starts from 3-4 days Peeling and swelling increases (Fig. 3 c). On the 7th day these phenomena gradually subside and the erythema remains the only noticeable side effect (Fig. 3d). The duration of the erythema depends on the parameters of laser exposure, and features of skin vascularization. According to the author's observations, the erythema lasts no more than 3 months.
The patient's loss of social activity after the FA procedure lasts 5 to 10 days.
To prevent scarring and the manifestation of post-inflammatory pigmentation, the skin must be carefully cared for. Decorative cosmetics can be used from 4-5 days. A prerequisite for a good result is the use of sun protection cosmetics with a high degree of protection (SPF at least 50) for at least 3 months after the procedure. The risk of post-inflammatory pigmentation occurs in 20% of patients and is generally higher in patients with skin IV-V phototypes. Such hyperpigmentation is temporary and can last from 1 week to 3 months, also depending on the depth of treatment and the area of the area being treated. For prevention 1-2 weeks before the procedure and for another 2 weeks after it, external agents based on hydroquinone (4%) and tretinoin (0. 1%) are prescribed. The main effects on facial skin after the FA procedure are as follows: pronounced tightening and reduction of excess skin, leveling of wrinkled skin and skin affected by acne scars, reduction of dyschromia, porosity.
This method was also tested by the author and his colleagues to remove stretch marks from the skin. As clinical studies have shown, the method has shown great efficiency in eliminating almost all types of stretch marks, both acquired during the puberty period and after childbirth. It has been found that the healing processes on the skin of the body are different than on the skin of the face.
Mechanism of skin remodeling when using fractional lasers
Let us consider the mechanisms of skin remodeling when using fractional lasers.
After exposure to the laser, aseptic inflammation develops in the area of the formed micro-wounds. The more aggressive the laser exposure, the more pronounced the inflammatory response, which actually stimulates the post-traumatic release of growth factors and fibroblast infiltration of damaged tissue. The coming reaction is automatically accompanied by a burst of cell activity, which inevitably leads to fibroblasts starting to produce more collagen and elastin. The skin remodeling process comprises three classic regeneration phases:
- Phase I - change (tissue inflammation). Starts immediately after the damage;
- Phase II - proliferation (tissue formation). Starts 3-5 days after the injury and lasts about 8 weeks;
- Phase III - remodeling the tissue. Lasts 8 weeks to 12 months.
It should be noted that all three phases of skin remodeling are observed both after fractional photothermolysis and after fractional ablation. In the first case, however, the damaging effect of the laser is moderately aggressive, creating an inflammatory cascade change is never too wild.
After exposure to the fractional ablation laser, a completely different image is observed. The trauma caused by this laser ruptures blood vessels and blood cells along with serum are released into the surrounding tissue. The full-fledged mechanism of skin regeneration - Pha change begins - aseptic inflammation develops. Platelets released from damaged vessels play an important role in activating blood clotting and releasing chemotoxic factors, which in turn attract other platelets, leukocytes and fibroblasts. Leukocytes, especially neutrophils, are involved in the cleansing of destroyed tissue and remove fragments of necrotic tissue that are partly destroyed by phagocytitis and partly in the form of microscopic deposits that come from epidermal and dermal tissue substrates and melanin - microepidermal necrotic deposits (MENO)exist, to the surface of the skin.
The proliferative phase begins in about 5 days. During this time, neutrophils are replaced by monocytes. Monocytes, keratinocytes and fibroblasts continue to influence the growth factors and at the same time are under their opposite influence. Keratinocytes stimulate the growth of the epidermis and the release of growth factors that are necessary to stimulate the production of collagen by fibroblasts. In this phase new blood vessels are formed and the extracellular matrix is intensively formed.
The last reconstructive healing phase after fractional laser exposure takes several months.
On the 5th day after the injury, the fibronectin matrix "fits" along the axis along which the fibroblasts are aligned and along which collagen is built. The transformation of the growth factor β (TGF-β is a highly chemotoxic agent for fibroblasts) and other growth factors play an important role in the formation of this matrix. The main form of collagen in the early stages of wound healing is type III collagen (this type of collagen is found in the top layer of the dermis, just below the base layer of the epidermis). The longer the alteration phase, the more type III collagen is produced, but in any case its amount increases to the maximum 5 to 7 days after the damage. Type III collagen is gradually replaced by type I collagen over about a year, which strengthens the skin. Blood circulation gradually normalizes, the skin becomes smoother and natural color.
Comparative analysis of laser methods for skin reshaping
In summary, here is a diagram that shows the relationship between the effectiveness and safety of laser skin remodeling techniques.
Advantages of fractional methods for track rejuvenation. The advantages of the fractional methods used in clinical practice include:
- controlled minimal skin damage. Post-procedure histological studies show an increase in the number of papillae in the dermis, which characterizes the changes that have occurred in the skin as productive regeneration;
- its effective rejuvenation: the skin becomes thicker, it increases significantly (more than 400% (! )) the production of collagen and elastin;
- short healing time: on average 3 days after FF and 7-14 days after PA;
- minimal risk of hyperpigmentation;
- the ability to perform the procedure on patients with thin skin;
- the ability to have a healing effect on any part of the body;
- the possibility of using light types of anesthesia: with fractional photothermolysis, only local anesthesia is used, with fractional ablation a combination of conduction and infiltration anesthesia is required.
- Disappearance of telangiectasias (due to the fact that blood vessels rupture in so many places that it is impossible to restore them).
Main indications for fractionated treatments
Indications for fractional photothermolysis:
- Increase in skin density in the early stages of aging. The FF procedure is relatively simple and can be administered without fear. The therapeutic effect can be exerted on the neck, décolleté, arms, abdomen, thighs and mammary glands.
- photoaging of the skin;
- hyperpigmentation, melasma;
- hypertrophic scars;
- stretch marks.
Indications for fractional ablation:
- Wrinkles of varying severity - from fine to very pronounced wrinkles (in the form of furrows);
- age-related loss of skin elasticity and firmness;
- excess skin on the eyelids, neck and face (as an alternative to plastic surgery);
- uneven skin structure;
- pronounced photoaging of the skin;
- acne scars;
- cicatricial deformity of the skin after injuries, operations;
- Hyperpigmentation: melasma, lentiginosis, speckled pigmentation, etc.
- vascular dyschromy;
- traces of skin stretching;
- actinic keratosis.
Finally, a few words on the prospects for the use of laser technologies in aesthetic medicine. We have to pay tribute to manufacturers for starting to pay more attention to the safety of laser medical procedures. Technology continuously developed. Often, however, the safety of a method has been sacrificed in order to increase its effectiveness. Or the other way around. A compromise was found in a new principle of delivering laser radiation to tissue. It should be noted that the types of lasers remained the same: erbium, carbon dioxide, neodymium. This suggests that:
- First, laser skin reshaping is considered the most effective today:
- Second, the breadth of coverage of aesthetic and dermatological problems solved with these methods is extremely wide - from skin rejuvenation to the treatment of congenital and acquired skin pathologies;
- Third, with the advent of fractional technology, the safety and effectiveness of treatment have become predictable.