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Associated Table
Since its infancy, literature has chronicled our desire to look younger. Some of the earliest prescriptions were elixirs for youth and salves designed to maintain a vibrant appearance.
However, a breakthrough came in the 1980s with the discovery of alpha hydroxy acids (AHA). These chemicals, when used in high concentrations as peels and at lower concentrations in daily care, reduced wrinkles and increased protein production in skin. In addition, a University of Michigan dermatology department study showed that topical tretinoin, a prescription drug, had similar results. The combination of these two phenomena, combined with the exquisite timing of the baby boom generation reaching middle age, finally allowed us to provide proven topical methods for turning back the clock.
Since then, various high-tech -reiterations have come center stage. Most recently, fillers and neurotoxins have dominated the field, pushing topical treatment further to the periphery. However, physicians who only center on these latest high-tech approaches are missing an important component of aesthetic practice. In a comprehensive treatment paradigm, chemical peels, whether as an office-based procedure or as an active ingredient in home-based products, remain just as relevant as the days before these newer approaches came on the scene.
Classification of Peels
Since the discovery of alpha-hydroxy acids, choices of chemical peels have multiplied and become increasingly sophisticated. Today, office-based peels are classified into superficial, medium and deep peels and are based on the approximate wound depth.
Superficial peels. Superficial peels pene-trate from the epidermis to the upper -papillary dermis. Superficial agents include glycolic acid (GA) up to 70 percent, trichloracetic acid (TCA) up to 20 percent, and Jessner's solution, which is a combination of resorcinol, salicylic acid, lactic acid and ethanol. These agents are effective for lentigines, inflammatory acne and post-inflammatory hyperpigmentation.
These peels do not produce frosting or self-neutralize. Rather, the health care provider controls the exposure time, depending on the desired depth. For example, mild acne and epidermal dyschromia will require shorter exposure times, while moderate photodamage will respond better to longer exposure times.
Neutralization is achieved with a sodium bicarbonate solution. Since this is an exothermic reaction, the patient may feel slight heat. The patient can then either rinse with cold water, or leave towels saturated with cold water on the face.
TCA is self-neutralized. Therefore, the penetration is related to the number of application coats, not exposure time. TCA application results in white frosting in approximately two minutes, indicating the completion of the peel. Patients will experience a burning discomfort during this process. Upon completion, water-soaked gauze or a towel is placed on the patient's face.
Erythema will persist for several days after the peel, depending on the depth. We sometimes prescribe mild topical steroids to reduce discomfort and the risk of post-inflammatory hyperpigmentation, especially for people with darker skin types.
We also tell patients to avoid retinoids for up to two weeks, until complete re-epithelialization. Some clinicians have started to offer specific wound healing creams and growth factor creams to hasten recovery.
Medium-depth peels-Medium-depth peels can penetrate the upper reticular dermis. Medium peels are characterized by TCA (35 percent to 40 percent) alone or in combination with Jessner's or 70 percent GA. TCA above 35 percent alone is less predictable, with increased risk of scarring and complications. When combined with GA or Jessner's, TCA achieves a more predictable medium-depth peel.
These peels are effective for dyschromia, photodamage, mild rhytides, scars and actinic keratosis. However, medium-depth peels require longer recovery, compared to superficial peels. In addition, collagen remodeling generally continues for several months.
Deep chemical peels. Deep chemical peels can penetrate to the mid-reticular dermis. They reduce severe rhytides and scarring and typically contain large concentrations of phenol. The most commonly available preparation is Baker's formula, composed of phenol, croton oil, septisol and distilled water. This is reserved for deep rhytides and severe photodamage only, due to the potential of cardiac arrhythmias, and renal and hepatic dysfunctions. Physicians usually administer intravenous access and sedation. Patients will need prolonged postoperative care. These potential complications have made phenol peels much less attractive to physicians, who are largely replacing this option with laser resurfacing.
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