Skin Rejuvenation Procedures
Gary D. Monheit, M.D.
Associate Professor
Department of Dermatology
University of Alabama at Birmingham
Birmingham, Alabama

The pursuit of youth and beauty has become a hallmark of the baby-boomer generation, which has now advanced to mid life and beyond. The distinct increase in an older population due to newer advances and career development has brought a larger healthy population interested in cosmetic procedures. This mid-age population has remained active in the workforce and now demands “no down time” procedures for skin rejuvenation that will maintain their appearance for work and pleasure. This has encouraged the development of new lasers, new fillers, Botox, cosmoceuticals and many other innovations that have reduced the down time and increased the safety of our cosmetic facial rejuvenation procedures. All of us interested in providing facial cosmetic procedures and surgery need to become familiar with all the procedures now available.

Aging of the skin is the combined result of both intrinsic factors and extrinsic external influences from the environment. Intrinsic aging is the role genetics play in relationship to chronologic age. These include alteration of skeletal mass and proportion, atrophy and redistribution of subcutaneous fat, increased laxity of underlying fascia and musculature and skin changes characterized by thinning and atrophy. Most intrinsic factors cannot be prevented but rejuvenative changes can be made with cosmoceutical agents and resurfacing procedures.

Extrinsic factors are those preventable environmental influences leading to premature aging of the skin including ultraviolet exposure, smoking, chemicals and gravity. UV exposure is the primary environmental factor, preferentially affecting those with a lighter skin color. The mechanism includes the production of UV inducing oxygenated fine radiants that have been shown to invite a cascade of molecular events leading to the production of collagen degrading enzymes. This creates the characteristic features of photoaging, including rough texture, atrophy, fine and coarse wrinkles, sallow and leathery appearance with dyschromia.1

In the evaluation of the patient with photoaging, equal emphasis must be placed on prevention as well as treatment. Agents available range from cosmoceutical topical agents to filling agents that include resurfacing devices such as chemical peels, ablative resurfacing lasers and dermabrasion. An initial consultation is performed to determine which of these tools is best for the patient based on severity and diversity of the condition.

Methods to evaluate photoaging include the Glogau classification of wrinkles. It classifies patients into one of four groups based on degree of severity (Fig I). Category I is “no wrinkles” with young patients who have minimal photoaging and are best managed with cosmoceutical agents and superficial resurfacing procedures such as light chemical peels and Microdermabrasion. Category II are patients in their 30’s with early to moderate signs of photoaging and characterized by wrinkles in motion. Category III has moderate to advanced photoaging with static wrinkles requiring more significant ablative resurfacing techniques. Category IV are the older patients with more severe photoaging changes and wrinkles significant enough to justify deep resurfacing and other surgical techniques.2

Ablative resurfacing injures the skin in a controlled fashion to a specific depth encouraging the growth of new and improved skin. These methods include chemical peeling, dermabrasion and laser resurfacing. Skin resurfacing techniques are divided into superficial, medium depth and deep relating to the level of injury. The deeper procedures are restricted only to the face, as other body areas do not have the healing capacity to rejuvenate new skin after such an injury. Care must also be taken with the neck, which may scar with medium depth or deep injury.3

The following classification system is useful in categorizing skin resurfacing methods (Table 1). It is based on the objective data done by Stegman et al. correlating strengths of TCA by biopsy of depth of tissue destruction and then new collagen rejuvenation. Thus superficial, medium depth and deep resurfacing correlates modalities of peeling, dermabrasion and laser to common denominators; inflammation and injury.4

A useful method of assessing skin related photoaging is the Monheit-Fulton Index of Photoaging Skin (Table 2). This system categorizes the visual changes in photoaging skin and quantitates the amount to guide the physician with appropriate therapy. The system combines age related textural and lesional changes into a numeric system that will predict how aggressive a physician should be in using superficial, medium depth and deep resurfacing procedures.5

Medical Care of Photoaging Skin
The basis of all rejuvenative therapy involves using sunscreen protection and cosmoceutical preparation that will help reverse photoaging changes. These products include sunscreens, retinoids, hydroxy acids, antioxidants and bleaching agents as needed.

Ultraviolet damage is caused by both UVB (290-320 nm) and UVA (320-400 nm) ultraviolet damage. Both the burning rays of UVB and the more deeply penetrant UVA cause problems of photocarcinogenesis and photoaging of the dermis. Most sunscreens provide adequate protection against the burning effects of UVB but only deliver partial protection against UVA. Sunscreens are divided into chemical and physician blockers. The chemical screens include oxybenzene, para-aminobenzoic acid (PABA) and octyl methoxycinnamate. The physical blockers now are transparent micronized formulations of titanium dioxide and afford more complete UVA and B protection.6

Topical retinoids have a direct effect on epidermal cell proliferation and dermal collagen growth. It has demonstrated significant effects on photoaging skin including dyschromias, epidermal growths and fine wrinkle lines. The Federal Drug Administration has approved topical retinoids for the treatment of aging and photodamaged skin in the form of tretinoin cream (Renova 0.05% or 0.02%) and most recently tazarotene cream 0.1% (Avage). Use of a retinoid with a sunscreen is basic in skin care for photoaging skin problems. It is also used prior to resurfacing procedures to enhance the epidermal and dermal regenerative effect after resurfacing injury.7

Hydroxy acids have become a part of skin care programs for its effect on thinning the stratum corneum and decreasing epidermal cell cohesion. This has a regenerative effect on epidermal cell kinetics giving the skin texture a plumper rejuvenative appearance. There is little definitive evidence that topical alpha-hydroxy acids have an effect on dermal collagen per se.8

Topical antioxidants have shown an effect in retarding the reactive oxygen species (ROS) created by ultraviolet damage. Vitamin C or ascorbic acid has been shown to be a potent scavenger of free oxygen radials. Topical products have shown activity in the experimental mode but clinical efficacy is as of yet anecdotal. Vitamin E is a lipid soluble antioxidant, which has become popular in topical form but little true objective data is present to document its effect on photoaging skin.9

Chemical Peeling
Chemical peeling remains one of the most popular choices for both patient and physician. In comparison to some of the newer options available, chemical peels have a long-standing safety and efficacy record, are performed with ease, are low in cost, and have a relatively quick recovery time. Various acidic and basic compounds are used to produce a controlled skin injury and are classified as superficial, medium-depth, and deep peeling agents according to their level of penetration, destruction, and inflammation. (Table 1) In general, superficial peels cause epidermal injury and occasionally extend into the papillary dermis, medium-depth peels cause injury through the papillary dermis to the upper reticular dermis, and deep peels cause injury to the midreticular dermis.10

Prior to the application of peeling solutions, the surgeon must vigorously cleanse the skin surface to remove residual oils, debris, and excess stratum corneum. The face is initially scrubbed with 4” X 4” gauze pads containing 0.25% Irgasan (Septisol, Vestal Laboratories, St. Louis, Missouri), then rinsed with water and dried. Because of the defatting and degreasing properties of acetone, gauze pads moistened in an acetone preparation are then used to cleanse the skin even further. The importance of cleansing in the peeling procedure cannot be overemphasized. A thorough and evenly distributed cleansing and degreasing of the face assures uniform penetration of the peeling solution and leads to an even result without skip areas. (Illustration II-A and B) 11

The effect of a chemical peel is dependent upon the agent used, its concentration, and the techniques employed before and during its application. Each wounding agent used in peels has unique chemical properties and causes a specific pattern of injury to the skin.3 It is important for the physician using these solutions to be familiar with their cutaneous effects and proper methods of application to assure correct depth of injury. The marketplace has been flooded with numerous proprietary formulations of these peeling agents, with each product claiming unique advantages. These products are often expensive and have not been unequivocally shown to be safer or more effective than the conventional solutions. This article will therefore focus on the specific chemical agents that are actively responsible for producing the various patterns of injury.

Superficial Chemical Peeling
Superficial chemical peels are indicated in the management of acne and its post-inflammatory erythema, mild photoaging (Glogau I & II), epidermal growths such as lentigines and keratoses, as well as melasma and other pigmentary dyschromias. Multiple peels on a repeated basis are usually necessary to obtain optimal results. The frequency of peels and degree of exposure to the peeling agent may be increased gradually as necessary. Results are enhanced by medical or cosmoceutical therapy. All superficial chemical peels share the advantages of only mild stinging and burning during application as well as minimal time needed for recovery. They are a part of office-based procedures.13

Superficial chemical peels are divided into two varieties – very light and light. (Table 1) With very light peels, the injury is usually limited to the stratum corneum and only creates exfoliation, but the injury may extend into the stratum granulosum. The agents used for these peels include low potency formulations of glycolic acid, 10 - 20% trichloroacetic acid (TCA), Jessner’s solution (Table 3), tretinoin, and salicylic acid. Light peels injure the entire epidermis down to the basal layer, stimulating the regeneration of a fresh new epithelium. Agents used for light peels include 70% glycolic acid, 25 - 35% TCA, Jessner’s solution and solid carbon dioxide slush.14 During the application of superficial peeling agents, there may be mild stinging followed by a level I frosting, defined as the appearance of erythema and streaky whitening on the surface. (Fig I-A)

Alpha-hydroxy acids (AHA) peeling agents have been used widely in skin rejuvenation programs since the early 1990’s. The depth of injury is determined by the specific AHA used, its pH, the concentration of free acid, the volume applied to the skin, and the duration of contact or time the agent is left on the skin before neutralization.15 In low concentrations, 20-30% - AHA's have been shown to decrease the cohesion of corneocytes at the junction of the stratum corneum and the stratum granulosum, while higher concentrations – 70% are associated with complete epidermolysis. Weekly or biweekly applications of 40 to 70% unbuffered glycolic acid with cotton swabs, a sable brush, or 2” X 2” gauze pads have been used most often for acne, mild photoaging, and melasma.15 The time of application is critical for glycolic acid, as it must be rinsed off with water or neutralized with 5% sodium bicarbonate after two to four minutes.

Application of 10 to 20% TCA with either a saturated 2” X 2” gauze pad or sable brush produces erythema and a very light frost within 15 to 45 seconds. The depth of penetration of the peeling solution is related to the number of coats applied, this deeper penetration and injury can occur with over coating. Ideally, a Level I frosting is obtained with superficial TCA peels. Protein precipitation results and leads to exfoliation without vesiculation. Concentrations of TCA up to 35% can also be used alone as a superficial peeling agent but may create an injury that extends partially into the upper dermis.16

Jessner’s solution is a combination of keratolytic ingredients that has been used for over one hundred years in the treatment of inflammatory and comedonal acne as well as hyperkeratotic skin disorders. (Table 3) Jessner’s solution has intense keratolytic activity, initially causing loss of corneocyte cohesion within the stratum corneum and subsequently creating intercellular and intracellular edema within the upper epidermis if application is continued.17 The mode of application for the Jessner's peel is similar to that of the 10 to 20% TCA peel. The clinical endpoint of treatment is erythema and blotchy frosting. It is a good repetitive peel for photoaging skin because of its inflammatory effects. The peel can be repeated every two weeks.

Salicylic acid, a beta-hydroxy acid that is one of the ingredients in Jessner's solution, can also be used alone in superficial chemical peeling.18 It is a preferred therapy for comedonal acne as it is lipophilic and concentrates in the pilosebaceous apparatus. It is quite effective as an adjunctive therapy for open and closed comedones and resolving post-acne erythema. (Fig II-A, B, C) It is also a peel of choice for melasma and pigmentary dyschromia because it has minimal inflammatory action. Used repeatedly, it has the least risk of post-inflammatory hyperpigmentation. Superficial peeling for abnormal pigmentation is combined with skin care and topical retinoids, a bleaching product (hydroquinone, including 4%-8%) and an adequate sunscreen.19

Prior to the initial treatment with a superficial peel, both patient and physician must understand the limitations, especially on photoaging, to avoid future disappointment. The effect of repetitive superficial chemical peels never approaches the beneficial effect obtained with a single medium-depth or deep peel, in that the improvements in photo aged skin following superficial peels are usually subtle because there is little to no effect on the dermis. Nevertheless, their ease of use and minimal down-time makes these “lunch time” peels rewarding for patients with realistic expectations and are a favorite among the busy baby-boomers.

Medium-depth chemical peeling
Medium-depth chemical peels consist of controlled damage through the epidermis and papillary dermis, with variable extension to the upper reticular dermis. During the next three months postoperatively, there is increased collagen production with expansion of the papillary dermis and the development of a mid-dermal band of thick, elastic-staining fibers.20 These changes correlate with continued clinical improvement during this time.

For many years, 40 - 50% TCA was the prototypical medium-depth peeling agent because of its ability to ameliorate fine wrinkles, actinic changes, and pre-neoplasia. TCA as a single agent for medium-depth peeling has fallen out of favor because of the high risk of complications, especially scarring and pigmentary alterations, when used in strengths approaching 50% and higher.21 Today, most medium-depth chemical peels are performed utilizing 35% TCA in combination with either Jessner’s solution, 70% glycolic acid, or solid carbon dioxide (CO2) as a 'priming' agent. (Table 4) These combination peels have been found as effective as 50% TCA alone but with fewer risks. The level of penetration is better controlled with these combination peels, thereby avoiding scarring seen with higher concentrations of TCA.

Brody developed the use of solid CO2 to freeze the skin prior to the application of 35% TCA. This causes complete epidermal necrosis and significant dermal edema, thereby allowing deeper penetration of the TCA in selected areas.11 Monheit then described a combination medium-depth peel in which Jessner’s solution is applied, followed by 35% TCA.23 Similarly, Coleman and Futrell have demonstrated the use of 70% glycolic acid prior to the application of 35% TCA for medium-depth peeling.24 The Jessner’s solution and glycolic acid both appear to effectively weaken the epidermal barrier and allow deeper, more uniform, and more controlled penetration of the 35% TCA.

Current indications for medium-depth chemical peeling include Glogau group II or moderate photoaging, epidermal lesions such as actinic keratoses, pigmentary dyschromias, mild acne scarring, as well as to blend the effects of deeper resurfacing procedures. The most popular of the medium-depth peels for facial rejuvenation is the Jessner's - 35% TCA peel, with other combination peels being utilized less frequently. This peel has been widely accepted because of its broad range of uses, the large number of people in whom it is indicated, its ease of modification according to the situation, and its excellent safety profile. It though is not a “lunch time” treatment and should be considered a surgical procedure requiring preoperative consideration and preparation, operative sedation and aftercare for one week or more.

The Jessner's - 35% TCA peel is particularly useful for the improvement of mild to moderate photoaging. (Fig III-A) It freshens sallow, atrophic skin and softens fine rhytids with minimal risk of textural or pigmentary complications. (Fig III-B) Collagen remodeling occurs for as long as three to four months postoperatively, during which there is continued improvement in texture and rhytides. When used in conjunction with a retinoid, bleaching agent, and sunscreens, a single Jessner's - 35% TCA peel lessens pigmentary dyschromias and lentigines more effectively than repetitive superficial peels. (Fig IV-A, B) Epidermal growths such as actinic keratoses also respond well to this peel. In fact, the Jessner’s - 35% TCA peel has been found as effective as topical 5-fluorouracil chemotherapy in removing both grossly visible and clinically undetectable actinic keratoses but has the added advantages of lower morbidity and greater improvement in associated photoaging.25 (Fig V-A, B, C)

This peel is also useful to blend the effects of other resurfacing procedures with the surrounding skin. Patients who undergo laser resurfacing, deep chemical peeling, or dermabrasion to a localized area such as the periorbital or perioral region often develop a sharp line of demarcation between the treated and untreated skin. This is because the surrounding photoaging skin has significant dyschromia and textural aging. The treated skin may appear hypopigmented (also known as pseudohypopigmentation) in comparison to the untreated skin. A Jessner’s – 35% TCA peel performed on the adjacent untreated skin helps to blend the treated area into its surroundings. For example, a patient with advanced photoaging in the periorbital region and moderate photoaging on the remaining face may desire CO2 laser resurfacing only around her eyes. In this patient, medium-depth chemical peeling of the areas not treated with the laser would improve the photoaging in these regions and avoid a line of demarcation.26 It is important to note that when used in combination with other resurfacing procedures such as laser irradiation or dermabrasion, the peel should be performed first in order to avoid accidental application of the peeling agent onto previously abraded areas of skin. (Fig VI-A, B, C)

Using either cotton-tipped applicators or 2” x 2” gauze pads, a single, even coat of Jessner’s solution is applied first to the forehead, then the cheeks, nose and chin, and lastly, the eyelids. Proper application of Jessner’s solution causes minimal discomfort and creates a faint frost within a background of mild erythema (level I). After waiting one to two minutes for the Jessner’s solution to completely dry, 35% TCA is then applied evenly with one to four cotton-tipped applicators. (Fig VII-A, B, C) The effectiveness of this peel is directly dependent upon the depth of penetration of the peeling solutions, and this depth is a function of the adequacy of degreasing and the amount of both solutions applied. The use of cotton swabs, particularly for the application of TCA, is advantageous because is allows the surgeon to easily vary the amount of solution applied according to the patient's specific needs. The amount of TCA delivered to the skin surface is determined by the number of applicators used, their degree of saturation, the amount of pressure applied to the skin surface, and the duration of their contact with the skin. Four moist cotton-tipped applicators are applied in broad strokes over the forehead and on the medial cheeks. Two mildly soaked cotton-tipped applicators can be used across the lips and chin, and one damp cotton-tipped applicator on the eyelids. The depth of penetration and completion of the peel reaction can be monitored by the level of frosting. A full combination Jessner’s – 35% TCA peel should obtain a level II to III frosting. One should never overcoat TCA on a level III frosting as the injury may be pushed to a level that can cause complications, i.e. pigmentation or scarring.

Anatomic areas of the face are peeled with TCA sequentially from the forehead to temple to cheeks and finally to the lips and eyelids. Careful feathering of the solution into the hairline and around the rim of the jaw and brow conceals the demarcation line between peeled and non-peeled skin. Areas of wrinkled skin are stretched taut with the help of an assistant to allow even application of the solution into the folds and troughs. This technique is particularly helpful on the skin of the upper and lower lips. For perioral rhytids, TCA is applied with the wood portion of a cotton-tipped applicator and extended onto the vermilion border. (Fig VII-D)

Eyelid skin must be treated delicately and carefully to avoid over-application and to prevent exposure of the eyes to TCA solution.27 The patient should be positioned with the head elevated at 30 degrees and excess peel solution on the cotton tip should be squeezed out so that the applicator is semidry. With the eyes closed, a single applicator is rolled gently from the periorbital skin onto the upper eyelid skin without going beyond the moveable lid. Another semidry applicator is then rolled onto the lower eyelid skin within two to three millimeters of the lid margin while the patient is looking superiorly. Excess peel solution should never be left on the lids because it can roll into the eyes and tears should be immediately dried with a cotton-tipped applicator because they may pull the solution into the eye by capillary action.

The white frost from the TCA application appears on the treated area within 30 seconds to two minutes.(Fig III-C) This response is representative of keratocoagulation and indicates that the TCA's physiologic reaction is complete. TCA takes longer to frost than phenol preparations, but a shorter period of time than the superficial peeling agents. The desired endpoint in medium-depth peeling is level II to level III frosting. (Table 5) Level II frosting is defined as a white-coated frosting with a background of erythema. (Fig I-B)

Level III frosting, which is associated with penetration to the reticular dermis, is a solid white enamel frosting with no background of erythema. (Fig I-C) A deeper level III frosting should be restricted only to areas of thick skin and heavy actinic damage. Most medium-depth chemical peels achieve a level II frosting and this is especially important over the eyelids and areas of sensitive skin. Areas with a greater tendency to form scars, such as the zygomatic arch, the bony prominences of the jawline, and chin, should receive no greater than level II frosting.

Before retreating an area with inadequate frosting, the surgeon should wait at least three to four minutes after the application of TCA to ensure that frosting has reached its peak. Each cosmetic unit is then assessed, and areas of incomplete or uneven frosting are carefully retreated with a thin application of TCA. Additional applications of TCA increase the depth of penetration as well as the risk of complications, so one should apply more solution only to the under frosted areas.

Though there is an immediate burning sensation as the peel solution is applied, the discomfort begins to subside as frosting occurs and resolves fully by the time of discharge. This peel can be performed with light sedation such as:
1) Diazepam 10 mg PO
2) Meperidine 50 mg IM
3) Hydroxyzine 25 mg IM
After cooling the skin with saline, the patient will remain comfortable throughout the post-operative period. Cool saline compresses offer symptomatic relief at the conclusion of the peel. Unlike the compresses in glycolic acid peels, the saline following a TCA peel simply provides relief and does not "neutralize" the acid.

Deep chemical peeling
Patients with more extreme photoaging skin may require deep chemical peeling, motorized dermabrasion, or laser resurfacing to improve their greater degree of skin damage. As discussed with medium-depth peels, deep chemical peeling leads to production of new collagen and ground substance down to a level in proportion with the depth of the peel. The peeling agent of choice is the Baker-Gordon phenol peel.
The Baker-Gordon peel utilizes phenol in a formulation that permits deep penetration into the dermis, deeper than full-strength phenol.28 The Baker-Gordon formula consists of Septisol (Vestal Laboratories, St. Louis, Missouri), croton oil, and tap water added to a solution of phenol, reducing its concentration to 50 or 55%.(Table 6) The mixture of ingredients is freshly prepared and must be stirred vigorously prior to application due to its poor miscibility. The liquid soap, Septisol, is a surfactant that reduces skin tension, allowing a more even penetration. Croton oil is a vesicant epidermolytic agent that enhances phenol absorption. Recent investigations into the effects of this peel using varying concentrations of both phenol and croton oil have suggested that the procedure's efficacy is more related to the amount of croton oil than phenol.29,30

There are two main variations in deep chemical peeling with the Baker-Gordon phenol formula – occluded and unoccluded. Occlusion of the peeling solution with tape is thought to increase its penetration and extend the injury into the mid-reticular dermis. This technique is particularly helpful for deeply lined, “weather-beaten” faces but should be utilized only by experienced surgeons because of the higher risk of complications.31 The unoccluded technique as modified by McCollough involves a more vigorous cleansing of the skin and the application of more peel solution.32 This may enhance the efficacy of the solution but without penetration as deeply as in an occluded peel. In the hands of a skilled and knowledgeable surgeon, both methods are safe and reliable in rejuvenating advanced to severe photo aged skin. Deep chemical peeling can significantly improve or even eliminate deep furrows as well as other textural and pigmentary irregularities associated with severe photoaging. (Fig VIII-A, B) A remarkable degree of improvement is the expected result of deep chemical peeling when performed properly on carefully selected patients.

The patient undergoing deep chemical peeling must understand and be willing to accept the significant risk of complications and the increased degree of morbidity. The most notable complications include scarring, textural changes such as “alabaster skin,” or “plastic skin” and pigmentary disturbances. It is not uncommon for patients to experience postoperative erythema that can take many months to resolve and may be followed by variable hypopigmentation. (Fig IX) Male patients and patients with darker complexions are less favorable candidates for deep chemical peeling since the hypopigmentation is less easily camouflaged. Since phenol is cardiotoxic , preoperative evaluation includes a complete blood count, liver function tests, serum urea nitrogen and creatinine and electrolyte determinations, and a baseline electrocardiogram. Any patient who has a history of cardiac arrhythmias or who is taking a medication known to precipitate arrhythmias should not undergo a full-face Baker-Gordon phenol peel. Patients with a history of hepatic or renal disease are also poor candidates.

Compared with medium-depth and superficial peeling, the Baker-Gordon phenol peel is a time-consuming procedure and it must be performed only in a properly equipped facility. The required waiting period after the treatment of each cosmetic unit limits the rate of cutaneous absorption, thereby preventing the serum levels of phenol from reaching a dangerous peak during the procedure. Intravenous hydration with a liter of lactated Ringer’s solution before the procedure and another liter during the peel also promotes phenol excretion and prevents toxicity. Continuous electrocardiography, pulse oximetry, and blood pressure monitoring are mandatory during the entire perioperative period. Any abnormalities, such as a premature ventricular contraction (PVC) or premature atrial contraction (PAC), necessitate abrupt stoppage of the procedure and careful evaluation for toxicity.33 Oxygen is supplemented throughout the procedure as some physicians feel that it has a protective effect against cardiac arrhythmias.

After thorough cleansing and degreasing of the skin, the chemical agent is applied sequentially to six aesthetic units: forehead, perioral region, right cheek, left cheek, nose, and periorbital region. There is a 15 minute time interval between the treatment of each cosmetic area, allowing 60 to 90 minutes for the entire procedure. Cotton-tipped applicators are used with a similar technique as discussed with the medium-depth Jessner's – 35% TCA peel, though less solution is used because frosting occurs very rapidly. (Fig X) Occlusion of the peel can be accomplished with strips of waterproof zinc oxide tape (e.g., one-half inch Curity tape) to each cosmetic unit just after the phenol is applied. Care is exercised to extend the peel slightly beyond the mandibular rim to conceal the demarcation between treated and untreated skin. The last aesthetic unit, the periorbital skin, is treated cautiously and conservatively to avoid over penetration which can lead to ectropion or scarring. It is important to remember that diluting a phenol compound with water may increase its penetration, so mineral oil rather than water should be used to flush the eyes if contact occurs.

Application of the peeling agent creates an immediate burning sensation, which lasts for 15 to 20 seconds, subsides for 20 minutes, and then returns for the next six to eight hours. Ice packs may be applied as necessary for patient comfort. Narcotics are usually prescribed upon discharge for adequate pain control. Systemic steroids are also administered by some surgeons to lessen the inflammatory response. For untaped peels, petrolatum is applied and a biosynthetic dressing can be used for the first 24 hours.

MECHANICAL RESURFACING PROCEDURES
During the last five decades, dermabrasion utilizing a rotating abrasive surface attached to a power-driven hand engine has been considered a premier skin resurfacing procedure for facial scars. It has generally been regarded as a deep resurfacing modality based on its depth of injury and its prolonged healing time. The original descriptions of modern dermabrasion involved the use of a wire brush which remains in use today.34,35 In 1957, the diamond fraise was introduced and became the preferred instrument for dermabrasion by some surgeons because it is less aggressive and more forgiving than the wire brush.36 Recently, there has been a resurgence of interest in manual dermasanding which allows for more deliberate and controlled skin planning and microdermabrasion.37,38

Microdermabrasion
Microdermabrasion is considered superficial because it removes the stratum corneum and outer epidermis. Whether it is classified as very light or light in comparison to the other superficial resurfacing procedures depends upon the techniques and aggressiveness of the operator. The microdermabrasion unit's handpiece is a closed system, which propels aluminum oxide crystals at the skin at high speeds and simultaneously removes them with suction. These units were developed commercially in the mid-1990's and are currently in widespread use in both physicians' offices and non-medical aesthetic spas. Microdermabrasion may be indicated for acneiform conditions, pigmentary dyschromias, and as a "lunchtime" procedure for facial rejuvenation in all skin types.39,40 Both the patient and physician must understand that the degree of objective improvement with microdermabrasion may be limited. This is a repetitive procedure performed every 2 weeks along with appropriate cosmoceutical agents. Ideal candidates for microdermabrasion typically are young patients that desire limited facial rejuvenation without "downtime" and thus must have realistic expectations of the limited anticipated results. Patients often report that their skin has a smoother texture and that cosmetics are easier to apply and blend in with their skin more easily. (Fig XI) Although the role of microdermabrasion in facial rejuvenation has grown dramatically since these units were developed, the scientific data to justify their use has been lacking.

Manual Dermasanding
Manual dermasanding involves abrading the skin by hand using silicon carbide sandpaper or wallscreen commercially available at any hardware store. Its classification as a wounding agent is entirely dependent upon the type of paper used, the force applied by the surgeon, and the duration of contact with the skin. Although it can be used to produce a wound as deep as with wire brush dermabrasion or several passes with a pulsed CO2 laser, manual dermasanding is probably most commonly used as a medium-depth or "minimally deep" resurfacing modality. (Table 7)

Manual dermasanding is most often utilized for resurfacing localized regions to minimize the appearance of a scar or to blend or enhance the effects of a medium-depth chemical peel or a combination procedure.41 It can be used following CO2 laser resurfacing to feather the transition into hair-bearing areas that are inaccessible to the laser. Manual dermasanding of the eyebrows and hairline and gently abrading the upper neck at the inferior aspect of the laser-irradiated zone are all effective at minimizing lines of demarcation between treated and untreated skin. (Fig XII) It can also be useful immediately after laser resurfacing for stubborn rhytids, particularly in the perioral region. Manual dermasanding can improve the outcome by producing a slightly greater depth of injury in a controlled fashion where further thermal injury would be risky. It will also remove adherent necrotic debris and thermal damage, thus speeding up the healing process. Similarly, a medium-depth chemical peel can be immediately followed by manual dermasanding on the more troublesome areas to enhance the results and also along the borders of the peeled skin to blend the effects. Our clinical experience suggests that dermasanding after a Jessner's - 35% TCA peel may yield impressive postoperative results that approach those seen with either motorized dermabrasion or CO2 laser resurfacing in patients with photoaging skin. (Fig XIII-A, B, C, D) This combination is particularly helpful in patients who may not tolerate the greater degree of sedation often necessary with CO2 laser resurfacing.

The necessary materials for manual dermasanding include silicon carbide sandpaper or wallscreen. Both may be purchased in a variety of grades: fine grade (#400), medium grade (#220-320), and coarse grade (#180). The sandpaper is easy to use because of its flexibility and is easily cut into smaller pieces, which can be steam autoclaved. A 1 1/2" X 3" piece of sterilized sandpaper is wrapped around either the barrel of a 3 cc syringe or a rolled up 2" X 2" gauze pad and moistened with saline or a soap-free cleanser (e.g., Cetaphil, Galderma Laboratories, Inc., Fort Worth, TX) for lubrication. A 1% solution of lidocaine with epinephrine may be used instead if additional anesthesia is necessary. Both back-and-forth and circular motions are used to gradually abrade the skin layer by layer until the hills and valleys are softened or adjacent areas are blended to the desired degree. Coarse grades may be used initially for "debulking" followed by finer grades later in the procedure. The fine grade is used to blend delicate areas of skin such as around the eyelids. At the completion of the procedure, the dark-colored silicon carbide particles remaining on the skin surface should be rinsed off because there is a theoretical risk of their becoming implanted.

Motorized Dermabrasion
Some of the units most commonly used today are the Bell hand engine (Bell International, Burlingame, CA), the AEV-12 hand engine (Ellis International, Madison, NJ), and the Osada surgical handpiece (Osada, Inc., Los Angeles, CA). A topical refrigerant spray (Frigiderm, Frigiderm Corp., Costa Mesa, CA) is used to produce anesthesia and to harden the skin as it is abraded. The spray immobilizes the topographic features so that there is no distortion by the pressure of the abrasive instrument.
The two abrasive instruments most often employed with these units are the wire brush and the diamond fraise. The wire brush has numerous, small-caliber stainless steel wires that project circumferentially from the curved side of a cylindrical hub. A diamond fraise consists of a stainless steel cylinder to which industrial-grade diamonds are bonded to create the abrasive surface. As compared with wire brush instruments, diamond fraises are manufactured with a greater variety in shape, width of abrasive surface, wheel diameter, and coarseness of grit. The wire brush is more aggressive and cuts more quickly and more deeply into the skin with each stroke, thereby posing a greater risk for injury and requiring more skill to operate. Though the diamond fraise is generally safer and more forgiving, it may not yield the degree of improvement possible with the wire brush, especially for more stubborn conditions such as deep acne scarring. (Fig XIV)

Because dermabrasion with either instrument is highly technique-dependent and its learning curve is steep, there may be considerable variability in the clinical results obtained by different operators. It is very important for beginning dermabraders to attain thorough hands-on instruction from an experienced operator in order to be adequately trained. The proper techniques for motorized dermabrasion have also been the subject of comprehensive reviews in the literature.42,43,44 Careful evaluation of the depth of injury throughout the procedure is critical to assure sufficient depth for optimal results without penetrating beyond the desired level and risk scarring. Because of the potential for aerosolization of infectious particles during dermabrasion, appropriate precautions are mandatory to protect the operating room staff. (Table 8)

Moderate to severe acne scarring is the most notable indication for dermabrasion as laser resurfacing has yielded variable results and chemical peeling is generally disappointing. Dermabrasion selectively planes off the "hilltops" that surround the atrophic "valleys" whereas chemical peeling and lasers produce an injury of equivalent depth in both areas. (Fig XV-A, B, C)

The use of CO2 lasers has revolutionized resurfacing techniques for photoaging skin. Because of the varying properties of lasers, the physician must be thoroughly familiar with the physics, the technology and operating geometry of the laser. Whether the laser is pulsed, continuous or computer scanned impacts the physiologic response. The level depth of destruction is different for each laser, thus the physician should be familiar with the laser of choice. For reliable vaporization of skin layers, a pulsed laser with a CPG (computer generated scanner) makes the procedure safer. Each pass destroys 75-100 microns of tissue with a zone of thermal damage below. Thus, two to three passes with an ultrapulse CO2 laser is maximal for rejuvenation of photo damaged skin; a deep resurfacing technique. The zone of thermal damage causes collagen shrinkage or contraction, which is a unique characteristic for CO2 laser resurfacing. This gives an added benefit to wrinkle treatment not found with either dermabrasion or chemical peeling. This is especially true with perioral and periorbital wrinkled skin.

Carbon dioxide laser resurfacing requires anesthesia; either general operative anesthesia or tumescent local anesthesia for the entire face. Laser safety precautions are needed to prevent laser fire or laser injury to the employees, the unprotected skin, the teeth or even the endotracheal tube for general anesthesia. These must be protected with appropriate laser resistant materials; eye shields, teeth guards and appropriate laser resistant endotracheal tube wrapping. Using the CPG, the operator must remember that the pulse overlap for a chosen pattern size and shape is set so that each pattern is made to touch yet not overlap. The density is an important parameter in determining laser beam intensity. One should not go above a density of 6 with facial resurfacing. Each pass should cover the face fully, vaporizing the tissue to ash and debris, which is wiped off between each pass. The visual endpoint is a mauve or slightly yellow discoloration indicating denaturization of dermal collagen. Further passes cause deeper dermal scarring. Special care must be taken over scar prone areas such as the bony prominences of the chin, jawline, malar ridge and forehead. The eyelid is treated more conservatively as collagen can precipitate an ectropion, with or without scar. The lips are treated with two to three passes but not over the vermilion line as this can flatten the lip in an unaesthetic manner. Bordered facial creases such as the jawline and neck should be blended with light chemical peeling and minimal dermasanding to soften the demarcations of treated and untreated photoaging neck skin.

As important as the operative technique is proper postoperative wound care. Partial thickness skin wounds heal fastest when kept at or near 100% humidity or occlusive or semi occlusive dressings. Non-stick pads and hydrogels such as Flexzan or Vigilon are changed daily to remove coagulation debris and necrotic tissue. This is important to prevent secondary wound infection with resultant scarring. My usual postoperative program is four to five days of biologic hydration changed daily followed by five days of ¼% acetic acid soaks (1 tsp. White vinegar in 1 pint warm water) four times a day followed by occlusive ointments such as petrolatum ointment or Eucerin cream. After ten days, the patient is usually ready for light cleansers and creams and a mild topical steroid cream for erythematous areas (Table 9).

Full makeup can be used with sunscreen after two weeks. Sunscreen with strong sun avoidance should be adhered to for two to three months to prevent post-laser hyperpigmentation.

Herpes simplex infection can occur during the healing period following medium depth or deep ablative injury. Antiviral prophylaxis should begin during the operative session and continue beyond reepithelialization, 10-14 days. If infection occurs, punctate vesicles occur with pain and full treatment therapy should begin to prevent scarring.

Delayed wound healing may be a sign of bacterial infection or resurfacing too deep to heal normally. It should be treated with biologic dressings, appropriate antibiotics and cortisones as indicated. The diligent physician must watch his patients carefully during the post-operative course to catch these complications early and prescribe appropriate treatment. This will prevent the permanent complications of pigmentation changes and scarring.

CONCLUSIONS
The general public has a renewed interest in skin rejuvenation. Although there are many techniques presently available, it is up to the cosmetic physician to match the appropriate tool with the patient’s needs to give proper benefit with the least risk. These tools need special training and experience and as one gains further knowledge and skill, these procedures generally occupy a rewarding part of ones practice.