Hair removal

Hair removal

Hair Removal MARCIA RAMOS-E-SILVA, MD, PhD MARIA CRISTINA RIBEIRO DE CASTRO, MD LUIZ VICTOR CARNEIRO JR, MD, FICS U nwanted hair is one of the oldes...

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Hair Removal MARCIA RAMOS-E-SILVA, MD, PhD MARIA CRISTINA RIBEIRO DE CASTRO, MD LUIZ VICTOR CARNEIRO JR, MD, FICS

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nwanted hair is one of the oldest enemies of women. For unknown reasons, our modern society prefers women to have luxurious heads of hair with totally hairless bodies.1 Nowadays, a hairless body also gives the idea of a sophisticated image to men, in contrast to the hairy cave man and, for this reason, the number of men who submit themselves to epilation is increasing. Women and men have many different motives, such as dermatological diseases, professional reasons (models or swimmers), increase of self-esteem, or just because they dislike their body or facial hairs.2 There are several different ways to hide or remove unwanted hairs. Each method has its advantages and disadvantages.2 Currently, there is no ideal method. The techniques must be appropriate for each person and/or for each problem. There are important factors to consider in each case: hair and skin type, frequency of removal, presence of skin problems, manual dexterity, cost and convenience, and individual preferences.3 It is very important to remember that in some cases excessive hair is a consequence of a systemic disease, hormonal unbalance (hirsutism),2 or even an undesirable effect of a drug (steroids, minoxidil, cyclosporin A, and diazoxide).2,4 A complete clinical investigation should be always done.2 There are transitory and permanent methods of hair removal.

Transitory Methods of Hair Removal Shaving Shaving is the most popular method of hair removal for men’s facial hair and for women’s underarm and leg hair. It is fast, cheap, and simple.5 Unfortunately, it is only temporary, and hair quickly returns at the normal rate of growth. The growing hair will present the same texture, except that a short hair is less flexible than a long one. The hair’s end stands out6,7,8 and feels more bristly2 because now it does not have a naturally thinFrom the Sector of Dermatology, HUCFF-UFRJ, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil (MRS and MCRC), and the Dr. Ivo Pitanguy’s Clinics, Rio de Janeiro, Brazil (LVC). Address correspondence to Dr. M. Ramos-e-Silva, Department of Dermatology, Rua Sorocaba 465/205, 22271-110 Rio de Janeiro, Brazil. E-mail address: [email protected] © 2001 by Elsevier Science Inc. All rights reserved. 655 Avenue of the Americas, New York, NY 10010

ner end, thus making it seem thicker when touched.6,7,8 There are two methods of shaving: wet shaving with a razor blade or dry shaving with an electric shaver. Wet shaving is more popular and common than other methods because it is easy, painless, and cheap. Another advantage is that the razor blade cuts hairs closer to the surface and leaves stubble of more uniform length, so blade shaving will produce a smoother, closer shave.3 A shaving angle of 28 to 32 degrees between the blade and the skin will give the closest shave with the least amount of irritation.5 It is a good option in extensive and well-keratinized corporal surface, like a woman’s leg and a man’s face.8 The razor has to be clean, and the blade sharp. Dull blades are uncomfortable and can cause irritation.9 The rate of growth varies with the area of the body and the age of the person; the beard, for example, grows more during the day than at night.5 Wet shaving may promote some problems: skin irritations, small cuts, and dissemination of local infections, like warts or impetigo.8 Excessive local pigmentation can occur when the beard is dark and hairs are arranged closely together and also for other reasons, as too close shaving or constant local irritation by frequently used photosensitizing preshave and aftershave products.3 Ingrown hair is also a common complaint. Many factors can play a role. Shaving too close or against the grain, especially in the neck area, can result in clipping off whiskers beneath the skin surface. This becomes worse when the hair is coarse and curly since they may have a tendency to curve back and re-enter in the skin, causing an inflammation around the ingrown hair tip and resulting in scarring. Another factor is the roughness of the hair’s surface after it has been cut. The rougher it is, the greater its chances of being caught, either along the side of the follicle or by the skin next to the follicle, becoming ingrown.3 WET SHAVING

DRY SHAVING The skin should be clean and dry, and the beard as stiff as possible. A preshave lotion can be used.9 There are basically two types of electric shavers: the foil head and the rotary head. A foil-head razor has a thin, flexible screen over the cutting head, which

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moves back and forth. The rotary blade, which is less common, has spring-mounted guards over the cutters. The closeness of the shave may be regulated by adjustable settings. Hair ends that have been cut tend to be more ragged and split after shaving with an electric razor than with a blade razor.3 Preshave lotions are used to make shaving faster, simple, and less uncomfortable and irritating. They are available for wet and dry shaving. Preshaving preparations for electric shavers are useful in removing perspiration and oily secretions so the hairs will be dry and stiff enough to be easily cut off. The product should have enough astringency to stiffen the beard, and be quick drying, and slightly acidic to prevent swelling of the hairs, and should not contain ingredients capable of corroding the blades or damaging the plastic parts of the shaver. After the use of a product like this, the razor will glide over the skin, producing minimal irritation. Other preparations are oily and act primarily as lubricants.3 For wet shaving, beard hairs must be wet, soft and swollen to facilitate removal and minimize irritation. Preshave lotions should help enhance the effects of water and shaving cream in softening and swelling the hairs. These products usually contain soaps or synthetic detergents and lubricants. If there is enough time to just wet the face with hot water and let the shaving cream act for some minutes, softening and swelling the beard hairs, a preshave preparation will not be necessary.3 PRESHAVE LOTIONS

There are thousands of different preparations for wet shaving. They include plain soaps, lather creams, brush-less shaving creams and aerosol foams. The lather and gels are by far the most popular preparations. Their purpose is to wet and soften the beard hairs to make shaving easier and more comfortable. If hairs are hard, dry, and stiff, they requires more pressure to cut them, and irritation is more likely to occur. A shaving preparation should soften the hairs quickly and hold them erect so that they can be easily cut. The most important step in wet shaving, however, is applying water. It is the most effective beard softener. As the hairs absorbs water (foremost hot water) and become thoroughly hydrated, they are easier to cut. The shaving cream will also help to increase hydration and keep the beard softened and simple to cut.3 WET SHAVING PREPARATIONS

After shaving preparations are generally applied only to the face. They feel refreshing and may soothe razor discomfort; however, it is doubtful that any of these preparations have therapeutic effects on the skin. The benefits are purely cosmetic, but the application of a moisturizer is recommended after shaving the legs.3

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Waxing Waxing is one of the oldest methods of hair removal. It is like a massive plucking,2 however, and is uncomfortable and is often not tolerated on the face.8 This procedure pulls out the hairs at the level of the hair bulb. Its results generally last 2 or 3 weeks longer than others temporary methods,5,9 but to repeat it one must wait for a new growth to be long enough to be plucked. This means stubble will show for a time, and many women find this unacceptable.2 The wax must be removed in one quick motion or the procedure can be very painful, and some hairs may not be plucked. Waxing kits are available for home use, but most waxing is done in beauty salons because removal techniques require a good deal of experience.2 Waxing has the advantage of adequate removal of both terminal and vellus hairs.5 There are two waxing techniques available: cold waxing and hot waxing. This method employs a wax-like substance that is squeezed as a liquid from a pouch, thus eliminating the need for melting.5 A strip of cloth or other material can also be used and it is applied over a thin layer of wax and “zipped off,” removing hairs embedded in the wax and cloth.2 The cloth provides strength so the wax can be removed in one piece.5 COLD WAX

HOT WAX This type of waxing consists on the application of a layer of heated, melted wax to the skin. The layer of wax must be thick enough to fix the hairs, but not so thick that it is not easily removed.2 Hairs become embedded in the wax as it cools and sets. Then the wax is stripped off the skin in the direction of the hair growth, plucking out the fixed hairs.2,10 The heat of the wax dilates the follicular opening and facilitates hair removal.10 Care must be taken with the temperature of the wax since it can be too hot and burn or irritate the skin.2,5

Chemical Depilatories The main advantage of chemical depilatories is the fact they are painless and have a slower regrowth than shaving.5 They can give results that last up to 2 weeks,11 and the hair that regrows does not feel as bristly as after shaving.2 The depilatory must be left on the skin for about 3 to 15 minutes, depending on the depilatory agent and the coarseness of the hair.9,11 All formulations act by disrupting disulfide bonds, especially those involving cystine,5,11 breaking the hair’s protein structure. The hairs break-off at or slightly below the surface of the skin and can be wiped off.9 Depilatories are composed of detergents, hair-shaft–swelling agents, adhesives, pH adjusters, and bond-breaking agents. Detergents such as sodium lauryl sulfate, laureth-23, or laureth-4 remove the protective hair sebum and allow penetration of the bond-breaking agent. Further pene-

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tration is accomplished with swelling agents, such as urea or thiourea. Adhesives, such as paraffin, allow the mixture to adhere to hairs, and adjustment of pH is important to minimize cutaneous irritation.5 Several bond-breaking agents are available, but the most widely used varieties are substituted mercaptans, 2% to 10% thioglycolates, mixed with 2% to 6% of either NaOH or CaOH.11 The sulfide depilatories agents are faster acting but are more irritating; they produce an undesirable odor of hydrogen sulfide gas and are poisonous if ingested.5,11 Sodium hydroxide, also known as lye, is the best bond-breaking agent but is extremely damaging to the skin.5 Depilatories are available in pastes, creams, and lotions. Formulations are specially adapted for the use on legs, bikini area, and face.5 A depilatory labeled for use on the legs should never be applied on the face; it is likely to be harsh.2,5 Unfortunately, skin irritation may develop after use because hair and skin are similar in the composition and any compound that has a destructive effect on hair will also affect the skin to some extent.9 The product should not be used in patients with any kind of dermatological problems. Both irritant and allergic contact dermatitis can occur with the use of chemical depilatories. The latter is rare and may be related to fragrances, lanolin derivatives, or the thioglycolate.5,11 Darkly pigmented hair seems somewhat more resistant to removal than lighter hair, and coarse hair is more resistant than fine hair.5

Abrasives Pumice stones are among the oldest devices employed for temporary hair removal, but also the least popular.2 This stone is a gray, solid, soft, and porous material of volcanic origin.10 The other alternative is a depilatory glove. It is made of fine sandpaper shaped into the form of a mitten.2 Rubbing it over the skin in circular movements,2,8 after cutting the hair as short as possible,10 at the site of hair growth produces mechanical friction, which wears off the hairs at the surface of the skin. They will remove hair closer to the surface of the skin than shaving does. In spite of that, it is a temporary method since it does not affect the hair roots. They are cheap, easy to use and do not cause skin irritation, as do chemical depilatories.2 Disadvantages of using abrasives are the slow and tedious application as well as its impracticability for large areas. If the abrasive is rubbed too vigorously, the skin will be irritated and with time lichenification of the area may occur.2,10 After the use of abrasives, a mild emollient cream should be applied to the area to relieve any kind of skin irritation.2

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Plucking with Tweezers This method involves the removing of the entire hair shaft, including the bulb, with a pair of tweezers. It is easy, inexpensive and requires minimal equipment. On the other hand, it is tedious and mildly uncomfortable.5,8,10 At times, it is very painful, especially on sensitive areas such as the upper lip, but it has no other adverse effects.2 It is a very effective way of removing hair from such small areas as the eyebrows, or even scattered hairs on the whole face.5,8,10 It is obviously impractical for extensive growth.2 Only the terminal hair can be efficiently plucked, because vellus hairs usually break close to the skin surfaces.5,8,10 The plucking produces little skin damage and provides a longer regrowth period because of complete hair shaft removal.5,8 Regrowth may occur after 2 to 12 weeks, depending on the density and speed of hair growth in a given area.2 Repeated plucking of a given hair, however, may result in follicular damage and failure of the hair to regrow,5,8 and the once coarse pigmented hair may revert to a small, colorless vellus hair.2

Khite Khite, which is English means “thread,” is the name of an uncommon technique of temporary hair removal widely practiced in the Middle East.8,12 This method, dating back to antiquity, is also know as fatlah in Egypt. Men regularly have hair removed from their cheeks, ears, and forehead by this technique, and women have fatlah performed for facial hair.12 The khite uses a 50 to 70 cm long cotton thread. Synthetic fibers are avoided because they can lacerate the operator’s fingers during the procedure. One free end of the twisted thread is held in the hand and the other free end is grasped by teeth. The index and middle fingers are placed within the single loop. The loop is opened by increasing the space between the middle and index fingers and shifting the loop toward the operator. The open loop is pressed against the area to be treated and as the loop decreases in size (due to a reduction of the space between the index and middle fingers) and moves away from the operator, hair in its path is trapped and pulled free. Lateral neck movement by the operator controls the direction of loop. Although khite is a painful method, it is very well accepted and tolerated and is a traditional cultural technique of hair removal in the Middle East.12

New Therapies Eflornithine (␣-difluormethylornithine) is an irreversible catalytic (suicide) inhibitor of ornithine decarboxylase,13 an enzyme that catalyzes the first and rate-limiting step in the biosynthesis of polyEFLORNITHINE

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amines.13,14 The polyamines putrescine, spermidine and, in mammals, spermine are required for cell division and for normal cell differentiation13 by regulating the growth and functioning of specialized tissues as the hair follicles and the inner-ear hair cells.15 Eflornithine affects the rate of hair growth by altering the length, diameter, and composition of the hair’s fiber.14 It was first used as an antitumor agent because it can arrest the growth of several types of tumor cells.13,16,17 In 1990, the FDA approved it as a successful chemotherapeutic agent for the African sleeping sickness, an infection caused by Trypanosoma brucei gambiense.13,18 This substance has an empirical formula C6H12F2N2O2 and a molecular weight of 236.65.13,19 According to promotional materials the Gillette Company and Bristol-Myers Squibb developed a cream that contains 13.9% (139 mg/g) of anhydrous eflornithine hydrochloride as eflornithine hydrochloride monohydrate (150mg/g) that was submitted to the approval of the FDA in 1999.19 Results of clinical randomized double-blind studies, including 596 women who used either this cream or a placebo, were presented at the fifty-eighth annual meeting of the American Academy of Dermatology in San Francisco, March 2000.20 The active drug or the placebo was applied to the affected areas twice a day for 24 weeks, with a follow-up without medication or placebo of 8 more weeks. At the end of 24 weeks, facial hair reduction was significantly greater in women who used the active medication compared to those who used the placebo. Seventy percent of the women showed improvement, 35% were classified as “clinical success,” which meant a marked improvement or a complete disappearance of facial hair, compared to 9% in the placebo group. Some women experienced improvement as early as 8 weeks after the beginning of the treatment.19 Long-term safety, quality of life after the topical use of the drug, percutaneous absorption, pharmacokinetics, and dermal safety were other topics addressed by unpublished studies about eflornithine presented at the same meeting, including data obtained by video imaging for the measurement of hair growth.19 –24 The cream should be used over the area of unwanted facial hair twice daily at least 8 hours apart because its steady-state plasma is of approximately 8 hours. There is no study about treatment of other areas or different scheme of application. After the application of the cream there must be an interval of at least 4 hours before the patient washes her face. The percutaneous absorption of eflornithine is less than 1%, following either single or multiple doses under conditions of clinical use. This method should be used in association with a current method of hair removing, but should not to replace such a method. Eflornithine complements the other technique used by slowing hair growth. It can be used for all skin types, and, for a visible result, it is

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necessary to wait for at least 8 weeks.19 According to the manufacturers, eflornithine should not be used in patients who are less than 12 years of age19; pregnant women, because it interferes with normal embryogenic development in experimental animals13; or nursing mothers since it is not known whether or not it is excreted in human milk.19 Local application may cause temporary redness, stinging, burning, tingling, or rash on skin area where it is applied, and folliculitis may also occur. Although eflornithine may provoke many adverse reactions and laboratory alterations when administrated orally or intravenously, such as anemia, diarrhea, leukopenia,13 and it has an ototoxic potential,25 these are usually reversible upon treatment discontinuation. There is no evidence that it will produce the same problem when used by percutaneous. Over 80% of eflornithine is eliminated by the kidney, largely in an unchanged form.13,19 The conclusions are that eflornithine produces a significant improvement on women’s unwanted hair by slowing its growth rate. It is well tolerated and safe, and for the time being it should be regarded as a adjunct therapy. The companies that produce and commercialize the cream of eflornithine for hair removal state that it is another helpful option against unwanted hair,19 –24 but further investigations about its efficacy and long-term safety are needed.

Camouflage Methods Bleaching agents are basically composed of hydrogen peroxide, which bleaches, softens, and oxidizes hair. They are inexpensive and easy to use even at home without any professional help. They remove the natural hair pigment, either partially or totally, and the hair looks discreet. The main disadvantage of bleaching is that the hair is still present and skin irritation is frequent.2,8,26 Repeated bleaching will damage the hair, which will tend to break off.2 Some hirsute women use heavy make up to disguise facial hair.26 BLEACHING AND MAKE UP

Permanent Methods of Hair Removal When properly executed, these techniques really provide a permanent hair follicle destruction.

Electrolysis Electrolysis is an electrical method of attempting to destroy permanently the hair follicle. Although it is almost definitive, there is long-term regrowth. This technique removes hairs one by one and consequently is expensive, slow, and tedious. It must be performed by experienced personnel because the needle’s position is critical to its success.2,26 In the hands of an skillful electrologist approximately 15–25% of the treated hairs can be expected to regrow.5

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There are three types of eletrosurgical methods available: galvanic electrolysis, thermolysis, and the blend method. All these techniques involve the insertion of a very thin wire metal needle into the follicular orifice in the germinative cells’ direction to the level of the bulb.8,27 The most popular electrical method of hair removal is thermolysis, in which a high-frequency alternating current is sent through the electrolysis needle. The current induces heating of water by molecular vibration, which subsequently destroys the follicular germinative cells. If the tissues have been adequately damaged to prevent hair regrowth, the hair shaft can be easily plucked with tweezers.2,5,26 In galvanic electrolysis, direct current conducted through the electrolysis needle is used to produce sodium hydroxide from water and sodium chloride present in the hair follicles. The follicular tissues are destroyed by a caustic chemical reaction. Tissue damage occurs preferentially in the deeper regions of the follicle, both because there is less salt and water in the follicular infundibulum and because sebum in the infundibulum acts as an insulator.26,27 This technique is extremely slow and consequently is rarely used.2,26 It is particularly suited for the treatment of curved or distorted follicles, as the hydroxyl ions are dispersed in a fluid medium and can therefore flow to proportions of the follicle that may extend beyond the site of needle contact.26 In blend technique, a single machine delivers both galvanic and high frequency currents through the electrolysis needle. It is consider by many users to be the most effective electrical method.2,5,26 Electrolysis is most appropriate for removal of localized, sparse areas of hair growth such as unwanted facial hairs in women or around the nipple.5 This treatment, however, is slow and may require months or even years. Improper techniques can result in permanent cutaneous burning or scarring, and some patients complain about the discomfort or pain.5,27 Patients who use pacemakers cannot be submitted to this method.

Lasers and Light Sources In recent years laser and light sources have been developed to remove unwanted hair, and they have received great popular and media attention.28 They provide permanent hair removal, which is defined as significant and stable loss of hair for a period longer than the complete natural hair growth cycle, usually one year.29 There are at least two structures that are essential to hair growth. These are “bulb,” which is responsible for active hair shaft growth, and the “bulge,” a region of stem cells in the midfollicle.30,31 Both of these areas contain pluripotential cells, which can regenerate an entire follicle.29 The bulb includes a neurovascular papilla and heavily pigmented matrix cells that form the hair shaft during anagen. This is the deepest part of the

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follicle, 3–7 mm deep, depending on the body site. The bulge, 1–1,5 mm deep,29,31 is localized at the region of stem cells found in the follicular epithelium near the insertion of the erector pili muscle, which appears to provide the necessary cells for the formation of a new matrix at the beginning of each anagen phase. The highest concentration of melanin is in the hair shaft and matrix.30,31 Little or no melanin, however, is present in the bulge. Irreversible damage to the bulb during the anagen phase would cause arrest of active hair growth until another anagen cycle could begin.31 Irreversible damage to the bulge alone might not inhibit active hair growth but could potentially prevent formation of a new hair at the subsequent anagen phase. Irreversible injury to both targets may logically lead to both hair growth arrest and permanent inhibition of new hair formation.30 The hair’s cycle has three phases: active growth (anagen), transition (catagen), and rest (telogen).30 –32 During anagen phase, the rapidly division of matrix cells period, the hair is most sensitive to thermal effects imparted from a laser or other light source.29,33 For this reason, laser is most effective during this phase; however, in a given part of the body, not all hairs are at the same time in anagen phase, which is why hair removal sessions need to be repeated.29 When light strikes the skin, it can be scattered, reflected, transmitted, or absorbed at each layer of skin. The dermis predominantly scatters light. Only the light that is absorbed produces tissue effects.34 The structures that absorbs the light are the chromophores,29 the pigmented (melanin) hair shaft.33,35 The advantage is the fact that hair is the only melanized pigmented structure normally present in the dermis.30 The principle of hair removal by lasers is based on the concept of selective photothermolysis.1,28 –30,34 This theory predicted that a selective thermal injury will be restricted if a given target is capable of absorbing light of a specific wavelength in an amount of time that is equal to or less than the thermal relaxation time of the target.29,34,36 Using the theory of selective photothermolysis to deliver light of the right combination of wavelength, energy fluence, and pulse duration, it is then possible to precisely target the hair follicle without injuring the surrounding tissues.34,36 Melanin functions as a natural chromophore11 over a wide range of wavelengths, up to about 1,100 nanometers (nm).26,37 The wavelength of the laser determines the depth of penetration of the skin. Longer wavelengths reduce scattering in the dermis and, consequently, have greater depth of penetration.34 The larger the spot size, the deeper the laser light can penetrate. Because of competition with epidermal melanin, the skin surface needs to be protected from damage.29 Each type of laser machine has its own method. The pulse duration has to be shorter than the thermal relax-

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ation time of the hair follicle so that collateral thermal damage is minimized.29,34 For tissue destruction, laser fluence must be greater than or equal to the threshold fluence. In addition, laser wavelength should be as long as possible, while still preserving melanin selectivity, because longer wavelength light penetrates deeper into the dermis as a result of reduced light scattering.29 There are two different laser surgical techniques. In the first technique, light is absorbed by a normal component of the follicular apparatus, like melanin or keratohyalin. Melanin in the hair shaft or the follicle provides a chromophore (endogenous chromophore) that is not present in the surrounding dermis and allows selective targeting of hair in the skin.28,36 Therefore, at deep penetration wavelengths in the 600 –1100 nm region, melanin absorption may be used for selective photothermolysis of hair follicle; however, because the epidermis is pigment laden, it must be protected from damage absorption by melanin. Protection of the epidermis is usually accomplished by cooling the skin surface.26,28,33,36 In the second technique, an exogenous material (exogenous chromophore) can be introduced into the follicular orifice or previously absorbed by the hair, which is then irradiated with light of a wavelength that matches the absorption peak of the exogenous chromophore used.28,36 The main problem is finding a reliable method for the chromophore to penetrate into all depths of the hair follicle. Endogenous melanin is important for hair removal with long-pulse ruby lasers (694 nm), long-pulse alexandrite lasers (755 nm), pulsed diode lasers (800 nm), Q-switched ND: YAG lasers (1,064 nm), and intense-pulsed light source (590 –1200 nm). Exogenous chromophores can be carbon particles, used with Q-switched ND:YAG lasers (1,064 nm), and 5-aminolevulinic acid (5-ALA), used as a photosensitizer together with a 630 nm light from an argonpumped tunable dye laser.28 Long-pulse ruby lasers were the first lasers ever made and were first reported for dermatological uses by Dr. Leon Goldman in the 1960s.35,37 There are two ruby laser systems now approved by the FDA for hair removal: Epilaser (Palomar Laser, Lexington, MA) and Epitouch (ESC/Sharplan, Needham, MA). Each of then delivers pulses of deep red light.28,37 The Epilaser uses a sapphire cooled handpiece that is placed directly in contact with the skin to protect the epidermis.28,37 Furthermore, the sapphire lens provides heat conduction from the epidermis before, during, and after the laser pulse. It also permits beam coupling into the skin, and internal reflection is reduced by index matching. In addition, it has other advantages.11 The sapphire lens provides a convergent beam to maximize delivery of light into the dermis.26 The convex surface of LONG-PULSE RUBY LASERS

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the sapphire lens allows the application of pressure on the skin surface, which deforms the dermis and decreases the distance from the epidermis to the deeper follicular structures. Moreover, the pressure blanches the underlying blood vessels, minimizing absorption of laser energy by hemoglobin.26,28 The Epitouch is a dual-mode ruby laser that can operate in the conventional Q-switched mode for treating tattoos and pigmented lesions or in the normal mode for hair removal.11 Cooling of the epidermis is achieved by applying a thick layer of cooled transparent gel on the skin immediately before laser pulse deliver.26,37 A thin, patented, laser aligning sheet can be placed on top of the cooling gel, which enables the proper positioning of the laser beam and helps to ensure uniform laser application to all intended areas.28 Although the efficacy of this method has been clearly shown, there are significant dose-related side effects, mainly with dark skins. A relative disadvantage is that slow pulse repetion rates make it difficult to treat large body areas.37 LONG-PULSE ALEXANDRITE LASERS Currently, several long-pulsed alexandrite lasers have been introduced for hair removal. The mechanism of action is thought to be similar to the ruby laser, except that the longer wavelengths allow a slightly greater depth of penetration, and there is a lower risk of epidermal damage owing to slightly less melanin absorption at this wavelength.26,28,32 Three different machines are available: Apogee (Cynosure, Chelmsford, MA), Epitouch ALEX (ESC/Sharplan, Needham, MA),11 the fastest,28 and GentleLASE (Candela, Wayland, MA).11 The first and the second achieve epidermal cooling by a cooling gel that is applied over the skin before the laser pulse is delivered. GentleLASE uses a dynamic cooling device (DCD) that uses a cryogen, tetrafluoroethane, as a surface cooling agent.28

Diode lasers are less costly to produce and more reliable than other laser sources. The LightSheer (Coeherent Medical, Santa Clara, CA) was approved for hair removal by the FDA,28,37 and its advantages include a longer pulse-width capability, small size, and high efficiency.11,38 Cooling is provided via a sapphire handpiece that is placed directly in contact with the skin.29,37 Because of the longer wavelength, the active cooling, and the longer pulse-widths, darker skin types can be treated more safely.26,28 The treatment efficacy varies with the anatomic location, pulse duration, and number of treatments.32 DIODE LASERS

Photoderm VL is a highenergy system which emits noncoherent,26,29,35 multiwavelenght light. It was used for hair removal, but it is now evolving with the ESC Epilight.29 By placing appropriated filters on the light source, wavelengths can INTENSE-PULSED LIGHT SOURCE

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be generated. The operator determines the treatment parameters depending on the patient’s skin type and hair color and coarseness.28,37 Cooling is achieved by a thick layer of transparent cooling gel. It is used to couple the quartz prism to the skin, or a cuff of cold water is affixed to the prism, cooling it and also the skin, thus protecting the epidermis.28,39 It is a successful method, and its great advantage is the large exposure area, which increases damage of the deep follicles; however, the slow pulse-repetition rate makes the device equivalent in speed to the diode array and alexandrite lasers.37 Recently a new machine has been introduced which was approved by the FDA in 2000. The SpaTouch (Radiancy) uses a broad spectrum of light for photoepilation. It is characterized by: large spot size (for deep delivery to the dermis and enough energy delivered to coagulate the follicle), longer wavelength (preferential to melanin), longer pulse width (to eliminate epidermal overheating), and no need for cooling.40 Q-SWITCHED ND:YAG LASERS Q-switched ND:YAG lasers have a very short pulse that, when used against the hair follicles, promotes hair removal by a extremely rapid heating of the chromophore (melanin). The rapid heating generates photoacoustic shock waves that cause focal photomechanical disruption of the melanocytes in the bulb, but does not complete follicular disruption.28,37,41 These lasers are very useful for the treatment of dark skin types but appears to be ineffective for long-term hair removal.29 New long-pulsed Q-switched Nd:YAG lasers are being developed and may provide a potentially effective treatment for dark-skinned individuals with excessive hair.28 CARBON PARTICLES ⴙ Q-SWITCHED ND:YAG LASERS In 1996, the FDA cleared for marketing a laser technique for hair removal that combined Q-switched ND:YAG laser therapy with pretreatment wax epilation or shaving and application of a carbon-containing solution (SoftLight, Thermolase Corp, La Jolla, CA).11,28,37 Carbon suspension, similar to India ink37 is massaged on the skin and partially taken into hair follicles.11,30 Unfortunately, this method has a lack of long-term efficacy, and all the hair grows back within 6 months.37 Hair color is a mixture of eumelanin (brown, black) and pheomelanin (red).30,37 In gray hair, melanocytes show degenerative changes such as vacuoles and poorly melanized melanosomes, whereas in white hair melanocytes are greatly reduced in number or are absent.31,37 Color contrast between epidermis and the hair shaft (and bulb) are paramount in determining the optimal wavelength.33 For high contrast (dark hair, light skin), the low range (650 –700 nm) can be used without risking great damage to the epidermis (and subsequent hypo- or hyperpigmentation). For lighter hair and darker skin, longer wavelengths (800 nm and greater) should be used.29,33

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Patients with dark hair are most likely to obtain long-lasting hair removal, whereas patients with blonde, red, gray, or white hair are unlikely to experience a permanent reduction; however, hair loss in these patients can be maintained by treating at approximately 3 month intervals.28 For patients with blond, gray, or red hair, an exogenous chromophore and a wavelength that matches its absorption peak can be used. The main problem is reliable penetration of the chromophore into all depths of the hair follicle. The short-pulse duration of the laser used in the SoftLight technique (carbon particles ⫹ Q-switched Nd:YAG laser) also limits the extension of follicle damage. This technique successfully induces a delay in hair growth, but fails to produce long-lasting hair removal.28 The maximum tolerated fluence is determined by the epidermal pigmentation. Fair skinned patients with dark hair are the most easily treated. Darker skin (types IV and V) should be treated first with lower fluences to prevent skin reactions.29 Although dark skin types are not readily treated with any of the ruby lasers because of melanin interference,28,29 the alexandrite lasers, diode lasers, and the intense pulsed light source, operating at longer wavelengths (near-infrared) and pulse duration, have been shown to treat darker skin types (IV-V) more safely if combined with cooling devices. A Q-switched Nd:YAG laser, with or without an external chromophore, has been shown to be very useful for treatment of dark skin types but appears to be ineffective for permanent hair removal. Long-pulsed Q-switched Nd:YAG lasers, currently being developed, may be useful.28 For patients presenting a tan, pretreatment with a bleaching agent, sunscreen, and sun avoidance for at least 6 weeks is recommended prior to laser treatment.28,35 Patients with tanned skin should never be treated.28 The ideal immediate response to laser treatment is vaporization of the hair shaft with no other apparent effect.33 After a few minutes, perifollicular edema and erythema appears. The intensity and duration depend on the hair color and hair density.28,33 Transient pigmentary changes such as hypo- or hyperpigmentation can be prevented if the ideal patient and treatment fluence are chosen.26 This is mostly seen in patients with darker skin types or when patients have a recent tan.28 Permanent pigmentary changes are unlikely except in dark-skinned individuals.28,29

Conclusions Although today there are products and surgical procedures that alleviate the presence of their excessive and unwanted hairs for both women and men, improving not only their appearance but also their self-esteem and quality of life. It is mandatory to continue researching new and more efficient techniques to remove unwanted hair, maximizing the possibility of satisfactory results with fewer risks and adverse effects.

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