Sandpaper abrasion

Cured phenolic resins have outstanding heat resistance, resistance to cold flow, good electric (insulation) properties, and good dimensional stability. Phenolic resins have good adhesive properties and are employed in the production of sandpaper, abrasive wheels, and brake linings. These resins are also used as casting resins. 

Deep Sandpaper abrasion + Easy TCA Unideep Only Touch (AHA + TCA > 40% m/m - localized deep)... 

TCA has some effect on shallow scars, but can only improve the general condition of the skin and cannot get rid of scars altogether. TCA can be combined with sandpaper abrasion (see the discussion of abrasive peels in Chapter 15) or scar subcision before the acid is applied. Even a phenol peel cannot always guarantee to heal acne scars. High concentrations of TCA can be directly applied on acne scars, levelly, with good results. 

Gentle abrasion with sandpaper or intraepidermal erbium laser treatment help accelerate penetration of the ETCA solution considerably. When sandpaper abrasion is used, a topical anesthetic should be applied (a swab with 2% lidocaine with adrenaline (epinephrine)) after the abrasion, before applying the acid. With an erbium laser, a nerve block or ring block is necessary. 

If photoaging is widespread, the ETCA abrasive protocol (see Chapter 21) can be used the decolletage is abraded with sandpaper abrasion up to the very first bleeding pinpoints. The area is covered with post-peel mask cream and left under occlusion for 24 hours. No acid is applied in this... 

The combination of sandpaper abrasion, with or without the application of the acid solution and occlusion of the ETCA post-peel cream, allows a whole range of different depths of action. 

The sandpaper abrasion kit consists of 10 sheets of singleuse sandpaper (3M Wet-or-Dry P220) sterilized with gamma rays and a yellow disinfecting and healing powder bismuth subgallate. 

The mechanism of action could be as follows the sandpaper abrasion and acid have a synergistic effect of physical and chemical resurfacing that improves the quality of the entire epidermis (Figure 21.1). When the post-peel cream penetrates the atrophic base of the stretch marks, it causes inflammation (controlled by the antioxidants) that stimulates fibroblast proliferation and metabolic production of the non-cellular components of the dermis (Figure 21.2). 

When done correctly, the sandpaper abrasion gradually permeabiHzes the skin, is not painful at first and is therefore done without anesthetic. The depth can be classified in four different grades (Figure 21.4). 

Objectively the keratinocyte touch is still negative -although the fingers can be felt to brake slightly as they slide from the healthy zone to the abraded zone, they still slide easily over the skin. Grade 1 sandpaper abrasion does not provide adequate topical anesthesia, and the peel is still painful and too superficial. 

Subjectively the patient starts to feel pain from the sandpaper abrasion. Usually the abrasion should be stopped here, but the pain thresholds vary from patient to patient. It is therefore essential to look out for the objective signs. 

The sandpaper abrasion technique has the advantage of being even over the whole area, and is cheap, fast and inexpensive. 

The sandpaper abrasion must be taken a step further (grade 111) on the face confluent pinpoint bleeding appears on the abraded area of the scars. This physical resurfacing makes the skin appear smoother after abrasion. 

Treatment of pilar keratosis aspect of the skin after sandpaper abrasion and application of Easy TCA solution. Points of frosting can be seen. 

This more aggressive protocol involves sandpaper abrasion prior to the application of Easy TCA solution and 12-24 hours occlusion of the post-peel mask cream. It causes severe erythema within the first few hours of occlusion. After the occlusion has been removed, the skin looks... 

We saw in Chapter 21 that it is possible to combine sandpaper abrasion with Easy TCA . 

Laser treatment is not a simple alternative to sandpaper abrasion. Unlike sandpaper, it is painful and requires prior anesthesia. Besides, it is most likely that gentle and gradual abrasion with sandpaper has a clear advantage over laser abrasion in that it does not put any heat stress on the skin. 

Skin electrodes have the largest commercial product volume, most of them are pregelled ready-to-use nonsterile products. Some of them have a snap-action wire contact others are prewired, for instance, adapted for babies. There is a contact electrolyte between the skin and the electrode metal. Dry SC is a poor conductor and this easily results in poor (high impedance) contact and noise. The contact area with the skin should be as large as practically possible, and reducing the SCs thickness by sandpaper abrasion is useful. Hydrating the skin with contact electrolyte or by the covering effect of the electrode will usually reduce the contact impedance with time (minutes to hours). 

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