Scientific Background

Aluminum oxide crystal particles (corundum crystals) are composed of white-fused alumina and bauxite. These particles are inert, water insoluble, and approximately 100 µm in diameter. The abrasive effect of these crystals results from their sharp edges, coupled with the flow generated by the positive stream of crystals flowing via a hand piece with vacuum suction [81]. The vacuum suction collects the crystals in a container that allows for their neat and safe disposal. The depth of penetration is controlled by the level of suction, the duration of time the suction hand piece is held in contact with the skin, and the number of passes. Typically, microdermabrasion treatments exert direct effects on the stratum corneum and epidermis. With high-pressure settings, more aggressive treatment regimens have reportedly affected the reticular dermis in some cases. The exfoliating effect is responsible for the improvement seen in clogged pores. Improved skin texture is a direct effect of removing superficial skin layers, [81] and, although somewhat controversial, the theory of microdermabrasion stimulating dermal collagen deposition is supported by at least one study evaluating the histology of three patients before and after six treatments [83]. In that study, posttreatment biopsies revealed an increase of collagen deposition in the papillary dermis thought to result from repeated intraepidermal injury. Significant epidermal thickening from 103 microns to 148 microns was demonstrated histologically in one study that evaluated the effects of 8 weekly microdermabrasion treatments. Photograph assessment of baseline and posttreatment photos of this same group of 17 patients revealed a rating of improved pigmentation as reported by all 30 evaluators, but improvement of fine wrinkling was noted only by the 14 nonmedical observers [84].Tan et al. described a slight abrasion of the stratum corneum following four passes of microdermabrasion at an aggressive setting (65 - mmHg). Clinical erythema, however, persisted for 5–6 days posttreatment and was thought to represent a biologic response. This response may help explain the mechanism behind the diminution of fine rhytids following microdermabrasion of photodamaged areas. In the treatment of depressed scars, formation of granulomas in the upper dermis due to retained aluminum oxide crystals is hypothesized, a histologic finding not typically found after traditional dermabrasion. Microdermabrasion may prove to be better than traditional dermabrasion in treating atrophic scars for this reason [85].