ABSTRACT
Over the latter part of the last century, the dry, oily, combination, or sensitive skin-type classifications, which were identified in the early 1900s by cosmetics magnate Helena Rubinstein, have held sway in terms of characterizing the skin. While there have been significant innovations and even more substantial growth in the skin care product market during this time span, few notable advances have been made to further our understanding or ability to characterize skin types. Consequently, practitioners have had insufficient information to use in divining the most appropriate skin care product selections for their patients. The Baumann skin-type indicator (BSTI) is a novel approach to categorizing skin types, which greatly expands on the skin-type designations of Rubinstein and, in the process, provides assistance to practitioners and patients/consumers alike in making sense of the numerous available skin care formulations, many of which are now touted for particular skin types, as well as in selecting the most suitable products. The BSTI is based on the identification of skin type using four dichotomous parameters characterizing the skin: dry or oily, sensitive or resistant, pigmented or nonpigmented, and wrinkled or unwrinkled (tight). A four-letter skintype designation is derived from the answers to a 64-item questionnaire and considers all the four skin parameters at once. Sixteen possible skin types, each delineated using the four-letter code denoting one end of each parameter, characterize the BSTI (Fig. 1). Ideally, patients will self-administer the BSTI to ascertain baseline skin type and reuse the questionnaire after significant life changes (e.g., moving to a different climate, pregnancy, menopause, andropause, chronic stress), which can induce modifications to skin type (1). This chapter focuses on the basic science underlying the four fundamental skin-type parameters and, in the process, characterizes in varying levels of depth the 16 skin types. In addition, some attention is paid to treatments, mainly topical and noninvasive, on the basis of the BSTI system.
