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Publisher Summary This chapter reviews the critical hair structures and hair growth processes that are either involved in converting the laser photons to thermal energy, or are part of the biochemical and molecular systems affected by the thermal energy. High laser fluences and energy levels can cause permanent reduction in hair desired by many consumers, and it has the potential for collateral skin damage. The level of efficacy versus dermal side effects is generally dependent on the difference in eumelanin levels between epidermis and the target hair follicle. To understand the mechanism of laser-induced changes in hair growth reduction, whether temporary or permanent, or changes in hair character after treatment, or to determine the treatment regimen for maximal hair reduction benefit, it is important to understand the impact that laser has on key biochemical and molecular targets that regulate hair growth, character, and cycling. At the basic biochemical and molecular level, the released thermal energy from laser treatment can either simply kill the fiber producing cells of the hair follicle by causing denaturation of cellular proteins and phospholipid membranes or can modify the molecular mechanisms and signaling pathways that control the growth and cycling of the hair follicle. |
