**1. Introduction**

The rapid development of high brightness light emitting diodes (LEDs) makes feasible the use of LEDs, among other light sources (such as laser, intense pulse light and other incoherent light systems), for medical treatment and light therapy. This chapter provides an overview of LED application in human health and the results in healing and cell rejuvenation [1].

The technique of LEDs used in tissue treatments is called LED Therapy and from now on we will treat it this way. With the use of electronic converters that supply the high brightness LEDs it is possible to control the spectral composition, allowing to obtain the wavelengths desired to apply the human tissue to obtain efficacy in phototherapy. High brightness LEDs can be easily integrated in digital control systems for the purpose of providing a variation in spectral composition over a phototherapy treatment stage. The colors emitted by the high brightness LEDs operate differently, i.e. depending on which layer of the human tissue that will be applied to light and which type of which will combat disease. In the skin, the red light has restorative action, healing and analgesic, while blue has a bactericidal action [19]. The intensity of the beams of light emitted by LEDs on the skin is lower, since its cells maintain a good interaction with the light [2, 21]. The high brightness LEDs respond effectively in the therapeutic appli‐ cation and can be used a variety of electronic converters that control the output current, output power, the duty cycle and other parameters that directly interfere in luminous efficiency and length of wave offering a positive response in phototherapy treatments.

LED Therapy is gaining ground every day in various areas, including in medicine, dentistry, physical therapy and aesthetics [20]. Biomedical engineering has made great strides in their research on the application of LEDs in the treatment of pre-malignant lesions and malignant,

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in the treatment of rejuvenation and acne, hair loss, skin lesions, wound healing in postoperative incisions in the patient's psychological recovery, where the lights are applied to the environment and on other fronts of medicine. In dentistry the development of modern photopolymerizable materials represents a great advance for restorative dentistry because they allow excellent aesthetics, ease in handling and control of the clinical time [3, 23].

Advances in the medicine are encouraging and research in the area grows every day, the intent of this chapter is to present a study and results in healing and cell rejuvenation.
