Since the 1960's, basic and clinical research has been conducted regarding the biostimulative effects of photobiomodulation (PBM) by means of low-reactive level laser therapy (LLLT). A number of studies have used low-level diode lasers in nearinfrared to infrared wavelengths because of their high degree of tissue penetration. In the dental field, it has been shown that LLLT enhances proliferation, migration, and differentiation of gingival fibroblasts, osteoblasts, periodontal ligament cells, as well as mesenchymal stem cells in vitro. Furthermore, LLLT promoted wound healing and bone formation in vivo. Currently, less invasive and safer procedures are desired for dental treatment, especially for regenerative therapy. It is expected that PBM by means of LLLT will contribute to attaining that goal. Consequently, we have reviewed basic and clinical studies using the diode laser for LLLT, and we discuss the potential of LLLT in promoting periodontal tissue healing and regeneration.