Background and objective: A variety of laser and IPL treatments with continued progress have been applied for nonablative skin rejuvenation; however, the complete understanding of working mechanisms and clinical appliance strategy is not clear.
Materials and methods: The rats were divided into three groups and irradiated with Q-switched 1064 nm Nd:YAG laser and IPL. Image analysis, chemical colorimetry method, and real-time PCR (RT-PCR) were used to detect the dermal thickness, hydroxyproline, and the expression of III procollagen mRNA, respectively, at sequential time points following irradiation. In addition, the ultra-structure changes of rat skin were observed by TEM at 3 weeks after irradiation.
Results: Two-light treatment contributed to increase in the dermal thickness, the hydroxyproline contents and the expression of III procollagen mRNA, and the dense arrangement of collagen. The effect of collagen synthesis and remodeling could last for at least 3 months after treatment, and the YAG group is more efficient than the IPL group. The expressions of procollagen type III mRNA reached peak level at 2 weeks.
Conclusion: The effect of different lights depends on the wavelength and the penetrated depth; the best referential treatment interval of two kinds of lights for nonablative skin rejuvenation on rat skin is 2 weeks.