Regenerative Effect of a 532-nm Diode Laser on Vocal Fold Scar in a Rabbit Model

Abstract

We evaluated the regenerative effect of a 532-nm diode laser in a rabbit model of vocal fold scarring. This study included 40 male New Zealand white rabbits: 20 underwent vocal fold scar surgery only (control group) and 20 underwent 532-nm diode laser glottoplasty 1 month after vocal fold scar surgery (glottoplasty group). Histological and high-speed video analyses of vocal fold vibration were performed 1 month after vocal fold scar surgery and laser glottoplasty. The maximum amplitude of vocal fold vibration and dynamic glottal gap was measured. Real-time polymerase chain reaction (PCR) was also performed to evaluate scar regeneration and wound remodeling. Transforming growth factor (TGF)-ß1, interleukin (IL)-6, procollagen-1, matrix metalloproteinase (MMP)-2, MMP-9, hyaluronan synthase (HAS)-2, and HAS-3 levels were measured. The maximum difference in amplitude of vocal fold vibration and the dynamic glottal gap was significantly greater in the glottoplasty than in the control group. Real-time PCR revealed significantly higher MMP-2, MMP-9, HAS-2, and HAS-3 levels, and lower TGF-ß1, IL-6, and procollagen-1 level, in the glottoplasty than control group. The histological findings showed that the lamina propria (LP) ratio (LP pixels/total vocal fold pixels) was not significantly different between the two groups. Based on the vocal fold vibration and real-time PCR results, the 532-nm diode laser improved vocal fold vibration in a rabbit model of vocal fold scarring.