RESUMO
BACKGROUND: Gingival melanin depigmentation procedures are commonly associated with recurrence of pigmentation, which starts with migration of melanocytes from the adjacent free gingiva. The extent and rate of recurrence varies according to the treatment modalities used and duration of follow-up. The aim of this study is to compare the surgical stripping; carbon dioxide (CO2); and erbium-doped:yttrium, aluminum, and garnet (Er:YAG) laser techniques for gingival depigmentation and to evaluate their effect on histologic changes in melanocyte activity and clinical repigmentation. METHODS: In this study, 140 sites from 35 patients with bilateral melanin hyperpigmentation were treated with surgical stripping (two sites per patient), "epithelial-peel" (CO2 laser, 2 to 4 W, continuous wave),and "brushstroke" (Er:YAG laser, 180 mJ, 10 Hz, long pulse) techniques. Surgical microscope monitoring was performed intraoperatively. Patient preference and perception of pain, change in Dummett oral pigmentation index (DOPI), Hedin index, and change in area of pigmentation from baseline to 6 months postoperatively were recorded. Twenty samples each from the three treatment modalities were selected for histologic analysis using hematoxylin and eosin and dihydroxyphenylalanine oxidase special stains. RESULTS: At the 6-month postoperative visit, 15 of 70 (21.4%) and three of 20 (15%) of the surgical-treated; 10 of 35 (28.6%) and six of 20 (30%) of the Er:YAG-laser-treated; and eight of 35 (22.8%) and four of 20 (20%) of the CO2-laser-treated sites showed clinical and histologic repigmentation, respectively. Paired t test, analysis of variance, and χ(2) tests were used for statistical analyses. P values for comparison of microscopic evaluation, change in DOPI, Hedin index, and area of pigmentation were 0.001, which were statistically significant. Comparison for patient preference and pain indices gave statistically significant values for Er:YAG laser depigmentation (P = 0.001). CONCLUSIONS: Clinical repigmentation after gingival depigmentation is an outcome of histologic changes in the melanocyte activity and density of the melanin pigments. Surgical stripping for gingival depigmentation remains the gold standard; however, Er:YAG laser and CO2 lasers can be effectively used but with distinct differences.
