A Randomized Comparative Clinical Study to Evaluate the Longevity of Esthetic Results of Gingival Melanin Depigmentation Treatment Using Different Laser Wavelengths (Diode, CO, and Er:YAG).

Gingival melanin hyperpigmentation is due to excessive deposition of melanin granules. The duration of pigmentation reappearance after treatment using different laser wavelengths remains controversial. The study aims to assess the longevity of gingival depigmentation (GD) and the consistency in esthetic results as three laser wavelengths (Er:YAG laser, CO laser, and diode laser, 980 nm) were used in two different groups (smokers and nonsmokers). This is attained by comparing the periods of time in each group before pigmentation reappearance. Seventy-two subjects were divided into daily smokers (S) and nonsmokers. Subjects underwent a randomized GD with: Erbium laser (Er), CO laser (CO), and Diode laser (Diode). The subjects were divided into six groups: S and nonsmokers were treated with three different wavelengths. Irradiation was performed until there was no visible pigmentation. For qualitative measurement, Hedin Melanin Index (HMI) was used, before treatment, after 2 weeks, and until 60 months. Pigmentation reappearance of degree 1 or above of the HMI was noted. Descriptive statistics were also calculated. HMI showed a 0 in all groups after 14 days of treatment. The time before pigmentation rebound was: Diode > CO > S-Diode > S-CO > Er > S-Er. The first signs of relapse shown among all groups were seen in the group S-Er group. The longest time before rebound was observed with the Diode group for the nonsmoker. Diode laser provides the longest-term stability in treatment. Smoking negatively affects the longevity of GD. Er laser gives the shortest time before the reappearance of gingival pigmentation.