Vaporization of melanin in oral tissues and skin with a carbon dioxide laser: a canine study

This study tested the efficacy of carbon dioxide (CO2) laser vaporization in ablating gingival, oral mucosal, and cutaneous melanin in dogs.

Three mongrel dogs with pigmentation of the oral mucosa, gingivae, and skin were used. Biopsy specimens from the melanin sites were obtained from all 3 dogs before laser application. Removal of the melanin sites was performed by using a 3 W continuous-wave CO2 laser. Biopsies of the treated areas were performed 1, 2, 4, and 6 weeks after laser treatment in all 3 dogs and also, at 11 weeks in 1 dog. The histologic sections were stained with hematoxylin and eosin and Masson-Fontana dye. A computerized morphometric program calculated the average percentage of the melanin layer in the Masson-Fontana-stained sections.

Clinical and histologic examination showed the CO2 laser to be effective in eliminating the pigmented areas in all tissues treated. No recurrence of melanin was detected in either the oral mucosa or gingiva at any of the follow-up times. In the skin, however, a small amount of melanin repigmentation was noticeable.

CO2 laser surgery proved an effective tool for obliterating superficial melanin discoloration. To prevent recurrence of the pigmentation, the area must be cleared completely of melanin, directing the laser beam carefully along the visible margins of the area.