A study on the removal of the melanin pigmentation of dog gingiva by CO 2 laser irradiation.

Removal of melanin pigmentation of the gingiva with CO 2 laser irradiation was investigated. The melanin-pigmented gingiva of 5 dogs were classified according to the degree of gingival pigmentation (slight, moderate, severe) and its extent (local, extensive). CO 2 laser was irradiated on the surface of the pigmented gingiva under the following conditions; defocused beams of spot size 4 mm, irradiation time 0.2(S), output 6-8(W)). That is, the irradiation energy density was 9.6-12.8 J/cm 2. The irradiated gingiva was examined macroscopically and histopathologically. The histopathological changes were investigated by hematoxylin-eosin staining and Masson staining for the differential diagnosis of melanin pigmentation cells. These examinations were done one week and three weeks after the laser irradiation. Immediately after irradiation, the gingiva surface showed white color and bulla-like appearance. One week after irradiation, the pigmentation of the lased gingiva disappeared in all cases macroscopically. Histologically, the pigmented-laden cells could not be found and no inflammatory cell infiltration was observed. Three weeks after irradiation, no reappearance of pigmentation was observed in either macroscopical or microscopical investigations excluding severe/extensive cases. These findings suggested that it is possible to remove gingival melanin pigmentation by CO 2 laser irradiation.