A male patient 9-year-old complains of greenish staining on upper front teeth and has a history of oral prophylaxis and recurrence of stain. Intra-oral examination reveals dark greenish stain seen on maxillary central incisors and roughening of enamel beneath the stain. This type of staining is commonly seen in patients with habit of-

The cause of green stain, which is most often seen on the teeth of children, is unknown, although it is believed to be the result of the action of chromogenic bacteria on the enamel cuticle. Boys are more frequently affected than girls. The colour of the stain varies from dark green to light yellowish-green. This tenacious deposit is seen most often in the gingival third of the labial surfaces of the maxillary anterior teeth. The stain collects more readily on the labial surfaces of the maxillary anterior teeth in mouth breathers. It tends to recur even after careful and complete removal. The enamel beneath the stain may be roughened or may have undergone initial demineralization. The roughening of the surface is believed to be related to the frequency of recurrence of the stain. Fungi (Penicillium and Aspergillus) and fluorescent bacteria have been associated with the discoloration.