An undesirable effect of fixed orthodontic appliances is irritation of the oral mucosa. Lesions are common, but they usually heal quickly because of the fast metabolism of oral mucosa cells. Alterations accompanying some injuries are temporary, but some are irreversible because of attrition. White sponge nevus constitutes a special situation, and little information about it is available in the orthodontic literature. This report presents a patient with white sponge nevus who received orthodontic treatment over a 40-month period. The condition was also noted in a sibling. Because of the similarity between white sponge nevus and other diseases, including some that are malignant, a thorough clinical history and differential diagnosis are essential.