Mandibular hyperostosis in a patient receiving orthodontic treatment while on isotretinoin for acne

Isotretinoin (13-cis-retinoic acid) is a vitamin A derivative used to treat patients with severe nodular acne nonresponsive to conventional therapy. Although the benefit–risk ratio of the use of retinoids is generally excellent, vitamin A has profound and complex effects on bone growth and metabolism. The toxic effects of vitamin A in humans and animals include hypercalcemia, new cortical bone formation; premature closure of epiphyses; and demineralization, which can lead to fractures. This article presents the case of a 19-year-old patient under orthodontic treatment who developed mandibular hyperostosis while on isotretinoin treatment for acne.