Most of the previous studies have reported the treatment of ankylosed anterior teeth with surgical luxation. To the best of our knowledge, this is the first report in the English literature about the treatment of a mandibular first permanent molar with a single-tooth dento-osseous osteotomy. We report a case of surgical treatment and perioperative management of an ankylosed mandibular molar with a single-tooth dento-osseous osteotomy.