This case report describes a successful orthodontic therapy of an adult female treated by mandibular central incisor extraction and vestibular fixed appliances. The patient presented a skeletal Class I with normodivergent facial pattern, Class II subdivision dental relationship, extremely deep Curve of Spee and severe overbite. Moreover, during the treatment, the upper left first molar does not respond to orthodontic forces due to tooth ankylosis, augmenting the difficulty of this case. Despite this, a good occlusal relationship on both sites and an optimal extraoral outcome have been achieved after a 26-months therapy. To our knowledge no case report with such entity of Curve of Spee with contemporary tooth ankylosis has been presented.