A Modified Hyrax-Type Expander Is Effective for Distal Bodily Movement of the Maxillary First Molar

Abstract

Impaction and eruption disturbance of permanent teeth are frequently encountered in orthodontic practice. The canine teeth play an important role both functionally and esthetically. Eruption disturbance of a maxillary canine, if left untreated, can cause not only disturbed jaw movement and esthetic problems, but also root resorption of adjacent permanent teeth, and thus should be diagnosed and treated appropriately. In this report, we present a case of a patient with eruption disturbance of the maxillary left canine in which the maxillary left second molar was extracted and the maxillary left first molar was distally moved with a Hyrax-type expander (Veltri Monolateral Screw®; Leone, Firenze, Italy) designed to enable the distal movement of a unilateral first molar in order to create eruption space for the maxillary left canine, resulting in smooth distal molar movement and alignment of the left maxillary canine in the dental arch. Furthermore, the maxillary third molar was also aligned to achieve a good occlusal relationship without reducing the number of teeth.