A New Approach to Maxillary Expansion: A Narrative Review and a Case Report on the ATOZ Pure Bone-Borne Spring Expander for Maxillary Transverse Deficiency

To overcome several disadvantages and limitations of tooth-borne rapid palatal expanders in fully grown patients with maxillary transverse deficiency, miniscrew-assisted rapid palatal expanders (MARPE) were introduced as an efficient alternative and have been widely used in the past decade. More recently, pure bone-borne MARPE has been introduced to reduce dentoalveolar side effects and its use has been increasing. This review article aims to report the characteristics and clinically important considerations of the innovative pure bone-borne ATOZ spring expander. This review article looks at the characteristics and placement procedure, expansion protocol, treatment effect and success rate with ATOZ expanders anchored to the bone by six-to-ten bicortical miniscrews as described in several papers and illustrated with some clinical cases. Unlike conventional MARPE, which is activated daily at home, the ATOZ is activated by the orthodontist every 4 weeks because activation is transmitted through four connector links tangent to the axis of the jack-screw, creating continuous tension across the midpalatal suture. Upon activation of the ATOZ expander with a 92.8% success rate, a more parallel expansion pattern is observed for the sutures within the bilateral nasomaxillary complex in the coronal view, while a V-shaped expansion pattern is observed at the level of the palatal basal bone in the horizontal view, with the anterior teeth showing greater expansion than the posterior teeth. In late adolescent or adult patients with maxillary transverse discrepancy, ATOZ spring expanders can provide efficient palatal expansion with reduced dentoalveolar side effects.