Many patients exhibit a V-shaped or Gothic arch form as a result of an abnormal habit or an airway problem experienced during development. When this occurs, the arch may only be narrow in the anterior region. Therefore, use of an expansion appliance that expands equally in the posterior and anterior region would be contra-indicated. To overcome said problem, the Swing-Lock Expander has been designed with an expansion screw and a posterior hinge. It gains anterior space without disturbing the posterior bite relationship, and since the expansion screw and the hinge are separate pieces, it is possible to keep the palatal acrylic thickness at a minimum and thus ensure greater patient comfort. Be advised that this design is only effective for an expansion of up to 4mm. If additional expansion is required, fabricate a second appliance or utilize an appliance with a larger fan screw.  Note: As in all removable expansion appliances, activation of any of the springs should take place after space has been created via the expansion process.