Abstract: A dental device for the correction of upper jaw transversal micrognathism in adult patients, which makes it possible to apply a slow expansion orthopedic technique, without osteotomy with osseo fixation by means of micro-implants, which comprises an expansion component, bilateral palatine support components, and a fixation component. The expansion component is an expansion screw joined to the palatine support components by means of lateral arms that extend out of it, where said palatine support components have perforations for receiving the fixation components defined by the micro-implants. The invention also provides a procedure for building the device and for setting up a surgical guide for said device.