Palatal expander

And about the ESRatio, if anything it'll probably increase- i don't think MARPE increases actual facial width because facial width is generally measured from the end of one zygomatic arch to the other which aren't affected by MARPE and lie beyond the zygomatic bone (check the anatomy of the skull) The expander will push the zygomatic bones outwards so unless it pushes them beyond the zygomatic arc…

Well there's no actual evidence but theoretically if you're 16-25 or around IPD could increase by 1-2mm depending on amount of expansion coz both the lateral walls and the floor of the orbits shift laterally after expansion, because at that age group the circum-maxillary sutures are not completely fused and susceptible to mechanical force. Oh yeah and make sure you get a MARPE and not a RME or a s…