There are many different kinds of expanders for kids and the Crozat is just one of them. The Crozat appliance was invented by Dr. Crozat in 1919. The Crozat is the sister appliance of the ALF appliance. It is a springy wire that is great for expansion and alignment in children. The Crozat is different than the ALF in that there is a metal connector that crosses from one side of the palate to the other. This feature helps in cases where more expansion in the back of the maxilla is necessary. The Crozat is a forward growth appliance and is also considered an arch development appliance. It is used to grow bone in a more forward and wider direction. The Crozat is capable of aligning teeth and making them straighter, but it does so by creating more room in the mouth for all the teeth to fit.