Mc Namarra There are two types of expanders. The first is a BONDED expander. This appliance is bonded (or glued) to the posterior teeth. This bonded expander not only covers the outside and inside edges of the posterior teeth, but also covers the biting surfaces of the back teeth. Thus, it is normal for the front teeth not to hit as they did before the appliance was placed. The second type of expander is a BANDED type. In adolescent patients or adults whose permanent teeth have erupted, the appliance is fixed to the first bicuspids and first molars by the use of orthodontic bands. Both of these appliances transmit the force of the jackscrew through the teeth to the underlying bony support.