MARA is an acronym for Mandibular Anterior Repositioning Appliance. This appliance is used to encourage forward growth of the lower jaw. Please do not be intimidated by its appearance. It is much easier to get used to than the pictures below would appear to indicate. Out of all of the types of appliances currently available to position the lower jaw forward, I feel that this appliance is the easiest to get used to and is the least obtrusive. Removable types of appliances that I have used or seen used that can address this problem (Activators, Bionators, Twin Block Appliances, etc.) are relatively bulky and patient compliance is usually not that good. Fixed appliances (ones that stay in all the time) eliminate most of the compliance problems, but the ones that I have used in the past (Herbst, Mandibular Corrector) are more difficult to tolerate and are prone to breakage.
The image below shows the MARA on a model (the orange stuff is wax that the lab used to hold the models together and the appliance in place):
The upper pieces consist of stainless steel crowns on the first molars with tubes soldered to their outside surface. There are small wire extensions that rest on the biting surface of the teeth behind them (the second molars) to prevent the second molars from erupting too much while the appliance is in.
A close-up of the stainless steel crowns shows the removal holes; these make it easier to remove the bands at the end of treatment. The bands are attached to the teeth with a Fluoride releasing cement, and as long as the cement is present, there is no risk of getting a cavity because of the holes in the crowns. (The other whiter looking areas are just reflections from the camera flash).
Pieces called "elbows" slide into the tubes on the sides of the stainless steel crowns and are attached to the crown using a blue elastic band.
(It's not dirty, it just appears that way from the reflection of the flash).
The pictures below show how much the appliance sticks out from the teeth. Your cheeks get used to this in a couple of days.
The lower pieces consist of stainless steel crowns on the first molars with loops soldered to their outside surface. The loops serve a guides that the elbows contact to push the lower jaw forward. A side effect of the elbows pushing on the loops is that the lower first molars would rotate inward. To prevent this from happening, a wire (lingual arch) connects the two crowns.
Without the elbows in place the lower jaw can close into its normal position.
With the elbow in place, the lower jaw is guided forward.
About a week before you are to get the MARA, I will usually need to put spacers around your first molars to make room for the crowns. At the visit that you are to get the MARA, I first remove the spacers and then clean the first molars with sandy stuff called "pumice" to make sure all of the plaque is off of these teeth. I will then try on the crowns to make sure they fit well and don't pinch you anywhere. The crowns are then cemented on with a gold colored cement (the color makes it easier to see to clean up after the crowns are removed). The cement tastes a little bitter if you happen to taste it. I have you bite down on a piece of cotton for about 5 minutes while the cement is setting up. After the cement has set, I clean up any excess (it usually just flicks off the smooth outer surface of the crown).
For more information on this appliance, AOA labs' download page has a free Clinical Management Book authored by Paula S. Allen-Noble:
The MARA appliance: Included are instructions for insertion, cementation, and patient instruction. This is followed by a discussion of the Expander MARA, treatment sequence and activation, removal and continuation of treatment.