A tongue thrusting habit is often the cause of a narrow maxilla. When such is the case, simply correcting the narrow arch through lateral development is often not enough to ensure a stable result. To maintain the correction, everything must be done to address the muscle imbalance that caused the problem in the first place. In other words, you cannot ignore the tongue habit. The Dillingham not only functions as an expansion appliance, it also discourages tongue thrusting and/or thumb sucking with the use of adjustable habit loops. When the appliance is delivered, these habit loops will prevent the tongue from thrusting forward against the anteriors. Instead, the tongue pressure is placed against the anterior loops, which flexes the framework laterally and actually aids in developing the maxillary cuspid region. The expansion screw used in this appliance is the same type of screw used to expand the maxilla rapidly. In fact, this appliance can be used effectively in either a slow expansion or rapid expansion approach. Note: Always send both upper and lower casts along with a construction bite to assure proper appliance fabrication.