Electromagnetic articulography as a method for detecting the influence of spikes on tongue movement.

In orthodontics dysfunctions of the tongue are discussed as a factor in the development of malocclusion. A new objective method for examining tongue movement is the electromagnetic articulography (EMA). This enables movements of the tongue to be followed using the principle of inductive distance measurements. A helmet made of acrylic material serves as a carrier for three transmitter coils. These are located in front of the forehead, in front of the chin, and at the back of the neck. Receiver coils are fixed to the tip of the tongue and at two points on the dorsum of the tongue. The distance between the receiver and the transmitter coils is calculated by means of a personal computer. The movement trajectories are displayed on a computer screen in x-y-coordinates. Tongue movements of one patient with an anterior open bite are shown during characteristic test sounds and during swallowing. The first examination took place without any orthodontic appliance. In a second series in the same session, tongue movement was recorded under the influence of an orthodontic appliance with spikes. While the patient shows vertical combined with sagittal components in the movement pattern of the tongue without an orthodontic appliance, the same patient, under the influence of an orthodontic appliance with spikes, shows a change of the rest and work position of the tongue and in the pattern of tongue movement with a more posterior position of the tongue, and with an increase in the vertical and a decrease in the sagittal components of the movement pattern.