A common misconception regarding the long term use of an AMPS therapeutically (while sleeping and occasionally throughout the day during stressful occasions) in that the posterior teeth will supraerupt.
     Posterior teeth erupt until they achieve a functional occlusal contact.  For example, In the event a molar is extracted, and the opposing molar has no functional occlusal contact, it may supraerupt (1) until contact is made (blue dots represent CEJs).  If however, a functional contact exists, there will be no supraeruption (CEJs remain in alignment (2)).

    Since an AMPS is impossible to use during function, supraeruption does not take place (example of 10 year AMPS use (4))  Dentistry is familiar with an anterior bite plane (3), where lower canines can occlude on an occlusal plane. By eliminating lateral interferences, the lateral pterygoids are relieved of resistance to their contractions, thereby reducing or eliminating TMJ or facial symptoms.  However, since the canine teeth can endure significant clenching forces, tension headaches may not resolve.  In this scenario, the patient may be convinced that their headaches and TMD are separate disorders.  Additionally, since the canine teeth can also endure significant masticatory forces (whereas the central and lateral incisors can not), the patient may inappropriately wear the bite plane during function (chewing).   Over time, the posterior teeth may make a functional adaptation by supraerupting until they make functional contact.

Although there is no tooth movement as a result of AMPS use, resolution of dysfunctional musculature activity and associated symptoms may result in the condyle(s) seating in their musculoskeletally stable position (one of the primary objectives of TMD splint therapy). If the condyle(s) had been functioning in position anterior and inferior to ideal (5), it may seat more distally and superiorly (6).  This repositioning only occurs in the presence of resolution or reduction of symptoms.  In order to reposition distally and superiorly, the mandible must pivot, usually at a distal most palatal cusp.  Depending on the original degree of incisal overlap, a anterior open bite may present.  Confirmation of lack of supraeruption can be accomplished occluding hand-held models of the teeth.

     Image 4 (above) demonstrates a degree of mandibular repositioning.  While the CEJs are still in alignment, there is tight occlusal contact posteriorly (green circle, the cusp tips have been reduced), and light occlusal contact anteriorly (yellow circle). (See the animation)

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