The retro-incisal bite plane is a palatal plate (Hawley plate type) to which is added a retro-incisal volume, plane, which constitutes an anterior stop eliminating all posterior contacts, both during closure and during all mandibular movements.Jeanmonod has well codified the characteristics (shape of the plate, shape and location of the hooks), the settings and the methods of use. The major indication for retro-incisor bite planes is the search for rapid relaxation of the masticatory muscles. Contraindications are primarily related to situations of acute disc dislocation. Ventral sleep is also presented as a contraindication, as is prolonged wear beyond 8 days.
From my experience of this type of equipment, I retain several points:
- The adjustment in the mouth of the retro-incisor surface must be perfect: plane (really), fixing a DV which is in the free space but eliminating any posterior or canine contact, for all mandibular positions. We must find 4 incisor contacts or 2 canines at least on the plane; which sometimes indicates a few coronoplasties of the mandibular incisor-canine free edges, or even of the last molars.
- With this demanding setting:
- The relaxation effect is very fast. A few hours at most.
- The mandibular position becomes reproducible in a few days. No manipulation by the operator is necessary for the mandibular position to be reproducible.
- The bite plan is worn 24 hours a day and the teeth should not touch during oral hygiene.
- It is very easy to record the intermaxillary ratios, bite plan in place. Again, no manipulation.
- The retro-incisal bite plane, to avoid the maintenance of a posterior inocclusion, must quickly either be transformed into an occlusal splint, or be deposited after the occlusal equilibration in ORC has made it possible to re-establish simultaneous wedging and centering of the the mandible.
Surprisingly, Dawson considers the condylar position achieved through the use of the retroincisal bite plane to be the same as that achieved through its bimanual manipulation. Obviously, each clinician finds the best condylar position, claiming that it is the same as that found by his neighbour; but without ever checking it.
Thanks to the retro-incisor bite planes, I learned to discover very important antero-posterior shifts; unsuspected. I also learned to feel what a relaxed mandible is when the patient was totally tense the day before. I finally learned that you should never try to force a mandible and that refraining from touching it is an interesting exercise.
I finally stopped using the retro-incisal planes because the initial adjustments are very delicate and take a lot of time, especially if you want to avoid doing coronoplasties right away.
But for all those who want to see what a very quickly relaxed mandible looks like, I'm not sure that there is a device more effective than Jeanmonod's retro-incisor bite plane.