Frequently asked questions and their answers:

Why does the FOS maxillary splint not have a labial extension?

In the last 15 years in practice, I have seen almost no "protrusive pressers". I always had to grind away the labial extension. In most cases, the labial extension prevents lip closure and patients complained about salivation from the corners of the mouth or a dry mouth when standing up.

Colour the entire bite surface with nail varnish or a permanent felt-tip pen, so you can see what the patients do with the lower jaw during the night. During the check-up appointments, it happened once with me that a patient protruded beyond the splint. The posterior disclusion seems to be enough to stop the protrusive habit.

Instead of grinding away the extension in over 90% of patients, it seemed more reasonable to simply leave it out. If necessary, it is relatively easy to supplement the copolymer with light-curing composite.

Gary Unterbrink DDS

The inclination of the occlusal surface does not correspond to the occlusal plane. Is this a disadvantage?

The first priority in the design was to load the antagonists as vertically as possible. This minimises time-consuming grinding work. There are no conclusive reasons for using the occlusal plane as a reference.

A disadvantage occasionally arises only in class II/1 occlusion when the overjet is relatively large and the overbite relatively small. In these cases, the vertical dimension may be too small. The necessary modification can be easily and quickly corrected with thermal fusion and light-curing composite.

Gary Unterbrink DDS

Which vertical dimension is optimal with an FOS mandibular splint?

The overbite of the central incisors in centric allows a quick assessment of whether an FOS-UK splint is suitable or not. If the overbite is greater than 4 mm, the FOS-UK splint will involve a strong vertical dimension increase. It is also partly related to the inclination of the maxillary anterior teeth; the more labially inclined these teeth are, the higher the vertical dimension. A difficult question without a simple answer.

Gary Unterbrink DDS

What to do if the antagonists react sensitively?

First check whether there is a vertical load on the antagonists. Adjust the angle if necessary. It may also be that a single tooth is in contact in some eccentric mandibular position. This is easiest to determine by having the patient rub on the splint in all directions.

It is not always possible to eliminate such contacts just by modifying the FOS splint. Modifications to the teeth themselves or a deep-drawing (hard) splint over the antagonists are two possibilities.

It should go without saying that mobile teeth are a contraindication for a deprogrammer!

Gary Unterbrink DDS

What to do if patients complain of sensitive teeth after getting up? (Sensitivity of the teeth covered by the splint)

This problem occurs when pressure is applied to the teeth during relining. It is possible to adjust internal surfaces (Fit Checker), but this is not easy.

The problem is relatively easy to avoid. Before relining, the splint should not rock over individual teeth, you simply grind away such spots internally. While the relining material is curing into the elastic phase, the splint is "passively" held in position.

It is sometimes recommended to let patients bite the splint during relining. I do not recommend this technique.

Gary Unterbrink DDS

What to do if patients have difficulty falling asleep or take the splint out of their mouths at some point during the night?

Getting used to a splint may take a few nights, although few patients have problems with a deprogrammer. If the acclimatisation period takes more than a week, you should reduce the vertical dimension. It can also be helpful to grind in the teeth. However, I always discuss such procedures with my patients first.

Gary Unterbrink DDS

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