Impressions for Functional Appliances

Usually you are taking impressions for study models at the same time as designing the patinets removable appliance. In this case it is not normally necsaary to take seperate impressions for the appliance.

However, if you are taking an impression only for the construction (or repair) of a functional appliance. You must take an impression of both archs.

Bite registration for Functional appliances

There 2 techniques for taking the registration for a function, try both before deciding which you prefer

Method 1

1. Explain to the patient what is required, ie that they posture forward to the required occlusion. NB Do not over posture the patinet or place them into a class III relationship.

2. Soften 2-3 sheets of pink modeling wax in hot water, folding them into a horseshoe shape.

4. Place them into the patinets mouth and get them to close into the postured position. You must ensure that the centre lines are correct.

5. Remove the wax registration and chill the wax under cold running water, cut away the wax as shown in the cabine/premolar region

6. Place back into the mouth to check the registration is correct - the lateral opening and that the centre lines are correct.

Method 2

1. Use either a thick or thin 'bite fork'. The thick (yellow) ones are for when an overbite needs reducing and thin (blue) for normal or reduced overbites.

2. Explain to the patient what is required, ie that they posture forward to the required occlusion.

3. Place the bite fork into the mouth and ask the pateint to practice biting into the required position NB Do not over posture the patinet or place them into a class III relationship. Use the single notch down and the middle notch to locate the upper teeth.

4. Soften a sheet of pink modeling wax in hot water, folding them into the bite fork.

5. Place the bite fork and soft wax into the mouth asking the patinet to close into the postured position. Excess wax can be mouled to aid location of the bite for teh laboratory. You must ensure that the centre lines are correct.

6. Remove the bite fork and chill the wax under cold running water

7. Place back into the mouth to check the registration is correct.