Final appliance for stabilization after treatment with fixed appliances, small corrections are possible with a set-up
After an occlusal registration on the patient, the casts are set into a semiadjustable articulator. The impressions can be taken after debonding or shortly before. Sometimes the brackets are left on the teeth to enhance the retention of the positioner.
When the impressions are taken in the last appointment before debonding, the brackets have to be erased on the cast. This method has the advantage that the technician has more time for the manufacture of the appliance and that the plaster can dry properly for the set-up. As an alternative the brackets can be left on the teeth. In this way, the positioner has notoriously more retention and single teeth can even be extruded.
After the active phase of treatment, for the finishing, the teeth to be slightly moved are set-up with wax into the desired position. After setting up all teeth correctly in the arch form, the gingival architecture is modeled harmoniously. This new situation is fixed with a wax bite with 2 mm of vertical opening and then the casts are duplicated.
On the basis of the new wax bite, the duplicated casts are set into the fixator. The fixator should allow a simple removal and insertion of the casts.
The positioner can be manufactured of different flexible silicone types. In this case, a vacuum forming technique with Bioplast was chosen. The casts are isolated, and over each single jaw, a 3 mm Bioplast foil is vacuum formed. The foil is trimmed up to its approximate length with a hot wax knife.
Afterwards, both casts are reset in the fixator and set under the heating of the vacuum forming machine. The foils are heated until they slightly stick to the finger when touched. The fixator is set together and the foils are adapted with wet fingers in the areas of contact; both single foils now stick together as one appliance.
The casts are removed from the fixator and set onto their dorsal side in the vacuum former with the foils in place. For reinforcement a 1.5 mm foil is vacuum formed onto the complete buccal surface.
After the cooling of the material, the positioner can be cut neatly with scissors. The edges are smoothed out with the “blue Jota”. As a conclusion, the positioner is set onto the casts; it is shortly passed through the flame of the Bunsen burner and is again adapted with damp fingers.
If the patient has problems breathing through his nose, holes can be drilled in the positioner with a sharp drill.
