Labial bow 0.9 mm spring hard, distalizing spring 0.9 mm spring hard
Function:
Therapy of a class III malocclusion
Description:
The class III activator should not hinder the buccal segments in their vertical eruption
In this class III activator, the labial bow in the lower jaw is bent as an intermaxillary bow; its task in the upper jaw is to shield off the lips through loops bent as labial pads. The retention lies as in the class II appliance, in the anterior area of the vertical opening. Also, the distalizing spring is bent with a big loop in the molar region. Although in this appliance the distal cantilevers are located behind the first molars, the retention ends in the anterior palatal area.
As before, the wax coverage is very important. The big vertical opening corresponds to the one in type-II. In this case, a wax plane that reaches over the half of the vertical opening is added onto the upper jaw. In the lower jaw, the posterior teeth are slightly covered with wax and in the incisal area, from canine to canine, the wax is concavely shaped; the loop and the distal cantilever of the distalizing spring are also covered with wax.
For its proper stability, the acrylic in the interocclusal area should show a thickness of one millimeter.
The acrylic shield of this appliance only covers the lower incisal area and is correspondingly framed with a wax limitation. Despite its location, a sufficient anchorage has to be guaranteed for the retention of the labial bow. Before adding the acrylic both models have to be hydrated.
In this class III appliance, the distal limitation is also marked by the A-line. Once again, only the retention of the distalizing springs is grasped in acrylic. In the upper jaw, the labial bow does not contact but shields off the lip.
The upper teeth only contact the acrylic shield. The acrylic can be trimmed and shaped individually by the orthodontist. The lateral bite plane allows more vertical eruption for the upper posterior teeth.
