The fan type expansion plate with different screws and applications
Elements:
According to the planned design
Function:
Enhanced expansion in specific areas
Description:
Enhanced expansion in the maxilla: 1. Anterior expansion, 2. Posterior expansion, 3. Eccentric expansion
The fan type expansion screw exists in two designs: As a one piece or two piece expansion screw. Both have the same function, to expand the anterior or posterior region fan shaped. The two piece expansion screw has the advantage that through the separate fixation of the screw and hinge, the lever is longer so that the fan type expansion is enhanced.
1. Anterior expansion Fan type expansion plate with divided screw The divided screw is smaller and is therefore favored in narrow jaws. This way, there is more space for the retentions of the wire elements. The separate joint that forms part of the hinge has to be covered with wax.
The finished appliance shows that the hinge which lies on the dorsal end of the plate is not covered with acrylic. The appliance has to be extended notoriously further into the palate than a simple split plate. It should not stand out over the A-line.
The appliance can be expanded like a fan after its sawing. To assure an opening without interference the hinge should lie uncovered on the posterior limit of the plate.
Fan type split plate with fan type expansion screw in one piece In the same way as in the two piece screw, the hinge of the one piece screw has to be covered with wax.
The finished appliance is also sawed, and the hinge has to be cleared of wax and acrylic residues. The fan type plate is often used for expansion in patients with lip and palate cleft.
The top view of an activated fan type split plate with one piece screw.
2. Posterior expansion Fan type plate with reverse built-in, divided screw The screw can also be adapted in the opposite direction; then its function is the posterior expansion of the maxilla.
The hinge is covered with wax as usual and the sawing cut is widened wedge shaped from the hinge to the front.
The activated screw shows that the wedge shaped cut is closed in the anterior region. If the wedge shaped cut is insufficient for the planned expansion, it can be cut wider.
3. Eccentric expansion Fan type appliance with one piece screw for eccentric expansion An eccentric expansion is achieved by the oblique fixation of the screw. The screw is built in as usual, then it is covered with wax and the plate is sawed.
Because of the oblique position of the screw, the activation results in an eccentric rotation of the arch. This way, space can be gained in specific parts of the arch, as in this example, in the area of the lip and palatal cleft.
