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Mandibular Schwartz

Appliance Purpose / Function:

This appliance is intended to create space in a crowded dentition in order to allow more room to align the teeth.  This is accomplished by utilizing a screw imbedded in the acrylic plate, which is opened in small increments over a prescribed treatment period using a wire key.

As the screw is opened, a split in the acrylic plate widens along the midline causing it to apply pressure laterally against the teeth. This pressure gradually widens the patient’s arch creating additional space in which to align the teeth.

Standard Materials:

  • 11 mm acrylic screw
  • Adams Clasp .028 Stainless Steel
  • Ball Clasp .028 Stainless Steel

Optional Materials:

  • Screw sizes may very due to best fit
  • .032 Ball Clasp for tall crowns


Appliance Fabrication Standards:


  • Uniform overall thickness of approximately 2mm except in area of screw where there should be enough acrylic to cover the acrylic borne screw.
  • All wires completely encased in acrylic on lingual portion.
  • Posterior border tapered towards the tissue with a rounded edge (thin, sharp knife-like edges not acceptable).
  • Acrylic must have full contact with all lingual surfaces of every posterior tooth involved in the requested plate design with the exception of the embrasures. There must be no “cupped out” areas around the teeth that can act as a food trap, instead the acrylic must butt directly against each tooth without dipping.
  • If severe crowding of the anterior is present, the interproximal fingers must be thoroughly rounded off to allow the appliance to seat easier.
  • The plate must be split along the midline in line with the expansion screw. This cut must be clean and straight.
  • The tissue side of the plate is generally left alone unless otherwise requested by the Client, but it must be inspected for pits/voids or sharp areas. Pits/voids must be patched with acrylic, and sharp areas must be carefully ground smooth without removing too much acrylic. Additionally, the tissue side of the midline split must be inspected and any sharp edges carefully removed without removing too much acrylic.


  • Ball Clasp between premolars.
  • Adams clasps on the first molars.
  • A 7mm acrylic borne screw must be placed on the midline in the depth of the palate as close to the tissue as possible without touching. The split of the screw must be in line with the patient’s mid-palatal suture.
  • Optional labial bow. This differs from a Hawley bow in that it is an ideal arch form and doesn’t necessarily contact all of the anterior teeth. Particularly those anterior more lingually placed than others in the arch. It still needs to be positioned in the middle third of the anterior teeth and cross the occlusion without interference.