Upper Three Way Sagittal (with up to four clasps)
Appliance Purpose / Function:
Three-way Sagittal appliances are intended to create space in a crowded dentition, but they do so by lengthening the patient’s arch. Screws imbedded in the acrylic plate are positioned so that they open in an anterior/posterior direction. When they are activated, the posterior teeth are gradually pushed back and the anterior teeth are gradually pushed forward. An additional screw positioned on the midline so that the arch can be widened and lengthened.
- Adams clasps on the 1st molars
- Ball clasps between the 1st and 2nd bi-cuspids
- Three way expansion screw
- Acrylic Plate
- Posterior Bite Plate
Wire: Chromium Cobalt or Stainless -Steel
Appliance Fabrication Standards:
- The standard design has Adams clasps on the first molars and ball clasps between the first and second bicuspids. The clasping scheme may be changed according to Client preference or the teeth present in the arch.
- The three-way screw must be placed in the vault of the palate like an upside down “T”, with the vertical portion of the “T” pointing towards the anterior and in line with the patient’s midline. It should be placed as close to the tissue without touching as possible for patient comfort
- Uniform overall thickness of approximately 2mm except in area of screw where there should be enough acrylic to cover the acrylic borne screws
- 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)
- The posterior bite plate must be built to the Client’s specifications or approximately 2-3mm thick
- The bite plate must be the approximate width of the posterior teeth which it is covering without excess bulk and the surface must be smooth and as flat as possible while still allowing for contacts with the opposing arch
- The side splits must begin at the embrasure between the cuspids and first bicuspids and proceed on a straight line to the middle of the right angle portion of the screw. The midline split must run along the middle of the plate from the posterior portion of the screw thru the posterior border of the plate. These cuts must be very clean and straight to avoid binding when the screw is activated.
- 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 three splits must be inspected and any sharp edges carefully removed without removing too much acrylic