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Upper Modified Spring Retainer


Appliance Purpose / Function:

Because of the lingual acrylic matrix mushroom spring provides a greater degree of flexibility in the spring mechanism than the standard spring retainer makes it a good choice for more extensive corrections to the anterior teeth.

Prior to fabrication a doctor may request the teeth to be reset to ideal alignment.

Appliance Components:

(1) Mushroom Spring- .028 spring wire
(2) Adams Clasps- .028 stainless steel
(1) Labial Bow- .030 duraloy wire

Appliance Fabrication Standards:


  • Uniform overall thickness of approximately 2.5mm
  • All wires and inlay pictures completely encased in acrylic on lingual portion
  • All borders must be tapered towards the tissue with a rounded edge (thin, sharp knife-like edges not accept-able)
  • Acrylic must be trimmed at the height of the gingival third of each posterior tooth and must not interfere with opposing cusps
  • Acrylic must have full contact with all lingual sur-faces of every 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
  • Acrylic in embrasures must be sufficient to prevent rotation of the teeth, but must have a rounded end to prevent a sharp uncomfortable point
  • All lingual acrylic from lateral to lateral must be removed except for a thin strip of acrylic covering the oval portion of the mushroom spring and all palatal acrylic must be removed except for a half moon shaped portion on each sagittal wall extending from first bicuspid to terminal molar
  • The tissue side of the plate is generally left alone unless otherwise requested by the Client, but it must be inspected for pits or sharp areas. Pits must be patched with acrylic, and sharp areas must be care-fully ground smooth without removing too much acrylic.
  • Labial Acrylic:

  • Uniform overall thickness of approximately 2.5mm
  • Unless otherwise specified by Client, acrylic must be approximately 2.5mm wide from the gingival border to the incisal border and extend from the mesial portion of one loop to the same point on the other loop
  • All edges must be straight and rounded towards the surface of the teeth to make the appliance more form fitting (square or sharp edges are not acceptable)
  • All wires completely encased in acrylic from lateral to lateral


  • Contact central and lateral incisors in middle 1/3 of labial sur-face Note: wire can be positioned slightly off of teeth in this area due to labial acrylic being placed there but gap must be slight
  • Loop must contour to the gingival margin of the canine in a rounded V shape
  • Crossing occlusion distal to canines wire must fit tightly into embrasure with no space underneath
  • Wire must fit snugly into the lingual side of the embrasure and follow the contour of the tissue with 1mm of space between it and the tissue (this will allow acrylic to flow behind the wire and fully encase it. Do not leave too much space here as this will cause the acrylic to be too thick in order to cover the wire.)
  • A 5mm foot must be bent on the end of the wire for acrylic retention

Mushroom Spring-

  • Wire must contact (or be very closely contoured to) the central and lateral incisors on the lingual just low enough to avoid interference with the opposing arch
  • At the middle 1/3 of the lateral incisors it must curve towards the midline forming an oval shape with the bottom portion of the oval running just above the gingival margin of the incisors
  • In the middle 1/3 of the central incisors, the wire should be bent down towards the lingual support wire closely contouring to the tissue of the lingual following its contours and extending back to the middle of the first bicuspids.

Support Wires-

  • Cross palate wire centered on the first molar with a 5mm foot on both ends for acrylic retention with feet located approximately 5mm below the gingival margin and out of the way of any clasping in the area
  • It must contour to the shape of the palate and be positioned 1mm off of the tissue
  • Lingual support wire begins just mesial to the first molars with a 2.5mm acrylic retention foot on both sides and follows the contour of the palate in the middle 1/3 of where the acrylic pads will be located
  • It must be 1mm off of the tissue and form an arch for the mushroom spring to rest on.