T-Rex

Appliance Purpose / Function:

The T-Rex variation is a Pendex design with additional wires extended out of the acrylic plate and soldered to the molar bands. These wires prevent the pre-activated springs from distalizing the molars until after the arch has been widened. When the clinician wishes to release the springs, they can clip these wires and smooth off the sharp ends to allow the springs to begin distalizing the molars.

The Pendex variation adds a screw to the acrylic plate. This allows the clinician to widen the patient’s arch while distalizing the molars

The Pendulum appliance performs the same basic function as the ACCO appliance in that it is intended to distalize molars. Aside from other design differences, there are 2 features that set the Pendulum Appliances apart. The Pendulum is a fixed appliance with pre-activated springs. Since the patient can not take it out, it applies force to the molars all of the time. The wire used to make the springs also has a great deal of what is referred to as “memory”, meaning it tends to spring back to its original shape. This prevents the clinician from having to make frequent adjustments to the springs.

Appliance Components:

Rests on d’s & e’s or 4’s & 5’s
Molar Distalizing Springs
Acrylic Palate
Lingual horizontal sheaths
Midline Expansion Screw
Soldered Wires from acrylic to molar bands
Bands on first molars

Suggested Materials:
.032 TMA wire for molar springs
.032 to .036 Chromium Cobalt or Stainless-Steel for the rests and soldered / laser welded Hold Wire on molar bands

Appliance Fabrication Standards:
WIRE STANDARDS:

A 7mm acrylic borne screw must be placed on the midline in the vault of the palate as close to the tissue as possible. Note: The acrylic retention portion of the springs will need to run under the screw in order to fit them in so this will need to be accounted for when placing the screw
The springs must have a 4mm helix positioned parallel to the palate on both sides of the midline approximately 2mm off the tissue. The arms of the springs must come out of the top of the helix and line up with the mesial edge of the first molars. The arms must contour to the curve of the palate just off the tissue and take a 90 degree bend into the mesial side of the lingual sheath. The acrylic retention portion of the spring must come out of the mesial side of the helix and extend approximately 8-10mm ending in 3 or 4 zig-zags for acrylic retention.
If the appliance is to be a banded appliance bands will be present on 2 or more of the bicuspids. If bands are present on the bicuspids there must be a soldered wire on each band that extends into the acrylic button. A foot must run across the middle third of the band then the wire must form a 90 degree bend and extend towards the button. The wire must be as close to the tissue as possible without touching it. It must extend into the acrylic button at least 4mm and end in a 90 degree bend forming an acrylic retention foot.
If the appliance is to be a bonded appliance, there will be no bands present on the bicuspids. In this case, occlusal rests must be placed on all bicuspids or primary molars present. The rests on the first bicuspids or first primary molars must approach the occlusal surface from the mesial side of the tooth and those on the second bicuspids or second primary molars must approach the occlusal surface from the distal side of the tooth. Each rest must be as long as the occlusal anatomy will allow in order to give the Client the most possible surface area to which to bond (this is all that will hold the appliance in place). From the occlusal surface, the wire must take a sharp bend towards the acrylic button. The wire must be as close to the tissue as possible without touching it. It must extend into the acrylic button at least 4mm and end in a 90 degree bend forming an acrylic retention foot.
Connector wires must extend from the mesial edge of the molars (where they are soldered to the molar bands) into the acrylic button. Be sure to place the wires against the bands in such a way as to avoid interfering with where the springs enter the sheaths. They must be as close to the tissue as possible without touching and end in the button in an acrylic retention foot

ACRYLIC STANDARDS:

The acrylic button must cover the vault of the pallet with its borders extending to approximately 4mm away from the gingival margins of the bicuspids and anteriors
Wherever possible the overall thickness must be approximately 2mm with a minimal amount of coverage over the acrylic borne screw
The edges of the button must be rounded and taper towards the tissue (thin, sharp knife-like edges not acceptable)
The tissue side of the split must be inspected for sharp edges. Any sharp edges must be removed without removing an excessive amount of acrylic