The Tridimensional Orthognathic Gauge
The tridimensional Orthognathic gauge™ is a measuring device that can target and verify the desired position of the maxillary teeth and therefore the upper jaw in three planes of space at the time of orthognathic surgery. It was designed by Dr. Tim Tremont, a practicing Orthodontist in Pittsburgh Pennsylvania and is the developer of a comprehensive system for orthognathic surgery treatment planning and execution that he calls, “The Four Faces of Orthognathic Surgery”. Its purpose is to establish the position of the maxilla in three planes of space, record a measurable starting point for the movement of the maxilla in the operating room, and then to verify the movement of the upper jaw to document that the surgeon has, indeed, duplicated the planned surgical procedure on the patient.
The TOG, as it is called, is manufactured by Mondeal Medical Corporation and consists of a halo device that is attached to the head with 6 screws. The 3-D measuring gauge consists of a red “x axis” horizontal measuring arm, a blue “y axis” vertical arm and, most importantly, a blue “z axis” calibrated target blade that is used to capture the facial midline and any change to it by the recording of the coordinates etched into its surface.
The 3-D measuring gauge is inserted into the adjustable ball housed in the halo. The set screws are tightened thereby “locking” in the horizontal and vertical position of the incisors (and thereby the position of the maxilla) at the start of the surgical procedure.
The blue target blade adjusts along the vertical arm to record changes in the vertical position of the maxilla but also forever records the midline and or any change treatment planned for the patient. More importantly it transfers the third plane of the face, the transverse plane from the patient clinically, and from the mounted models in the lab to the patient on the operating room table. This is accomplished by an ingenious but beautifully simple device called this Tridimensional Orthognathic Surgical Plate.
Highlights
- Accurately targets and verifies movement of the maxilla in three planes of space.
- Is independent of bite registration recorded during pre surgical records appointment
- Precisely and definitively verifies the patient’s facial midline to the midline of the central incisors during surgery.
Application
The halo is positioned on the forehead parallel to the plane of the maxilla. It is stabilized with finger pressure as the screws are tightened incrementally and in succession.
The halo is placed approximately two fingerbreadths above the ear. The screws are tightened first with hand pressure and finally by the use of the torque wrench.
After securing the halo to the head, the 3-D measuring gauge is inserted into the adjustable ball and securely tightened. By adjusting the red “x axis” horizontal arm and the blue “z axis” target blade to the incisal edge, the horizontal and vertical position of the maxilla can be “locked” into place.
By locking the blue target blade along the vertical “y-axis” measuring arm and using the coordinates etched on it, the midline or planned changes to the midline can be recorded.
Resetting the 3-D Measuring Device
The 3-D measuring arm is adjusted using the coordinates along the sides of the “x-axis” horizontal arm and “y-axis” vertical arm to duplicate the surgical movement of the maxilla as planned by the surgeon. Any change in the position of the maxillary midline is documented by the coordinates on the blue target blade.
Conclusions
Accurately measures the original position of the maxillary teeth (jaw) and targets the desired A-P and vertical change in the position of the maxilla.
Regardless of errors in capturing centric relation whether from inaccuracies in bite registration or changes in condylar position with general anesthesia, the Tridimensional Orthognathic Gauge™ gives a true reference to maxillary position before and after down fracture of the maxilla.
In cases of maxillary asymmetry, canting and especially when segmentalization of the maxilla is performed, the Tridimensional Orthognathic Gauge™ ensures both dental-facial midline accuracy and vertical-horizontal jaw position accuracy at the time of surgery.
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