THE HINGE AXIS CONCEPT

 

What types of hinge axis do we have?

#terminal hinge position
#hinge movement
#hinge axis

The terminal hinge position occurs when the condyles are located in the articular fossae, and the mandible is capable of pure rotary opening.

In Centric Relation (CR), the mandible can rotate around the horizontal axis for approximately 20-25 mm, and this measurement is typically taken between the maxillary and mandibular incisal edges of the teeth.

The horizontal axis around which the hinge movement occurs is referred to as the hinge axis.

Since the temporomandibular joint (TMJ) has two condyles, the right condyle connects imaginarily with the right condyle to create an axis of rotation.”

 
 


HOW DO WE RECORD THE HIINGE AXIS?

I am utilizing the KINEMATIC FACEBOW technology, which allows me to assess the following information:

• Anatomic hinge axis
• Graphic/needle and papaer
• Computerized hinge axis












THE ANATOMIC HINGE AXIS

“It is considered that the anatomic hinge axis is around 11-12 mm from the higest point of the meatus acusticus. However, in the picture below, it is represented as being 15 mm from this reference position.”





GRAPHIC /NEEDLE AND PAPER/ 


We employ a professional open/close movement technique to record the pure rotation of the pointer on paper. As seen in the images, the pointer exhibits different positions during the opening and closing movements. We repeat these movements until the open/close axis aligns into a single axis.

 

THE COMPUTERIZED HINGE AXIS/electronic(CADIAX)/

We utilize special electronic sensors along with software to precisely determine the electronic HINGE AXIS. This axis is represented as a point within a circle, close to the MECHANICAL HINGE AXIS.


As per the concept, we transfer the computerized hinge axis onto the red board and designate the right and left sides with points in the circle.

 




We connect the right and left points on a professional transfer table, and we secure the maxilla to this table. Now, the maxilla is mounted in alignment with the axis of rotation.




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