Semi-Adjustable Average-Value Articulators

An attempt is made with these devices to optimize the simulation of movements achieved with average-value articulators. These devices can be adjusted to different reference planes. The fixed geometric values are the following:

• Intercondylar distance: The gap between the two condyles is fixed.
• Condylar guidance: The condylar path is preset as straight or curved.
• Bennett movement: The paths are straight.

The following are variable values on semi-adjustable articulators:

• Sagittal condylar inclination, right and left
• Bennett angle, right and left
• Anterior guidance by variable horizontal inclination of the guide table
• Position of the occlusal plane at the hinge axis, determined by transferring models using face-bows

Semi-adjustable average-value articulators require clinical identification of the joint values and the joint-related position of the occlusal plane.

As a result of the Bennett side shift, the arched movement curve of the balancing mandibular condyle in the anatomical system flattens out slightly (Fig 8-14). In the device, the condyle slides on a straight, rigid condylar path guidance. If the Bennett movement follows a straight course in an articulator, the endpoint of the Bennett movement is actually the same as in the natural case. However, because the balancing mandibular condyle does not describe a circular arc but rather follows a straight path, variations in the paths are unavoidable in the occlusal field. This is why some semi-adjustable articulators are fitted with curved condylar inserts.