Analysis of the guidance parameters for mandibular movement shows how the movement capabilities of the temporomandibular joint (TMJ), the neuromuscular system, and the shape and arrangement of the teeth relate to each other. All the parts of the system are in harmony. The shape and arrangement of the occlusal surfaces must be related to the TMJ for a properly functioning denture.
To produce a denture that takes account of the special function of the TMJ or mandibular movements, a device is required that can simulate the movements of the joint and the mandible. Occlusal surfaces are created in this device by replicating mandibular movement while constantly checking the occlusion. As the occlusal surfaces become more accurate and more functional, the individual mandibular movements of the patient can be better replicated.
Mechanical articulator devices reproduce the centric occlusal position or jaw relationship and the movement function with tooth contact (ie, articulation). That is why these devices are commonly called articulators. However, the function of the neuromuscular system cannot be replicated by a mechanical device.
Despite all the special structural features of the different devices, the basic components of any articulator are the same (Fig 8-1). Each device has an upper part (arm or member) and a lower part (arm or member), and each part has a removable model holder. The upper part of the device is connected movably to the lower part by means of a simulated joint, which is arranged as a condylar roller or a condylar housing (casing or box). The joints are fixed to the joint columns (or condylar supports); in many articulators, the joints can be variably moved on these joint columns (eg, to measure the Bennett angle, condylar inclination, or intercondylar distance).
In most articulators, the incisal guide pin is fitted to the upper arm, while the incisal guide stop with the adjustable or exchangeable incisal guide table is fixed to the lower arm. The guide pin and guide table can also be interchanged. The incisal guide table represents tooth guidance in an articulator by enabling the upper part of the device to be guided against the lower part via articular guidance and the incisal guide table. In average-value articulators, the incisal guide pin carries an incisal indicator that denotes the mandibular incisal point or the occlusal plane.
Articulators can be classified according to the following:
- Reference planes for model adjustment
- Nature of the joint and movement simulation
- Range of anatomical values used