Читать книгу Fundamentals of Fixed Prosthodontics - James C. Kessler - Страница 51

To mount the mandibular cast on the articulator, it is necessary to record the relationship of the dental arches to each other. There are three techniques that are frequently used in locating the centric relation position: (1) chin point guidance, (2) bilateral manipulation, and (3) the unguided method. With a computer-assisted three-dimensional mandibular recording device, Hobo and Iwata³ analyzed condylar position achieved by the three methods. Chin point guidance puts the condyles in the most posterior and superior position, while the bilateral and unguided methods allow the muscles to guide the condyles into a physiologic anterosuperiorly braced position on the articular disc along the articular eminence.

The unguided method produces a physiologic “muscle position,” but it can be difficult to achieve consistent results because of the patient’s muscle activity. Muscle proprioception is minimized by separating the teeth with a leaf gauge composed of several 0.1-mm-thick plastic strips, which help to eliminate direct proprioceptor responses. While the patient occludes with light pressure, strips are added one at a time in the anterior region until the patient no longer feels any posterior tooth contact. This permits the muscles to act freely and allows the condyles to move into a physiologic position.^4,5 Then the muscles will rotate the mandible anteriorly and superiorly.