Diagnosis and Treatment of the Mandibular Position of a Case Associated with Temporomandibular Joint Dysfunction that Employed the Computerized Axiographic System

Abstract

The craniomandibular system (CMS) is composed of the bones of the temporomandibular joint, cartilage, the articular disk, connective tissue behind the articular disk, and ligaments, in addition to the muscles associated with the masticatory system. The CMS functions in cooperation with the neuromuscular system and occlusion, carries out the functions of mastication, swallow, phonation and respiration, which are the principal functions of the masticatory organ.
While performing these activities it also carries out the task of preventing excessive retrusive and lateral deviations of the mandible, and positions the mandible in the correct anterior position. For example, because of the blood supply from an abundant vascular network, the connective tissue behind the joint, together with the lateral and collateral ligaments, prevent retrusive deviations of the mandibular condyle. The important function of positioning the mandible to the anterior is performed by the closing muscles, which include the superior head of lateral pterygoid muscle in conjunction with the mandibular condyle and articular disk, a portion of the anterior region of the temporalis muscle, and a portion of the deep head of the masseter muscle.
The mandibular condyle is prevented from excessive retrusion by guidance of the mandible to the anterior owing to interdigitation of the maxillary and mandibular teeth, as well as to their occlusal guidance. It appears that this functions to protect the organs of hearing and equilibrium, which are behind the temporomandibular joint. In addition, the harmonious relationship of the CMS and occlusion are thus able to function together to maintain balance by placing the mandible in a forward position.
It has been suggested that most of the functional disturbances in the temporomandibular joint result from imbalances in the CMS and occlusion. The basic issues are the function of occlusal guidance, whereby the mandibular condyle is positioned forward by the CMS, and the forced retrusion of the mandible caused by occlusion. In other words, a problem arises when the position of the mandible goes beyond the appropriate biological limits because of malocclusion. Furthermore, occlusal treatment must begin with determination of the physiological position of the mandible. However, it is not necessarily easy to determine a physiological mandibular position for each patient and devise a treatment plan. This is because the correct three-dimensional position must be found in order to reposititon the deviated mandible, which then must be placed in this precise position.
Furthermore, it is necessary to obtain the scientific data needed to establish this position. It is regrettable that in the past, measurement apparatuses were often not adequate to establish the appropriate mandibular position. One method for searching out the physiological position of the mandible is to determine its deviation (shown by the abnormal path of movement) by observing the path of movement of the condyle from its deviated position.
This reports presents a case where occlusal reconstruction was performed after determining the position of the mandible using the condylar path of movement obtained from a computerized axiograph.