Comparative Tests Of The Functional Occlusion Clutch And Occlusal-covering Clutch On Recording Of Condylar Movement

Recording of mandibular movements is one important mean of functional examination of the stomatognathic system, The main purpose of recording mandibular movements is to study the functional status of mandibular movement guided by the condyle. So the mandibular movement can be reflected by the movement of condyle, as one part of mandible, truely. Therefore recording the path of condylar movement is able to make the mandibular movement research more detailed and more accurate.The path of condylar movement is commondetermined by articular fossa and disc, the shape of condylar surface, elasticity and tensity of joint capsule and ligament, contract of masticatory muscles and occlusion etc. However occlusion can be changed by occlusal-covering clutch on recording of condylar movement.The objective of the study is through investigating the occlusal-covering clutch repetition , and comparing the functional occlusion clutch and occlusal-covering clutch on recording of condylarmovement, trying to give the clinic some enlighten. At the same time, the correlation between tooth guidance and the path of condylar movement is discussed.10 subjects with individual normal occlusion (6 women, 4 men; mean age 25.4 years) participated in this study. The path of condylar movement, the sagittal condylar inclination (SCI) angle, and the transversal condylar inclination (TCI) angle were recorded in each subject with computerized axiograph, the Cadiax Compact system, by use of first an occlusal-covering and second a functional occlusion clutch. Measurements of occlusal-covering clutch were made and recorded twice, on different days under similar circumstances. Results From this research we found that:1. The traces of condylar movement and hinge axis movement, which were recording twice by use of occlusal-covering clutch , were similar. The characteristic of curvatures, including the protrusion, opening and mediotrusion track, had good congruence (Kappa >0.41). The data of SCI and TCI angle at any of the millimeter intervals of all cases revealed no significant difference (p>005).2. In order to find similarities and differences between the functional occlusion clutch and occlusal-covering clutch on recording of condylar movement, a functional occlusion clutch was mede by, ourselves, which is convenient and is fixed to lower tooth stably enough to support the mandible writing bow.3. The track of condylar movement and hinge axis movement, recorded by use of the occlusal-covering clutch and the functionalclutch , were also similar. The congruence of the tracing characteristic is acceptable (Kappa>0.21). There was no significant difference (p>0.05) to be founded in the value of SCI and TCI angle regardless of whether the occlusal-covering clutch or functional clutch was used. But among those tracings of the occlusal-covering clutch, there were 2 tracings showing crossing. Among those time curves of the occlusal-covering clutch, 3 curves showed increase suddenly at the speed and velocity at some interval.Conclusions and implications Within the limits of this researchi conclusions can be drawn to the following:1. Repetition of the condylar track recording was good with the Cadiax Compact system by use of the occlusal-covering clutch.2. No significant difference was founded in the path of condylar movement of the functional occlusion clutch and occlusal-covering clutch. However it is easier to induce abnormal tracings by use of the occlusal-covering clutch, therefore producing false positive results.3. In diagnosis of TMD, the functional clutch is better than the occlusal-covering clutch. And the the utilizable value of the former in clinic may be more than the later, since the condylar's position can be recorded directly by use of the former.4. Considering, however, the amount of work involved in each procedure, the occlusal-covering clutch should probably be given preference, when there is no intention of recording occlusal guidedmovements.5. The influence of occlusion contact changing to the path of condylar moverment is limit, unless it cause TMD.6. The self- made functional clutch shows good reliable to achieve the recording of condylar movement.