The influence of the leaf gauge and anterior jig on jaw muscle electromyography and condylar head displacement: a pilot study.
BACKGROUND
A leaf gauge and an anterior jig may be used to assist the recording of a reproducible jaw position for restorative and prosthodontic treatment. This study investigated possible condylar displacement using an opto-electronic jaw-tracking device and a leaf gauge or anterior jig. The effect of a leaf gauge and anterior jig on jaw muscle electromyography was also examined.


METHODS
Five healthy adults without symptoms of temporomandibular disorders were selected. Condylar displacement during clenching were recorded simultaneously with electromyographic activity of superior and inferior heads of the lateral pterygoid, anterior and posterior temporalis, masseter, and suprahyoid muscles. Subjects were trained to bite at maximum and half-maximum bite-force using an anterior jig incorporating a force transducer.


RESULTS
No consistent condylar displacement was observed in x, y and z axes between different bite-forces although there was a trend towards superior displacement. Comparison of maximum intercuspal clench and maximum clench on a leaf gauge and an anterior jig produced significant decrease in anterior temporalis activity (p < 0.05), whilst an anterior jig with maximum clench significantly decreased posterior temporalis muscle activity.


CONCLUSIONS
Within the limits of this pilot study, no consistent change in condylar position was identified with these appliances.
Santosa
R E
RE
Jaw Function and Orofacial Pain Research Unit, Faculty of Dentistry, The University of Sydney, Westmead Hospital Centre for Oral Health, Westmead, New South Wales.
Azizi
M
M
Whittle
T
T
Wanigaratrne
K
K
Klineberg
I J
IJ