Cineradiography in odontology.

Using cineradiographic equipment with 35 mm film, the application of cineradiographic technique in odontology has been investigated with special reference to observation of bolus-position, the mandibular movement pattern, chewing velocity and the stability of full dentures. The study is divided in two parts. In the first part an assessment is made of the theoretical and practical error of the method and the radiation dose is determined. In the second part limited studies are performed on test-subjects before and after different types of oral rehabilitation. The mathematically estimated geometrical errors almost coincided with the results of the clinical test of the distortion and, together with the tracing error, were of such magnitude that high precision measurements were not possible. By using metal indicators the error could be reduced and movements or differences in the X-ray film greater than 1 mm could be observed with good accuracy. The absorbed dose was determined using the method of thermoluminescent dosimetry and was found to be approximately 5 rad for a cineradiographic investigation of the cranium. The studies of bolus position, mandibular movements etc. revealed, that after oral rehabilitation the patient's oral behaviour may change dramatically. New occlusal surfaces were in most cases used for mastication after a short period of adaptation after rehabilitation. The mandibular movement pattern was also markedly influenced. It is concluded that cineradiography is very suitable for observations of intra-oral behaviour, such as bolus position, and for functional movement analyses. For high-precision measurements other methods should be used.