The pourpose of this study is to develop a more scientific system which can objectively catch the biophysical qualities of the tooth supporting structures, for the proper evaluation of the actual conditions of the structures.
The experimental tests have been started by bonding a force transducer and an accelerometer onto a maxillary central incisor. A certain amount of impact force has been applied by a spring-driven impactor to the force transducer to vibrate the tooth and its supporting structures, and then the force signal and the acceleration signal have been recorded simultaneously.
In the next experimental stage, a new analysis system has been developed and improved for easier application in the clinic, and put to the test on the subjects with teeth of different degree of clinical mobility.
The following results were obtained by this study:(1) The behavior of the impact force has been caught by the piezo-plastic-film force transducer.
(2) It has been found that the analysis of the vibration response obtained from the tooth and its supportingstructures under the impact force requires special consideration of the influence from the time duration of the impact force.
(3) There have been some differences in the results of the frequency analyses between the case where the whole acceleration response was taken as the object of the analysis and the case where only the free vibration was taken, in vivo.
(4) Both results obtained by the new analysis system and by the forced excitations (random excitation and swept-sine excitation) agree with each other.
(5) In the normal teeth tested, three peaks on the Fourier spectrum have been observed.
(6) It has been also observed that the peaks shown in the cases of the abnormal teeth move toward the lower area, compared with the cases of normal teeth.
From the above test results, it is obvious that the application of this new analysis system makes possible more objective evaluation of the tooth supporting structures.
