Dynamic Study Of The Normal Occlusion From Muscular Position To Intercuspal Position

Objective To study the biting process from muscular position (MP) to intercus-pal position(ICP)dynamically in the normal occlusion subjects. Methods The biting process from MP to ICP with maximal bite force was record-ed by T-Scan II system for 123 healthy subjects with normal occlusions. The records were analyzed in behavior.Results The T-Scan system was proved to be a reliable method for the measure-ment of the center of force ( COF) and the bite force percentage and occlusal contact numbers in ICP(P>0.05). The COF and the difference value of the dual bite-force percentage in normal occlusions with maximal bite force were belong to normal dis-tribution. 95% normal range of the difference time between the dual first contact was 0- 0.2 second. 95% normal range of the difference time between the first con-tact and the multi-contacts was 0-0.2 second also. The contact points in MP appeared in ICP were found in 97.56% of subjects . Conclusion (1) T-Scan II system was showed acceptable reproducibility. The sensor can be repeated three times at least. (2) The standard of premature contact in MP is that the difference time between the first contact and the multi-contacts is more than 0.2 second,or the difference time between the dual first contact is more than 0.2 second,or the contact points in MP do not appear in ICP. (3) The standard of normal occlsion in ICP is that intercuspal occlusion in maximal bite force is stable , the COF and the dual bite-force percentage and the contact points are reproducibility, the COF in maximal bite force distribute in molars area and the range is 0.4±7.30 mm , the range of the dual bite force percentage is -1.7%±13.31%, and there is not any prema-ture contact in MP.