Masticatory function in normal and crowded occlusion using Hellman's dental stages.
As a consequence of this study, the following conclusions were obtained by means of an estimate of the interocclusal point number of the integrated value of the electromyographs, of the masticatory rhythm with 40 subjects in each group (the normal groups: IIA 10. IIIA 10, IIIC 10, IVA 10; the crowding groups: IIA 10, IIIA 10, III C 10, IVA 10). 1. From the view of the integrated value of the electromyographs. In the normal groups with a normal occlusion. TA% to the total active potentials turned out to be less in proportion to the advancement of the dental stages, while TP% remained as the same. M% should an increase, whose ratio turned out to be high enough to take TA's place. 2. In the crowding groups, in spite of the indication of TA's decrease, M's increase, a comparison with the normal groups' that even after the stage IIIC TA-M-type masticatory pattern had to be maintained. 3. Regarding the interocclusal point number, in IIIC, IVA, the total amount and number at the molar segments indicated a significantly smaller value in the crowding groups. 4. Concerned with the integrated value of the masticatory muscle, the most related factor to yield the characteristic masticatory pattern observed in the crowding groups could be considered the number of the interocclusal points, which proved that great importance should be paid to the maintenance of the well harmonized status of the upper and lower occlusion.