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The purpose of this experimental prospective study was to determine whether there is a possible influence of a reduced vertical dimension, as it is distinctive for wearers of a complete denture, on the center of gravity. 12 patients with an average age of 65,5 ± 17,5 years, who were edentulous at least in one jaw, took part in the study. The subjects received a new denture with a correct vertical dimension at least two weeks before the trial. Additionally the participants got a doubled prosthesis with a reduced vertical dimension of 7mm, measured at the front teeth, compared to their physiological height of bite. The perfect fit of the doubled denture was ensured by manual inspection and additional use of electromyography.
The posturographic examination of the center of gravity was carried out by using a plate of force (Zebris).
Five different randomized measurements were taken both habitual occlusion and resting position under EMG-control of the Mm. masseteres over a period of 15 seconds with and without vertical reduction. The trials were conducted with open and closed eyes. The measurement of the rest jaw relation acts as a reference level.
A general shift of the center of gravity resulting from a short and reversible reduction in the vertical dimension of wearers of a complete denture while clenching in maximal occlusion, could not be statistically proven. Yet, while eyes closed without visual balance control, a statistically significant change could be observed. This proves that a change in vertical dimension can lead to alterations even outside the stomatognathic system. Further no significant influence neither on the distance that the center of gravity uses during one measurement or on the size of the area it covers could be found. However single subjects show results that differ from those outcomes.
Effects do exist, but so slightly that they could just be observed with the used recording system while eyes closed without visual balance control.