Anteroposterior and mediolateral variability of the closest speaking space.

The variability of the closest speaking space (CSS) was compared to that of interocclusal distance (IOD) in the anteroposterior and mediolateral planes. Data were obtained from 30 dentulous subjects during two recording sessions using a mandibular kinesiograph set to display the frontal and sagittal planes. The two variables were measured in random order 20 times each. Mean variances were compared using a paired t test. The difference between the mean variances was statistically significant (P less than 0.05), with a greater value for CSS, only on the mediolateral projection. The small numerical value of this difference, however, makes any inference of clinical signifiance questionable.