Variability of closest speaking space compared with interocclusal distance in dentulous subjects.

Variability of closest speaking space was compared with that of interocclusal distance in 30 dentulous subjects to the nearest 0.1 mm on the screen of a mandibular kinesiograph. Postural rest position was elicited by the subjects saying /M/ and relaxing the jaw. Closest speaking space was defined as the vertical difference in the position of the mandible from the immediate end of rapid counting from 60 to 66 to centric occlusion. The two variables were measured in random order 20 times each. The subjects were examined for two data collecting sessions. The variance of the closest speaking space was smaller than the variance for interocclusal distance for 26 of 30 subjects. The difference between the mean variances was statistically significant, p greater than 0.1 (t 3 and t 3.41, df 29).