Background & Aim: There are several methods for determination of occlusal vertical dimension. The vertical dimension of rest position, interocclusal distance and closest speaking space are two important methods. The purpose of this study was comparison the variability of interocclusal distance and closest speaking space in denture wearers.
Method &Materials: The subjects were 34 edentulous patients (18 males & 16 females with mean age of 56) who had received complete dentures in the prosthodontics department of Isfahan dental school. They had good residual ridges. The dentures had correct clinical vertical dimension with 1-2mm overjet and 0.5 -1mm overbite. There was no evidence of neuromuscular and TMJ problems. The TOM guage was used for measuring the vertical dimension of rest position and «S» position.
Results: The results showed that the mean and standard deviation of interocclusal distance were smaller than closest speaking space. Paired T-test and Levene's test were used for statistical analysis. There was a statistically difference between interocclusal distance and closest speaking space, so the interocclusal distance was less variable than closest speaking space (P<0.05).
Conclusion: The closest speaking space during S position is affected by the occlusion, vertical and horizontal overlap of anterior teeth. These factors are up to dentist's judgement in complete denture and can influence the variability of vertical dimension of S position. Because of this variability it is recommended to use several methods for determining of vertical dimension.