The Effect of Changing Vertical Dimension of Complete Denture Within its Normal Range on Sound Production With The Presence or Absence of Palatal Rugae.

Purpose: To investigate the effect of changing vertical dimension of complete denture within its normal range on phonation with the presence or absence of palatal rugae, using Computerized speech lab (CSL). Material and Methods: Ten completely edentulous patients (aged 50-60 years) were selected for reading some sentences. Each patient had two maxillary and two mandibular dentures with an adaptation period between each denture. The patients’ speech records were divided into four groups,Group I: Maxillary acrylic denture had polished anterior palatal surface without rugae reproduction and a free-way space of 2 mm.Group II: Maxillary acrylic denture with rugae reproduction on its polished surface and a free-way space of 2 mm.Group III: Maxillary acrylic denture had polished anterior palatal surface without rugae reproduction and a free-way space of 4 mm.Group IV: Maxillary acrylic denture with rugae reproduction on its polished surface and a free-way space of 4 mm, the samples selected were s/sh/t sounds   . Results: There is no significant difference was recorded in mean value of first formant frequency in dentures with and without Ruge using freeway of 4 and 2 mm for S and Sh sounds and in the voice onset time (VOT) of T sound. Conclusion: Any change in the normal cross section of the oral cavity by a removable prosthesis will affect the properties of normal human voice, so it is not recommended to construct thick areas in the anterior region of denture even if it contains palatal rugae so that it will not affect palatolingual sounds.