Effect of Investing Materials on Changes in Occlusal Vertical Dimension of Complete Dentures: A Comparative Experimental Study from Jamshoro, Pakistan

Objective: The purpose of this study is to compare changes in occlusal vertical dimension when dental plaster versus dental stone is used as the investing material.Study Design: Comparative experimental study.Place and Duration of Study: This study was conducted at the Department of Prosthodontics, Liaquat University of Medical and Health Sciences, Jamshoro, Pakistan, from December 2024 to May 2025.Methods: An edentulous silicone mould was used to fabricate sixty identical sets of maxillary and mandibular stone casts. Pre-polymerisation occlusal vertical dimension (OVD) was recorded at the wax denture stage, and post-polymerisation OVD was measured after denture deflasking using a digital caliper. The difference between the two measurements represented the change in occlusal vertical dimension. Prior to the main study, a pilot study was conducted to estimate the sample size. The mean change in occlusal vertical dimension for Type III dental stone was 1.098 ± 0.107 mm, while the mean change for the comparison group was 0.602 ± 0.033 mm. The dentures were then divided into two groups based on the investing medium: Dental Stone Type II and Dental Stone Type III. Data were analysed using SPSS version 22. The Mann–Whitney U test was applied, and P ≤ 0.05 was considered statistically significant.Results: Median occlusal vertical dimension was 1.115 mm (interquartile range = 0.14) in the hard plaster group and 0.605 mm (interquartile range = 0.04) in the soft plaster group. A statistically significant difference was observed (U = 900, P = 0.005), with greater dimensional changes in the hard plaster group (effect size r = 0.859).Conclusion: The investing medium significantly affects changes in the occlusal vertical dimension of complete dentures. Using high-expansion dental stone type III investment material may increase occlusal vertical dimension discrepancies during denture fabrication in comparison with dental stone type II investment material. How to cite this: Memon S, Sajji A, Kumari P, Memon N, Memon H, Butt AM, Memon MR. Effect of Investing Materials on Changes inOcclusal Vertical Dimension of Complete Dentures: A Comparative Experimental Study from Jamshoro, Pakistan. Life and Science. 2026;7(1): 112-117. doi: http://doi.org/10.37185/LnS.1.1.991