Comparison of Dimensional Stability of Casts Obtained from Elastomeric Impression Materials with Different Impression Techniques at Different Time Intervals of Cast Pouring after Subjecting them to Disinfection Protocols: An In-vitro Study

Introduction: The success of fixed prosthodontic treatment depends on many steps among which impression making is critical step. During impression making, the impression material is exposed to infected blood and saliva which is the potential source for cross contamination especially to clinicians and laboratory workers. When an impression is subjected to disinfection there may be change in dimensional accuracy which results in faulty prosthesis. Aim: To evaluate the dimensional stability of two elastomeric impression materials namely Vinyl Poly Siloxane (VPS) and Vinyl Poly Ether Siloxane (VPES) after subjecting them to chemical disinfection and making models through multiple pours at varying time intervals. Materials and Methods: The present in-vitro study was conducted in KIMS Dental College and St. Joseph Dental College, Andhra Pradesh, India, over a period of 5 months from August 2023 to December 2023. A total of 480 samples were prepared by pouring the casts with VPS and VPES materials using one stage and two stage impression techniques and then the impressions were subjected to korsolex and surfasept disinfectants. After disinfection the casts were poured at time interval of one hour, 24 hours, one and two weeks. Stereomicroscope was used to measure the diameter and height of die and digital calipers were employed to measure the inter distance between the dies. Four-way factorial Analysis of Variance (ANOVA) and pair wise comparisons were done using Least Significant Difference (LSD) Bonferroni test to analyse the data. The level of significance was set at p<0.05. Results: Significant differences were noticed (p=0.001) between VPS (7.99±0.05), and VPES (7.95±0.11) where the mean die height was significantly lower in VPS and VPES. Method of disinfection yielded an F ratio of 8.019 (p=0.001), indicating a significant difference between three disinfection protocols. The mean die diameter was significantly lower after Korsolex disinfection. Conclusion: Disinfection of VPES with korsolex, showed decrease in mean die height when the impressions are made with two step impression technique at two week time interval. When VPS was disinfected with surfasept, the mean values of die diameter are decreased for casts poured at one week time interval.