Improving dimensional stability of irreversible hydrocolloid by condensation silicone incorporation

Background: Irreversible hydrocolloid (alginate) is widely used for dental impressions, but its poor dimensional stability over time limits accuracy when delays in pouring occur. Enhancing its stability through material modification, such as incorporating condensation silicone, may improve clinical outcomes. Material and methods: Three groups (n = 10) were evaluated: Group I (conventional alginate, Avagel), Group II (extended-pour alginate, Hydrogum 5), and Group III (alginate modified with condensation silicone). Specimens were fabricated using standardized molds and stored under controlled humidity. Dimensional stability was assessed at five time points (immediate, 24, 48, 72, and 120 h) by measuring mass and linear dimensions. Data were analyzed using ANOVA and Bonferroni tests (p < 0.05), with effect size (η^2p) and 95% confidence intervals reported. Results: The experimental group demonstrated more consistent dimensional behavior over time, with reduced variability and more controlled effect sizes compared with conventional materials. Significant differences were observed at later time points, particularly at 72 h (p < 0.05), where the modified material showed smaller dimensional changes. The incorporation of condensation silicone resulted in improved stability, as evidenced by more controlled dimensional variation. Conclusions: The addition of condensation silicone to an irreversible hydrocolloid significantly improved its dimensional stability, suggesting a promising approach to enhance clinical performance, especially when immediate pouring is not feasible.