Comparative Evaluation of Water Absorption, Solubility, Degree of Conversion, and Color Stability in Ormocer-Based and Flowable Bulk-Fill Composites

Objective: This study aimed to evaluate the water absorption, solubility, degree of conversion, and color stability of flowable bulk-fill composites and ormocer-based resin. Materials and Methods: Five flowable bulk-fill composites (SDR, Beautifil Bulk, Omnichroma Flow Bulk, Venus Bulk Fill, Charisma Bulk Flow One) and two composites (Filtek Z250, Admira Fusion 5) were tested (n=40). Color and mass measurements were taken initially, after 24 hours, and after 28 days. Statistical analyses were performed using IBM SPSS V23 and the R program with the WRS2 package. Non-normally distributed data were analyzed using the Kruskal-Wallis H test and Dunn test for post-hoc comparisons, while robust ANOVA with Bonferroni correction was used for group and time comparisons. The significance level was set at p < 0.050. Results: Charisma Bulk Flow had the highest solubility, Admira Fusion 5 the lowest (p=0.02). Degree of conversion and color stability showed significant differences (p<0.001). Conclusion: The tested composite materials showed significant differences in water absorption, solubility, degree of conversion, and color stability, influenced by their monomer composition and filler content. Admira Fusion 5 exhibited the lowest water absorption and solubility alongside the highest degree of conversion, indicating its potential for superior clinical performance. In contrast, SDR and Venus Bulk Fill demonstrated the highest color changes over time, underscoring the importance of material selection for aesthetic restorations. These findings highlight the critical role of material composition in determining the physical and optical properties of dental composites.