Creep deformation of restorative resin-composites intended for bulk-fill placement

S. El-Safty, N. Silikas, D. C. Watts

    Research output: Contribution to journalArticlepeer-review


    Objectives: To determine the creep deformation of several "bulk-fill" resin-composite formulations in comparison with some other types. Methods: Six resin-composites; four bulk-fill and two conventional were investigated. Stainless steel split molds (4 mm × 6 mm) were used to prepare cylindrical specimens for creep testing. Specimens were thoroughly irradiated with 650 mW cm -2. A total of 10 specimens for each material were divided into two groups (n = 5) according to the storage condition; Group A stored dry at 37°C for 24 h and Group B stored in distilled water at 37°C in an incubator for 24 h. Each specimen was loaded (20 MPa) for 2 h and unloaded for 2 h. The strain deformation was recorded continuously for 4 h. Statistical analysis was performed using a two-way ANOVA followed by one-way ANOVA and the Bonferroni post hoc test at a significance level of a = 0.05. Results: The maximum creep strain % ranged from 0.72% up to 1.55% for Group A and the range for Group B increased from 0.79% up to 1.80% due to water sorption. Also, the permanent set ranged from 0.14% up to 0.47% for Group A and from 0.20% up to 0.59% for Group B. Dependent on the material and storage condition, the percentage of creep strain recovery ranged between 64% and 81%. Increased filler loading in the bulk-fill materials decreased the creep strain magnitude. Significance: Creep deformation of all studied resin-composites increased with wet storage. The "bulk-fill" composites exhibited an acceptable creep deformation and within the range exhibited by other resin-composites. © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.
    Original languageEnglish
    Pages (from-to)928-935
    Number of pages7
    JournalDental Materials
    Issue number8
    Publication statusPublished - Aug 2012


    • Bulk-fill
    • Resin-composites
    • Viscoelastic time-dependent creep
    • Water storage


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