Mechanical properties of bulk-fill versus nanohybrid composites: Effect of layer thickness and application protocols Propriedades mecânicas de compósitos de resina bulk versus nano-híbrida: Efeito da espessura da camada e protocolos de aplicação

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Cilingir A., Özsoy A., Mert-Eren M., Behram Ö., DİKMEN B., Özcan M.

Brazilian Dental Science, vol.22, no.2, pp.234-242, 2019 (Scopus) identifier

  • Publication Type: Article / Article
  • Volume: 22 Issue: 2
  • Publication Date: 2019
  • Doi Number: 10.14295/bds.2019.v22i2.1719
  • Journal Name: Brazilian Dental Science
  • Journal Indexes: Scopus
  • Page Numbers: pp.234-242
  • Keywords: Bulk-fill composites, Compressive strength, Flexural modulus, Flexural strength, Mechanical properties
  • Istanbul Medipol University Affiliated: Yes


Objective: The objective of this study was to evaluate the compressive strength, flexural strength and flexural modulus of high-viscosity, low-viscosity bulk-fill, and conventional nano-hybrid resin composite materials alone and when covered with nano-hybrid resin composite at different incremental thicknesses on the bulk-fill composites. Material and Methods: Specimens (N=60) were fabricated from the following materials or their combinations (n=10 per group): a) conventional nano-hybrid composite Z550 (FK), b) high-viscosity bulk-fill composite (Tetric N Ceram-TBF), c) low-viscosity bulk-fill composite SDR (SDR), d) Sonicfill (SF), e) SDR (2 mm)+FK (2 mm), f) SDR (4 mm)+FK (4 mm). After 24 h water storage, compressive strength was measured in a universal testing machine (1 mm/min). Additional specimens (N=40) (25x2x2 mm3) were made from FK, TBF, SDR and SF in order to determine the flexural strength and the flexural modulus, (n=10) and subjected to three-point bending test (0.5 mm/min). Data were analyzed using one-way ANOVA and Tamhane’s T2 post-hoc tests (p<0.05). Results: The mean compressive strength (MPa) of the nano-hybrid composite (FK) was significantly higher (223.8±41.3) than those of the other groups (123±27-170±24) (p<0.001). SDR (4 mm)+FK (2 mm) showed significantly higher compressive strength than when covered with 4 mm (143±30) or when used alone (146±11) (p<0.05). The mean flexural strength (159±31) and the flexural modulus of FK (34±7) was significantly higher than that of the high-or low-viscosity bulk-fill composites (p<0.001). The mean flexural strength of SF (132±20) was significantly higher compared to TBF (95±25) (p<0.05). Conclusion: Bulk-fill resin composites demonstrated poorer mechanical properties compared to nano-hybrid composite but similar to that of SF. Increasing the thickness of low-viscosity bulk-fill composite (SDR) from 2 to 4 mm underneath the nano-hybrid composite (FK) can improve the mechanical properties of the bulk-fill composites.