Effect of Filler Distribution on Fracture Resistance of Modern Dental Composites
Abstract
Introduction: Failure of dental composite restorations is closely associated with the fracture processes of the filler-matrix systems. Objective: The purpose of this study is to investigate how various filler-matrix systems (i.e., hybrid, nanohybrid, and microfill) with different microstructural characteristics and filler distributions (i.e., unimodal, bimodal, and multimodal) can influence time-dependent fracture resistance of resin based composites. Materials and Methods: Twenty rectangular (2.75x5x25mm3), single-edge notch specimens (2.5mm notch depth) per composite (n=20) were made from a stainless steel mold with a razor blade insert. The samples were tested using a universal testing machine (Instron ElectroPuls E3000). Fracture toughness, KIC [MPa m0.5], values were calculated via measurements from the 3-point bending test (span = 20 mm, cross-head speed = 0.5 mm/min) applied on the single-edge notched-bend specimens. Composite microstructural features were analyzed by scanning electron microscopy and laser diffraction particle size analyzer. Filler content was measured by thermogravimetric analysis. All specimens were stored in 37 deg C distilled water for 24 hours prior to testing. Data were analyzed with ANOVA/Tukey (a=0.01) and regression. Results: Fracture toughness values were found rankings in descending order were:Nanohybrids > Hybrids > Microfills. Additionally, composites with multimodal distribution demonstrated significantly less fracture resistance than composites with either unimodal or bimodal distribution. Conclusion: Fracture toughness as a function of filler content increased with percent filler weight. In a similar behavior, fracture toughness as a function of filler size range the highest fracture resistance at 750nm. However, composites containing nano-fillers showed significantly higher fracture resistance than composites containing only micro-fillers.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 21, 2019
- Accession Number
- AD1128125
Entities
People
- Carolina Wentworth
Organizations
- Uniformed Services University of the Health Sciences