Fabrication and evaluation of Bis-GMA/TEGDMA dental resins/composites containing halloysite nanotubes.
OBJECTIVE
To investigate the reinforcement of Bis-GMA/TEGDMA dental resins (without conventional glass filler) and the corresponding composites (with conventional glass filler) containing varied mass fractions of halloysite nanotubes (HNTs).


METHODS
Three dispersion methods were studied to separate the silanized halloysite as individual HNTs and to uniformly distribute them into dental matrices. Photopolymerization induced volumetric shrinkage was measured by using a mercury dilatometer. Real time near infrared spectroscopy was adopted to study the degree of vinyl double bond conversion and the photopolymerization rate. Mechanical properties of the composites were tested by a universal mechanical testing machine. Analysis of variance (ANOVA) was used for the statistical analysis of the acquired data. Morphologies of halloysite/HNTs and representative fracture surfaces of the reinforced dental resins/composites were examined by SEM and TEM.


RESULTS
Impregnation of small mass fractions (e.g., 1% and 2.5%) of the silanized HNTs in Bis-GMA/TEGDMA dental resins/composites improved mechanical properties significantly; however; large mass fractions (e.g., 5%) of impregnation did not further improve the mechanical properties. The impregnation of HNTs into dental resins/composites could result in two opposite effects: the reinforcing effect due to the highly separated and uniformly distributed HNTs, and the weakening effect due to the formation of HNT agglomerates/particles.


CONCLUSIONS
Uniform distribution of a small amount of well-separated silanized HNTs into Bis-GMA/TEGDMA dental resins/composites could result in substantial improvements on mechanical properties.
Department of Chemistry, South Dakota School of Mines and Technology, Rapid City, SD 57701-3995, USA.
Qi
Q
Chen
Yong
Y
Zhao
Weidong
W
Wu
Tao
T
Xu
Hao
H
Fong
D000538:Aluminum Silicates / Q000737:chemistry*; D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry*; D003188:Composite Resins / Q000138:chemical synthesis*; D005898:Glass / Q000737:chemistry*; D006244:Hardness; D055115:Light-Curing of Dental Adhesives; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D043942:Nanotubes / Q000737:chemistry*; D058105:Polymerization; D011109:Polymethacrylic Acids / Q000737:chemistry*; D019265:Spectroscopy, Near-Infrared
D000538:Aluminum Silicates; D003188:Composite Resins; D011109:Polymethacrylic Acids; D017438:Bisphenol A-Glycidyl Methacrylate