Reinforcement of flowable dental composites with titanium dioxide nanotubes

Manal O Dafar; Matthew W Grol; Peter B Canham; S Jeffrey Dixon; Amin S Rizkalla

doi:10.1016/j.dental.2016.03.022

Reinforcement of flowable dental composites with titanium dioxide nanotubes

Dent Mater. 2016 Jun;32(6):817-26. doi: 10.1016/j.dental.2016.03.022. Epub 2016 Apr 6.

Authors

Manal O Dafar¹, Matthew W Grol², Peter B Canham¹, S Jeffrey Dixon³, Amin S Rizkalla⁴

Affiliations

¹ Department of Medical Biophysics, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, Ontario, Canada.
² Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, Ontario, Canada.
³ Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, Ontario, Canada; Dentistry, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, Ontario, Canada; Bone and Joint Institute, The University of Western Ontario, London, Ontario, Canada.
⁴ Department of Medical Biophysics, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, Ontario, Canada; Dentistry, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, Ontario, Canada; Department of Chemical and Biochemical Engineering, Faculty of Engineering, The University of Western Ontario, London, Ontario, Canada; Bone and Joint Institute, The University of Western Ontario, London, Ontario, Canada. Electronic address: arizkalla@eng.uwo.ca.

PMID: 27059772
DOI: 10.1016/j.dental.2016.03.022

Abstract

Objectives: Flowable dental composites are used as restorative materials due to their excellent esthetics and rheology. However, they suffer from inferior mechanical properties compared to conventional composites. The aim of this study was to reinforce a flowable dental composite with TiO2 nanotubes (n-TiO2) and to assess the effect of n-TiO2 surface modifications on the mechanical properties of the reinforced composite.

Methods: n-TiO2 were synthesized using an alkaline hydrothermal process and then functionalized with silane or methacrylic acid (MA). Nanotubes were characterized by scanning and transmission electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy. Commercially available flowable composite (Filtek™ Supreme Ultra Flowable Restorative, 3M ESPE) was reinforced with varying amounts of nanotubes (0-5wt%). Flowability of the resulting composites was evaluated using a Gillmore needle method. Dynamic Young's modulus (E) was measured using an ultrasonic technique. Fracture toughness (KIc) was assessed using a notchless triangular prism and radiopacity was quantified. Viability of NIH/3T3 fibroblasts was evaluated following incubation on composite specimens for 24h.

Results: Electron microscopy revealed a tubular morphology of n-TiO2. All reinforced composites exhibited significantly greater values of E than unreinforced composite. Composites reinforced with 3wt% n-TiO2 functionalized with MA exhibited the greatest values of E and KIc. Cytotoxicity assays revealed that reinforced composites were biocompatible. Taken together, flowable composites reinforced with n-TiO2 exhibited mechanical properties superior to those of unreinforced composite, with minimal effects on flowability and radiopacity.

Significance: n-TiO2-reinforced flowable composites are promising materials for use in dental restorations.

Keywords: Cytotoxicity; Dynamic Young's modulus; Flowability; Flowable dental composites; Fracture toughness; Radiopacity; TiO(2) nanotubes.

MeSH terms

Composite Resins*
Dental Materials*
Materials Testing
Nanotubes*
Titanium*

Substances

Composite Resins
Dental Materials
titanium dioxide
Titanium

Grants and funding

102542/CIHR/Canada