Abstract
Nanotechnology can improve the performance of dental polymers. The objective of this study was to modify the surfaces of nanoparticles with silanes and proteins, characterize nanoparticles’ agglomeration levels and interfaces between nanoparticles and the polymeric matrix. Undoped (n-TiO2), nitrogen-doped (N_TiO2) and nitrogen-fluorine co-doped titanium dioxide nanoparticles (NF_TiO2) were synthesized and subjected to surface modification procedures in preparation for Small-Angle X-Ray Scattering (SAXS) and Small-Angle Neutron Scattering (SANS) characterizations. Experimental adhesives were manually synthesized by incorporating 20% (v/v) of n-TiO2, N_TiO2 or NF_TiO2 (as-synthesized or surface-modified) into OptiBond Solo Plus (OPTB). Specimens (n = 15/group; d = 6.0 mm, t = 0.5 mm) of OPTB and experimental adhesives were characterized using Time-of-Flight Secondary Ion Mass Spectroscopy (ToF-SIMS), 2-D ToF-SIMS chemical imaging and SANS. SAXS results indicated that surface-modified nanoparticles displayed higher scattering intensities in a particle-size dependent manner. ToF-SIMS results demonstrated that nanoparticles’ incorporation did not adversely impact the parental polymer. 2-D ToF-SIMS chemical imaging demonstrated the distribution of Ti+ and confirmed nitrogen-doping levels. SANS results confirmed nanoparticles’ functionalization and revealed the interfaces between nanoparticles and the polymer matrix. Metaloxide nanoparticles were successfully fabricated, incorporated and covalently functionalized in a commercial dental adhesive resin, thereby supporting the utilization of nanotechnology in dentistry.
Highlights
Nanotechnology can improve the performance of dental polymers
The findings reported are in agreement with the results from the Small-Angle X-Ray Scattering (SAXS) experiment, and have indicated that surface-modification strategies used in the present study were successful in grafting APTES and Alb onto the surfaces of metaloxide nanoparticles
The present study has successfully demonstrated the synthesis (n-TiO2), doping (N_TiO2 or NF_TiO2) and surface modification (Dn-TiO2, DN_TiO2, DNF_TiO2) of titanium dioxide nanoparticles, as well as, their incorporation into a commercially available dental adhesive resin (OPTB)
Summary
Nanotechnology can improve the performance of dental polymers. The objective of this study was to modify the surfaces of nanoparticles with silanes and proteins, characterize nanoparticles’ agglomeration levels and interfaces between nanoparticles and the polymeric matrix. The reduced longevity observed has been attributed to a combination of factors including polymerization shrinkage, incomplete enveloping of the dentin matrix and biodegradation This problem is exacerbated on resin composites and dental adhesive resins, because these materials were demonstrated to upregulate the aggregation and growth of oral microorganisms, and biofilms accumulated, are typically more cariogenic in nature[3]. Approaches to improve the antibacterial functionalities of dental polymers include the utilization of functionalized quaternary ammonium polyethyleneimine nanoparticles (QPEI)[14] Even though such approach was demonstrated to result in promising initial antibacterial properties against Streptococcus mutans, the excess iodine attached to these highly cross-linked silica-based nanoparticles, was shown to adversely impact free-radical polymerization reactions, which inevitably led to experimental materials with low degree of polymerization, reduced mechanical properties and leaching of uncured monomers[15]. Nanofillers’ dissolution within the hybrid layer was shown to result in the formation of water channels, higher water uptake, leaching of unbound hydrophilic components, and to further accelerate hybrid layer’s hydrolytic degradation[16]
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