Nanostructural characterization of a dental filling for wide color matching

Objective: The aim of this thesis was to inspect the chameleon effect of a resin-based dental composite material for wide color matching. Therefore, the nanostructures of the ceramic fillers were investigated using non-destructive methods. Additionally, the color adjustment performance of the composite material was instrumentally evaluated on extracted human teeth restorations.
Material and Methods: In order to resolve the nanostructures, thin OMNICHROMA (OC) samples (diameter _ 100 `<) were investigated by nanotomography (beamline ANATOMIX, SOLEIL) and small-angle X-ray scattering (SAXS; beamline cSAXS, swiss light source PSI). Additional SAXS, SEM, EDX and transmission measurements were performed. Furthermore, the color adjustment performance of OC in extracted human teeth restorations were instrumentally observed by the spectrophotometer Vita EasyshaderV.
Results: The nanostructures were resolved by nanotomography, SAXS and EM using a 100 `m thin sample. The filler diameter measured on 2D EM image was 250 _ 50 nm. The one calculated by SAXS fit were 260.2 nm and 232 nm for the form and structure factor, respectively. Additionally to the single fillers, micro-domains were found.The main composition of the sample was C, O, Si, Zr. The cSAXS and lab-SAXS data were complementary and correlated to the nanotomography results. The transmissionmeasurement showed a peak at 263 nm and a rising transmission from 88 T% to 90 T% in the Vis region. Overall, the color adjustment performance of OC was clinically acceptable.
Significance: In order to minimize chair-time, reduce costs and improve aesthetics, it is important to understand the wide color matching principle and the underlying chameleon effect.