Short CommunicationNanostructure of healthy and caries-affected human teeth
Graphical Abstract
The scattering pattern related to the 67-nm signal shows abundance, degree of anisotropy, and orientation of the nanostructures between 57 and 69 nm according to the color wheel. Comparing the spatially resolved collagen-related signal with the total scattering signal of the early stages of caries in human dentin, the authors find that the ceramic parts are affected, but the collagen is unchanged, which may have an important impact on the development of future dental treatments of carious teeth.
Section snippets
Methods
Eight teeth, five carious and three healthy, were extracted for clinical reasons and cut into 200- to 500-μm-thin slices parallel to the tooth's long axis with a diamond band saw (Exakt Apparatebau GmbH, Norderstedt, Germany). The slices of the teeth were stored in phosphate-buffered saline (PBS). Only one slice from the healthy teeth was stored in air.
Synchrotron radiation-based micro computed tomography (SRμCT) measurements were performed at the beamline W 2 (HASYLAB at DESY, Hamburg,
Results
The organic ingredients of dentin contain mainly collagen-I fibrils. The building blocks of collagen arrange themselves along the collagen fibril with a main periodicity of 67 nm, as determined, for example, by means of atomic force microscopy and SAXS.17, 18
Figure 1 shows, in the top row, a typical scattering pattern from healthy dentin and the corresponding radial-integrated intensity (q-plot). A distinct peak, associated with collagen-I, is found at the q-values between 0.091 and 0.111 nm-1,
Discussion
The scanning SAXS images of human teeth show similarities to polarization microscopy pictures obtained from tooth slices many decades ago.23 The preparation of the tooth slices for polarization microscopy, however, is much more laborious. The slices have to be thin enough for the optical transmission and their surfaces have to be well prepared to avoid artifacts. Because the photon energy can be adapted to the slice thickness in scanning SAXS, much thicker tooth slices can be investigated,
Acknowledgments
The technical support of F. Schmidli (Basel) for the tooth preparation and of Xavier Donath during SAXS measurements is gratefully acknowledged. Extracted teeth were kindly provided by Dr. Marlen Luckow, Dr. Gabriel Krastl and Prof. Dr. Nicola Zitzmann. The SAXS experiments were performed on the cSAXS beamline at the Swiss Light Source, Paul Scherrer Institut, Villigen, Switzerland.
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No comflict of interest is reported by the authors