Journal of Dental Research, Vol 80, 1555-1559, Copyright © 2001 by International & American Associations for Dental Research Online Journals

ARTICLES

Intrafibrillar mineral may be absent in dentinogenesis imperfecta type II (DI-II)

J. H. Kinney, J. A. Pople, C. H. Driessen, T. M. Breunig, G. W. Marshall and S. J. Marshall
Department of Preventive and Restorative Dental Sciences, University of California, San Francisco 94143-0758, USA. jkinney@itsa.ucsf.edu

High-resolution synchrotron radiation computed tomography (SRCT) and small-angle x-ray scattering (SAXS) were performed on normal and dentinogenesis imperfecta type II (DI-II) teeth. The SRCT showed that the mineral concentration was 33% lower on average in the DI-II dentin with respect to normal dentin. The SAXS spectra from normal dentin exhibited low-angle diffraction peaks at harmonics of 67.6 nm, consistent with nucleation and growth of the apatite phase within gaps in the collagen fibrils (intrafibrillar mineralization). In contrast, the low-angle peaks were almost non-existent in the DI-II dentin. Crystallite thickness was independent of location in both DI-II and normal dentin, although the crystallites were significantly thicker in DI-II dentin (6.8 nm [SD = 0.5] vs. 5.1 nm [SD = 0.6]). The shape factor of the crystallites, as determined by SAXS, showed a continuous progression in normal dentin from roughly one-dimensional (needle-like) near the pulp to two-dimensional (plate-like) near the dentin-enamel junction. The crystallites in DI-II dentin, on the other hand, remained needle-like throughout. The above observations are consistent with an absence of intrafibrillar mineral in DI-II dentin.

This article has been cited by other articles:

				J.H. Kinney, S. Habelitz, S.J. Marshall, and G.W. Marshall The Importance of Intrafibrillar Mineralization of Collagen on the Mechanical Properties of Dentin J. Dent. Res., December 1, 2003; 82(12): 957 - 961. [Abstract] [Full Text]