Investigation of the early mineralisation on collagen in dentine of rat incisors by quantitative electron spectroscopic diffraction (ESD).
The earliest crystallites in dentine appear as chains of "dots" in ultra-thin sections viewed by transmission electron microscopy. These dots rapidly coalesce along the longitudinal directions of the collagen microfibrils to form needle-like structures that coalesce preferentially in lateral directions to form ribbon-like or plate-like crystallites. This morphological interpretation is supported by line-scans of the corresponding zero-loss filtered electron spectroscopic diffraction patterns, which demonstrate the crystalline structure of the dentine mineral (apatite). The intensity ratio of the Debye-Scherrer rings of the characteristic Bragg-reflections (002 to 300, together with 1 or 2 unresolved reflections) shows a maximum in the region of early chain-like and needle-like crystallites, decreasing with maturation of the dentine mineral to the ribbon-plate-like crystallites. Detailed investigations using line-scans of the zero-loss filtered electron spectroscopic diffraction patterns through the dentine zone show that the intensity ratio found near the mineralisation front is repeated 3-5 times at distances of about 10-20 microns. This may represent a circadian pattern of mineralisation corresponding to light microscopically visible incremental lines in dentine.
Physikalisches Institut, Universität Münster, Germany.
U
U
Plate
S
S
Arnold
L
L
Reimer
H J
HJ
Höhling
A
A
Boyde
D000818:Animals; D002113:Calcification, Physiologic; D003094:Collagen / Q000737:chemistry*; D003460:Crystallization; D003804:Dentin / Q000737:chemistry* / Q000648:ultrastructure; D008854:Microscopy, Electron; D051381:Rats; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D013057:Spectrum Analysis
D003094:Collagen