Improved lipid preservation by malachite green-glutaraldehyde fixation in rat incisor predentine and dentine.

A network of granules and filaments stained with malachite green-aldehyde (MGA) was observed in predentine in the spaces between the collagen fibres and many small granules were associated with these fibres in peripheral and circumpulpal-dentine. The granules were present throughout the entire thickness of the dentine, especially at the periphery of the calcospherites, although scarce or absent at their centre. This MGA-stainable material (i) resisted demineralization in acetic acid and EDTA solutions, and (ii) differed from non-collagenous material and crystal ghosts which stained on control sections after prior demineralization. In predentine, transport and diffusion of MGA-stainable material occurred in the direction of the dentine in which this material was associated with periodical striation of mineralized collagen fibres. This suggests that true matrix-associated lipids might play a role in dentine mineralization.