Lipids in Predentine and Dentine

Abstract

Using two histochemical methods, malachite green-aldehyde and iodoplatinate, phospholipids were visualized in the predentine of rat incisors in the spaces located between collagen fibers and in dentine as needle-like structures located along individual or groups of mineralizing collagen fibers. The same staining pattern was seen with phospholipase A2-gold. Autoradiographic investigation using 3H choline as labelled precursor, visualized the incorporation of membrane-associated and extracellular choline-containing phosphatidyl choline and sphingomyelin. The cell and membrane-associated labelling decreased gradually between 24 and 4 days, whereas incorporation of the labelled precursor as stable extracellular matrix component was seen in dentine. In addition to these investigations, pharmacologically induced (suramine) and genetically (Krabbe's disease) lysosomal storage pathology was investigated. Defects due to lipid metabolism alterations were seen in predentine and/or in dentine. The major differences visualized here between the non-mineralized and mineralized compartments and interactions between phospholipids and proteoglycans, support the view that phospholipids as matrix components play an important role in the mechanisms of dentine formation and mineralization.

Leukodystrophy associated with oligodontia in a large inbred family: Fortuitous association or new entity?

“…The possibility of segregation of two independent but very closely linked genes because of the high degree of consanguinity in this family, with either two independent mutations, or a deletion of two contiguous genes was possible. Nevertheless, although it is still difficult to understand the relationship between white matter degeneration and abnormal development of teeth, alterations in predentine and/or in dentine in patients with lysosomal storage pathology [Bloch‐Zupan et al, 1994; Goldberg et al, 1995], and accumulation of lysosome structures in secretory ameloblasts and odontoblasts of animals in which mucopolysaccharidosis‐like disease was induced have already been reported [Goldberg et al, 1993; Gritli‐Linde et al, 1995]. Thus, in the present family, a disturbance in the synthesis or catabolism of myelin or a synthesis of an abnormal proteolipid protein leading to the accumulation of this substance in the tooth germs may have altered the normal formation of the teeth.…”

Biological Calcification

“…Using electron microscopy and malachite green-glutaraldehyde fixation (Goldberg and Septier 1985), rapid-freezing and malachite green-acroleinosmium tetroxide freeze-substitution fixation (Goldberg and Escaig 1987), osmium fixation-p-phenylenediamine staining (Goldberg et al 1985), iodoplatinate (Vermelin et al 1994), or imidazole-osmium tetroxide fixation (Goldberg and Septier 2002), phospholipids have been demonstrated in interfibrillar spaces in predentin and as needle-like structures along the collagen fibrils and at the surface of calcified areas in dentin (Goldberg et al 1995b). They appear to be combined with filamentous proteoglycan structures (Chardin et al 1990).…”

Influence of specimen preparation on the identification of phospholipids by the phospholipase A2-gold method in mineralizing cartilage and bone

“…Moreover, dentine, and mainly its mineralization front, appears to be more rich in phospholipids with respect to predentine (Goldberg et al 1995). Therefore, it can be hypothesized that phospholipids may provide an anhydrous environment where the precipitation of mineral ions and the formation and growth of crystals are favored (Goldberg et al 1995).…”

“…The loss of lipids during specimen preparation, in particular during dehydration and Epon polymerization (Carlier 1976), has been only prevented by albumin embedding (Maraldi et al 1985) and by cryo-ultramicrotomy (Boyenval and Droz 1976). The possibility of identifying phospholipids by autoradiography in the matrix of calcifying tissues has been only partly fulfilled (Dircksen et al 1970;Eisenberg et al 1970;Wuthier et al 1977;Goldberg and Escaig 1984;Goldberg et al 1994). …”