Recently, we have shown that, in rodent incisors, the crown- and root-analogue dentin (enamel- and cementum-related dentin) show differences in mineralization rates (Beertsen and Niehof, 1986) and composition of the organic matrices (Steinfort et al. , 1989). It was the aim of the present study to determine whether these differences were accompanied by differences in the inorganic components.
Rat incisors were analyzed by means of hardness measurements, microradiography, and the determination of Ca, Mg, and PO4 content. The outer circumpulpal dentin layer of the enamel-related dentin (ERD) was considerably harder and denser than the comparable layer of the cementum-related dentin (CRD). Concomitantly, a higher Ca and P04 content was found for the ERD than for the CRD, while the reverse occurred with respect to Mg. From the apical end of the incisor toward the incisal edge, the Ca/PO4 ratio tended to decrease for both ERD and CRD, while the Mg/PO4 ratio increased. All differences appeared to be statistically significant.
It is concluded that differences in the non-collagenous organic matrix were accompanied by differences in the inorganic components. More specifically, a relatively high content of highly phosphorylated phosphoproteins (ERD) was associated with a higher Ca and a lower Mg content.
Get full access to this article
View all access options for this article.
References
1.
Addadi, L. and Weiner, S. (1985): Interactions between Acidic Proteins and Crystals: Stereochemical Requirements in Biomineralization, Proc Natl Acad Sci USA82:4110-4114.
2.
Angmar, B.; Carlstrom, D.; and Glas, J.E. (1963): The Mineralisation of Normal Human Enamel, J Ultrastruct Res8 :12-23.
3.
Beertsen, W. and Niehof, A. (1986): Root-Analogue versus Crown Analogue Dentin: a Radioautographic and Ultrastructural Investigation of the Mouse Incisor, Anat Rec215:106-118.
4.
Bishop, M.A. and Boyde, A. (1986): Distribution of Capillaries in Relation to the Life Cycle of Odontoblasts in the Rat Incisor. The Fate of the Pulp at the Incisal End, Anat Embryol175 :189-198.
5.
Boskey, A.L. (1989): Noncollagenous Matrix Proteins and their Role in Mineralization, Bone Miner6:111-123.
6.
Driessens, F.C.M. and Verbeeck, R.M.H. (1985): Dolomite as a Possible Magnesium-containing Phase in Human Tooth Enamel, Calcif Tissue Int37:376-380.
7.
Engel, M.B. and Hilding, O.H. (1984): Mineralization of Developing Teeth, Scan Electr MicroscIV:1833-1845.
8.
Featherstone, J.D.B.; Mayer, I.; Driessens, F.C.M.; Verbeeck, R.M.H.; and Heijligers, H.J.M. (1983): Synthetic Apatites Containing Na, Mg, and C03 and their Comparison with Tooth Enamel Mineral, Calcif Tissue Int35:169-171.
9.
Forssell-Ahlberg, K.; Brannstrom, M.; and Edwall, L. (1975): The Diameter and Number of Dentinal Tubules in Rat, Cat, Dog and Monkey, Acta Odontol Scand33:243-250.
10.
Fujisawa, R.; Kuboki, Y.; and Sasaki, S. (1987): Effects of Dentin Phosphophoryn on Precipitation of Calcium Phosphate in Gel in vitro, Calcif Tissue Int41:44-47.
11.
Glick, P.L. (1981): Identification of Mineral Fractions in Developing Rat Incisors. In: The Chemistry and Biology of Mineralized Connective Tissues, A. Veis, Ed., New York: Elsevier North Holland, pp. 309-311.
12.
Guis, M.B.; Slootweg, R.N.; and Tonino, G.J.M. (1973): A Biochemical Study of Collagen in the Periodontal Ligament of Erupting and Non-erupting Bovine Incisors, Arch Oral Biol18 :253-263.
13.
Johnson, A.R. (1972): Strontium, Calcium, Magnesium and Phosphorus Content of Rat Incisor as Determined by Electron Microprobe Analysis, J Dent Res51:115-121.
14.
Kirkpatrick, D.S. and Bishop, S.H. (1971): Simplified Wet Ash Procedure for Total Phosphorus Analysis of Organic Phosphates in Biological Samples, Anal Chem43:1707-1709.
15.
Linde, A. (1985): Non-Collagenous Proteins and Proteoglycans in Dentinogenesis. In: Dentin and Dentinogenesis, Vol. II, A. Linde, Ed., Boca Raton, FL: CRC Press, pp. 55-92.
16.
Lussi, A.; Crenshaw, M.A.; and Linde, A. (1988): Induction and Inhibition of Hydroxyapatite Formation by Rat Dentine Phosphoprotein in vitro, Arch Oral Biol33:685-691.
17.
Marsh, M.E. (1989): Self-Association of Calcium and Magnesium Complexes of Dentin Phosphophoryn, Biochem28:339-345.
18.
Marsh, M.E. and Sass, R.L. (1984): Phosphoprotein Particles: Calcium and Inorganic Phosphate Binding Structures, Biochem23:1448-1456.
19.
Mishima, H. and Sakae, T. (1986): Demonstration of Structural Variation in Rat Incisor Dentin as Determined by the X-ray Laue Method, J Dent Res65:932-934.
20.
Mishima, H.; Sakae, T.; Kozowa, Y.; and Hirai, G. (1988): Structural Variation in Labial Dentin and Lingual Dentin in the Rat Incisor, J Nihon Univ Sch Dent30:1-10.
21.
Moe, H.; Thorball, N.; and Nielsen, H.W. (1979): Structural Alterations in Proliferating, Remodeling and Regressing Tooth Pulp Arterioles, Cell Tissue Res203:339-354.
22.
Munhoz, C.O.G. and Leblond, C.P. (1974): Deposition of Calcium Phosphate into Dentin and Enamel as shown by Radioautography of Sections of Incisor Teeth following Injection of 45Ca into Rats, Calcif Tissue Res15:221-235.
23.
Okazaki, M.; Takahashi, J.; and Kimura, H. (1986): Unstable Behavior of Magnesium-containing Hydroxyapatites , Caries Res20:324-331.
24.
Rasmussen, P. (1972): Effect of Extreme Calcium Deprivation on Degree of Mineralization of Alveolar Bone, Dentin and Enamel in Rats, Scand J Dent Res80:327-333.
25.
Shaw, J.H. and Yen, P.K.J. (1972): Sodium, Potassium and Magnesium Concentrations in the Enamel and Dentin of Human and Rhesus Monkey Teeth, J Dent Res51:95-101.
26.
Steinfort, J.; Van Den Bos, T.; and Beertsen, W. (1989): Differences between Enamel- and Cementum-related Dentin in the Rat Incisor with Special Emphasis to the Phosphoproteins, J Biol Chem264:2840-2845.
27.
Termine, J.D. and Conn, K.M. (1976): Inhibition of Apatite Formation by Phosphorylated Metabolites and Macromolecules, Calcif Tissue Res22: 149-157.
28.
Termine, J.D.; Eanes, E.D.; and Conn, K.M. (1980): Phosphoprotein Modulation of Apatite Crystallization , Calcif Tissue Int31:247-251.
29.
Terpstra, R.A. and Driessens, F.C.M. (1986): Magnesium in Tooth Enamel and Synthetic Apatites, Calcif Tissue Int39 :348-354.
30.
Udich, H.J.; Hoft, H.D.; and Bornig, H. (1986): Effect of Phosphoprotein on Precipitation and Crystallization of Calcium Phosphate Salts. An in vitro Study using an Agar Gel Matrix Model, Biomed Biochim Acta45:703-711.
31.
Veis, A. (1985): Phosphoproteins of Dentin and Bone. Do They have a Role in Matrix Mineralization? In: The Chemistry and Biology of Mineralized Connective Tissues, W.T. Butler, Ed., Birmingham, AL: Ebsco Media, pp. 170-176.
32.
Weinreb, M.; Steigman, S.; Zajicek, G.; and Michaeli, Y. (1985): Odontoblast Turnover in the Impeded and Unimpeded Rat Incisor Derived from Computerized Histomorphometry, Anat Rec211:218-225.
33.
Zanetti, M.; DE Bernard, B.; Jontell, M.; and Linde, A. (1981): Ca2+-Binding Structures of the Phosphoprotein from Rat-Incisor Dentine, Eur J Biochem113:541-545.
