Structural and Chemical Organization of Teeth, Volume 2
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Twenty-two chapters by specialists present "an overall view of the teeth in vertebrates as a whole" with the intention of emphasizing the dynamic aspects of structures wherever possible. All levels of organization from light microscope resolution down to the molecular are used to elucidate the structural and chemical characteristics of the normal states of dentition and tooth tissues. The first six chapters are introductory, providing zoological background for the remaining sections on structural organization of the tooth during development, the microanatomy of tooth tissues, physsical and chemical organization of the tooth and physiology of dental supporting tissues.
Chapters on the phylogeny of calcified tissues in Early and Recent vertebrates are presented provocatively preceding chapters on tooth morphogenesis, definition of the vascular supply, and innervation of dental tissues. Amelogenesis, dentinogenesis, and the maturation of enamel are exhaustively discussed with liberal use of electron micrographs and X-ray microradiographs. Details of chemistry and ultrascructure of the mineral phase and organic constituents of dentine, enamel, and connective tissue components of the periodontum are presented. The physiology of the dentino-gingival junction is outlined.
These volumes are encyclopædic of the normal processes and structure of teeth.
. Osteodentine , Distribution and Structure 5 III . Vasodentine , Distribution and Structure 7 IV . Plicidentine, Distribution and Structure 8 V. Orthodentine 9 VI . Nonmammalian Orthodentine 10 VII . Mammalian Orthodentine A . Primary Curvatures B. Secondar y Curvatures C. Controversy on Structure of the Dentine D. Present Concept E. The Submicroscopi c Structure of Dentine F. Changes in Dentine G. Species Differences 12 13 14 14 17 24 26 30 VIII . Summary 31 Reference s 32 I.
INTRODUCTION. CLASSIFICATION OF DENTINES A study of published work would suggest a general definition of dentine as a tissue which is situated superficially in the body and forms the basis of the teeth of vertebrates and of the exoskeletons of the elasmobranch s and some primitive agnathans . It is of mesoderma l origin, develops in a centripetal direction from a dermal papilla or dental pulp and in the mature state is usually mineralized (see Volume I, Chapters 2 and 3). Such a definition,
presents a uniform appearanc e due to the similar refractive index of the parts. In polarized light also such sections are uniform in appearance . The outer layer is composed of dentine of the mantle type and is the concern of Chapter 3 (Volume I). The canals in osteodentin e are very irregular both in cross section and in the direction they pursue. They anastomos e frequently with adjacent canals and there are marked dilatations at points of intersection. The incremental pattern of growth shows
RY OF ENAMEL 91 Fig. 10. Incremental Retzius lines ending on the surface of human enamel. The lines show a step-like appearance . The inner (right-hand) side of each line is demarcate d sharply by lines transverse to the prism axes but on the other side towards the outer enamel surface the demarcation is much less sharp and less segmented . The lines are first isotropic and then slightly negatively biréfringent, χ 1100. (From A.-G. Gustafson, 1959.) 92 G. G U S T A F S ON AND A . - G. G
been proved that the difference in staining reactivity between forming and adult enamel depends on the removal of certain ingredients. It is more likely that there is a transformation into less reactive combinations. It must, however, be expected that the histochemical investigation of the enamel wil l continue to add to our present knowledge of this tissue, and it is to be hoped that more workers wil l turn their attention to these aspects . XIV. ENAMEL STRUCTURES IN S O M E MAMMALS Al l the