Dental Anatomy and Occlusion (original) (raw)
Related papers
Developmental movements of the inner enamel epithelium as derived from micromorphological features
European Journal of Oral Sciences, 2006
The enamel rods are known as the structural units of human (if not all mammalian) dental enamel (1,2). It is believed that the enamel rods are the products of ameloblasts, and that the arrangement of the enamel rods within the enamel reflect the developmental movement of ameloblasts . We know that -in human teeth -the enamel rods do not simply run straight from the dentino-enamel junction towards the enamel surface, as previously thought (5). As the enamel rods do not increase in diameter (6,7), although the outer surface of the enamel is larger than the surface at the dentinoenamel junction, the enamel rods must form a specific arrangement to fill the expanding volume of the enamel mantle. The question remains as to how the form of the tooth crown is dependent on the orientation of the enamel rods within the enamel (5,7-15).
The Development of Dentin Microstructure Is Controlled by the Type of Adjacent Epithelium
Journal of Bone and Mineral Research, 2021
Considerable amount of research has been focused on dentin mineralization, odontoblast differentiation, and their application in dental tissue engineering. However, very little is known about the differential role of functionally and spatially distinct types of dental epithelium during odontoblast development. Here we show morphological and functional differences in dentin located in the crown and roots of mouse molar and analogous parts of continuously growing incisors. Using a reporter (DSPP-cerulean/DMP1-cherry) mouse strain and mice with ectopic enamel (Spry2 +/À ;Spry4 À/À), we show that the different microstructure of dentin is initiated in the very beginning of dentin matrix production and is maintained throughout the whole duration of dentin growth. This phenomenon is regulated by the different inductive role of the adjacent epithelium. Thus, based on the type of interacting epithelium, we introduce more generalized terms for two distinct types of dentins: cementum versus enamel-facing dentin. In the odontoblasts, which produce enamel-facing dentin, we identified uniquely expressed genes (Dkk1, Wisp1, and Sall1) that were either absent or downregulated in odontoblasts, which form cementum-facing dentin. This suggests the potential role of Wnt signalling on the dentin structure patterning. Finally, we show the distribution of calcium and magnesium composition in the two developmentally different types of dentins by utilizing spatial element composition analysis (LIBS). Therefore, variations in dentin inner structure and element composition are the outcome of different developmental history initiated from the very beginning of tooth development. Taken together, our results elucidate the different effects of dental epithelium, during crown and root formation on adjacent odontoblasts and the possible role of Wnt signalling which together results in formation of dentin of different quality.
Critical reviews in oral biology and medicine : an official publication of the American Association of Oral Biologists, 1993
The formation of dentin, dentinogenesis, comprises a sophisticated interplay between several factors in the tissue, cellular as well as extracellular. Dentin may be regarded as a calcified connective tissue. In this respect, as well as in its mode of formation, it is closely related to bone. Using dentinogenesis as an experimental model to study biomineralization provides several practical advantages, and the results may be extrapolated to understand similar processes in other tissues, primarily bone. After describing dentin structure and composition, this review discusses items such as the morphology of dentinogenesis; the dentinogenically active odontoblast, transport, and concentrations of mineral ions; the constituents of the dentin organic matrix; and the presumed mechanisms involved in mineral formation.
Molecular Determinants of Tooth Development: A Review
Critical Reviews in Oral Biology & Medicine, 1990
Critical Reviews In ectomesenchyme determination and subsequent cytodifferentiation presumably coordinate the timing and positional information required for Meekers cartilage, tooth formation, and bone formation (see discussions in References 5, 25, and 26). Earlier experimental efforts found that Theiler stage 20 (Ell to El2) mandibular processes could be cultured as explants in a serumless and chemically defined medium which was permissive for chondrogenesis andosteogenesis. 2728 More recently, Theiler stage 20 mandibular processes were cultured for 9 d in vitro and formed Meekers cartilage, both incisor and molar tooth organs, osteogenesis, and tongue formation in serumless medium (Figure I). 2931 IV. MANDIBULAR FIRST MOLAR TOOTH ORGAN MODEL SYSTEM A. Epithelial-Derived Signals for Tooth Determination During the determination of mouse tooth morphogenetic positional values, branchial arch-derived epithelia appear to provide positional information for subsequent tooth development. Recent evidence demonstrates that heterotypic tissue recombinations, formed between first branchial arch epithelia and second branchial arch ectomesenchyme, showed that early mandibular arch epithelia, before Theiler stage 20, possessed odontogenic potential and could elicit the formation of a dental papilla in non-odontogenic neural crest-derived ectomesenchyme of the second branchial arch. 32 Mandibular ectomesenchyme appears, therefore, to be required to interact with mandibular epithelia and to provide competence (e.g., specific receptors?) for incisiform and molariform tooth determination (Figure 2). 4-5-33