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Several members of the transforming growth factor (TGF)-beta superfamily are expressed in developing teeth from the initiation stage through adulthood. Of those, TGF-beta1 regulates odontoblast differentiation and dentin extracellular matrix synthesis. However, the molecular mechanism of TGF-beta3 in dental pulp cells is not clearly understood. In the present study, beads soaked with human recombinant TGF-beta3 induced ectopic mineralization in dental pulp from fetal mouse tooth germ samples, which increased in a dose-dependent manner. Further, TGF-beta3 promoted mRNA expression, and increased protein levels of osteocalcin (OCN) and type I collagen (COL I) in dental pulp cells. We also observed that the expression of dentin sialophosphoprotein and dentin matrix protein 1 was induced by TGF-beta3 in primary cultured dental pulp cells, however, not in calvaria osteoblasts, whereas OCN, osteopontin and osteonectin expression was increased after treatment with TGF-beta3 in both dental pulp cells and calvaria osteoblasts. Dentin sialoprotein was also partially detected in the vicinity of TGF-beta3 soaked beads in vivo. These results indicate for the first time that TGF-beta3 induces ectopic mineralization through upregulation of OCN and COL I expression in dental pulp cells, and may regulate the differentiation of dental pulp stem cells to odontoblasts.
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The control of tooth development by 1,25-Dihydroxyvitamin D3 is analyzed by light- and electron-microscope immunocytochemistry and Northern-blotting in vitamin D-deficient rats. The receptor for 1,25-Dihydroxyvitamin D3, immunostained at the light microscope in all stem-cells, became immunodetectable only at the ultrastructural level in the ameloblasts which elaborate enamel and odontoblasts which synthetize dentin. Moreover, 1,25-Dihydroxyvitamin D3 induces an up-regulation specifically in these cells. In parallel, the calbindins-D9k, -D28k and osteocalcin, in contrast to the phosphoprotein, appear sensitive to vitamin D-deficiency. A single injection of 1,25-Dihydroxyvitamin D3 led to the increase of steady-state levels of the corresponding calbindin mRNAs. These data show that tooth constitutes a target-organ for 1,25-Dihydroxyvitamin D3, as other components of the phospho-calcic metabolism.
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OBJECTIVE: Clinical and histopathological evaluation of mechanical trauma on the development of maxillary first molar with Scanning Electron Microscope. DESIGN: Experimental study with four newborn Wistar rats. Trauma induced on 1st, 3rd, 7th and 10th postnatal days with dental K file. Right first molar region of the maxilla was the experimental side and the left side as control. Animals were sacrificed on the 42nd Postnatal day when the teeth came into functional occlusion. Teeth were evaluated clinically and SEM study of the crown was performed. RESULTS: Marked disfigurement of cusps, roughened defective, enamel, crown dilacerations and enamel hypoplasia were observed. Damage was less severe to the tooth subjected to trauma on the 10th postnatal day.
In this case the permanent successor was so radiographically indistinct due to the inflammatory process that this three-year-old Arab boy might have been classified as having congenital absence of the mandibular left first premolar, if the mass had not been sent for histological section. The clinical implications are identical.
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The distribution of two cell-adhesion molecules, E- and P-cadherin, was studied in relation to morphological changes in Hertwig's epithelial root sheath Before root dentinogenesis had started, the root sheath expressed both cadherins. As dentinogenesis proceeded, the sheath fragmented and lost P-cadherin rapidly and E-cadherin slowly, whereas the intact sheath at the apical end continued to express both. These results suggest that the two cadherins play a part in root as well as in crown development, and indicate that the decrease in the amount of these molecules and the fragmentation of the epithelial root sheath are interrelated.
With regard to medicolegal problems, semantics are of considerable importance: indeed, depending on whether we call grafting or transplantation of an organ the operation that takes a living organ to reimplant it in the same person or the operation that takes a living organ from a donor to reimplant it in a recipient, the issues raised are completely different. The transposition of a dental organ does not raise any particular problems apart from the technical requirements to be met; there is no special problem of prevention or ethics to be taken into consideration. The problem is a completely different one when it means taking a living organ from a living or dead subject and reimplanting it in another subject. All measures decreed from the point of view of law and regulations that are dictated by considerations of prevention and ethics must then be strictly applied.
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