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At least 577 records · Page 32Linked to original sources
PubMed1989

[Early development of human tooth germs including the surrounding structures].

It could be shown by means of 3-dimensional reconstructions made from serial sections of human embryos, that the dental lamina of the lower jaw as well as that of the upper jaw is spatially impeded at its distal ends by the presence of the mandible and Meckel's cartilage. This spatial impediment of the odontogenetic epithelium can be seen to be of influence during the formation of the tooth buds.

Humans↗
PubMed1988

Spatial organization of the epithelium and the role of neural crest cells in the initiation of the mammalian tooth germ.

Teeth develop from composite organ rudiments that are formed through the interaction of oral epithelium and mesenchyme of the first branchial arch; cells of the former differentiate into enamel-secreting ameloblasts whereas those of the latter differentiate into dentine-secreting odontoblasts. Experimental analysis of odontogenic tissue interactions in mammalian embryos has focused on the late developmental stages of morphogenesis and cytodifferentiation; little is known about initial pattern-forming events, during which presumptive tooth-forming cells are specified and the sites of tooth initiation become established. It requires to be shown, for example, whether the mesenchymal cells of mammalian teeth are derived, like those of amphibians, from the cranial neural crest, and if so, whether these form a specified subpopulation in the neural folds. Alternatively, are they specified after migration into the mandibular arch, possibly by interaction with the oral epithelium? The developmental potentials of mouse embryo premigratory cranial neural crest cells (CNC - explanted from the caudal mesencephalic and rostral metencephalic neural folds) have been studied in intraocular homograft recombinations with various regions of embryonic surface ectoderm. Cartilage, bone and neural tissue developed in all combinations of CNC and epithelium. Teeth formed in combinations of CNC with mandibular arch epithelium but not in combinations of CNC with limb bud epithelium. Teeth also formed in combinations of mandibular arch epithelium with neural crest explanted from the trunk level. These results indicate that mammalian neural crest has an odontogenic potential but that this is not restricted to the crest of presumptive tooth-forming levels. Normal migration appears not to be a prerequisite for expression of odontogenic potential but this does require an interaction with region-specific epithelium. It is reasonable to infer that during normal development the neural crest that enters the mandibular arch is odontogenically unspecified before or during migration and that the oral epithelium is the earliest known site of tooth pattern.

Amelogenesis↗
PubMed1983

Histochemical demonstration of activity of acid phosphatase and beta-glucuronidase in bovine incisor tooth germs.

Activity of acid phosphatase and beta-glucuronidase was shown in bovine preodontoblasts and preameloblasts prior to the onset of secretion. In the preameloblasts the rather weak reaction consisted of small discrete granules dispersed in the cytoplasm apical, lateral, and proximal to the nucleus. After initiation of enamel formation, a change in localization and intensity of the colored reaction product was observed in the ameloblasts. The activity appeared stronger and was restricted to a narrow zone just apical to the nucleus. It is proposed that the acid hydrolases in the tooth forming cells are located to the Golgi complex. The differences in activity of acid hydrolases between bone and tooth forming cells are expounded.

Acid Phosphatase↗
PubMed1992

Comparative immunohistochemical analysis between jaw myxoma and mesenchymal cells of tooth germ.

The histogenesis of jaw myxoma is still debated. According to some authors it arises from the primitive mesenchymal components of developing teeth. In this study, we have studied the expression of S-100 protein and vimentin in dental follicle, dental papilla and periodontal ligament cells using monoclonal and polyclonal antibodies. Myxoma of the jaw expresses vimentin and S-100 protein. On the contrary, as compared to jaw myxoma, the normal developmental structures were immunonegative for S-100 protein but stained for vimentin. These results could indicate a difference in the derivation other than tooth mesenchyma.

Biomarkers, Tumor↗
PubMed1976

[Effect of insulin on the development of the tooth germ in mice].

After recalling the interactions affecting dental differentiation, the authors analyze the effects of various concentrations in insulin on dental rudiments cultivated in vitro. They found: an oedema causing histological lesions, no anticipation of cell differentiation or stimulation of collagen secretion, a decrease in mitotic activity but stimulation of thymidine 3H incorporation after short contact times.

Animals↗
PubMed1989

Immunocytochemical detection of proliferating cells in the rat tooth germ by monoclonal antibodies against 5-bromo-2'-deoxyuridine.

5-Bromo-2'-deoxyuridine incorporated into DNA synthesizing cells in vivo is detected by a monoclonal antibody. The results are similar to those obtained with cytoautoradiography, but show variance with data from some past autoradiographic studies. This immunocytochemical technique may be a useful tool for study of cell kinetics in the oral tissues.

Animals↗
PubMed1989

Micro-PIGE determination of fluorine distribution in developing hamster tooth germs.

A micro-PIGE (Proton-Induced gamma-ray Emission) technique based on the delayed 5/2+----1/2+ nuclear transition of fluorine (E gamma = 197 keV, t1/2 = 87 ns) emitted after 19F(p,p', gamma)19F reaction was used to detect and study the distribution of fluorine in the developing enamel organ during pre-eruptive stages, i.e., the transitional to early maturation stages of enamel formation in neonatal hamsters administered a single IP dose of sodium fluoride (20 mg NaF/kg body weight). The aforementioned nuclear reaction is unique for fluorine, and therefore detection of gamma-rays emanating from this reaction in a biological specimen implies a positive identification of fluorine at that particular site. Calcium and phosphorus X-rays were also recorded and used as parameters for assessment of the relationship between the degree of mineralization and fluoride incorporation into the enamel organ. The highest fluorine concentration in the enamel organ was recorded in the dentin near the dentin-enamel junction (DEJ). In the enamel, the highest concentration of fluorine was found to be associated with the more mature areas of the enamel near the DEJ, but gradually decreased in the direction of the enamel surface. Fluorine was not detected in the control germs. These results suggest that administration of fluoride in high doses during the pre-eruptive stages of enamel formation leads to incorporation of the ion into the forming dentin and enamel mineral, and that the enamel matrix does not seem to bind fluoride avidly.

Animals↗
PubMed1979

[Data on the preventive removal of wisdom tooth germs].

Prophylactic removal of wisdom teeth was carried out in 559 children during a five-year period in the Department of Oral and Maxillofacial Surgery. Orthodontic indications were present in 525 of the children (94%). The number of removed teeth, the operative procedure, the anesthesia, the medication, and the postoperative complications were discussed. The survey points out the focal points of operative prophylaxis in adolescents between the ages of 14 and 16.

Adolescent↗
PubMedDate not supplied

Meningococcal septicemia and disseminated intravascular coagulation affecting the premaxillary permanent tooth germs.

The following case describes the dental effects resulting from a case of meningococcal septicemia which caused a disseminated intravascular coagulation and premaxillary osteomyelitis at age two years. The effects went unnoticed for eight years when delayed development of the maxillary incisors was noted. Treatment involved surgical removal of the dental remnants and provision of a removable partial denture. Implants and ridge augmentation will be considered in early adulthood.

Child↗