PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Tooth Calcification”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 163 records · Page 9Linked to original sources
PubMed1995

[Pharmacological study of tooth formation and mineralization using a tooth germ cultivation system].

In this study, we introduce a cultivation method for mandibular first molars from mouse embryos. We also investigate the in vitro effects of several drugs on tooth formation. Histological observations demonstrated that the tooth germ dissected from 17-day-old embryonic mice and cultivated for 7 days under the conditions described here showed clear mineralization in the dentin and enamel. Alkaline phosphatase (ALP) activity and calcium content in the tooth germ increased developmentally during 7-day cultivation. The increase of calcium was preceded by that of ALP in the germ. The removal of ALP attached covalently to the external surface of plasma membranes by phosphatidylinositol specific phospholipase C disturbed in vitro mineralization in the tooth germ, suggesting that ALP functioning as an ectoenzyme is involved in the physiological process of tooth formation. To elucidate the effects of calcium regulating hormones and several drugs on tooth mineralization, ALP and calcium content were measured and also the tooth germ was observed histologically. The results obtained from the present study suggest that this in vitro system provides a useful tool for investigating both the direct action of drugs on tooth formation and the mechanisms of drug action.

Alkaline Phosphatase↗
PubMed1991

[In vitro effect of chlorpromazine on the mineralization of tooth germ in mice--comparison with that of retinoic acid and HEBP].

Effects of chlorpromazine on the mineralization and alkaline phosphatase activity (ALP) in the tooth germ were examined and compared with those of retinoic acid and HEBP (1-hydroxyethylidene-1, 1-bisphosphonate). Mandibular first molars from 17-day-old mouse embryos were cultured with or without drugs. Calcium content and ALP in the tooth germ increased gradually from 0 to 7 days in culture, the increase of calcium being preceded by that of ALP. Retinoic acid suppressed increases of calcium and ALP in the tooth germ but not in the specimens precultured for 2 days, suggesting that retinoic acid inhibits the mineralization at an early developmental stage of the tooth. HEBP, a physiochemical inhibitor of mineralization, suppressed the increase of calcium, but significantly enhanced the increased of ALP in the tooth germ. Chlorpromazine, which has an antagonistic action towards calmodulin, also suppressed the increases of calcium and ALP in the tooth germ. Calmodulin antagonists W-7 and W-5 similarly suppressed the increases of calcium and ALP; W-5 had less effects on both calcium and ALP. These results indicate that calmodulin may be involved in the regulation of the mineralization in the tooth germ. These drugs are shown to possess different modes of inhibitory action on the mineralization.

Alkaline Phosphatase↗
PubMed1979

The hypermineralization of diseased root surfaces.

Root surfaces which have lost their attachment due to chronic inflammatory periodontal disease present significant increases in calcium, magnesium, phosphorus, and fluoride. The clinical significance of this effect is not known in regards to wound healing, but it may be helpful in control of cervical sensitivity.

Adolescent↗
PubMed1978

Maternal diabetes and changes in the hard tissues of primary teeth. III. A histologic and microradiographic study.

According to clinical studies, infants of diabetic mothers (IDM) seem to run a higher risk of mineralization disturbances in the enamel than normal healthy infants. In order to evaluate this observation at the histologic level, exfoliated primary incisors were collected from 74 IDM, representing two types of care during gestation and the perinatal period, and from 52 healthy children. The width of the neonatal line was evaluated in the enamel and the dentin by study of bucco-lingual undemineralized sections. Pre- and postnatal enamel was classified according to discolorations, deviations of prisms and hypoplasia. Microradiographic studies included measurements of the neonatal lines and classification of the degree of mineralization in the pre- and postnatal dental hard tissues. Irrespective of treatment, the IDM showed a significantly higher incidence of widened neonatal lines and also an increased frequency of postnatal disturbances compared to the controls. The observations are discussed against the background of the neonatal hypocalcemia reported in IDM.

Amelogenesis Imperfecta↗
PubMed1983

Enamel structure in deciduous teeth from low-birth-weight infants.

Ground sections of deciduous teeth from 64 infants with birth weights below 2000 g and from 43 healthy full-term infants were examined in polarized light and by microradiography. The deciduous enamel displayed various changes, which were more frequent and pronounced in the low-birth-weight group. The main findings were diffuse areas of increased porosity and distinct subsurface lesions in the postnatal enamel. Five teeth with enamel hypoplasia from the low-birth-weight group were also examined. The hypoplasias were all located along the neonatal line. The postnatal enamel seemed to be more susceptible to disturbances in the mineralization than the prenatal enamel. The subsurface lesions showed an arrest in the very late stages of enamel maturation, which frequently occurred in the cervical deciduous enamel. Enamel hypoplasia is considered to be a result of severe neonatal hypocalcemia.

Dental Enamel↗
PubMed1995

Analysis of amelogenin proteins using monospecific antibodies to defined sequences.

Amelogenins are the predominant proteins found in the developing enamel matrix and are believed to play a crucial role in normal mineralization. Although the amelogenin gene is found as a single copy in all species in which it has been examined, multiple amelogenin polypeptides ranging in size from 5 to 25 kDa are obtained upon extraction of developing enamel matrix, making identification and characterization of individual components difficult. This heterogeneity may be ascribed to transcription of divergent genes located on the X and Y chromosomes, alternative splicing of the primary transcripts, physiologic degradative processing, and artefactual degradation. In order to characterize individual components, antibodies were produced to the following peptides: (1) QPLQPMQPMQPLQPLQPL (corresponding to the repeat sequence encoded only in the bovine X chromosome gene), (2) IRHPPLPP (corresponding to a unique sequence generated by alternative splicing found in leucine-rich amelogenin peptide (LRAP), (3) LPDLPLEAWPATDKTKREEVD corresponding to the amelogenin carboxy-terminus. Amelogenin proteins obtained from fetal bovine molars were subjected to SDS PAGE and Western electrotransfer, and immuno-ultrastructural analysis. These analyses demonstrated that: (1) the distribution of amelogenin polypeptides isolated from male fetuses differed appreciably from that of females, (2) the LRAP junctional peptide sequence can be specifically identified, and (3) the LRAP peptide can be immunolocalized in the enamel matrix of both males and females.

Alternative Splicing↗
PubMed1995

Coronal dentinal nodules induced by single or multiple injections of HEBP in young rats.

In the developing tooth, the bisphosphonate HEBP causes hypoplasias and hypomineralization of the enamel and dentine as well as inhibition of acellular cementum formation. Here, we describe a novel effect, associated with dentine mineralization. HEBP was administrated to young rats, and the maxillary molars were analyzed histologically. Localized dentinal nodules, protruding towards the pulp, were found in the developing crown of the molars. They occurred in regions, where the mantle dentine was about to mineralize at the time of the injection, and were more frequent at the mesial cusp side. The nodules accumulated mineral, as evidenced by the fluorescence after calcein and tetracyclin labelling. Histologically, the nodules were separated from the enamel by a layer of mantle dentine and were progressively surrounded by predentine and dentine. The nodules were interpreted to contain transport or metabolism intermediates, which were locally accumulated due to the interruption of the mineralization process by HEBP.

Animals↗
PubMed1995

Effects of vincristine on the developing hamster tooth germ in vitro.

Vincristine is one of the cytostatic drugs present in cocktails commonly used for the treatment of cancer in children. The aim of this study was to evaluate biochemically and histologically the toxic effects of this drug on the developing tooth in vitro using the organ culture model in order to be able to predict what damage the drug can induce in the developing teeth from children undergoing anti-neoplastic chemotherapy. The most profound effect of the drug (10(-8)M-10(-4)M vincristine) on the developing tooth germ was the induction of mitotic arrests at the cervical loop and in the inter-cuspal regions. The 10(-4)M-10(-6)M vincristine doses were cytotoxic to most cells in the developing tooth germ. The 10(-7)M vincristine dose apart from induction of mitotic arrests, did not appear to be cytotoxic to the mature differentiated secretory cells. However, this dose induced incomplete nuclear polarization of the differentiating ameloblasts and odontoblasts. At 10(-8)M vincristine, the only effect observed were mitotic arrests; the secretory cells did not appear to have been affected at all. On the other hand, mineralization (TCA-soluble 45Ca and 32P uptake) was dose-dependently decreased from 10(-7)M vincristine upwards. 10(-9)M vincristine, the lowest dose tested, did not induce any changes in the developing tooth germ. The organ culture data indicate that 10(-9)M vincristine is the highest (safe) dose which does not induce any toxic effects in the developing hamster tooth germ.(ABSTRACT TRUNCATED AT 250 WORDS)

Ameloblasts↗
PubMed1995

Role of two mineral-associated adhesion molecules, osteopontin and bone sialoprotein, during cementogenesis.

Adhesion molecules and their cell membrane receptors are known to play important regulatory roles in cell differentiation. Consequently, the following experiments were conducted to determine the role of two adhesion molecules, bone sialoprotein (BSP) and osteopontin (OPN) in tooth root formation. Developing murine molar tooth germs at sequential stages of development (developmental days 21-42) were analyzed using immunohistochemical and in situ hybridization techniques. While BSP was localized to alveolar bone and odontoblasts early in development, BSP was distinctly localized to the cemental root surface at latter periods coincident with the initiation of root formation and cementogenesis. Conversely, OPN was distributed in a nonspecific fashion throughout the PDL and the eruption pathway of the forming tooth. In situ hybridization confirmed that cells lining the root surface express BSP. The fact that BSP is specifically localized to the cemental surface suggests that this protein is involved in cementoblast differentiation and/or early mineralization of the cementum matrix. Localization of OPN to non-mineralized tissues further suggests that OPN functions as an inhibitor of mineralization during periodontal ligament formation. These findings collectively suggest that BSP and OPN are intimately involved in the sequence of cellular and molecular events accompanying cementogenesis.

Alveolar Process↗
PubMed1995

Ultrastructural characterization of mesenchymal and epithelial cells co-cultured from human dental root apical explants.

Previous studies have shown the role of cell-cell and cell-matrix interactions in the differentiation of the specific secretory cells of the tooth. In order to elucidate the mechanisms implicated in root dentin formation, we developed a co-culture system of human pulpal mesenchymal and epithelial root sheath cells. Root tips of premolars were cultured in Eagle's basal Medium supplemented with fetal calf serum, ascorbic acid, antibiotics and, for some of them, with sodium beta-glycerophosphate. After 60 days of culture, cells were prepared for light and electron microscopy. Three main cell types were observed: (1) polygonal mesenchymal cells showing a functional polarity and producing a dense network of tactoid collagenous fibers. The latter had a specific circular organization that delimited small lacunae around the cells and mineralized in the presence of beta-glycerophosphate; (2) spindle-shaped mesenchymal cells mainly localized inside epithelial-mesenchymal knots and synthesizing an abundant collagenous matrix; and (3) epithelial cells lying on the plastic culture dish, on the dense collagenous matrix, or on spindle-shaped cells. Epithelial cells deposited a structured basement membrane when they were lying on the plastic culture dish or on spindle-shaped cells. On the contrary, no basement membrane was found when epithelial cells were overlying the dense collagenous network. Immunoelectron microscopic analysis of type IV collagen and laminin indicated that these two specific basement membrane components were produced by all cell types. These results show that the co-culture system should be valuable for (1) studying the in vitro formation of human dental root hard tissues, (2) characterizing cell-cell and cell-matrix interactions implicated in dental basement membrane production, and (3) isolating populations of cells implicated in dental root formation.

Adolescent↗
PubMed1995

The control of ingress of albumin into developing enamel from adjacent dentine of the rat incisor.

The present study used an immunohistochemical approach to map the distribution of albumin within the dentine adjacent to the developing enamel of both impeded and unimpeded rat incisors to determine if the dentine could be a possible route of entry for this protein into the developing enamel matrix. In dentine adjacent to the secretory and transition stages of the developing enamel, the dentinal tubules were labelled only over approximately the pulpal quarter of their length. The bulk of the dentine showed no labelling. However, labelling within the dentine appeared at the ADJ at a position approximately 2.5 mm occlusal to the distal root of the first molar, adjacent to enamel with no visible residual matrix. The results of this study suggest that adventitious ingress of albumin into enamel from the dentine is restricted during enamel secretion and can only potentially occur once enamel maturation has been initiated.

Albumins↗
PubMed1995

Elemental distributions in predentine associated with dentine mineralization in rat incisor.

Electron probe microanalysis was applied to study quantitatively and semi quantitatively the elemental concentrations and distributions that occur in predentine during the dentine mineralization of rat incisor. Apex regions of the continuously growing incisors were rapidly dissected and cryofixed in liquid nitrogen-cooled propane. Ultrathin cryosections were prepared from the dentine tissue. On the average in the extracellular predentine element concentrations of calcium and phosphorus were about 0.5% (w/w) and 0.5-1% (w/w), respectively; so the calcium content in the extracellular predentine is higher while the phosphorus content is much lower than in the odontoblast area. Due to the high content of glycosaminoglycans in the extracellular matrix the concentration of sulfur in the predentine was more than 1% (w/w); the potassium content was found in the range of 0.6-0.8% (w/w) which is quite high for an extracellular area and the concentrations of sodium and chlorine were higher than 2% (w/w). Elemental mapping analysis was carried out to demonstrate the distribution of some important elements at the predentine/dentine border during mineralization.

Animals↗
PubMed1992

A method for histological examination of undecalcified teeth.

A method is presented for histological examination of undecalcified ground sections of tooth roots affected with periodontal disease. The roots were placed in Karnovsky's fixative overnight, postfixed in 2% buffered osmic acid, and dehydrated in an ascending series of ethanol. The specimens were then infiltrated with propylene-oxide and Epon-Araldite resin, embedded in Epon-Araldite, and sections were prepared using a cutting and grinding system. The resulting ground sections were 8-12 microns thick. The sections were allowed to air dry at room temperature. When thoroughly dried, a coverglass was applied using resinous mounting medium DPX. The specimens were examined by phase-contrast microscopy. The method is useful for simultaneous examination of mineralized dental tissue and bacterial morphotypes covering the root surface of teeth involved with periodontal disease.

Histological Techniques↗