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At least 1,405 records · Page 78Linked to original sources
PubMed1991

A histologic study of the biocompatibility of a dentinal bonding system.

To assess the biocompatibility of an adhesive system, standard Class V cavities were prepared in vivo in human premolars that were to be extracted for orthodontic purposes. Histologic observation revealed that the Gluma Bond System elicited slight to severe pulpal responses, altered odontoblastic layers, and inhibited dentinogenesis. These alterations were observed after in vivo periods of up to 120 days. In this experiment, the dentinal adhesive was polymerized separately from the composite resin, a procedure not recommended by the manufacturer. This may explain the differences in the present results and those reported by the manufacturer.

Adolescent↗
PubMed1991

The connective tissue cells of human dental pulp: an histologic and immunohistochemical study.

Twenty human healthy teeth were extracted for orthodontic purposes and processed for histological, and immunohistochemical examination. Odontoblasts were pseudostratified in depth of 1-8 cells in pulpward direction showing the zone of Weil and the cell-rich zone in coronal third pulp. In the central part of pulp tissue, fibroblasts were arranged as a network. These cells strongly immunoreacted with an antibody (monoclonal and polyclonal) directed against the intermediate filament vimentin. The product reaction was specifically located in the cytoplasm. Near vessels occasional lymphocytes and mast cells were also present. Collagen fibers formed a plexus below the cell-rich zone in middle and coronal pulp.

Connective Tissue↗
PubMed1991

[An ultrastructural study of the fibrillary component of dental tissues].

The recent interest for highly sophisticated techniques of dental tissue preparation aiming to display very particular structures, moved the AA. to improve the literature suggestions. In particular they made TEM and SEM observations of transitional zones between healthy and normal pulp and dentin after decalcification and trypsin at different concentrations treatment. The images obtained draw in the attention the study facilities of a technique that really removes all the non collagenic material. The data obtained in the pericellular zones also allowed some interventions in the recent literature discussion about inter-odontoblastic fibres.

Decalcification Technique↗
PubMed1991

[Morphological changes in the lower incisor of suckling rats induced by large dose of aspirin].

Large doses of aspirin (200 mg/kg or 400 mg/kg, s.c) caused marked hypocalcemia in suckling rats, two hours after administration. The hypocalcemic effect was more evident in two week old rats than in one week old ones. Although the mechanism of aspirin-induced hypocalcemia is not clear at this moment, the drug can be a useful tool for inducing experimental hypocalcemia in suckling rats, besides hormonal and/or nutritional controls. In this report, large doses of aspirin were administrated to new born rats, once at one week after birth, or twice at one and two weeks after birth. The morphological changes of the lower incisor were examined using computer programs which have been developed for the analysis of plane curves such as the traces of the side view of the incisor. Aspirin administration shortened the length of the lower incisor and its labial trace. The width of the incisor, especially in the middle, was also diminished by aspirin administration. These observations suggest that the drug not only induced hypocalcemia in suckling rats but also to some extent suppressed the activity of odontoblasts which produce the dentin of the incisor. Analysis of curvature variance, calculated with the labial trace of the lower incisor, also suggested that large doses of aspirin had two effects. It suppressed mineralization of the teeth through its hypocalcemic effect, and it inhibited synthesis of the collagenous matrix. The computer programs applied in this study have proved useful in determining and analyzing morphological changes of bio-materials which are difficult to measure directly.

Analysis of Variance↗
PubMed1990

A radioautographic comparison of in vivo 3H-proline and 3H-serine incorporation in the pulpal dentine of rat molars: variations according to the different zones.

3H proline and 3H serine were injected intraperitoneally to rats which were killed 4 and 24 hours later. The incorporation of the labelled precursors was studied in the odontoblasts, predentine and dentine of the first lower molars. After radioautography, statistically significant differences in grain density appeared between the furcation, occlusal and lateral areas of the pulp chamber. The incorporation of predentine components into dentine was faster in the lateral than in the occlusal area, the slowest being detected in the furcation area. These differences may be related to the distribution of occlusal forces in the rat molar.

Animals↗
PubMedDate not supplied

[The ultrastructure of the circumpulpal dentin of the human tooth].

Ultrastructure of cellular and extracellular constituents of the predentin and adjacent strip of dentin was investigated in both erupted and unerupted but completely shaped third molars of human adults using cautious fixation and demineralization techniques. The odontoblast processes (OP) were slightly bent at their bases to run further straight and parallel to each other across dentin and predentin. The OP cytoplasm contained numerous microfilaments and solitary microtubules. Occasional mitochondria, lysosomes, microvesicles, lipid globules and endoplasmatic reticulum profiles could be found throughout the whole length of the OP under study. Axons and their terminals of apparently efferent type attached to some of the OPs were found in both dentin and predentin. A great bulk of dentin was occupied with the collagen fibers intermingled with the amorphous matrix and occasional dense precipitates next to dentin. Intensive mineralization was found in dentin except the spaces occupied by dentin canaliculi.

Adult↗
PubMed1990

Calcium transport in dentinogenesis.

A fundamental question in biomineralization research is the metabolism of the ionic constituents of the mineral phase. Mechanisms for the transport of Ca2+ ions have been identified and characterized in detail for various types of cells. Surprisingly little is known about osteoblasts and odontoblasts in this respect. This paper reviews what is known about calcium metabolism during dentinogenesis.

Animals↗
PubMed1977

[Cellular relations during odontogenesis].

Epithelial-mesenchyme interactions during mouse molar tooth morphogenesis were observed by electron microscopy. The basal lamina was intact from day 10 to day 18. Aperiodic, later also periodic fibrils were deposited on the basal lamina. Ectomesenchymal cell processes were always in close relation with the basal lamina or with the fibrillar material. On day 19 some direct heterotypic cell contacts between odontoblasts and preameloblasts were observed. At all stages, especially the preodontoblasts but also preameloblasts, gave rise to aggregated vesicles, which were extruded in the epithelial-mesenchymal space.

Ameloblasts↗
PubMed1979

Collagen in dentin.

The collagen synthesized by cultured odontoblasts related to dentin, was identified as type I and as type I trimer in nearly equal amounts. Analysis of in vivo synthesized collagen extracted from unerupted bovine teeth confirmed that type I trimer is a constituent of dentin, but presumably in small amount compared to type I collagen.

Animals↗
PubMed1979

[The fine structure of the dental pulp].

Root pulp usually contains more collagen fibrils than coronal pulp. The fibrils consolidate to form fibrinous bundles only to a very slight extent. Involution of the odontoblasts occurs with advancing age. If such involution is absent, an irregular layer of hard substance is deposited on the canal wall. A homogeneous line of adhesive can be seen on the wall at the border with the root pulp. The tissue character of the pulp however is preserved. Perineurium is absent around the nerves in human pulp.

Adolescent↗
PubMed1979

Sensitivy of mouse molar tooth germs to x-ray irradiation in vitro.

Molar tooth germs, extirpated from 18-day mouse fetuses were cultured on Millipore filter strips in Falcon organ culture dishes. The tooth germs were exposed to 250 kVcp X-rays at 106 R/min. for a total exposure of 1 600 R. Tissues were harvested on a daily basis for a total period of 12 days and were examined microscopically, utilizing H and E stain. Severe disorganization of the tooth germs was evident within 24 hours of irradiation. The basement membrane became hyalinized; pyknotic nuclei and lysed cells were observed throughout the dental papilla, but mostly in the regions of the presumptive cusps. Although a thin layer of predentin was elaborated by the odontoblasts, the matrix failed to calcify and enamel matrix was not produced. Cultures older than 10 days demonstrated extensive cell death. The entire pulp was reduced to a mass of necrotic cells and the ameloblastic layer consisted of an epithelial remnant covering the cuspal tips.

Ameloblasts↗
PubMed1979

Electrophysiological properties of human dental pulp cells.

Resting membrane potentials and electrotonic potentials of human dental pulp cells (peripheral and inner cells) were recorded from intracellular measurements. The results show a high resting membrane potential (- 80 mV) for peripheral cells and a low resting membrane potential (- 30 mV) for inner cells. The peripheral cells present rectification properties (outward going rectification and delayed rectification) and a negative post potential at the end of the depolarizing current. These properties are similar to those found in some receptor cells. On the basis of their morphological characteristics, these peripheral cells are compared to odontoblasts in their early stage of development.

Adolescent↗
PubMed1985

[Experimental research on the preparation of dentin-pulp tissue of teeth exposed to CO2 laser beams in dogs and macaques (Macaca mulatta and Macaca fascicularis].

Traumatic inflammation due to application of CO2 laser radiation (lambda = 10.6 microns) on the dentin and on pulp of 342 teeth of 8 dogs (Beagle) and of 6 monkeys (Macaca sp. mulatta et fascicularis) stimulate in dentino-pulpal tissue morphological phenomenon, studied after 5 days, 1 and 3 months by microscopy and microradiography. The dentin exposed to a density of energy of: 2 X 10(3) J/cm2 shows a burn, a rarefaction and a cellular degeneration, followed by a neoformation of calcified dentin, of about 300 microns thick in 3 months, due to the excitation of odontoblasts or produced by pulpal cells functioning before. A density of energy of 10(3) J/cm2 order applied to the pulp beads to its partial necrosis, to various inflammatory aspects (vascular, cellular, tissular) and to a quasi-constant regeneration of by a neo-dentin bridge of 200 micron at 1 month. This method seems able to allow the analysis of cell activity (start, activation, blocking).

Animals↗
PubMed1978

Root formation in ectopically transplanted teeth of the frog rana pipiens. II. Comparative aspects of the root tissues.

In the second part of an experimental study of the behavior and fate of the roots of ectopically transplanted frog teeth the comparative aspects of the tooth root and its tissue composition were examined. Experimental results showed that the root or pedicel area of the frog tooth was an intrinsic part of the tooth. The tooth was capable of growth to normal size and shape with or without the presence of underlying bone. When compared with existing descriptive exidence and analysis it was determined that the best terminology for the amphibian root tissues would be dentin right up to the point of attachment where cellular basal bone is seen. This is because it is an intrinsic part of the tooth, if formed on the pulpal side of the root sheath, and is formed by odontoblasts. Because of the above observations, the original Hertwig's epithelial root sheath appeared both homologous and analogous with the mammalian sheath, but since all the root tissues were under this sheath, no tissues homologous to any of the paradental tissues of cementum, periodontal ligament, or alveolar bone could be found except when the root sheath injury resulted in induction of an acellular tissue upon the outer surface of dentin.

Animals↗
PubMed1978

[Ultrastructural study of odontogenesis in the frog (Rana temporaria L.)].

Differentiation of the cells of the dental bud which produce the hard tissues of teeth was studied at the ultrastructural level; the activity of these cells (odontoblasts and ameloblasts), the laying down of organic matrices elaborated by them, the mineralization of these matrices, and the maturation of dentine and enamel are described. Injections of tritiated proline enabled us by the autoradiographic method, to confirm and to indicate more precisely the activity of these cells. Dental calcified tissues of Rana exhibit the general properties of these tissues among Vertebrates: high content of apatite, low content of organic materials (collagenous in dentine, non-collagenous in enamel), precise orientation of crystals, and true but non-prismatic enamel. The enamel of Anura as well as enamel of Urodela is a true enamel of epithelial origin.

Ameloblasts↗
PubMedDate not supplied

[Development of dental tissues innervation in primary teeth. Experimental study on dogs].

In this work it was studied the innervation of pulp-dentin in primary premolars on experimental - dogs of 15, 35, 55 days old, with the aid of stainings Alcian blue/PAS and Bielschowsky. On 15 days old experimental dogs there were seen nerve fibres subodontoblastically. On 35 days old experimental dogs nerve fibres were directed towards the odontoblasts, there were also seen neural loops subodontoblastically and terminal nerve fibres on the exterior surface of the vessels. On 55 days old experimental dogs there was seen a great number of argyrophilic fibres in the district of the relapse of the dentine and pulp.

Animals↗
PubMed1984

Immunohistochemical localization of fibronectin in structures of the human oral cavity: dental pulp and gingiva.

The distribution of fibronectin (FN) in the dental pulp and gingiva of the human adult was investigated by indirect immunofluorescence and indirect immunoperoxidase techniques. FN could not be demonstrated in the connective tissue of the dental pulp even in the blood vessels. On the contrary, a positive stain was obtained in the ground substance at the base of the odontoblast cell bodies and in various structures of a denticle which was accidentally found in the pulp of one of the examined teeth. The lack of FN in the dental pulp could mean that this tissue, sometimes considered to be of an immature and undifferentiated type, is instead a mature one. The subepithelial connective tissue and the epithelium of the gingiva were examined. The distribution of FN in the connective tissue of the gingiva was found to be similar to that described in other types of connective tissue; high concentrations were found both in the epithelial cells and around them. This finding is described here for the first time and remains to be verified in other types of stratified epithelia.

Dental Pulp↗