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At least 1,153 records · Page 64Linked to original sources
PubMed1990

[Studies on the influence of composite resin filling material (Command Ultra fine) on the dental pulp].

Studies on the influence of composite resin filling material on the dental pulp of human 1st premolar are reported in this thesis. An other experiment was carried out on rabbit with the left 1st molar in their lower jaw as subject and the right 1st molar in the lower jaw as a control. In both experiments with human and rabbit, routine operations were performed to prepare the cavities and filled with composite resin material. The human teeth were extracted 21 days afterwards and the rabbit teeth were extracted 7 days afterwards. Edema was found in the dental pulp of both human and rabbit teeth by pathologic examination and was accompanied by hemangiectasis and lymphaniectasis. There was also vacuolar degeneration in the odontoblasts. Some of these cells were reticulated and the of number of odontoblasts was fewer than in the control. Hemangiectasis was even more serious in the rabbit's teeth than those of human.

Animals↗
PubMed1990

In vivo morphogenetic activity of dentine matrix proteins.

Matrix proteins (EDTA-soluble and collagenase-released) from rabbit dentine have been demonstrated to show in vivo morphogenetic activity in exposed pulps of ferret canine teeth. In young adult ferrets, the reparative dentine resembled normal primary tubular dentine with odontoblast-like cells lining its formative surface. The reparative response in older animals was seen as osteo-dentine deposition. In both cases, the reparative response was characterized by its intensity within a comparatively short time period and also by the low grade or complete absence of any localized inflammatory response. Dentine matrix proteins implanted in exposed pulps of teeth provide a good experimental model for analysing the cell-matrix interactions and events taking place during odontoblast differentiation and dentinogenesis.

Aging↗
PubMed1990

Molecular changes during determination and differentiation of the dental mesenchymal cell lineage.

The lineage of dental mesenchymal cells originates in the cranial neural crest, and after sequential determination and differentiation, gives rise to all structures of the tooth and its supporting tissues, except the enamel. Reciprocal interactions between the epithelial and mesenchymal tissues are conceivably the most important regulators of dental mesenchymal cell differentiation. The molecular mechanisms of this epigenetic regulation are not known at present. In order to examine the mechanisms of regulation of gene expression in the lineage of dental mesenchymal cells, information is needed on the molecular changes that accompany advancing differentiation. By using the molar tooth germ of mouse embryos as a model system, the changes in the expression of some molecules have been analysed by immunohistological localization and in situ hybridization, and the roles of tissue interactions in this process examined. This has shown that syndecan, a recently characterized cell surface proteoglycan, and tenascin, a matrix glycoprotein, appear in the condensing dental mesenchyme during the bud stage of tooth development. During the cap stage, dental mesenchyme is characterized by continued intense expression of syndecan, but this is lost during terminal differentiation of odontoblasts. Tenascin and syndecan may mediate cell-matrix interactions during condensation of dental mesenchymal cells. Expression of the Int-2 proto-oncogene, coding for a fibroblast growth factor-related molecule, can be detected by in situ hybridization in dental mesenchyme at the cap stage. This expression persists in cuspal mesenchyme at the bell stage but is lost from odontoblasts and from pulpal mesenchyme at progressive stages of tooth development. The advancement of tooth morphogenesis from cap to bell stage is accompanied by expression of alkaline phosphatase in the cuspal mesenchyme. Also tenascin, which is only weakly expressed during the cap stage, appears in the cuspal areas and shows codistribution with alkaline phosphatase. These observations indicate that the sequential determination and differentiation of the dental mesenchymal cells are characterized by a cascade of specific molecular changes. The cell surface proteoglycan syndecan and the Int-2 proto-oncogene are specific and transient markers of early dental mesenchymal cell differentiation. This information allows studies on the mechanisms of developmental regulation. These experimental tissue recombination studies indicate that the expression of syndecan and tenascin in the early dental mesenchyme is induced by the presumptive dental epithelium.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

[Immunohistochemistry of the distribution of alpha-tubulin in rat-incisor tooth germs and changes in it caused by vinblastine administration].

The present work used 2 groups of Wistar rats, weighing 100g each. Rats in the first group served as the controls; those in the second group were given 2 mg/kg of vinblastine in single intravenous injections. The animals were then fixed by perfusion with a mixture of 0.1% glutaraldehyde and 4% paraformaldehyde. After having been dissected out of the jaws, upper incisors were demineralized in EDTA and prepared into longitudinal sections (3 microns thick) for immunohistochemical demonstration of alpha-tubulin by means of indirect methods using an anti-alpha-tubulin monoclonal antibody as the primary antibody and peroxidase-labeled anti-mouse sheep IgG as the secondary antibody. 1. Control group. In controls, diffuse alpha-tubulin reaction was observed in the distal cytoplasm of inner enamel epithelial cells, differentiating ameloblasts, and ameloblasts in the stage of matrix formation. In the ameloblasts, the reaction was especially strong in the distal ends and Tomes processes in the matrix-formation stage. It gradually decreased until the transitional stage, in which the ameloblasts regained intense reaction to alpha-tubulin. Reaction to alpha-tubulin was generally low in the enamel-maturation stage in both smooth-ended and ruffle-ended ameloblasts but grew somewhat intense in the stage in which ferritines were precipitated in the cells. Although dental papilla cells reacted only faintly to alpha-tubulin, when they started differentiating into odontoblasts, reaction grew stronger in their distal end regions and in processes extending from the distal ends into the dentin. But this reaction decreased and ceased at a middle dentin level. Fairly high reaction was observed in the cells of the outer enamel epithelium, the stratum intermedium, the stellate reticulum, the papillary layer, the pulp and the dental sac. 2. Experimental group. Reaction to alpha-tubulin described in the preceding sections generally decreased in from 1 to 6 hours after vinblastine administration. Reaction recovery appeared to begin at from 12 to 24 hours and almost reached control degree by 48 hours after administration. Following the decrease of alpha-tubulin reaction in ameloblasts and odontoblasts, their shapes and polarities changed dramatically. In other cells, however, in spite of decreased alpha-tubulin reactions, no noticeable morphological alteration took place.

Animals↗
PubMedDate not supplied

[Effects of Anhidrin on dog's dental pulp in vivo].

The purpose of the article was to investigate in vivo effects of Anhidrin, a cavity cleansing agent, on dog's dental pulp. Following class V cavity preparation, with a depth referred to caries media, dentine walls were cleaned with Anhidrin. Cavity floor was lined with denatured dentine powder and permanently filled with silver amalgam. Animals were sacrificed after experimental period of 14, 45 and 90 days, respectively. Decalcified tooth sections were prepared by standard histologic technique stained with HE. The results achieved using light microscopy showed the most intensive changes in pulp tissue beneath cavity preparations treated with Anhidrin 14 days postoperatively, characterized with hyperaemia and bleeding in odontoblast and subodontoblast layer, reduction in odontoblast number and disturbed cell arrangement. In the second experimental period after 45 days, the changes were less expressed. Ninety days after the operation pulp tissue appeared in normal histologic structure of sound dental pulp, with significant layers of tertiary dentine beneath the area of cavity preparation and application of Anhidrin.

Animals↗
PubMed1989

Freeze-dried bone in pulpotomy procedures in monkey.

The purpose of this study was to evaluate the effect of freeze-dried bone on amputated pulps. Fifteen primary and one permanent monkey teeth were treated with freeze-dried bone. As the control group, another fifteen primary teeth were treated with calcium hydroxide and fifteen primary and one permanent teeth with formocresol. Four other primary teeth pulps were amputated and sealed with tin foil and IRM as controls. Twelve mandibular incisors were left intact. Histologically all but three teeth treated with human freeze-dried bone after three months showed a complete or partial calcific barrier directly below the amputation site. Normal appearing odontoblastic cells were noted below the calcific barrier. The apical third was vital with an occasional chronic inflammatory cell visible. The histological findings of teeth treated with calcium-hydroxide were very similar to freeze-dried bone. All but four teeth showed a complete calcific barrier at the amputation site. The odontoblastic cells were normal in appearance and the inflammatory cell reactions decreased from the middle portion toward the apical region. The histological evaluation of the formocresol-treated teeth was comparable with previously published studies.

Animals↗
PubMed1989

[The structure and ultrastructure of the pulp in Vipera aspis (Viperidae)].

The present paper using classical and transmission electron microscopy brings the first data on the pulp of the fangs of Viperidae (poisonous serpents with terrestrial or semi-aquatic habits). The pulp of the fangs of Viperidae shows a poor collagen and fibroblast content and a high developed vascular system. The odontoblasts are polarized, with a high organelle content. The interconnections are constituted of lateral "gap junction" systems. At a late secretion stage, the odontoblastic processes show a poor cytoplasm, mainly constituted of microfilaments.

Animals↗
PubMed1979

Buccal organogenesis in Pleurodeles waltlii Michah (urodele amphibian). Study by intrablastocelic transplantation and in vitro culture.

Various embryonic areas liable to take part in the mouth's formation are extirpated from neurulae of Pleurodeles at stages 15 and 18 and tested either separately or in association with others. The comparison of the results obtained by the transplantation into the gastrula blastocele of the same species and in vitro culture allows us to define the conditions for organogenesis of buccal structures. The formation of complete mouths can be obtained by association of the stomodeal area with neural fold, precordal mesoderm and lateral cephalic mesoderm. The formation of opening alone can only be obtained in transplantation through interaction of stomodeum with lateral mesoderm of the host. The mouth opening and complete mouth formation therefore can be dissociated and seem to be two different steps. The buccal structures (bones, cartilages and teeth) were never produced separately. Their differentiation depends on interactions of the stomodeal endoderm together with the neural fold. The neural crest is the source of the one hand of mesenchyme operating in the formation of the buccal opening and on the other hand of cells predetermined to provide chondroblasts and odontoblasts. The differentiation of chondroblasts and odontoblasts is dependent on the stomodeal endoderm. The latter also induces the ectoderm to form a buccal opening. The schema of the Pleurodeles buccal organogenesis we propose is compared to that of Cusimano (1972) for Discoglossus.

Amphibians↗
PubMed1986

[Odontogenic myxoma. A histoenzymologic and ultrastructural study. Apropos of 5 cases].

The myxoma of the jaws represent 8% of the odontogenic tumours in our series (324 cases). The 5 cases described here were studied by histoenzymological and electron microscopic methods. The first method demonstrated in the majority of tumoral cells a high level of activity of alkaline phosphatases and ATPases similar to that noted in odontoblasts of the dental pulp. In addition, an acid phosphatase activity was also present in numerous cells but usually at a low intensity. Ultrastructurally, the tumour was composed of 3 main cellular types: young round cells with numerous ribosomes; stellate secretory cells with well-developed granular ergastoplasma and Golgi apparatus; fusiform cells with characteristics of fibroblasts. Some macrophages and myofibroblasts were also present. The intercellular substance was granulofilamentous and in one of our cases calcifications were obvious upon some collagen fibers. All these results seem to corroborate the hypothesis of odontogenic nature of the tumour. Early odontogenic induction induces the transformation of fibroblasts into cells with enzymatic activities similar to those of odontoblasts and the calcification of collagen fibers seen in one of our cases would express an early mineralization.

Esterases↗
PubMed1979

Industrial fluoride pollution. Chronic fluoride poisoning in Cornwall Island cattle.

An aluminum plant on the south bank of the St. Lawrence river, southwest of Cornwall Island, Ontario, Canada, has emitted 0.816 metric tons of fluoride daily since 1973; considerably higher amounts were emitted from 1959 to 1973. The plant has been designated as the "major source of fluoride emissions impacting on Cornwall Island." Chronic fluoride poisoning in Cornwall island cattle was manifested clinically by stunted growth and dental fluorosis to a degree of severe interference with drinking and mastication. Cows died at or were slaughtered after the third pregnancy. The deterioration of cows did not allow further pregnancies. Fluoride concentrations in ash of biopsied coccygeal vertebrae increased significantly with age and were dependent on distance from and direction to the aluminum plant. Fluoride in bone ash of a 7-month old-fetus exceeded 500 ppm; fluoride thus was passed transplacentally. Analyses of fluoride in ash of bones obtained at necropsy of cattle from 4 months of age to 4 to 5 years of age showed increased amounts with age. Cancellous bone retained far higher amounts than cortical bone, a reflection of the normally higher metabolic rate of cancellous bone. Concentrations exceeding 10,000 ppm fluoride were recorded in cancellous bone of a 4-to 5-year-old cow. The target cells for fluoride in chronic fluorosis were shown to be the ameloblasts, the dental pulp cells and the odontoblasts and, in bone, primarily the resorbing osteocytes and also the osteoblasts. Atrophy and necrosis of the ameloblasts were responsible for enamel defects. The existing enamel showed brown discoloration from fluoride deposits. The pulp cells underwent fibrous and osseous metaplasia and necrosis of the ectopic bone occurred. The odontoblasts were atrophic and the dentin showed brown discoloration. The resorbing osteocytes were inactive and osteosclerosis resulted. This was especially pronounced in areas of normally great apposition, i.e. in the metaphyses. The epiphyseal plate became squeezed between petrotic bone and growth was stunted. Resorption of alveolar bone surrounding the deciduous teeth was severely retarded or arrested. A delay in eruption of permanent teeth occurred; it was up to 3.5 years in incisor teeth. Interference with the resorbing osteocytes in fluorotic bone was also demonstrated by loss of collagen birefringency in such bone. Failure of bone resorption also caused retention of trabecular bone in the cortices; this was observed even in a 4-t0-5-year-old cow. In areas where modeling into osteonic bone had begun, fluoride deposits were extremely heavy but this bone showed numerous soft osteons in microradiographs. The toxic effect of fluoride on osteocytes also resulted in the death of the cells. Such osteonecrosis occurred mainly in gnathic bone. There was atrophy of the osteoblasts. Osteopenia thus resulted from osteonecrosis and osteoporosis. Subperiosteal exostoses were not observed in long bones. The degree of fluorosis in Cornwall Island cattle was severe...

Air Pollutants↗
PubMed1983

Autoradiographic study using 3H-thymidine on rat incisal pulp cells in vitro.

An autoradiographic study using 3H-thymidine (3H-TdR) was carried out to investigate which cells migrate from the pulp explant of the rat incisor in vitro. The cells close to the arterioles (perivascular cells) were especially labeled after 3H-TdR incubation following the dissection of the pulp explant. In tracing these 3H-TdR-labeled perivascular cells, about 15 per cent of the outgrowth cells were the perivascular cells after 2 days of culture and these perivascular cells had a high mitotic activity in vitro. On the other hand, it was ascertained that the odontoblasts in the pulp explant underwent necrotic changes and that the odontoblasts had no ability to migrate from the pulp explant.

Animals↗
PubMed1981

The effects of nicotine on mouse first molar tooth germs in organ culture.

Mandibular first molars, extirpated from 18-day mouse fetuses were cultured in BGJb medium (Fitton-Jackson modification) in a Trowell type culture system. Two-day cultures were treated with 78, 117, 156, and 312 microgram/ml nicotine sulfate. Untreated control tooth germs demonstrated normal growth in vitro. The peripheral cell layer of mesenchymal papilla and the inner enamel epithelium differentiated into odontoblasts and ameloblasts respectively with subsequent elaboration of extracellular matrix. Tooth germs treated with 78 microgram/ml nicotine were only slightly affected where as higher doses of the drug produced extensive cell damage. Dental papilla appeared more sensitive than the enamel organ. Large necrotic foci were present in the pulp mesenchyme involving in some cases the odontogenic layer and severely limiting production of predentin. The basement membrane in these areas was partially disrupted and stained poorly for PAS. The inner enamel epithelium was not affected by 78 microgram/ml dose of nicotine, however, higher doses produced extensive cell necrosis in this layer. Although enamel matrix was abundantly present in untreated controls, the tooth germs exposed to 117, 156, and 312 microgram/ml nicotine sulfate failed to elaborate this extracellular matrix. Tooth germs exposed to nicotine for 24 hours followed by culturing in control medium demonstrated complete recovery. Treated cultures maintained in vitro for 7-9 days in control media had replaced the necrotic cells in the ameloblastic and odontoblastic layers and demonstrated abundant dentin and enamel matrices.

Animals↗
PubMed1995

Root formation.

This paper provides an overview of recent studies that have enhanced our understanding of the biological mechanisms that operate during root development. For the most part, these studies have been performed on rodents. As significant species differences have been shown to exist, this data cannot necessarily be extrapolated to the human model. The events associated with root odontoblast differentiation are reviewed in comparison to similar events in coronal odontoblast differentiation. Morphological as well as phenotypic differences are outlined and the inductive role of the epithelial root sheath is discussed. Both acellular and cellular cementum formation are reviewed highlighting morphological and phenotypic differences. The potential influence of the epithelial root sheath in the formation of both tissues is compared and contrasted. Finally, a discussion of the fate of the epithelial root sheath is presented with emphasis placed upon the possible roles of apoptosis and epithelium-mesenchymal transition.

Animals↗
PubMed1994

Effects of fluoride on dental pulp of young rabbits.

Fluoride has been adopting as an anticariogenic agent for many years. Many histologic experiments with the effect of fluoride were made on dental hard tissue, but little is known about its effect on dental pulp. We made histopathological tests on dental pulp of rabbits during administration of fluoride. In this study, 24 young New Zealand rabbits aged 7 days were used. The experimental group (N = 20) was given two intraperitoneal injections of sodium fluoride that contained approximately 7 mg F/kg body mass. The control group (N = 4) was injected with an equivalent volume of normal saline. At the thirteenth day after the final injection, the mandibles were collected and processed according to routine histologic methods. Selected sections were stained with hematoxylin and eosin stain. The mandibular incisor pulp was microscopically examined. The following results were obtained. In the experimental group, histopathologic alterations were observed in the pulp, with loss of palisading of the odontoblastic layer. Slightly elongated swollen odontoblasts were found which showed hydropic alterations. Dilatation and hyperemia of blood vessels were also noted. This dose affected deciduous root resorption and changes in secretory ameloblasts; and also appeared to disturb the dental pulp. The present observations of initial reactions in the pulp following intraperitoneal injection of fluoride are considered suitable as a basis for detailed discussion of histopathologic implications.

Animals↗
PubMed1994

Immunolocalization of connexin 43 in the tooth germ of the neonatal rat.

Rabbit polyclonal antibodies to amino acids 346-360 of connexin 43, the 'heart' gap junction protein, were employed to immunolocalize connexin 43 gap junctions in the neonatal rat molar tooth germ. Connexin 43 appears early in the differentiation of both ectodermally derived and ectomesenchymally derived cells of the developing tooth. Connexin 43 immunoreactivity is present in the epithelial components of the enamel organ, including the area of the proximal and distal junctional complexes of the ameloblast layer, and the stratum intermedium, stellate reticulum and outer enamel epithelium. Secretory odontoblasts and developing alveolar bone also display a pattern of connexin 43 immunostaining. Both the epithelial and ectomesenchymally-derived components of the developing tooth acquire connexin 43 channels in a manner that correlates with cell differentiation. In addition, three regions can be defined by connexin 43 immunostaining: the epithelia of the enamel organ that are derived from the oral epithelium, the odontoblast layer derived from the ectomesenchyme, and the alveolar bone. The results suggest that connexin 43 may provide the mechanism for functional compartmentalization of the tissues associated with tooth formation. Compartmentalization suggested by connexin 43 expression could play important roles in the development and functions of these tissues.

Animals↗
PubMed1994

Histopathological investigation of the effects of various glass-ionomer cements on dental pulp.

In this study, an attempt was made to examine the effects of 4 glass ionomer cements on pulp. For this purpose, 30 incisors from 3 dogs were employed. Glass-ionomer cements commercially known as Ketac-bond, Kromoglass 1, Vitrebond and Logobond WM were administered in Black Class V cavities drilled on the vestibular surfaces of the teeth, with zinc oxide/eugenol cement being applied to a control group. Teeth were extracted at 7, 30 and 90 days and assessed accordingly. The pulpal tissues of the teeth were reviewed under light microscope with respect to odontoblastic activity, odontoblast aspiration, fibrosis, vascularization and erythrocyte accumulation, presence of inflammatory cells, necrosis, and reparative dentine. Various findings were obtained from 4 different glass-ionomer cements, which were evaluated according to the criteria stated above; however, in no section were inflammatory cells or necrosis encountered. Therefore, none of the substances utilized in our study was found to have an excessive toxic effect on pulpal tissue.

Animals↗
PubMed1985

Effects of 1-hydroxyethylidene-1, 1-bisphosphonate (HEBP) on the formation of dentin and the periodontal attachment apparatus in the mouse.

The effects of the bisphosphonate HEBP on dentin formation and the structural relationship between the dentin and the developing periodontal attachment apparatus have been studied in the continuously growing mouse incisor. It was observed that HEBP (in doses greater than or equal to 8 mg P/kg b.w/day) not only inhibited the deposition of mineral crystallites in newly formed dentin matrix, but also entirely prevented the formation of a layer of acellular root cementum. It was further noticed that the drug interfered with the deposition of 3H-serine-containing substances at the predentin-dentin border. This was not always accompanied by an inhibition of dentin mineralization, thereby suggesting that 3H-serine-containing proteins (presumably phosphoproteins) do not play a critical role in the deposition of mineral layers onto previously formed ones. The absence of a cementum layer did not prevent the developing periodontal ligament from establishing matrix-to-matrix connections with the root-analogue dentin. Collagen fibrils of the ligament intermingled with those of the mantle dentin, which in contrast to teeth not exposed to the drug were clearly visible and not masked by electron-dense matrix components. Finally, it was found that the drug had distinct effects on the formation of root-analogue and crown-analogue dentin. Whereas during the course of the experiment the odontoblasts along the crown-analogue aspect of the tooth continued to produce circumpulpal dentin matrix, those along the root-analogue aspect of the tooth did so only when the mantle dentin layer had been mineralized prior to HEBP administration. This phenomenon is interpreted as being indicative of fundamental differences between the formation of crown and root dentin.

Animals↗
PubMed1980

Microtubule and microfilament populations of cell processes in the dental pulp.

An attempt has been made to characterize the nature of the unidentified cell processes participating in gap junctions in the odontoblast layer. In peripheral and pulpal nerves, there is a strong relationship between together with the ratio of microtubules to microfilaments, has been measured and compared for four types of cell processes found in the dental pulp, including those participating in gap junctions. The processes taking part in the gap junctions cannot be distinguished from pulpal axons on the basis of microtubule-to-microfilament ratio nor on the relationship between microtubule and microfilament population and process caliber. While these findings do not prove that the "gap members" are nerve fibers, it does support the hypothesis that the processes taking part in gap junctions in the peripheral dental pulp are nerve fibers.

Animals↗