Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “ODONTOBLASTS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 1,099 records · Page 61Linked to original sources
PubMedDate not supplied

Hexachlorobenzene-induced incisor degeneration in Sprague-Dawley rats.

Hexachlorobenzene (HCB) was administered to female Sprague-Dawley rats in a 13-week toxicity study conducted for the National Toxicology Program (NTP). Groups of 10 rats were treated by gavage with 0.0, 0.03, 0.1, 0.3, 1.0, 3.0, 10, or 25 mg/kg HCB in corn oil 5 days/week for 13 weeks. Dose-dependent, region-specific, maxillary incisor degeneration was observed in animals given HCB at doses of 1.0 mg/kg/day and higher. Treatment with 1.0 mg/kg/day resulted in focal mesenchymal cell vacuolation and focal osteodentin formation within the pulp. Lesions were restricted to a short linear region subjacent to the odontoblast layer along the lateral aspect of the incisor at the level of the dentin-enamel interface. When observed in both incisors, lesions were bilaterally symmetric. Treatment with 3.0 mg/kg/day resulted in lateral and medial pulp lesions and focal odontoblast degeneration with dentin niche formation along the lateral incisor margin in some animals. Treatment with 10 mg/kg/day resulted in a higher incidence of lateral dentin niches and a low incidence of medial dentin niches. In animals treated with 25 mg/kg/day, a high incidence of bilaterally symmetric, lateral and medial, dentin niches were observed. The morphology and distribution of HCB-induced incisor lesions in rats are consistent with injury to a selective population of preodontoblasts.

Administration, Oral↗
PubMed2002

Transcriptional regulation of dentin matrix protein 1 (DMP1) by AP-1 (c-fos/c-jun) factors.

Dentin matrix protein 1 (DMP1) is an extracellular matrix phosphoprotein whose expression is precisely controlled temporally and spatially during the differentiation of the odontoblasts. Odontoblasts are postmitotic cells that differentiate to mature polarized cells and are responsible for the synthesis of a calcified dentin matrix. Although the DMP1 promoter has been isolated from the mouse and the rat, little is actually known about their control by specific transcription factors. Analysis of the rat DMP1 promoter has identified several regulatory transcription factors. These factors include AP-1 family members, SP1 and ETS. Therefore the transcription of DMP1 may be controlled positively or negatively by a variety of stimuli resulting in a developmentally regulated gene expression. This study demonstrates the role of c-fos and c-jun on the transcriptional regulation of DMP1 gene.

Animals↗
PubMed2002

Extracellular matrix proteins and the dynamics of dentin formation.

Dentinogenesis involves controlled reactions that result in conversion of unmineralized predentin to dentin when apatite crystals are formed. This process is dynamic: Maturation events occur within predentin beginning at the proximal layer and progressing to the predentin-dentin (PD) border. One type of controlled reaction is the proteolytic processing of dentin sialophosphoprotein (DSPP) to dentin sialoprotein (DSP) and dentin phosphoprotein (DPP), by cleavage of at least three highly conserved peptide bonds. We postulate that this processing event represents an activation step, resulting in release of DPP, which is active in its effects on formation and growth of apatite crystals. Dentin matrix protein 1 (DPM1), present as a processed fragment (57-kD protein) in bone, is seen in dentin on sodium dodecyl sulfate polyacrylamide gel electrophoresis as one intact protein of 150-200 kD. Anti-57-kD antibodies elicit immunoreactivity in bone, dentin, and cellular cementum. In bone, the reactivity is associated with osteocytes and their cell processes. Similarly, dentin shows reactivity in odontoblasts, predentin, and the odontoblast processes. In summary, the processing of large sialic acid-rich proteins into smaller fragments may be an important part of the controlled conversion of predentin to dentin and osteoid to bone.

Animals↗
PubMed2002

In vivo and in vitro expression of connexin 43 in human teeth.

Gap junctions are composed of transmembrane proteins belonging to the connexin family. These proteins permit the exchange of mall regulatory molecules directly between cells for the control of growth, development and differentiation. Although the presence of gap junctions in teeth has been already evidenced, the involved connexins have not yet been identified in human species. Here, we examined the distribution of connexin 43 (Cx43) in embryonic and permanent intact and carious human teeth. During tooth development, Cx43 localized both in epithelial and mesenchymal dental cells, correlated with cytodifferentiation gradients. In adult intact teeth, Cx43 was distributed in odontoblast processes. While Cx43 expression was downregulated in mature intact teeth, Cx43 appeared to be upregulated in odontoblasts facing carious lesions. In cultured pulp cells, Cx43 expression was related to the formation of mineralized nodules. These results indicate that Cx43 expression is developmentally regulated in human dental tissues, and suggest that Cx43 may participate in the processes of dentin formation and pathology.

Adolescent↗
PubMed2003

Growth of porcine enamel-, dentin-, and cementum-derived cells in collagen-glycosaminoglycan matrices in vitro: expression of alpha-smooth muscle actin and contraction.

The objective of the study was to investigate the behavior of porcine enamel, dentin, and cementum cells, isolated from tissue digests and growing out from explants, in monolayer culture and in a collagen-glycosaminoglycan (GAG) matrix for tissue engineering. A notable finding of the study was the expression of a contractile muscle actin isoform, alpha-smooth muscle actin (SMA), by each cell type and their contraction of the collagen-GAG scaffold. Of importance was the immunohistochemical demonstration that the majority of ameloblasts and odontoblasts in vivo contained SMA. Western blot analysis demonstrated the presence of SMA in all of the cell types. A large amount of SMA was found in the odontoblasts after the first passage. SMA expression in the enamel- and cementum-derived cells appeared to increase with time in culture and with passage number. The implications of this finding for tissue engineering and the possible roles for SMA in dental tissue cells are discussed.

Actins↗
PubMed2007

Effects of a new antibacterial adhesive on the repair capacity of the pulp-dentine complex in infected teeth.

AIM: To evaluate the effects of a self-etching/priming adhesive system, containing the antibacterial monomer 12-methacryloyloxy-dodecylpyridinium bromide (MDPB), on the repair capacity of the pulp-dentine complex in infected cavities in dog's teeth. METHODOLOGY: Class V cavities with a residual dentine thickness ranging from 0.3-0.8 mm were prepared on the buccal surface of permanent teeth in four dogs. Pulpal exposures were performed in half of the cavities. Millipore filters that had been incubated for 3 h in a 10(5) milky suspension of a-streptococci were placed in the cavities, which were then filled temporarily. After 24 h, the filters were removed and both the exposed and non-exposed cavities were washed with sterile saline and assigned to four groups which were treated with either the experimental antibacterial adhesive system, or Clearfil SE bond, Dycal and Teflon discs. Stereotype connective tissue reactions (inflammatory cell response and/or tissue necrosis) and pulp-specific reparative tissue responses (reduction of odontoblasts and tertiary dentine formation) were assessed at post-operative periods of 4 and 8 weeks. RESULTS: Neither severe inflammation nor tissue necrosis was observed, either in the dentinal cavities or pulpal exposures treated with the self-etch adhesive containing MDPB. Rates of tertiary dentine formation in infected dentinal cavities treated with this system were comparable with those observed after dentine treatment with the Ca(OH)2-based material. Dentinal bridging was not seen in pulpal exposures treated with the experimental adhesive. CONCLUSIONS: The new antibacterial adhesive system maintained pulp vitality and primary odontoblastic function in infected nonexposed and exposed cavities but interfered with reparative dentine formation in infected pulpal exposures.

Animals↗
PubMed1990

Chondroitin sulfates in developing mouse tooth germs. An immunohistochemical study with monoclonal antibodies against chondroitin-4 and chondroitin-6 sulfates.

The role of glycosaminoglycans and proteoglycans during ontogenesis is not known. The developing tooth offers a potentially important model for studies of structure-function relationships. In this study, we have analysed the temproal and spatial expression of chondroitins of differing sulfation patterns in embryonic molars and incisors. For this purpose, we have used monoclonal antibodies (Mabs) specific for unsulfated, 4-sulfated, and 6-sulfated forms of chondroitin in conjunction with indirect immunofluorescence or immunoperoxidase labeling. Unsulfated chondroitin was not detected in embryonic teeth. Chondroitin 4- and chondroitin 6-sulfates were present in the stellate reticulum but otherwise they were confined to the dental mesenchyme. The 3B3 and MC21C-epitope, which are markers of 6-sulfated chondroitin, were uniformly distributed in the dental mesenchyme during the bud stage; they disappeared from the dental papilla of the cusps and of the anterior region of the incisor as development proceeded. These epitopes were absent from the basement membrane and from the predentin. In the odontoblastic cell lineage, the 3B3 and MC21C-epitopes were detected only between preodontoblasts at an early stage of differentiation. The monoclonal antibody 2B6 served as a probe to localize chondroitin 4-sulfate. This glycosaminoglycan was detected as early as the dental lamina stage but its expression was restricted to the basement membrane of the teeth until the late bell stage. After the onset of cusp formation, strong staining was also observed over the occlusal region of the dental papilla while the cervical region of the dental papilla remained 2B6-negative. Incisors at the bell stage exhibited a decreasing gradient of immunostaining by 2B6 from their anterior region to their posterior end. The extracellular matrix surrounding preodontoblasts reacted with 2B6 and the predentin, produced by the odontoblasts, was also intensely labeled with this antibody. Comparison between immunostaining with 3B3 and 2B6, on consecutive sections revealed a mutually exclusive pattern of distribution of the corresponding epitopes during odontogenesis. Furthermore, in the continuously growing incisor, a striking positive correlation was found between the immunostaining patterns produced by 3B3 and MC21C and the mitotic indices along the anterior-posterior axis of the tooth. Hence, sulfation of chondroitin seems developmentally regulated. We postulate that changes in the sulfation pattern of chondroitin might play a role in ontogenesis by locally altering the functional properties of the extracellular matrix.

Animals↗
PubMed1992

Immunohistochemical localization of nerve growth factor (NGF) and NGF receptor (NGF-R) in the developing first molar tooth of the rat.

Nerve growth factor (NGF) is a well established target-derived trophic factor supporting sympathetic and sensory innervation in the peripheral tissues as well as cholinergic innervation in the brain. Despite its name, NGF may have broader biological functions early in development in a wide range of non-neuronal differentiating cells. The many effects of NGF are directly dependent on initial binding of NGF to specific plasma membrane receptors on target cells. Here we use immunohistochemical methods to show that NGF and its receptor (NGF-R) are localized in a variety of embryonic epithelial and mesenchymal cells in the rat developing molar tooth. Dental cells known to play important roles in morphogenesis and inductive tissue interactions show NGF-like reactivity. Thus, labelling is seen in epithelial preameloblasts and mesenchymal odontoblasts. We also show a transient expression of NGF-R in restricted parts of the dental epithelium (inner dental epithelium) and dental mesenchyme differentiating cells (post-mitotic, polarizing odontoblasts). The expression patterns of NGF are different to those of NGF-R during embryogenesis and this is illustrated in detail in the developing tooth. The histochemical findings reported here support the notion that NGF may have multiple roles during morphogenetic and cytodifferentiation events in the tooth.

Animals↗
PubMed2005

TGF-beta3 induces ectopic mineralization in fetal mouse dental pulp during tooth germ development.

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.

Animals↗
PubMed1996

Identification of the cell type origin of odontoma-like cell masses in microphthalmic (mi/mi) mice by in situ hybridization.

Tooth abnormalities occur in microphthalmic (mi/mi) mice. The elongated odontogenic epithelium is interrupted by unresorbed bone at the basal end of the mi/mi incisor, with the epithelium gathered into cell clusters. These clusters develop to odontoma-like masses. To identify the origin of the cell types of these odontoma-like masses, the localization of osteonectin (Osn), osteocalcin (Osc), osteopontin (Osp), matrix Gla protein (MGP) and amelogenin (Am) mRNA in the process of tooth development in mi/mi and +/+ mice was investigated by means of in situ hybridization. Decalcified mandibles of neonatal, 5-, 10-, 14-day-old mice were examined. Osn and Osc mRNA, which localized in osteoblasts and odontoblasts, were also detected in the cells of odontoma-like masses in mi/mi mice. The cells expressing these mRNA were short, columnar and odontoblast-like. Am mRNA was detected in ameloblasts. In mi/mi mice, Am mRNA was also detected in ameloblastic cell clusters, which were formed by the tall columnar cells in the odontoma-like masses. No apparent Osp mRNA expression was detected in the masses. These results indicated that even in odontogenic abnormal cells resulting from physical obstruction in mi/mi mice, the genes that are involved in normal tooth development were still expressed.

Animals↗
PubMed1984

Effects of vitamin A deficiency on rat incisor formation.

Vitamin A deficiency (A-) is known to cause morphologic changes in tooth structures. However, its effects on glycosaminoglycan (GAG) distribution in dental pulp, and the role of retinoic acid (RA) in altering these effects are not clearly defined. Tissue changes induced by vitamin A deficiency and RA administration were evaluated histologically in incisors of rats fed on one of 3 different diets: a) vitamin A sufficient (A+); b) vitamin A deficient (A-); and c) vitamin A deficient supplemented with retinoic acid (A-/RA). Four weeks after the onset of vitamin A deficiency, all rats were killed and their 4 continuously erupting incisors evaluated histologically. A- rats had altered dentine and pulp with disrupted histodifferentiation of pulpal mesenchymal cells to normal odontoblasts. The frequency of these abnormalities in dentine and pulp was lower in A-/RA rats. The enamel organ was unremarkable in the 4-week deficient period. Using special stains, we noted that pulpal GAG accumulation in A- and A-/RA rats was limited to the lingual area, while in A+ rats, GAG were distributed throughout. These data suggest that vitamin A deficiency affects histodifferentiation of pulpal mesenchymal cells to odontoblasts, as well as GAG distribution in pulp. RA administration reduces the A- changes and therefore, appears to have some activity in dentinogenesis.

Animals↗
PubMedDate not supplied

Apoptosis in human and rat dental pulp.

Apoptotic cells were visualized in human premolar and rat molar pulps using either the TUNEL method, which stains DNA strand breaks by in situ nick end labeling, or labeling sections with an anti-transglutaminase antibody. Apoptotic cells were evident at the periphery of the pulp, mostly in a sub-odontoblastic location, and were more numerous in the crown than in the root region of the pulp. Most odontoblasts were unlabeled. A few apoptotic nuclei in the pulp of rat molars displayed the characteristics of chromatin condensation, as observed by electron microscopy. Many cell debris resembling apoptotic bodies were also observed. The 3 methods support the occurrence of apoptosis in the dental pulp. As this phenomenon was observed in healthy teeth apoptosis is probably involved in the regulation of the pulp cell population.

Animals↗
PubMed1998

Six decades of dentinogenesis research. Historical and prospective views on phosphophoryn and dentin sialoprotein.

The molecular basis underlying the mineralization process associated with the conversion of predentin to dentin is poorly understood. What is clear is that a unique set of non-collagenous proteins (NCPs) participate in the nucleation process and in hydroxyapatite growth during dentin formation. Phosphophoryn (PP), the most abundant NCP in dentin, is secreted by odontoblasts and appears at the mineralization front. Dentin sialoprotein (DSP), another NCP, also appears at the mineralization front, but only accounts for 5-8% of the weight of dentin NCPs. Functionally, PP is believed to be directly involved in tile nucleation process by virtue of its ability to bind to collagen type I, and its high affinity for calcium ions. Based on the analysis of the putative rat PP amino acid sequence, this latter activity is believed due to the highly phosphorylated character of PP, which results from the dual actions of casein kinases I and II at selected domains within PP. The precise role of DSP is currently unknown. In situ studies demonstrate that DSP is substantially expressed in odontoblasts and transiently expressed in preameloblasts. However, no information is currently available to directly explain DSP's role in mineralization. Genetically, we and others have now identified a novel DSP-PP bicistronic mammalian transcriptional unit, suggesting that the functional roles of these two NCPs may also be tightly coupled with respect to dentinogenesis. Certainly, further exciting studies are now needed to explain how this DSP-PP transcriptional unit is finally expressed: whether DSP and PP associate with one another, or with collagen at the mineralization front: and how selective mutations in either gene may influence dentin mineralization.

Amino Acid Sequence↗
PubMed2005

Activation of the Notch signaling pathway in response to pulp capping of rat molars.

Notch signaling is an evolutionarily conserved pathway that controls the developmental choices made by individual cells. Cells communicate via Notch receptors and their ligands, which direct decisions on the fate of stem cells according to the states of their neighbors. In this study we explored Notch signaling after the pulp capping of adult first upper rat molars. The wound was capped with calcium hydroxide. In situ hybridization revealed an increased expression of Notch signaling genes on day 1, which showed a tendency to decrease on day 3. Notch1 increased in the subodontoblast zone and close to the lesion limited to a few cells. Notch2 increased in pulp stroma surrounded by coronal odontoblasts. Notch1 and, especially, Notch3 expression increased, corresponding to perivascular cell groups. A low increase of ligand expression was observed near the injury with Delta1 expression along the dentin wall and Jagged1 in the stroma. Expression of the downstream target, Hes1, was observed along the lesion and adjacent dentin walls. Hes5 expression was not observed. The results indicate that Notch signaling is activated in response to injury and associated with the differentiation of pulp cells into perivascular cells and odontoblasts. The findings are consistent with the concept that the Notch pathway controls stem cell fate during pulp regeneration.

Animals↗
PubMed1997

Expression of osteocalcin in cementoblasts forming acellular cementum.

To determine the phenotypic expression of cementoblasts responsible for acellular cementum, an immunohistochemical study was performed using a polyclonal antibody raised against the aminoterminal peptide of rat osteocalcin (OC). Maxillary first molars of Wistar male rats aged 2 and 3 wk were used for observations. Serial sections of decalcified paraffin embedded specimens were stained either with hematoxylin and eosin or with the anti-OC antibody. In 2-wk-old rats, apical roots were lined with the epithelial root sheath. A thin layer of acellular cementum was seen at most of the root surface, but was not seen near to root apex. In 3-wk-old rats, cellular cementum began to be formed at root apex, and acellular cementum became more thick than in 2-wk-old rats. Acellular and cellular cementum were lined with the fibroblast-like cells. Osteocalcin staining was detected in cells lining root surface in both 2- and 3-wk-old rats. Almost all cells lining cellular cementum were positive for OC. In contrast OC positive cells lining acellular cementum and root surface devoid of cementum appeared at a specific site of the root. The cells at the interradicular area of root surface were positive but the cells at the outer area (the opposite side of the interradicular area) were negative for OC. Osteoblasts and odontoblasts were positive with the antibody. The present results suggest that the OC expression of cementoblasts forming acellular cementum is similar to that of cells forming cellular cementum as well as osteoblasts and odontoblasts, and has a role for calcification of acellular cementum.

Animals↗
PubMed1994

Histological observations of hard tissue barrier formation in amputated dental pulp capped with alpha-tricalcium phosphate containing calcium hydroxide.

This study was performed to evaluate the pulpal response to alpha-tricalcium phosphate (alpha TCP) containing calcium hydroxide (Ca(OH)2). The dental pulps of monkeys were amputated and dressed with four agents: alpha TCP, alpha TCP containing 1% Ca(OH)2, alpha TCP containing 5% Ca(OH)2, and Ca(OH)2 being used as a control. The pulpal responses were histologically evaluated after 4 and 8 weeks. The pulp tissue treated with alpha TCP proliferated above the level of the original wound surface, and a thin layer of hard tissue barrier was formed directly against the capping agent. The barrier demonstrated atubular matrix lined with flattened or cuboidal cells, but occasionally appeared irregular in form. Ca(OH)2 dressing resulted in destruction of pulp tissue, with a thick hard tissue barrier being formed below the level of the exposure site. The barrier consisted coronally of osteodentin and pulpally of tubular dentin lined with odontoblast-like cells. By contrast, 1% Ca(OH)2 added to alpha TCP produced a slight proliferation of pulp tissue. An atubular matrix barrier, pulpally lined with cuboidal cells, formed above the exposure site. It was later followed by the formation of tubular matrix lined with columnar cells. Teeth treated with 5% Ca(OH)2 showed a thin necrotic layer and a thick barrier formation. The barrier was composed of tubular dentin-like tissue lined with odontoblast-like cells. It would appear that alpha TCP containing a small amount of Ca(OH)2 may be clinically useful as a capping agent, as it induced consistent hard tissue formation, without excessive destruction of underlying pulp tissue.

Animals↗
PubMed1998

Pulp and root development after partial extrusion in immature rat molars: a histopathological study.

Experimental studies were undertaken in immature rat molar teeth to investigate the relationship between root development and the prognosis after partial extrusion. The experimental partial extrusion was induced at 1/2 root formation, 2/3 root formation and 3/4 root formation, using an extrusion device designed by the author. Histopathological studies and SEM observation of the pulpal tissue in rat maxillary first molars with partially formed roots after partial extrusion were conducted and evaluated. The degree of extrusion was changed according to the development of the root to produce a similar luxated state. The rats were sacrificed immediately after experimental extrusion, immediately after operation, and after 3 days, 7 days, 14 days, 30 days, and 60 days to compare the histopathological and SEM findings between experimental groups and control groups. Immediately after the extrusive injury, ablations of the odontoblast layer from dentin were seen with retention of a fluid component in the ablated spaces in the pulp. On 1 and 3 days after surgery, cellular components such as erythrocytes and leukocytes due to bleeding were seen. Ablations of the odontoblast layer were seen in the coronal pulp most frequently in the pulp horn, cervical area and floor of the pulp chamber. In general, pulp reaction after extrusion in groups with more complete root formation was more severe than in groups with less complete root formation. It is suggested that the more complete the root formation, the greater the effect on the pulp as result of partial extrusion, while with less complete root formation, the greater the malformation of the root apices.

Animals↗
PubMed1995

Localization and expression of osteopontin in mineralized and nonmineralized tissues of the periodontium.

To summarize results from various studies focusing on determining the expression/localization of BSP and OPN during tooth root development, there is general agreement that OPN is expressed/localized to the root surface during cementogenesis and is also seen throughout the PDL region. The expression/localization of OPN to odontoblasts and its role in dentinogenesis is less apparent. Recent studies directed at establishing odontoblast cell lines should help to resolve this conflict. Studies on BSP expression during tooth root formation indicate a very precise expression and localization of this molecule during cementogenesis indicating that this molecule may play an important role in the formation of this mineralized tissue. However, as with OPN, the expression of BSP and its role in dentin formation is not clearly defined.

Animals↗