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At least 577 records · Page 32Linked to original sources
PubMed1988

The effects of colchicine on prostaglandin I2 and thromboxane A2 biosynthesis in the rat dental pulp.

Pulp tissues isolated from rats treated with either colchicine (0.5, 0.75 or 1.0 mg/kg) or beta-lumicolchicine (1.0 mg/kg) for 24 h were incubated in Tyrode buffer. Prostaglandin (PG) I2 and thromboxane (TX) A2 released into the medium were determined by radioimmunoassay as their stable metabolites, 6-keto-PGF1 alpha and TXB2, respectively. Colchicine generally enhanced PGI2 and TXA2 production concomitantly with hypocalcaemia, except that 0.5 mg/kg dosage had no significant effects. This enhancement was greater in PGI2 than in TXA2 synthesis, but was not observed in PGI2 release from aortic tissue. beta-Lumicolchicine (1.0 mg/kg) had no effect on PG and TX synthesis, nor on serum calcium. Kinetic studies revealed that after a lag period of more than 12 h, 1.0 mg/kg colchicine caused a progressive increase in the production of PGI2 and TXA2, which reached a maximum at 24 h and decreased thereafter gradually to the basal level within 168 h (7 days). In contrast, the hypocalcaemic effect of colchicine appeared rapidly, reached a maximum within 3 h and gradually recovered to the control level within 7 days. Colchicine at concentrations of 1-1000 microM had no stimulatory effect on PGI2 and TXA2 biosynthesis when incubated in vitro with isolated pulp tissues; it was inhibitory at higher concentrations. The enhancing effect of colchicine treatment on PGI2 and TXA2 production in dental pulp tissue may be caused indirectly by interaction of this agent with microtubules, but the precise mechanisms are unclear. Thus, a drug known to affect dentinogenesis modifies arachidonic-acid metabolism in dental pulp.

Animals↗
PubMed1990

An ultrastructural study of the differentiation of mesenchymal cells in implants of allogeneic dentine matrix on the amputated dental pulp of the dog.

The sequential transition of the cells adjacent to autolysed antigen-extracted allogeneic dentine matrix was observed in a cavity on the amputated pulp in vivo. One week post-operatively, cells having poorly developed organelles and many free ribosomes, reminiscent of dedifferentiated or embryonic cells, were seen in migration and forming attachments to the allogeneic dentine matrix. Two weeks post-operatively, the cells close to that matrix had polarized nuclei and a clear distal area with minute processes, suggestive of preodontoblasts. Matrix vesicles were observed in the newly formed predentine-like matrix close to the allogeneic matrix. Some of the matrix vesicles contained needle-like crystals. Four weeks post-operatively, long, polarized cells with a well-developed endoplasmic reticulum and Golgi apparatus were seen. They contacted via a terminal web with desmosomes and tight junctions, and each had a long process extending into the predentine-like matrix, suggesting that they were identical to odontoblasts. These findings suggest that in the repair of the amputated pulp implanted with allogeneic dentine matrix the differentiation of odontogenic cells and initial mineralization may be analogous to those in normal dentinogenesis.

Animals↗
PubMed1992

Amino acid composition of dentine in permanent human teeth.

Dentine of permanent mandibular incisors from nine individuals was hydrolysed and the amino acid composition determined by ion-exchange chromatography against a standard calibrant of 41 amino acids. Nineteen amino acids were detected, including small quantities of 1-methylhistidine and asparagine, two amino acids whose existence had apparently not been recorded before in human dentine. The total content of hydroxylysine plus lysine varied between 2.6 and 3.3 residues per 100 (SD, 0.74) in different teeth, which therefore did not support previous studies that had proposed a constant total value. This and other quantifiable differences between present and previous findings may be the result of the different methods and the influence of dietary and other regional factors on dentinogenesis.

Amino Acids↗
PubMed1980

Overdentures for treatment of severe attrition.

This treatment of dentinogenesis imperfecta presented many problems because of the severe attrition of the existing teeth. An overdenture may be used in similar situations of extreme attrition.

Adolescent↗
PubMed1978

Radiographic manifestations of an unusual combination Types I and Type II dentin dysplasia.

Dentin dyslasia is a rare autosomal dominant hereditary variant of dentinogenesis imperfecta. The primary defect is mesodermal and involves the dentin. Two types (Type I and Type II) of dentin dysplasia have been described previously. The current case presents radiographic findings which include characteristics common to both types. It is proposed that either a third type (Type III) be recognized or the variability of the developmental defect precludes definitive subclassification.

Adult↗
PubMed1995

Neurotensin-like immunoreactivity in odontoblasts and their processes in rat maxillary molar teeth and the effect of pulpotomy.

A strong neurotensin-like immunoreactivity (NT-like IR) was detected in the odontoblast cells of the rat teeth. 4 h after a partial pulpotomy performed in two maxillary molar teeth a decreased NT-like IR was observed in the odontoblast layer located at the vicinity of the lesion together with edema and nuclear pyknosis. NT-like IR became further decreased after 24 h. After 7 days NT-like IR had almost fully disappeared with signs of necrosis of the dental pulp and infiltration of polymorphonuclear lymphocytes. It seems possible that NT like peptides in the odontoblast cell layer may play a role, e.g., in dentinogenesis and/or nociception.

Animals↗
PubMed2004

TGF-beta activated Smad signalling leads to a Smad3-mediated down-regulation of DSPP in an odontoblast cell line.

OBJECTIVE: Transforming growth factor-beta (TGF-beta) regulates odontoblast differentiation and stimulates dentine extracellular matrix synthesis. However, until recently, the molecular mechanisms of action of TGF-beta have been unknown. Smad proteins have recently been identified as intracellular signalling mediators of TGF-beta. In this study, we characterise the role of Smad proteins as mediators of TGF-beta in a mouse odontoblast cell line MDPC-23. METHODS: Transcription of Smads was detected by RT-PCR. The change of intracellular location of Smad proteins treated by TGF-beta1 was evaluated immunocytochemically. Smad function and its role in transcription of dentin sialophosphoprotein (DSPP) were investigated in cotransfection experiments using promoter-luciferase reporter gene constructs. RESULTS: MDPC-23 cells expressed Smad2, Smad3 and Smad4 mRNA. Endogenous Smad2, Smad3 and Smad4 rapidly translocated from the cytoplasm into the nucleus in response to TGF-beta1. The activity of the TGF-beta-responsive p3TP-Lux reporter construct was stimulated by 12.7-fold with TGF-beta1 treatment. Over-expression of wild-type Smad3 promoted TGF-beta1-induced luciferase activity, whereas dominant negative Smad3 inhibited it. TGF-beta1 also inhibited the activity of DSPP promoter luciferase reporter construct containing the sequence between -791 bp and +54 bp of the mouse DSPP gene. Over-expression of wild-type Smad3 potentiate the inhibitory effect of TGF-beta1 on transcriptional regulation of DSPP, while dominant negative Smad3 decreased the effect. In contrast to Smad3, wild-type Smad2 or its dominant negative mutant had little effect on TGF-beta1 regulation of the promoter activity of DSPP. CONCLUSIONS: Smad2, Smad3 and Smad4 are present and activated by TGF-beta1 in MDPC-23 cells. The Smad pathway is functional in these cells and Smad3 appears to be involved in down-regulation of DSPP by TGF-beta1. These findings raise the possibility that Smad signalling plays a role in dentinogenesis.

Animals↗
PubMed2006

HGF enhanced proliferation and differentiation of dental pulp cells.

Hepatocyte growth factor (HGF) is mesenchymal-derived growth factor acting through a transmembrane tyrosine kinase receptor, c-met. HGF has multiple effects on different cells. However, its function in dentinogenesis remains unclear. In this study, the expression of HGF in human dental pulp cells (DPCs) in vitro was studied by immunostaining and RT-PCR. The effect of HGF on DPCs proliferation was determined by MTT, while its effect on cell differentiation was analyzed using ALPase activity, and further confirmed with ALP and DSPP mRNA and protein expression. Immunostaining revealed that HGF was found mainly in the cytoplasm of DPCs. RT-PCR analysis showed that both HGF and c-met were expressed from the DPCs. Exogenous addition of HGF enhanced proliferation and differentiation of DPCs by up-regulating CREB, ELK-1, and PPAR-gamma. U0126, an ERK/MAPK inhibitor, inhibited the effects of HGF on DPCs. It was concluded that HGF stimulated both proliferation and differentiation of DPCs, at least partially through the ERK/MAPK pathway.

Adult↗
PubMed2006

Prosthodontic and psychological factors in treating patients with congenital and craniofacial defects.

This article addresses treatment of patients with various types of congenital defects, including partial and total anodontia, hypohydrotic ectodermal dysplasia, dentinogenesis imperfecta, and cleft lip and palate. The psychosocial aspects of these patients and rehabilitation with removable, fixed, and implant-supported prostheses are discussed. The factors to be considered are altered anatomy, lack of teeth or malformed teeth, teeth in abnormal positions, lack of facial growth, and altered arch development. The short- and long-term treatment of patients in these categories is discussed.

Anodontia↗
PubMed2005

A rat 8 kb dentin sialoprotein-phosphophoryn (DSP-PP) promoter directs spatial and temporal LacZ activity in mouse tissues.

Dentin sialoprotein (DSP) and phosphophoryn (PP) are two major dentin noncollagenous proteins that are encoded on a single DSP-PP transcript whose expression is tightly regulated during tooth dentinogenesis. The recent identification of this gene transcript in other tissues, including inner ear and jaw tissue, suggests that DSP and PP may have pleiotropic effects on other organs besides teeth. To identify candidate regulatory elements that control DSP-PP temporal and spatial expression, we constructed a -5 kb upstream region rat DSP-PP promoter into the beta-galactosidase expression vector pnLacF plasmid and used this construct to prepare DSP-PP-LacZ transgenic mice. Multiple mouse tissues including teeth, bone, and kidney obtained from the six resulting transgenic mouse lines displayed strong LacZ activity. This spatial distribution was confirmed in several of these tissues by in situ hybridization studies. LacZ activity was transiently expressed in preameloblasts and continuously expressed in odontoblasts demonstrating that this -5 kb rat promoter-dependent LacZ expression mimics reported DSP-PP mRNA expression patterns. Interestingly, this -5 kb rat promoter construct drives LacZ expression according to the rat developmental clock. Based on identified transcription factors present in this -5 kb promoter region, we have identified several probable cis-regulatory modules whose interaction with one another could account for the spatial and temporal distribution of DSP-PP transcripts in developing tissues.

Animals↗
PubMed2002

Differential repair responses in the coronal and radicular areas of the exposed rat molar pulp induced by recombinant human bone morphogenetic protein 7 (osteogenic protein 1).

Bone morphogenetic protein 7 (BMP 7), also termed osteogenic protein 1, a member of the transforming growth-factor superfamily, was examined for its efficacy in inducing reparative dentinogenesis in the exposed pulps of rat molars. To determine if the reaction was dose-dependent, collagen pellets containing 1, 3 or 10 microgram of recombinant BMP 7 were inserted in intentionally perforated pulps (10-12 pulps per group) in the deepest part of half-moon class V-like cavities cut in the mesial aspect of upper first molars. As controls, the collagen carrier (CC group) alone and calcium hydroxide (Ca group) were used as capping agents. All cavities were then restored with a glass-ionomer cement. Half of the animals were killed after 8 days and the other half after 28 days, by intracardiac perfusion of fixative. The molars were processed for histological evaluation by light microscopy. No difference in effect could be detected between the three concentrations of BMP 7 groups at either time interval. After 8 days, all groups showed varying inflammation, from mild of severe, and the Ca group demonstrated early formation of a reparative dentine bridge. At 28 days the CC group displayed irregular osteodentine formation, leaving some unmineralized areas at the exposure site and interglobular unmineralized areas containing pulp remnants. In the Ca-treated pulps, the initial formation of thick reparative osteodentine bridges that sealed more or less completely the pulp perforation was followed, in the deeper part, by irregular tubular dentine. In most BMP 7-treated specimens, the initial inflammation has resolved at 8 days and at 28 days heterogeneous mineralization or osteodentine filled the mesial coronal pulp. They also had complete filling of the radicular pulp by homogenous mineralization in the mesial root; this reaction was found in 11 teeth in the BMP 7 group, one tooth in the CC group an none of the Ca group. These results emphasize the biological differences the coronal and radicular parts of the pulp, and the potential of bioactive molecules such as BMP 7 to provide an a alternative conventional endodontic treatments.

Animals↗
PubMed2003

Piezo-power microdissection of mature human dental tissue.

Isolation of sufficient quantities of pure populations of odontoblasts from healthy and diseased teeth will facilitate our understanding of dentinogenesis during development and repair. Here we describe a novel Piezo-power microdissection (PPMD) technique for the isolation of pure populations of odontoblasts and pulpal tissue from formalin-fixed, paraffin-embedded, mature, healthy and carious human teeth. Odontoblasts and pulpal tissue gene expression were subsequently studied in ribonucleic acid isolated from PPMD preparations using a semi-quantitative reverse transcription polymerase chain reaction approach. Data confirmed that the genes for dentine sialophosphoprotein and Nestin are preferentially expressed in odontoblasts, whilst the genes for both collagen-1alpha and collagen-3alpha were expressed preferentially in pulpal tissue, particularly in carious samples. PPMD provides a novel and powerful approach to isolate pure populations of dental tissues and cells from fixed specimens for subsequent downstream molecular analyses.

Base Sequence↗
PubMed1997

Temporal changes in expression of transforming growth factor-beta superfamily members and their receptors during bovine preodontoblast differentiation in vitro.

Transforming growth factor (TGF)-beta superfamily members and their receptors play a part in the differentiation of pulp cells into odontoblasts during reparative dentinogenesis. Bovine primary pulp-cell culture has been used as an in vitro model for proliferation and differentiation of pulp cells into preodontoblasts. To explore the molecular cascade of odontoblast differentiation, Northern blot analyses and reverse transcriptase polymerase chain reaction were here used to investigate the expression patterns of the genes for TGF-beta superfamily members: TGF-beta 1, namely bone morphogenetic protein (BMP)-4, BMP-7, activin-beta A and activin-beta B, and their type I and type II receptors, namely activin receptor-like kinase (ALK)-2 (ActR-I), ALK-3 (BMPR-IA), ALK-4 (ActR-IB), ALK-5 (T beta R-I), BMPR-II and T beta R-II, during differentiation of pulp cells into preodontoblasts in bovine adult pulp-cell culture. TGF-beta 1 and BMP-4 mRNAs were expressed from day 14 when matrix formation increased. BMP-7 mRNA was expressed only on day 28 when osteocalcin appeared. ALK-2 mRNA was increased from the beginning of the culture. ALK-3 and ALK-5 mRNAs first decreased on day 14 and increased again on day 21. T beta R-II and BMPR-II mRNAs were almost constant. These results suggest that the differentiation of pulp cells into preodontoblasts may be regulated by changes in the temporally coordinated expression pattern of TGF-beta superfamily members and their receptors, including up-regulation of transcription of TGF-beta 1, BMP-4, BMP-7, ALK-2, ALK-3, and ALK-5.

Amino Acid Sequence↗
PubMed1998

Regulation by serotonin of tooth-germ morphogenesis and gene expression in mouse mandibular explant cultures.

Serotonin (5-HT) stimulates tooth-germ development in embryonic mouse mandibular explant cultures, but it is not clear whether this is due to a direct action on epithelial-mesenchymal interactions, or whether development was stimulated indirectly by serotonergic regulation of other morphoregulatory molecules. A calcium-binding protein, S-100beta, and the extracellular-matrix molecule, tenascin, two molecules thought to be important in craniofacial development, together with cartilage proteoglycan core protein, a marker for chondrogenesis, are modulated by serotonergic ligands in mandibular micromass cultures. Here, it was demonstrated that 5-HT stimulates expression of cartilage proteoglycan core protein, and inhibits expression of S-100beta and tenascin in mandibular explants. Further, ondansetron (Zofran), a 5-HT3 receptor antagonist, and NAN-190, a 5-HT1A antagonist, reversed the serotonergic stimulation of core protein and tooth germ development. In contrast serotonergic modulation of S-100beta and tenascin expression was not reversed by any of the 5-HT receptor antagonists tested, although the 5-HT uptake inhibitor, fluoxetine, did reverse the effect of 5-HT on S-100beta expression, as well as tooth-germ development. These results support previous work suggesting that 5-HT plays an important part in craniofacial development, especially in dentinogenesis and chondrogenesis. However, the possibility that tenascin or S-100beta mediate the effects of 5-HT on tooth-germ development is not supported. Rather, these results raise the possibility that 5-HT may exert effects directly on tooth-germ morphogenesis mediated by intracellular uptake of 5-HT and/or activation of 5-HT1A and 5-HT3 receptors.

Aggrecans↗
PubMed1998

Osteogenesis imperfecta in childhood: treatment strategies.

Osteogenesis imperfecta (OI) is a skeletal disorder of remarkable clinical variability characterized by bone fragility, osteopenia, variable degrees of short stature, and progressive skeletal deformities. Additional clinical manifestations such as blue sclerae, dentinogenesis imperfecta, joint laxity, and maturity onset deafness are described in the literature. OI occurs in about 1 in 20,000 births and is caused by quantitative and qualitative defects in the synthesis of collagen I. Depending on the severity of the disease, a large impact on motor development, range of joint motion, muscle strength, and functional ability may occur. Treatment strategies should primarily focus on the improvement of functional ability and the adoption of compensatory strategies, rather than merely improving range of joint motion and muscle strength. Surgical treatment of the extremities may be indicated to stabilize the long bones to optimize functional ability and walking capacity. Surgical treatment of the spine may be indicated in patients with progressive spinal deformity and in those with symptomatic basilar impression.

Activities of Daily Living↗
PubMed1992

Symmetrical pulp obliteration in mandibular first molars.

Pulp obliteration is an extremely rare morphological type of pulp calcification, with calcified material completely occupying the pulp chamber and root canal spaces. The etiology of pulp obliteration may be trauma or systemic diseases such as secondary hyperparathyroidism. Pulp obliteration may also be seen in dental anomalies such as dentinogenesis imperfecta and dentinal dysplasia. In cases of pulp obliteration with periapical disease, the preferred treatment is surgery, while calcified canals without symptoms or periapical lesions are best left untreated.

Adolescent↗
PubMed1987

Effects of 1-hydroxyethylidene-1, 1-bisphosphonate (HEBP) on the synthesis of dentin matrix proteins in the mouse.

The drug 1-hydroxyethylidene-1,1-bisphosphonate (HEBP) is known to inhibit the mineralization of bone and dentin. Its mechanism of action, however, has not yet been elucidated. In order to study its effects on dentinogenesis, mice were supplied with either physiological saline or HEBP in a dose of 10 mg P/kg body weight. This dose is known to interfere with the deposition of mineral crystallites in dentin matrix. The animals were then given a combined injection of [3H]-serine and [14C]-proline (or [14C]-glycine) and killed 8-9 days thereafter. The dentin proteins were isolated and fractionated in soluble proteins among which phosphoproteins, CNBr-peptides of collagen and collagen-associated phosphoproteins. It was found that HEBP had a strong inhibitory effect on the synthesis of phosphoproteins and to a lesser extent on that of collagen. The inhibition of the formation of these proteins is supposed to be related to the impaired calcification of dentin under the influence of the bisphosphonate.

Animals↗
PubMed2000

Human odontoblast cell numbers after dental injury.

OBJECTIVES: The purpose of this study was to measure the changes in odontoblast cell numbers in response to cavity restoration variables and patient factors, and the effect these factors have on dental repair by tertiary dentinogenesis. The number of vital odontoblasts is a critical factor for pulpal repair following restorative surgery, and yet little information is available on these cell numbers. METHODS: Class V non-exposed cavities were prepared in the buccal surface of intact first or second premolar teeth of 27 patients, between 9 and 17 years of age. Following tooth extraction (28-163 days) the area of reactionary dentine and the area of the odontoblasts were measured histomorphometrically. RESULTS: Patient factors, as well as cavity preparation and restoration variables, had little effect on the numbers of odontoblasts per pulpal unit area. However, the age of the patient did appear to have an effect on the reactionary dentine secretory capacity of odontoblasts per unit area, and on the relative number of odontoblasts beneath cut dentinal tubules. CONCLUSIONS: Odontoblast cell numbers were maintained following the preparation of cavities cut into dentine with a 0.5mm residual dentine thickness. The repair capacity of the pulp-dentine complex would appear to be age dependent, this may explain differences in the success of various restorative treatments between patients.

Adolescent↗