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At least 397 records · Page 22Linked to original sources
PubMed2006

Abnormal dentin structure in two novel gene mutations [COL1A1, Arg134Cys] and [ADAMTS2, Trp795-to-ter] causing rare type I collagen disorders.

Histological and ultrastructural observations of dentin of two patients affected with rare types of type I collagen disorders are presented. In the first case, a homozygous nonsense mutation in ADAMTS2 (substitution of a codon for tryptophan by a stopcodon) causes type VIIC Ehlers-Danlos syndrome (EDS) with multiple tooth agenesis and focal dysplastic dentin defects. In the second case, a missense mutation in COL1A1 (substitution of arginine by cysteine) results in a type I EDS phenotype with clinically normal-appearing dentition. Tooth samples are investigated by using light microscopy (LM), transmission electron microscopy (TEM) and immunostaining for types I and III collagen, and tenascin. These are compared with samples from patients with types III and IV osteogenesis imperfecta (OI) in association with dentinogenesis imperfecta (DI), showing a consistently abnormal appearance of the dentin in all specimens, with variations being primarily those of degree of change. Similarities in histological changes include the alternating presence of normal and severe pathological areas in primary and secondary dentin, the latter being characterized by large canal-like structures in atubular areas. Ultrastructural evidence of pathological dentinogenesis include abnormal distribution, size and organization of collagen fibers, which may also be found in clinically unaffected teeth. The histological and ultrastructural changes seen can be explained on the basis of odontoblast dysfunction which may be secondary to the collagen defect, interfering with different levels of odontoblast cell function and intercellular communication. These observations on (ultra)structural dentin defects associated with the two novel gene mutations are the first ever reported.

Collagen Type I↗
PubMed2002

Effect of dietary carbamyl phosphate on dentine apposition in rat molars.

In rats, sucrose increases dental caries and impairs odontoblastic function by reducing dentine apposition during primary dentinogenesis. A high-sucrose diet also affects negatively a pulp or dentine function that appears to regulate solute or fluid movement within rat dentinal tissue. In earlier work it was found that carbamyl phosphate could significantly reverse sucrose-induced cariogenesis and also stimulate sucrose-depressed movement of dentinal fluid through a mechanism involving parotid function(s). In the current study, the possibility that carbamyl phosphate could overcome the sucrose-induced reduction in dentine apposition was examined. Weanling rats were fed a high-sucrose diet supplemented or not with carbamyl phosphate for 5 weeks. Dentine apposition was measured planimetrically in sagittal sections of the molars. The effect of carbamyl phosphate was similarly tested in parotidectomized animals. Carbamyl phosphate significantly reduced the deleterious effect of sucrose on dentine apposition by 58% in the first molars. However, the reduction in dentine apposition that followed parotidectomy was not altered by carbamyl phosphate supplementation. The possibility that the beneficial effect of carbamyl phosphate on dentinogenesis involves a parotid function is entertained.

Analysis of Variance↗
PubMed1999

Immunofluorescence detection of cadherins in mouse tooth germs during root development.

The distribution of two cell-adhesion molecules, E- and P-cadherin, was studied in relation to morphological changes in Hertwig's epithelial root sheath Before root dentinogenesis had started, the root sheath expressed both cadherins. As dentinogenesis proceeded, the sheath fragmented and lost P-cadherin rapidly and E-cadherin slowly, whereas the intact sheath at the apical end continued to express both. These results suggest that the two cadherins play a part in root as well as in crown development, and indicate that the decrease in the amount of these molecules and the fragmentation of the epithelial root sheath are interrelated.

Animals↗
PubMed2000

The effect of sucrose diet of rat dams on the dentine apposition and dental caries of their pups.

The purpose was to examine whether a sucrose diet in rat dams reduces dentine apposition and enhances dental caries in their pups. Sprague-Dawley rat pups were randomized into four groups on the day of birth. During the lactation period three dams received a standard rodent diet and three a diet containing 41% sucrose. At the age of 3 weeks the pups were weaned and given an intraperitoneal injection of oxytetracycline hydrochloride. During the experimental period, half of the pups of control dams received a sucrose diet (Cnt-Suc pups) and half of the pups of sucrose dams received a standard diet (Suc-Cnt pups). The pups in the other halves received the same diet as given to their dams during lactation (Cnt-Cnt and Suc-Suc pups). Urine samples were collected from dams and pups during the test periods. After 4 weeks the pups were killed, their blood was collected and their jaws sectioned sagittally. Dentine apposition was determined planimetrically and dental caries using Schiffs staining. Ca, K and Na of serum and urine were measured flame photometrically and P using an ultraviolet method. The lactational sucrose diet was associated with decreased P and Na excretion in the dams, and also with reduced dentine apposition in their pups. Reduced dentine apposition and induced Ca excretion with decreased P, K and Na excretions were observed in Suc-Suc pups and Cnt-Suc pups during the experiment period. Fewer intact teeth with more enamel and dentinal caries lesions occurred in sucrose-exposed groups (Suc-Cnt, Cnt-Suc and Suc-Suc pups). It was concluded that the sucrose diet given to dams during lactation changed the function of the pulp dentine complex of their pups leading to reduced dentinogenesis, but also predisposed to a reduction of dentinogenesis in pups during the experimental period and enhanced the occurrence of dental caries.

Analysis of Variance↗
PubMed1998

cDNA cloning of bovine thrombospondin 1 and its expression in odontoblasts and predentin.

The extracellular matrix protein thrombospondin 1 (TSP1) was cloned from odontoblasts of bovine mandibular teeth which participate in dentinogenesis. The 5289 bp cDNA contains a complete open reading frame of 1170 amino acids. Bovine TSP1 has high homologies to its human and mouse counterparts. In immunohistochemical analyses of bovine anterior teeth with anti-TSP1 monoclonal antibody, TSP1 was only detectable at the position of predentin, located between dentin and unmineralized dental pulp. Northern blot analysis showed high levels of two sizes of TSP1 mRNAs in odontoblasts but not dental pulp and gingiva. Previously we found that osteotropic factors such as calcitriol and TGF-beta induce TSP1 at the transcriptional level in clonal rat dental pulp cells. These results suggest a role of TSP1 in dentinogenesis and/or maintenance of dentin and dental pulp.

Amino Acid Sequence↗
PubMed2000

Treatment of inflamed ferret dental pulps with recombinant bone morphogenetic protein-7.

Recombinant human BMP-7 (bone morphogenetic protein-7, osteogenic protein-1) is osteogenic, dentinogenic and cementogenic when implanted into the appropriate tissue in vivo. However, most studies characterizing the induction of these tissues have implanted BMP-7 into freshly surgerized, clinically healthy tissues. To determine if BMP-7 is dentinogenic in inflamed dental pulps, we applied BMP-7 to inflamed ferret pulps. A single application of 5 microg of a commercial preparation of lipopolysaccharide (LPS) from Salmonella typhimurium directly to the coronal pulp induced a reversible mixed inflammatory exudate of moderate intensity within 3 d. Treatment with a single application of 2.5, 7.5 or 25 microg recombinant human BMP-7/mg collagen (2 mg total mass/tooth) induced reparative dentinogenesis in controls but not LPS treated dental pulps. These data reveal that a single application of up to 50 microg/tooth of exogenous recombinant BMP-7 is insufficient to induce reparative dentinogenesis in ferret teeth with reversible pulpitis. Given that pulp cells in the inflamed tissues likely retain the capacity to respond to exogenous BMP-7, it is possible that insufficient active recombinant protein is available to induce tissue formation in experimentally inflamed dental pulps.

Animals↗
PubMed1998

Radiological features of hereditary opalescent dentin.

A case of hereditary opalescent dentin is described, which showed the same clinical and radiological features as those reported previously. However, there was no evidence of osteogenesis imperfecta. While a diagnosis of type II dentinogenesis imperfecta was therefore made, this case also had features characteristic of type III dentinogenesis imperfecta. Treatment by means of an overdenture is described.

Cephalometry↗
PubMed2001

Pulp-capping with recombinant human insulin-like growth factor I (rhIGF-I) in rat molars.

The aim of this study was to explore pulp healing and reparative dentinogenesis following pulp-capping by using recombinant human insulin-like growth factor I (rhIGF-I). Exposures were made through the mesial pulp horn in first upper molars in two-month-old Wistar rats. The pulp was covered with one dose of sterile 4% methylcellulose gel containing either 400 ng rhIGF-I or saline in contralateral controls. The exposure site was closed with sterile Teflon membrane, and the cavity was filled with IRM cement. Additional molars were capped with Dycal as controls. After 3, 7, or 28 days, animals were anesthetized and fixed by intravascular glutaraldehyde perfusion. Molars were decalcified and processed for histological analysis and cut with membrane and residual methacrylate from IRM in situ. Only specimens with acceptable pulp sealing according to blinded microscopy control were included. On day 3, identical inflammatory responses in the upper pulp were observed in molars with rhIGF-I gel or control gel. On day 7, granulation tissue ingrowth had partly replaced inflammatory infiltration in both groups. After 28 days, complete dentin bridging and tubular dentin formation were observed more frequently and closer to the test substance containing rhIGF-I. The reparative dentin response to capping with rhIGF-I was similar to that after the use of Dycal. In conclusion, microscopic control of membrane sealing in situ gives valid information on the more subtle pulp effects of growth factors. The observations suggest that pulp-capping of rat molars by means of rhIGF-I enhances reparative dentinogenesis in comparison with vehicle controls.

Animals↗
PubMed2002

Parotid gland function and dentin apposition in rat molars.

Previous studies have clearly established the down-regulating effect of a sucrose-rich diet on primary dentinogenesis in rat molars. Earlier observation of the negative effect of a high-sucrose diet on a parotid function involved in the control of intradentinal solute movement led us to hypothesize that parotid gland function(s) may have a role in regulating dentinogenesis. Dentin apposition in 1st and 2nd molars of young rats was measured by planimetry in sagittal sections. The following experimental variables were tested: standard and high-sucrose diets, removal of the parotid or the submandibular/sublingual glands, and diets in powder or pellet form. Removal of the submandibular/sublingual glands and changes in diet consistency did not significantly affect dentin apposition. Dentin apposition was significantly depressed by the high-sucrose diet or following parotidectomy. A further decrease followed the combination of the two treatments. Parotid glands appeared to exert a positive effect on dentin apposition in rat molars.

Analysis of Variance↗
PubMed1992

[The radiology of osteogenesis imperfecta].

The term "osteogenesis imperfecta" refers to a heterogeneous group of hereditary diseases characterized by osteopenia, increased bone fragility, blue sclerae and dentinogenesis imperfecta. The abnormal synthesis of type-I collagen is responsible for the pathologic changes occurring not only in bone, but also in skin, tendons and ligaments, sclerae and teeth. The clinical and radiographic features of 5 cases (2 males and 3 females; age range: 1 month to 29 years) were analyzed. The patients were unrelated with each other. The diagnosis of the different types of osteogenesis imperfecta is as difficult as the identification of the various genotypes which are responsible for the different clinical pictures. The most characteristic radiographic pattern--which is observed in any type of the disease--consists in osteopenia associated, in most cases, with multiple fractures and deformities--e.g., micromelia, large metaphysis, archon long bones. Typically, "pop corn" calcifications are observed in both epiphysis and metaphysis of long bones. Dentinogenesis imperfecta is one of the most significant clinical patterns, and it can be the only bone abnormality. The prognosis of osteogenesis imperfecta is as varied as its genetics--i.e., the fractures discovered at birth are not necessarily a negative prognostic sign.

Adolescent↗
PubMedDate not supplied

Three patient reports illustrating the use of dentin adhesives to cement crowns to severely worn teeth.

PURPOSE: Severely worn and broken down teeth present clinical treatment planning dilemmas. Extreme examples of worn teeth present in patients suffering from bulimia nervosa and dentinogenesis imperfecta. Bulimia nervosa typically presents early in adult life with a myriad of clinical features and a most important dental sign of eroded palatal surfaces on the maxillary teeth. Dentinogenesis imperfecta is a relatively uncommon disorder that presents with varying severity of unsupported enamel and results in teeth more susceptible to wear. MATERIALS AND METHODS: Dental treatment for both conditions when wear has resulted in the complete loss of the tooth can either be directed toward restoring remaining tooth tissue or extraction and replacement with implants or dentures. This article presents the clinical management of three case histories, each with one or more severely broken down teeth, which were restored with adhesively retained crowns. RESULTS: Treatment lasted nearly 10 years in one patient and failed after 6 years in another. The third patient was treated more recently. CONCLUSION: All three case histories serve as examples of using adhesive cements to retain indirect restorations as a possible prosthodontic management strategy.

Adult↗
PubMed1990

Preliminary studies on the in vivo morphogenetic properties of dentine matrix proteins.

Two fractions of isolated noncollagenous extracellular matrix proteins from dentine have been implanted into the base of exposed cavities in ferret canine teeth. After sealing the cavities, reparative dentinogenesis was assessed histologically after 14 and 28 days as compared to control cavities. Reparative dentinogenesis was enhanced in the presence of these matrix proteins with evidence of tubular dentine along the walls of the exposure and on the cavity floor demonstrating the in vivo morphogenetic properties of the dentine matrix proteins.

Animals↗
PubMed1978

A fine structural study of coronal and root dentinogensis in the mouse: observations on the so-called 'von Korff fibres' and their contribution to mantle dentine.

The fine structure of mantle dentine formation has been studied in the mouse molar. No evidence was found for the presence of collagenous von Korff fibres arising from the dental papilla, passing between odontoblasts and fanning out to form the collagenous matrix of mantle detine. Instead, large collagen fibrils were first demonstrable in the matrix peripheral to the dential aspect of an extensive junctional complex system occurring at the necks of the odontoblasts. The orientation of the fibres was at right angles to the future amelo-dentinal junction in coronal dentinogenesis, but parallel to the root surface in radicular dentinogenesis. These large collagen fibrils formed the mantle dentine. It is concluded that von Korff fibres, as strictly defined, are artefacts. Photographs in the literature purporting to show von Korff fibres are attributable to obliquity of section. Also, is suggested that the difference in fibril orientation in coronal and root mantle dentine is the reason for the conflicting opinions on the pattern of fibril orientation in this tissue.

Animals↗
PubMedDate not supplied

[Pulp and dentin responses to topical dexamethasone application].

The Authors have proposed to develop this research employing a preparation containing exclusively a cortisonic, the desametazone, in order to evaluate the alterations of the dentinogenesis to be attributed to such component. 32 cavities have been carefully drilled in dogs' cuspids. The 16 experimental cavities were dressed with desametazone, asbestos and amalgam in successive strata while in the 16 control cavities only asbestos and amalgam were used. Stainless steel bands were cemented on the processed teeth. The animals received 9 I.V. injections of tetracycline (10 mg per kg) each at 7 days interval. In the observation of the tetracycline markings under the experimental cavities (with desametazone) alterations of the dentinogenesis were not observed. Consequently, it seems that the action of desametazone is not to be considered harmful for the pulp tissue under the freshly cut dentine, as far as duration of the experiment is concerned.

Administration, Topical↗
PubMed1981

[Structural organization of the microcirculatory bed of the primordia of human deciduous teeth].

By means of injection and noninjection techniques structural organization of microcirculatory bed in the deciduous (milk) teeth germs have been studied in human fetuses, newborns and children. A definite dependence of the angioarchitectonics on the developmental stage of every tooth has been stated. Morphological differentiation of separate parts of the microcirculatory ways in the dental papilla is connected with dentinogenesis, and in the dental saccule--with amelogenesis, periodontum and alveolar wall formation. Those dental germ zones which have a peculiar functional importance (peripheral parts of the dental papilla, dental saccule in the area of the epithelial dental organ) are characterized by the presence of certain structural-functional apparatuses which provide increasing contact areas between blood and the tissues. Intraorganic circulatory bed of the dental papilla consists of identically constructed vascular complexes. The conformity coefficient between the arteriolar inlet and the venular outlet of the dental papilla microcirculatory ways during dentinogenesis is between 0.16--0.3. It has been stated that devices regulating the blood stream in the deciduous tooth germs (anastomoses, sphincters, arcades, etc.) are forming during the antenatal and early postnatal periods.

Amelogenesis↗
PubMedDate not supplied

Recent findings in classification of osteogenesis imperfecta by means of existing dental symptoms.

The findings are based on a clinical investigation conducted on forty-nine patients suffering from osteogenesis imperfecta (OI), as well as on a questionnaire study in which 117 osteogenesis imperfecta-affected persons or their parents were involved. The survey established pathological tooth discolorations as well as tooth abrasions. Dentinogenesis imperfecta (DI) was more frequently found in primary teeth than in permanent teeth. There were no gender-specific differences. Radiological abnormalities were found in both, abraded and/or discolored teeth, as well as in clinically normal appearing teeth. In most cases there were club-shaped extensions of the pulp chambers and obliterations of the root canals. The probability that dentinogenesis imperfecta occurs as an accompanying symptom of osteogenesis imperfecta was not dependent on the degree of skeletal severity. The self-assignment according to A and B forms of osteogenesis imperfecta types I and IV in accordance with the presence/absence of dental symptoms was contradictory, since the literature was based on varying classifications.

Adolescent↗
PubMed1989

Dentin matrix proteins: composition and possible functions in calcification.

Dentin may be regarded as a mineralized connective tissue. In its composition as well as its mode of formation, dentin exhibits several similarities with bone, but also definite differences. The dentin organic phase, the matrix, determines its morphology and is believed to be instrumental in the formation of the mineral phase. A fibrous web of collagen type I dominates the organic matrix. Also, minor amounts of other collagen types may be present. The noncollagenous proteins (NCPs), which constitute about 10% of the matrix, fall into several categories: phosphoproteins, Gla-proteins of the osteocalcin type as well as matrix Gla-protein, proteoglycans, different acidic glycoproteins, and serum proteins. Some of these NCPs have unique chemical compositions that give them specific properties. Dentinogenesis occurs by two simultaneous processes: the formation of a collagenous web in predentin, which is followed by the formation of the inorganic phase at the mineralization front. The composition of the predentin organic matrix differs from that of dentin, as some NCP components are secreted extracellularly just in advance of the mineralization front. In addition, some constituents of predentin seem to be metabolized. The NCPs may be important to several processes during dentinogenesis. Much evidence indicates that noncollagenous components in the matrix are instrumental in mineral formation. New data show that polyanionic NCPs, such as phosphoprotein and proteoglycans, when immobilized on a solid support, induce apatite formation under physiological conditions. These data indicate that polyanionic NCPs may function as mineral nucleators in vivo. They may also act as size and rate regulators for crystallization and promote calcium ion diffusion in the tissue. In addition, NCPs may regulate collagen fibrillogenesis.

1-Carboxyglutamic Acid↗
PubMed1985

Evidence for tight junctions between odontoblasts in the rat incisor.

Odontoblasts are known to be involved in the process of dentinogenesis but it is not clear whether substances may also be deposited in predentine and dentine by passing between these cells. Although tight junctions have been described, it is not clear if they are macular or "leaky" as opposed to continuous or "tight". In this study use has been made of the permeability of fenestrated capillaries amongst the odontoblasts to deposit the penetrative tracer lanthanum in the interodontoblastic space. This was done by perfusion of anaesthetized rats with physiological solutions containing lanthanum nitrate at 37 degrees C. Immersion fixation of transverse segments of mandibular incisors and examination with an electron microscope showed that lanthanum could permeate 40-50 microns between the odontoblasts to reach the peripheral pulp. Towards the predentine, often less than 10 microns from the capillaries, its progress was abruptly and completely halted by the junctions at the apical ends of the odontoblast cell bodies. Lanthanum was not found in the predentine. The mature secretory odontoblasts in the rat incisor have therefore been shown to be joined by continuous tight junctions. In the process of dentinogenesis this means that all substances deposited in predentine and dentine must arrive by passing through the odontoblasts.

Animals↗