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At least 19 recordsLinked to original sources
PubMed1975

Uninherited dentinogenesis imperfecta.

The rare hereditary disease, dentinogenesis imperfecta, is a disturbance of dentin formation in both the deciduous and permanent dentitions. It may be associated with osteogenesis imperfecta, though it is probably that the two diseases are carried by different genes. This association was recognized in a 19-year-old man. Dentinogenesis imperfecta had been diagnosed at the age of 6 and had been regarded as a mutation; 11 years later, an atypical form of osteogenesis imperfecta developed. The case is atypical because of the apparent absence of dentinogenesis imperfecta in the patient's family. The dental manifestations may have heralded the bone disease.

Adult↗
PubMed1990

The crown odontoblasts of rat molars from primary dentinogenesis to complete eruption.

The involution of crown odontoblasts after primary dentinogenesis in teeth of limited eruption is discussed. The odontoblasts of rat first lower molars were analyzed morphometrically from the tenth day to the 40th day of age, i.e., from the late phase of primary dentinogenesis to complete eruption. All the organelles underwent atrophy, but at different rates. In particular, the membranes of the endoplasmic reticulum decreased progressively in surface area from day 10 to day 40, whereas those of the Golgi apparatus decreased significantly between day 10 and day 14, and then remained practically unchanged in size. The volume of the lysosome compartment never increased beyond that during primary dentinogenesis. The profile length of the endoplasmic reticulum in each observed cell section was taken as an estimate of secretory activity. At day 40, this organelle was smaller in approximately 95% of the cells than it had been in any cell at day 10. These results suggest that cell atrophy may occur without any increase in the degradation processes of the cytoplasmic components and that the organelles along the secretory pathway may have independent regulatory systems. In the odontoblasts, as in several types of secretory epithelial cells, only a small fraction of the cells is engaged in appreciable secretory activity. This occurs, however, when the overall activity of the same cell population is relatively low.

Analysis of Variance↗
PubMed1992

Dentinogenesis imperfecta: a case report.

Dentinogenesis imperfecta is a localized form of mesodermal dysplasia of the dentin affecting both the primary and permanent dentitions. Most previous reports on dentinogenesis imperfecta describe treatment with overdentures, which have several disadvantages. The present report describes a case of dentinogenesis imperfecta in an 11-year-old girl. A combination of restorative, prosthetic, and surgical treatment was used to resolve the condition.

Cephalometry↗
PubMed1986

Quantitative histological analysis of the human coronal dentine in dentinogenesis imperfecta types I and II.

The coronal dentine of 3 teeth from dentinogenesis imperfecta (DI) type I, 9 teeth from DI type II and 4 controls were examined by a quantitative histological technique. In each case, two representative demineralized sections, one stained in H + E and the other in Schmorl's picrothionin were used. The relative amount of dentinal tubule, atubular dentine and canals/clefts were assessed using the point-counting method. Three basic patterns of distribution of tubules were observed. Pattern 1 formed the largest group and showed a gradual decrease in tubule count from enamel-dentine junction (EDJ) pulpwards, pattern 2 was characterized by a drop in tubule count approximately midway between EDJ and pulpal border, and pattern 3 exhibited a gradual increase in tubule score as the pulp was approached. At the 5 per cent level, both patterns 1 and 2 were found to be statistically significant. Pattern 3 was statistically insignificant for the test specimens and highly significant for the controls. The variation in the distribution of the tubules in coronal dentine in this study indirectly supports the concept of abnormal dentinogenesis in DI attributable to a diminution or lack of normal functional odontoblasts.

Adolescent↗
PubMed1992

Unusual dentinal changes in dentinogenesis imperfecta associated with osteogenesis imperfecta. A case report.

A case is described of a boy with dentinogenesis imperfecta associated with osteogenesis imperfecta. The dentin of extracted deciduous teeth was found to show an abrupt transition to a normal tubular structure before a reversion to the more typical structure seen in dentinogenesis imperfecta. This change in the dentin appeared to have occurred in a chronologic manner. The possibilities that either a metabolic disturbance or a temporary reduced expression of the mutant gene had caused the abnormality and could account for the unusual histologic findings are discussed.

Child↗
PubMed1992

Calcium ion transport kinetics during dentinogenesis: effects of disrupting odontoblast cellular transport systems.

Due to strongly discrepant results in the literature, controversy exists about the timing of the transport of Ca2+ ions to the mineralization front during dentinogenesis and the role of the odontoblasts in this transport. The present study gives evidence, by means of autoradiography as well as by a radiochemical technique, that the transport time for Ca2+ ions into the dentin mineral phase is about 10-15 min in the rat incisor. The results also show that technical factors, such as mode of tracer injection and the use of perfusion fixation, may influence the results more or less strongly. Finally, by disturbing odontoblast microtubules, involved in intracellular transport processes, and by blocking odontoblast calcium uptake channels by nifedipine and neomycin, the Ca2+ ion transport into dentin mineral was found to be strongly impaired. This may be taken as an indication that transcellular calcium transport mechanisms have a role during dentinogenesis.

Animals↗
PubMed1975

[Dentinogenesis imperfecta: a structural and ultrastructural study].

Histopathology of dentinogenesis imperfecta shows a haphazard distribution of dentinal tubules as well as changes in their diameters, sometimes narrowed, sometimes widened. These tubules appear as bundles or sheaves. This kind of dentine is often similar to secondary (also called tertiary) dentine, only mantle dentine preserving a normal structure. There is a complete obliteration of the pulp chamber and an almost complete obliteration of the root canal. Through SEM, the tubules appear to be few in number, their diameters are small and their fine ramifications are intricate through all planes. An heterogenous intertubular substance can be seen. Through TEM, collagenous fibers appear to be uncalcified or incompletely calcified, with a haphazard distribution. There are wide differences in the sizes of crystals and numerous spaces appear between crystals and collagen. Differences between the ultrastructure of human dentinogenesis imperfecta and the dentine of some lower vertebrates are clearly pointed out.

Dental Cementum↗
PubMed1992

Protein kinases in dentinogenesis.

Protein modifications such as phosphorylation and dephosphorylation are known to control several cell functions including regulation of the cell cycle, signal transduction and enzyme activation/inactivation. Bone and dentin contain highly phosphorylated anionic proteins that appear to be involved in the regulation of mineralization. This study was designed to identify and characterize the enzyme(s) responsible for phosphorylation (kinases) of dentin phosphoprotein (DPP) during dentinogenesis. DPP-protein kinase activity was demonstrated in a crude homogenate of dental pulp and odontoblast cells. In parallel studies, oligonucleotides to conserved amino acid sequences present in the active site of kinases were constructed and used to screen a lambda-gt11 tooth organ cDNA library. Several cDNA clones were isolated, the size of the insert determined by PCR (polymerase chain reaction) amplification, and in situ hybridization was used to determine cellular localization during tooth organ development. Preliminary evidence provides additional molecular determinants involved with candidate kinases responsible for DPP phosphorylation and dentinogenesis.

Animals↗
PubMed1992

Repair dentinogenesis following transplantation into normal and germ-free animals.

UNLABELLED: The purpose of this study was to investigate the dentinogenesis of dental pulp tissue following transplantation and during regeneration in normal and germ free animals, as well as in vitro experiments. EXPERIMENTS: (1) Partial and complete exposure of dental pulp in germ free rats by removing the enamel and dentin of molars. (2) The central portion of rat incisor which consisted of pulp and pulp chamber were autografted into various tissues. (3) Explants of rat pulp tissue were cultured on dentin matrix. (4) Resin bonding agent, 4-META/MMA-TBB-O (Superbond), was placed directly on surgically-exposed dental pulp. RESULTS: (1) Dentin bridge formation was recognized at 5 days after operation in germ free rat. (2) The cut surface of the transplant exhibited dentin bridge at 7 days after implantation, and the thickness of the newly formed dentin increased gradually thereafter up to 30 days. (3) Cultured pulp cells had high alkaline phosphatase activity and bone- or dentin-like hard tissue was synthesized on the dentin matrix in vitro. (4) Dentin bridge formation was evident on the surgically-exposed dental pulp even after application of Superbond. From these results, it is suggested that pulp tissue has a high activity of dentinogenesis both in vivo and in vitro and 3 days is enough for pulp cells to express the odontoblast phenotype when inflammatory factors are not present.

Animals↗
PubMed1992

Molecular control of dentinogenesis: a reaction.

This paper represents an invited reaction to three papers presented at the International Conference on Pathobiology of the Dentin/Pulp Complex, June, 1991. Repair dentinogenesis following transplantation into normal and germs free animals are correlated with results elucidating the expression of dentin phosphoproteins, collagen, and osteocalcin. The importance of transcription and translation controls of dentin matrix components are discussed and reviewed. In addition, possible implications of a molecular chaperone protein, Hsp47, in controlling dentinogenesis is introduced. Future research directions are developed and include: (a) identification of odontoblast precursors; (b) delineation of markers for odontoblasts at varying degrees of differentiation; (c) characterization of environmental conditions leading to odontoblast differentiation; (d) determination of the nature of repair and regenerated tissues; (e) elucidation of transcription and translation control factors, and (f) mapping the human genome for dentin matrix constituents.

Collagen↗
PubMedDate not supplied

[Oral rehabilitation in dentinogenesis imperfecta. Report of a case].

We present a case of Amelogenesis imperfecta associated with Dentinogenesis imperfecta, affecting the primary dentition which is rehabilitated under general anesthesia. Dentinogenesis imperfecta is a tooth abnormality which presents clinical, radiological and histological characteristics, they should be recognized by the dentist who will determine the treatment depending on age and grade of affection. In the primary dentition we recommend the use of stainless steel crowns do to it's resistance and easy adaptation which will remain in the mouth until it's normal exfoliation.

Child, Preschool↗
PubMed1989

Immunohistochemistry of extracellular matrix proteins during various stages of dentinogenesis.

During dentinogenesis the expression of extracellular matrix (ECM) proteins by (pre)odontoblasts changes concomitantly with the stage of differentiation. Of these ECM proteins some are present throughout all stages of dentinogenesis, while others can only be demonstrated at particular stages of differentiation. Utilizing immunohistochemical techniques, positive detection of ECM proteins within the (pre)odontoblast or in their extracellular matrices has been demonstrated for (pro)collagen type I, III, IV, V and VI, fibronectin, tenascin, laminin, basement membrane heparan sulfate, nidogen, dentinophosphophoryns (DPP), osteocalcin (OC), osteonectin, osteopontin and 95 kDal glycoprotein. Early predentin before onset of dentin mineralization also reacts with antibodies to enamel matrix proteins. Of these ECM proteins, only DPP are exclusively synthesized by odontoblasts; DPP thus can be regarded as specific biochemical markers for odontoblast activity. A second marker for odontoblasts (but also synthesized by osteoblasts and osteocytes) is OC. In some species however OC levels in dentin seem very low. The initiation of dentin mineralization may be a matrix-mediated process in which preameloblasts also seem to be involved. Current data suggest that the DPP-collagen complex is associated with the mineralization process in dentin.

Animals↗
PubMed1986

An autosomal-dominant form of juvenile periodontitis: its localization to chromosome 4 and linkage to dentinogenesis imperfecta and Gc.

Study of a large five-generation kindred from southern Maryland revealed that type III dentinogenesis imperfecta (DGI-III) and a localized form of juvenile periodontitis (JP) were both segregating as autosomal-dominant traits. Linkage analyses demonstrated that these were two distinct clinical entities, making this family the first documented instance of an autosomal-dominant form of JP. Since the locus for the more common form of dentinogenesis imperfecta (DGI-II) is on chromosome 4q [Ball et al, 1982], a linkage analysis of genetic and chromosomal markers on chromosome 4 was undertaken. The results suggested that the locus for the DGI-III subtype is located a similar distance from the Gc locus (theta = 0.12) as the distance previously observed between Gc and DGI-II loci (theta = 0.11) [Ball et al, 1982; Conneally et al, 1984]. Most likely the two DGI subtypes are determined by genes at closely linked loci, by allelic genes, or by the same gene with the variable expression in different families. In addition, close linkage between the Gc locus and that determining the autosomal-dominant form of JP was observed in this family (theta = 0.05). The known map of chromosome 4q and our analysis of the markers tested suggested the gene order to be 4cen----JP----Gc----DGI----MNS----qter with a large distance (at least 15 cM) between 4cen and JP.

Aggressive Periodontitis↗
PubMed1988

Molecular determinants of cranial neural crest-derived odontogenic ectomesenchyme during dentinogenesis.

Positional information on tooth morphogenesis is investigated by the identification of when and where phenotypic markers are expressed during odontogenesis. This temporal and positional information is correlated with the instructive and permissive signaling required for both dentinogenesis and amelogenesis. Of particular interest is the establishment of a map for the cranial neural crest-derived dental papilla ectomesenchyme and the odontoblast cell lineages. The expression of ectomesenchyme-derived cytotactin, dentin phosphoprotein, and epithelial-derived enamel proteins was studied in mice using embryonic, fetal, and postnatal mandibular first molar tooth organ development. This review summarizes the observations in the context of instructive epithelial-mesenchymal interactions and suggests that amelogenesis imperfecta and dentinogenesis imperfecta may in part be explained by alterations in these differentiation markers. Recombinant DNA methods should facilitate future investigations of these inherited dental disorders.

Animals↗
PubMed1992

Dentin phosphoprotein in dentin development: implications in dentinogenesis imperfecta.

Dentin phosphoprotein (DPP, phosphophoryn) is the major non-collagenous protein component of the dentin extracellular matrix. This highly acidic phosphorylated protein is solely expressed by ectomesenchymal-derived odontoblast cells of the tooth organ. Previous biochemical studies have suggested the absence of this protein associated with the human genetic disease dentinogenesis imperfecta (DGI) Types I and II. However, due to the normal degradation of human DPP during dentin maturation, it has not been possible to establish if these reported differences were due to changes in DPP expression or secondary degradation rates in DGI affected versus normal teeth. Recently, we have taken both a molecular and biochemical approach to address this problem. Molecular studies have utilized genetic linkage studies performed on several multi-generation informative DGI kindreds. These studies have determined linkage between DGI Types II and III and two markers localized to the long arm of human chromosome 4 in the region 4q11-4q21. The strategy used in our study was to map the DPP gene locus to the long arm of human chromosome 4, in the same region as DGI, using a DPP oligonucleotide probe and somatic hybrid cell lines. The results indicate DPP is not localized to any region of human chromosome 4. Our data indicates that a mutation within the DPP gene locus is not associated with DGI Types II or III. This data is supported by the identification of human DPP (95 kDa) within the dentin extracellular matrix of molars isolated from an affected DGI type II patient using a mouse anti-DPP antibody. However, this does not exclude the possibility that enzymes associated with DPP post-translational modifications (ie. phosphorylation or degradation) might be responsible for this genetic disease.

Animals↗
PubMed1992

Type II collagen defect in two sibs with the Goldblatt syndrome, a chondrodysplasia with dentinogenesis imperfecta, and joint laxity.

We report on a syndrome of spondylo-epimetaphyseal dysplasia, dentinogenesis imperfecta, and ligamentous hyperextensibility in two sibs born to nonconsanguineous parents. This chondrodysplasia was characterized by severe shortness of stature and an osteoporosis without fractures. Electron microscopic examination of the cartilage documented large vacuoles of dilated rough endoplasmic reticulum within the cytoplasm of chondrocytes. Gel electrophoresis of pepsin-soluble collagen extracted from cartilage demonstrated the presence of type II collagen chains with an abnormal mobility. Prolyl and lysyl hydroxylations were slightly increased. The abnormal molecules melted at a higher temperature than the normal ones. CNBr peptide mapping of type II collagen showed an altered electrophoretic migration of peptides CB 11, CB 8, and CB 10,5 whereas CB 9,7 looked normal. In addition, two small non-collagenous proteins isolated from cartilage were not found in an age-matched control individual but were detected in a normal newborn infant. The quantitation of proline-labelled collagen synthesized by dermal fibroblasts demonstrated a 50% reduction of total collagen. This decrease essentially affected the amount of extracellular type I collagen, which was secreted less efficiently than in control cells. Nevertheless, type I collagen chains behaved normally on 5% polyacrylamide gels. The reduced mRNA levels of alpha 1I and alpha 2I chains might reflect either a transcriptional defect or a decreased stability of mRNA transcripts. We suggest that the association of both pathological chondrocytes producing altered collagen type II and decreased synthesis of type I could be responsible for this peculiar phenotype. The overmodification of alpha 1II CNBr peptides is consistent with the presence of a single-base substitution in the COL2A1 gene. Whether there is a direct causal relationship between the type II collagen defect and the underexpression of type I collagen will require clarification.

Abnormalities, Multiple↗
PubMed1985

The ultrastructure of the dental tissues in dentinogenesis imperfecta in man.

Eight primary incisors obtained from a child with dentinogenesis imperfecta (DI) type II were examined histologically using light microscopy and scanning electron microscopy. In both the DI and control teeth, large dentinal canals were observed along the midline of the crown distributed mesial-distally and coursing towards the pulp. Variably-structured mantle dentine was seen in the DI teeth ranging from tubular to virtually atubular. Enamel separation occurred at the dentine-enamel junction despite apparently normal scalloping. In the enamel, fractures occurred along accentuated striae of Retzius where ultrastructurally there was prism bending and discontinuity. The structure of DI teeth probably results from a structural or regulatory protein abnormality and irregular epithelial-mesenchymal interaction. The combined influence of these factors appears to cause variable histologic appearances and rates of tissue deposition.

Child, Preschool↗