scholarly journals Outer Enamel Epithelium

2020 ◽  
Author(s):  
Keyword(s):  
Enamel Epithelium

Opg, Rank, and Rankl in Tooth Development: Co-ordination of Odontogenesis and Osteogenesis

2004 ◽  
Vol 83 (3) ◽  
pp. 241-244 ◽  
Author(s):  
A. Ohazama ◽  
J.-M. Courtney ◽  
P.T. Sharpe
Keyword(s):  
Tooth Development ◽  
Nuclear Factor Κb ◽  
Cellular Interactions ◽  
Rankl Expression ◽  
Dental Papilla ◽  
Spatiotemporal Expression ◽  
Receptor Activator ◽  
Explant Cultures ◽  
Enamel Epithelium ◽  
Tooth Germs

Osteoprotegerin (OPG), receptor activator of nuclear factor-κB (RANK), and RANK ligand (RANKL) are mediators of various cellular interactions, including bone metabolism. We analyzed expression of these three genes during murine odontogenesis from epithelial thickening to cytodifferentiation stages. Opg showed expression in the thickening and bud epithelium. Expression of Opg and Rank was observed in both the internal and the external enamel epithelium as well as in the dental papilla mesenchyme. Although Rankl expression was not detected in tooth epithelium or mesenchyme, it was expressed in pre-osteogenic mesenchymal cells close to developing tooth germs. All three genes were detected in developing dentary bone at P0. The addition of exogenous OPG to explant cultures of tooth primordia produced a delay in tooth development that resulted in reduced mineralization. We propose that the spatiotemporal expression of these molecules in early tooth and bone primordia cells has a role in co-ordinating bone and tooth development.

Lesions of the Enamel Organ of Developing Dog Teeth following Experimental Inoculation of Gnotobiotic Puppies with Canine Distemper Virus

1981 ◽  
Vol 18 (5) ◽  
pp. 684-689 ◽  
Author(s):  
R. R. Dubielzig ◽  
R. J. Higgins ◽  
S. Krakowka
Keyword(s):  
Canine Distemper Virus ◽  
Giant Cells ◽  
Enamel Organ ◽  
Post Inoculation ◽  
Canine Distemper ◽  
Experimental Inoculation ◽  
Enamel Epithelium ◽  
Viral Inclusions ◽  
Reduced Enamel Epithelium ◽  
Multinucleate Giant Cells

Ten 7-day-old gnotobiotic Beagle puppies were inoculated intraperitoneally with virulent canine distemper virus (R252-CDV). The dogs were killed and perfused with paraformaldehyde/glutaraldehyde from eight to 36 days after inoculation. The developing teeth of the mandibles were examined by light microscopy, and the teeth from three dogs were examined by electron microscopy. Necrosis of individual cells in the stratum intermedium of the developing tooth was the first change, detectable at day 9 post-inoculation. At day 16 post-inoculation, there was disorganization of the ameloblasts. In the stratum intermedium, multinucleate giant cells and large eosinophilic cytoplasmic viral inclusions were prominent. Ultrastructurally, these inclusions consisted of clusters of tubular aggregates typical of canine distemper virus nucleocapsids. At 28 to 36 days post-inoculation, the changes were seen in the reduced enamel epithelium. Multinucleate cells were seen, but no inclusions. Some necrotic cells were seen. In these teeth, ameloblastic cells of the root were morphologically normal. Our results suggest that distemper virus affects developing teeth by direct infection of the enamel organ.

scholarly journals WNT5A Expression in Ameloblastoma and Its Roles in Regulating Enamel Epithelium Tumorigenic Behaviors

2010 ◽  
Vol 176 (1) ◽  
pp. 461-471 ◽  
Author(s):  
Waleerat Sukarawan ◽  
Darrin Simmons ◽  
Cynthia Suggs ◽  
Kimberly Long ◽  
J. Timothy Wright
Keyword(s):  
Wnt5a Expression ◽  
Enamel Epithelium

scholarly journals Pericoronal Follicles of Asymptomatic Impacted Teeth: A Radiographic, Histomorphologic, and Immunohistochemical Study

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Laura Villalba ◽  
Federico Stolbizer ◽  
Fabián Blasco ◽  
Néstor Raúl Mauriño ◽  
María Julia Piloni ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Immunohistochemical Study ◽  
Squamous Metaplasia ◽  
Ki 67 ◽  
Impacted Teeth ◽  
Positive Expression ◽  
Dentigerous Cysts ◽  
Proliferation And Apoptosis ◽  
Enamel Epithelium ◽  
Reduced Enamel Epithelium

Objective. To associate radiographic and histopathological features of pericoronal follicles (PFs) of asymptomatic impacted teeth and evaluate cell proliferation and apoptosis in the epithelium.Study Design. Epithelium and mesenchyme of radiographically normal (NPF≤2.5 mm) and hyperplastic (HPF 2.6 to 5 mm) PF (n=140) were studied histologically. Cell proliferation (PI) and epithelial apoptosis were evaluated by Ki-67 and bcl-2 expression in 14 NPFs and 10 dentigerous cysts (DCs).Results. Radiographically, 127 were NPFs and 13 were HPFs; 87.8% of total PFs exhibited epithelium on the surface. Reduced enamel epithelium was observed in 78 (61.4%) NPFs and 6 (46.2%) HPFs, squamous metaplasia in 17 (13.4%) NPFs and 4 (30.8%) HPFs, and cystic epithelium in 15 (11.8%) NPFs and 3 (23%) HPFs. Mean PI was1.97±1.25and7.97±1.74in the epithelial component of NPF and DC, respectively; bcl-2 positive expression was observed in 9 (64.3%) NPFs and 7 (70%) DCs.Conclusion. The scant epithelial remnant proliferation could imply low risk for development of odontogenic pathologies in the absence of an additional stimulus.

Phosphohydrolase Activities in Developing and Mature Dental Tissues

1990 ◽  
Vol 45 (3-4) ◽  
pp. 280-292
Author(s):  
Edda Warth ◽  
Reinhard Jeck
Keyword(s):  
Alkaline Phosphatase ◽  
Root Formation ◽  
Specific Activity ◽  
Tooth Development ◽  
Inorganic Pyrophosphatase ◽  
Dental Tissues ◽  
Dental Hard Tissues ◽  
Hard Tissues ◽  
Enamel Epithelium ◽  
Enamel Mineralization

Abstract In the course of the odontogenesis of bovine incisors several clearly distinguishable phosphohydrolase activities are observed in the pulp and in dental hard tissues. Using various substrates and inhibitors, unspecific alkaline phosphatase, two isoenzymes of acid phosphatase, Ca2+-activated ATPase and inorganic pyrophosphatase are characterized. The enzymatic activity of alkaline phosphatase in pulp and hard tissues is significantly high at the beginning of dentine and enamel mineralization. The specific activity of this enzyme decreases quite fast with the beginning of root formation, then more slowly, until it reaches a constant final value. Histochemical studies show that during mineralization the maximum of alkaline phosphatase activity is in the subodontoblasts. Lower enzyme concentrations are found in the stratum intermedium and in the outer enamel epithelium during that process. The specific activities of ATPase, acid phosphatases and pyrophosphatase show little temporal variation during tooth development, but they also appear in a characteristic spatial pattern in the dental tissues.

scholarly journals A contribution to the diagnosis of the small dentigerous cyst or the paradental cyst

2001 ◽  
Vol 15 (3) ◽  
pp. 238-246 ◽  
Author(s):  
José Humberto DAMANTE ◽  
Raul Negrão FLEURY
Keyword(s):  
Squamous Epithelium ◽  
Statistical Significance ◽  
Dentigerous Cyst ◽  
Radiographic Analysis ◽  
Dentigerous Cysts ◽  
Enamel Epithelium ◽  
Microscopic Features ◽  
Stratified Squamous Epithelium ◽  
Unerupted Teeth ◽  
The Relationship

The aim of this study was to verify the relationship between the radiographically measured width of the pericoronal space (PS) and the microscopic features of the follicle in order to contribute to the diagnosis of small dentigerous cysts and paradental cysts. One hundred and thirty unerupted teeth (UT) and thirty-five partially erupted teeth (PET) were radiographed and extracted. The radiographic analysis consisted of measuring the width of the PS. The results of the radiographic analysis were compared with those of the histopathologic examination of the dental follicle. The width of the PS ranged from 0.1 to 5.6 mm. The most frequently observed lining of the follicles was a reduced enamel epithelium (REE) (68.4%) in UT and a hyperplastic stratified squamous epithelium (HSSE) (68.5%) in PET. Inflammation was present in 36.1% of the UT and in 82.8% of the PET. There was a statistically significant association between the presence of stratified squamous epithelium (SSE) and PS enlargement for UT (p < 0.05). There was a tendency of association between inflammation and PS enlargements in PET and, possibly, in UT, despite the absence of statistical significance. Surgically, we did not detect bone cavitation or luminal cystic contents in pericoronal spaces smaller than 5.6 mm. We suggest that the first radiographic diagnosis for a PS enlargement, in most of the routine clinical cases, should be of "inflammation of the follicle". The hypothesis of "dentigerous cyst" or "paradental cyst" is suggested as a second diagnosis. The final differential diagnosis between a small dentigerous or a paradental cyst and a pericoronal follicle depends on clinical and/or surgical findings, such as the presence of bone cavitation and cystic content.

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