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Biomedical subjects

L M Kerebel

Publications and source records attributed to L M Kerebel.

At least 19 recordsLinked to original sources
PubMed1991

Scanning electron microscopic study of odontoblasts and circumpulpal dentin in a human tooth.

Two combined scanning electron microscopic methods including modified fixative procedures were used for studying the morphologic aspects of the odontoblasts and the corresponding dentinal wall at different endodontic levels. The odontoblasts were tightly packed in the pulp horn, where they assumed pear-shaped profiles and, from crown to apex, successively looked spindle shaped, club shaped, and globular. Their number decreased in the pulp radicular portion, where the interglobular spaces were enlarged. The filling fibrillar material varied from crown to apex. A globular circumpulpal dentin was observed at all levels of the root canal. The tubule openings varied in number and size.

Adult↗
PubMed1989

A transmission electron microscope study of fibroblast changes in human deciduous tooth pulp.

The coronal pulps of four primary canines, free from radicular resorption, and of three primary teeth, with roots entirely resorbed, were prepared for electron microscopy. Mature fibroblasts, similar to those reported in the pulps of permanent teeth, were present in the pulps of the clinically mature teeth. Regression of fibroblasts, evident in the pulps of deciduous teeth at the root resorption stage, was characterized by cytoplasmic changes, modifications in the cytoskeleton and dissociation of cells and fibrils. Deciduous teeth might provide a model for studying pulp fibroblast ageing.

Actin Cytoskeleton↗
PubMed1989

Regional odontodysplasia: new histopathological data.

Light microscopy, microradiography, SEM and TEM of 4 tooth follicles in a 12-year-old caucasian girl presenting regional odontodysplasia showed widespread globular dentin, calcifications located in the enlarged pulp chambers, hypoplastic and hypomineralized enamel. Hypomineralized strands were sandwiched between two normal enamel layers, which indicates that amelogenesis, interrupted for a while, has once more become established. The enamel surface was covered with calcoglobules. Numerous rounded calcifications were scattered within the dental follicles. Some of these occurred in microfibrils (possibly oxytalan fibers), distinct from collagen fibers. Calcification of the sheath surrounding epithelial rests was a conspicuous feature. The fibroblasts in contact with calcifications developed numerous cytoplasmic extensions, which suggests that they may have assumed a phagocytosis behaviour.

Child↗
PubMed1989

[The structure, ultrastructure and physicochemical analysis of the hard dental tissues of the Viperidae].

The present study, using classical microscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, infrared spectroscopy, has shown the dental hard tissues of the fangs of Viperidae (poisonous serpents with terrestrial or semi-aquatic habits) to be constituted of: a calcified outer layer, 0.4 microns thick, made of very small needle-like crystals, randomly distributed. The calcified outer layer contains organic invaginations inducing pores at the surface and many collagen fibres incompletely mineralized, which may suggest enameloid. a calcified inner layer, in the wall of the poison canal. The calcified inner layer, 0.6 microns thick, is constituted of very small crystals, which are parallel to each other and perpendicular to the calcified outer layer. It might be the inner layer of enameloid, an orthodentine, whose tubules present a special lateral branching system resembling a fish bone. The TEM data, which show the dentine to be constituted of very small ill-defined crystals and incompletely mineralized collagen fibres are corroborated by chemical analyses which reveal a poorly mineralized apatite with high carbonate content.

Animals↗
PubMed1989

[The structure and ultrastructure of the pulp in Vipera aspis (Viperidae)].

The present paper using classical and transmission electron microscopy brings the first data on the pulp of the fangs of Viperidae (poisonous serpents with terrestrial or semi-aquatic habits). The pulp of the fangs of Viperidae shows a poor collagen and fibroblast content and a high developed vascular system. The odontoblasts are polarized, with a high organelle content. The interconnections are constituted of lateral "gap junction" systems. At a late secretion stage, the odontoblastic processes show a poor cytoplasm, mainly constituted of microfilaments.

Animals↗
PubMed1989

Structural and ultrastructural study of the teeth in a suspected case of pseudohypoparathyroidism.

Two premolars removed from a 14 year old girl, with suspicion of pseudohypoparathyroidism (PHP) have been studied, using several of the correlated techniques applied to the study of calcified tissues (light microscopy, microradiography and scanning electron microscopy). Enamel gross and micro hypoplasia, hypomineralization of the enamel surface and dentin hypocalcification were similar to dental abnormalities observed in pseudohypoparathyroidism. Microradiography showed for the first time calcifications present in blood vessels of the dental pulp. Light microscopy and SEM revealed dystrophic globular calcifications within enamel hypoplastic pits. Cemental changes consisting of hypoplasia, aplasia, localized hyperplasia and cementicules were described for the first time. It is suggested that enamel, dentine and pulp abnormalities observed in the present case might be pathognomonic of PHP.

Adolescent↗
PubMed1989

[Epidemiologic survey of orodental health in Fada N'Gourma (Burkina Faso)].

In 1983 an investigation involving a homogeneous population sample from a western city of Burkina Faso has been performed in 1983 in order to estimate the oral health status of the population cut off from any dental assistance and to assess the importance of traditional practices in the city. The investigation, performed using World Health Organization techniques (WHO, 1977) involved 354 subjects, male and female, divided into age groups from 10 to 54. It was shown that: although the oral hygiene level was very low and no dental treatments were performed, caries level was very low--although gingivitis rate was high, advanced periodontitis rate was low--the frequency of interincisive diastema (one subject out of 4 in the 15-19 age group), the progressive decline of tooth cutting, a traditional practice, in town people but the large extent of cola use (one adult out of two). The present data will be used as base-line reference to evaluate the incidence of a dental care and prevention program which has just started in the same city of Burkina Faso.

Age Factors↗
PubMed1988

Transmission electron microscopy of the morphological relationship between fibroblasts and pulp calcifications in temporary teeth.

Calcifications found in the coronal pulps of primary teeth extracted in an 8-year-old child were studied by TEM. Different types of relationship were observed between fibroblasts and pulp calcifications: extension of cell processes towards calcifications, modelling of the cells upon calcifications, internalizing process of calcifications. Fibroblasts proved to be able to enclose small pulp calcifications within intracytoplasmic vesicles. There was no evidence of any active role played by fibroblasts in the genesis of pulp calcifications. It was shown that collagen fibres could be involved or not in the mineralizing process. It is suggested that mitochondria might provide an adequate environment for initial mineralization. It is likely that the role played by the cytoskeleton in the internalizing process of calcifications is important.

Child↗
PubMed1987

In vitro effects of calcium phosphate biomaterials on fibroblastic cell behavior.

The effect of synthetic granular hydroxyapatite (HAP) on cultured fibroblastic cells (L929, human bone and gingiva cells) was studied. Phagocytosis of HAP particles and resulting morphological cell changes were demonstrated by microscopic examinations. Cell counts and [3H]thymidine uptake indicated significant increases in cell proliferation and DNA synthesis. These results could account for some of the alterations of the fibroblast behavior induced by changes in intracellular levels of calcium ions released from the material.

Animals↗
PubMed1986

Scanning electron microscope study of the predentin-pulpal border zone in human dentin.

Fragments of sound human molars were prepared for the scanning electron microscope (SEM) using modified fixative procedures and the carbon dioxide critical-point method to study the predentin-pulpal border zone. This technique minimizes the usual artifacts related to SEM procedures. The elongated odontoblast bodies are closely related to each other at the predentin level. For the first time in SEM procedures, the cell processes almost completely fill the predentinal tubules. Fibers measuring 0.3 to 0.5 micron in diameter are visible between the odontoblasts and fan out into the predentin. They correspond to the so-called Korff's fibers. Others, measuring less than 0.2 micron in diameter, are visible on the predentinal surface and follow the cell processes into the predentinal tubules. They correspond to nerve fibers. This study demonstrates that the proper use of improved SEM fixative techniques and the carbon dioxide critical-point method provides data on the relation between the different components of the predentin-pulpal border zone, which are in agreement with transmission electron microscope data.

Dental Pulp↗
PubMed1986

[Dental enamel pearls: histopathological study].

Enamel pearls are small rounded or egg-shaped nodules which most frequently develop in the furcation area of molars. They may consist of enamel only or enamel containing a small core of tubular dentin. They often sit upon strands of cementum or Tomes granular layer. Histologically, the enamel surface of enamel pearls resembles immature enamel and may be covered with cementum. Small calcoglobules presenting varying degrees of organization are often found related to enamel pearls. Some of them, which have the same radiodensity as the enamel of the pearl and of the affected tooth, may be considered as an enamel-type of calcifications. Others, which present a concentric structure revealed by a polarization cross when viewed between cross polars, may be similar to cementicles. All calcifications located in contact with enamel pearls or at a distance, from them are dystrophic calcifications.

Calcinosis↗
PubMed1985

Ghost cells in complex odontoma: a light microscopic and SEM study.

Ghost cells in complex odontoma were studied by light microscopic and scanning electron microscopic examination of decalcified sections. They were found at different locations in odontomas: next to tubular dentin, at the site where enamel would be expected; adjacent to remnants of enamel matrix or surrounded by enamel matrix; within granular calcified masses in contact with bone or tubular dentin; in contact with ameloblasts or adjacent to small rests of odontogenic epithelium. They were either isolated or arranged in groups. Their cytoplasm presented a fibrillar component and a lack of keratohyaline. In a complex odontoma, ghost cell keratinization occurs as a result of metaplastic transformation. The calcifying process in these cells was found to be a passive one, with the cells becoming gradually entrapped within the calcified material--bone, osteoid, dentin, dystrophic osteodentin, or dystrophic granular or lamellar types of calcification. Complex odontomas contain both normal and metaplastic odontogenic epithelial cells, which may have lost their developmental and inductive properties.

Ameloblasts↗
PubMed1985

Report on caries reduction in French schoolchildren 3 years after the introduction of a preventive program.

A combination of preventive methods have been used to reduce dental caries in children aged 7-8 at baseline, living in a non-fluoridated area in the West of France. The preventive program involved a daily supervised toothbrushing at school with 180 mg of fluoridated toothpaste, professional prophylaxis every 2 months with topical application of fluoride gel and reinforced motivation. The oral hygiene level was measured using the Silness-Löe plaque index and caries were recorded using the def and DMF surface indices, including incipient lesions. The 3-yr results showed a significant 52% plaque reduction in the test group compared with the control group. Caries reduction was significant at the 0.01% level: 44% for primary teeth and 60% for permanent teeth.

Child↗
PubMed1984

Length and shape of enamel crystals.

An original method for fractionating and preparing isolated crystals of homogeneous size was developed. It was demonstrated that enamel apatite crystals are at least 100 micron long. The flexibility of the very long crystallites was demonstrated. Crystal curvatures, accounting for the irregular course of the prisms through the enamel thickness, were visualized and measured. It was shown that in the deep forming enamel layer, lateral branches may grow out of the crystals and crystal fusing often occurs, inducing the crystallites to assume pyramidal shapes with their wide bases pointing toward the dentino-enamel junction and one or two tops toward Tomes' processes. During the maturation process, the two tops of the still immature crystals also fuse so that the mature crystals acquire a rodlike aspect, with parallel faces and steplike graduations along the c axis, allowing a close contact between the crystals. These results support the hypothesis that the crystallites would be continuous from the dentino-enamel junction to the surface.

Animals↗
PubMed1984

Dysplastic enamel in odontoma: a light microscopic, microradiographic and SEM study.

Dysplastic enamel and calcifications at the enamel surface in 7 odontomas were studied, using correlated light microscopy of decalcified and undecalcified material, microradiography and SEM. Much of the dentin in the odontomas was not covered with enamel. When present, the enamel was immature and assumed a prismatic structure. The prisms were irregular distributed and associated with spherical calcifications. The calcifications adhering to the enamel surface or separated from it presented variations in size, morphology, staining reactions and radiodensity. The correlated techniques of light microscopy, microradiography and SEM indicated that all the calcifications adhering to the enamel surface and part of those separated from it may be related to a pathological process of amelogenesis. Most of the calcifications separated from enamel and often formed around nidi of ghost cells, are the result of a dystrophic mineralizing process, definitely distinct from amelogenesis.

Calcinosis↗
PubMed1984

Dental involvement in congenital chloride diarrhea.

Dental involvement in a case of congenital chloride diarrhea (CCD) was studied using light microscopy of decalcified and undecalcified sections, microradiography and TEM. Mixed enamel lesions were found, involving gross hypoplasia at the cuspal level and hypocalcification occurring all over enamel. The hypocalcification resulted in the immature aspect of the prismatic enamel, porosities, amorphous areas, prominent incremental lines and round-ended crystallites. A marked hypocalcification suggests a temporary break of amelogenesis likely related to acute episodes of the disease. Globular calcifications were associated with enamel formation. Dentinal hypocalcification was conspicuous and diffuse all over dentine. A globular mineralization pattern was revealed by the tretracycline (TC) stain which was well preserved in decalcified sections, thus indicating that TC uptake is related to the organic matrix. It is unlikely that TC alone is responsible for the hypocalcified areas which extended widely beyond the TC-stained bands. It is suggested that TC uptake only adds to dental defects induced by the metabolic troubles of CCD.

Alkalosis↗