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At least 19 recordsLinked to original sources
PubMed1988

Scanning electron microscopic study of dentin walls of the pulp chamber by a replica technique.

Precise replicas of the pulp chamber were made with a low-viscosity synthetic resin and examined with a scanning electron microscope. As a result, it was confirmed that the pulp horns and the pulp roof were clearly observed at both low and high magnification by this replica technique. Furthermore, interesting findings were made. That is, a vessel-like linear ridge or groove, measuring 5 micron in diameter, was observed on the surface of the replica. The ridge or groove ran across the top of the pulp horn to the pulp roof in the direction of the other horns. Such a linear ridge or groove was found in 32 of 50 specimens (64%). It may be interpreted that there was a stringy structure embedded in the calcospherites beneath the predentin. However, the origin of these structures could not be determined in this experiment.

Dental Pulp↗
PubMed1990

Cytopathology of adenovirus keratitis by replica technique.

Corneal replicas were made from the severely affected eyes of 12 patients presenting with typical signs and symptoms of epidemic keratoconjunctivitis. Adenovirus was isolated from the eyes. Histopathological study of the replicas and cytology of diseased cells removed with the replica showed diffuse mild oedema of the epithelium, with scattered moderately swollen and deformed cells. The clinically observed punctate lesions histologically consisted of markedly swollen cells that had become oval or rounded. Fusion of these cells led to small syncytial formations, and the development of pseudopodia-like processes was occasionally observed. Loss of cell contents resulted in the formation of plicae on the surface of many cells. Two types of inclusion bodies were detected in the epithelial cells. The first type, intranuclear vacuolar inclusions, contained homogeneous material. The second type of inclusions were round, dense bodies, that developed in the homogeneous material of intranuclear vacuolar inclusions. The dense bodies contained the replicating and maturing virus particles. After cell degeneration the dense bodies become extracellular. Making a corneal replica had a beneficial effect on the clinical course of adenovirus keratitis.

Adenoviridae↗
PubMed1981

An universal and accurate replica technique for scanning electron microscope study in clinical dentistry.

One of the main concerns of dental research is the observation of the oral tissues and the materials applied to the dentition. The changes in composition and structure of the outer surfaces and the materials deposited on these surfaces are of special interest. In the literature, a variety of replica techniques for these purposes is described (Grundy in 1971 [12]; Saxton in 1973 [25]). The use of these techniques is limited because of artifacts in the samples, and a restricted resolution power resulting from useful magnifications in the order of 800x. An accurate and universal replica technique for the examination of specimens to be viewed under the SEM has been developed. The first impression is made by a light body silicone elastomer (President Coltene). The positive replica is made by electrodeposition of copper in an electro plating bath (Acru plat 5 electronic, Dr. Th. Wieland, D-7530 Pforzheim). The reliability and accuracy of this replica technique was verified by a scanning electron microscopic comparison of the replicas and the actual structures of etched enamel. To illustrate the applicability of the replica technique to structures with much lower hardness, also high resolution images of dental plaque were produced. The copper surface offers a perfect, original and proper electroconductive medium that withstands the bombardment of electrons and the relatively severe conditions in the scanning electron microscope. Reproducibility was accurate as judged by the duplication in position, size, and shape of the fine detail at magnifications of 7500x offering a resolution of 25 nm.

Bacteria↗
PubMed1982

A new in vivo replica technique for scanning electron microscope study of dental plaque morphology.

For the micro-morphological investigation of soft oral tissues and deposits on the teeth in vivo, the use of an accurate replica technique is essential if the object under study cannot be examined directly. The conventional replica techniques based on resin or elastomer positive dies, have some limitations due to the instability of the sample die in the scanning electron microscope (S.E.M) conditions and artifacts induced at higher magnifications. Therefore, a new replica technique has been developed using a low viscosity impression material that is subsequently copperplated and poured with synthetic plaster. This offers a stable metal positive die suitable for direct examination in the S.E.M. without prior gold evaporation. Higher magnifications (greater than 7500) are easily obtained without the danger of artifacts. Reproduction of details is of a high order, and the reproduction ability depends only on the accuracy of the first impression. This technique offers new possibilities of discerning fine changes in surface detail in longitudinal clinical investigations.

Adult↗
PubMed1996

Fracture surface characteristics of damaged acrylic-resin-based dentures as analysed by SEM-replica technique.

The aim of this study was to determine some characteristics of the fracture surface of an acrylic resin denture. For this purpose, five complete upper dentures and two complete lower dentures that had fractured into two pieces were collected, the fracture surfaces were duplicated with the SEM-replica technique and duplicated surfaces were investigated with a scanning electron microscope. The reproducibility of the SEM-replica technique was tested by comparing one original sample surface and its replica surface of the same area. The SEM-photomicrographs revealed a series of fine striations in the fracture surfaces of both the upper and lower dentures perpendicularly orientated to the direction of the fracture propagation. A smooth area on the fracture surface was assumed to indicate a slow fatigue fracture process, and a rougher area fracturing with increased velocity.

Dental Restoration Failure↗
PubMed1982

Labelled-replica techniques: post-shadow labelling of intramembrane particles in freeze-fracture replicas.

Three methods are described for direct post-fracture, post-shadow labelling of individual classes of intramembrane particles (IMPs) in freeze-fracture replicas of biological membranes. The P-face IMPs corresponding to the acetylcholine receptor complexes (AChRs) of vertebrate neuroeffector junctions are identified by post-replication labelling with ferritin-antibody complexes and with neurotoxin-biotin-avidin-colloidal gold affinity ligands. (The freeze-etch nomenclature of Branton et al., 1975, is used in this report.) These post-shadow labelling techniques resemble conventional en bloc labelling techniques except that the labelling reagents must penetrate a thin but discontinuous layer of platinum superimposed on the molecules of interest. In the 'sectioned labelled-replica technique', the replicated and labelled tissues are stained, embedded in plastic and sectioned parallel to the replica-tissue interfaces. In the direct 'labelled-replica techniques', the replicated and labelled samples are freeze-dried or critical point dried, the labelled surfaces are stabilized by carbon coating, and the underlying tissues are dissolved, allowing the labelled-replicas to be examined as conventional freeze-fracture replicas. The unshadowed side of each AChR IMP is shown to retain sufficient biochemical information to permit both immunospecific and neurotoxin specific labelling despite formaldehyde fixation, freezing, fracturing, platinum shadowing, and thawing in aqueous media. A new mixed ferricyanide-osmium staining method reveals electron opaque structures spanning the membrane bilayer in the same size, number and distribution as the labelled IMPs. These experiments demonstrate the feasibility of identifying individual IMPs in freeze-fracture replicas and may allow the identification of specific membrane lesions in human disease.

Animals↗
PubMed1979

Study of filamentary keratitis by replica technique.

Histopathological study of filamentary keratitis was done by using replica technique in five patients. The filaments are produced by sliding of the epithelial cells around small areas of focal degeneration of the superfical epithelium. In comparison to the filaments in other conditions, the filaments in KCS are smaller and thicker and do not show the torsional segment. The filaments contain degenerated epithelial cells and alcian blue-PAS positive mucoid material. Making a corneal replica may result in healing of filamentary keratitis.

Corneal Ulcer↗
PubMed1979

Double replica technique applied to choroid plexus from early foetal sheep: completeness and complexity of tight junctions.

Choroid plexuses from early and late sheep foetuses were examined by an improved freeze-fracture technique and the use of double-replicas to define the structure of the tight junction network of the epithelial cells. 'Complex' strands which consist of two normal parallel strands separated by a single row of pits or particles are defined and demonstrated in complementary faces. Since this strand variety was encountered in the same proportion in the different development stages investigated, it could not be correlated with changes in permeability. It is more likely that the 'complex' strands are associated with the transfer of gap junction particles within the membrane. The question of the significance of discontinuities in P face ridges was also resolved by the double replica technique: the few discontinuities which were observed could be accounted for by particles in the complementary E faces. Furthermore, approximately the same number of such junction displacements was found in early and late stages which makes it unlikely that this phenomenon could contribute to changes in permeability. Thus it has not been possible so far to relate any structural feature of the tight junction network in developing choroid plexus epithelial cells with the reported changes in permeability of the blood-C.S.F. barrier.

Animals↗
PubMed1991

Use of the metal replica technique in the electron microscopy of collagen.

The authors present a survey of visualization of the individual types of collagen by the metal replica technique, special attention was paid to the visualization of type IX collagen, which, together with type XI, is a minor component of cartilage collagen. The molecule of this collagen type contains three collagen and four non-collagen domains and during the isolation involving pepsin digestion it is cleaved into MHW and LMW fragments. The HMW fragment can be further cleaved into shorter and longer arm. Results of statistical evaluation of 199 measured molecular fragments showed the following length: whole molecule 194 +/- 23 nm, HMW 136 +/- 16 nm, the longer arm of the HMW 87 +/- +/- 12 nm and the LMW of shorter arm of the HMW 43 +/- 9 nm.

Collagen↗
PubMedDate not supplied

The agar-replica technique for dental caries diagnosis. Has its time arrived?

The agar-replica technique of Bahn et al is described. This caries-diagnostic technique detects the site of lactobacillus infection on the teeth. Evidence and logic indicate that this technique is more accurate than current caries-diagnostic methods. The method appears to answer the recent call for diagnostic methods which identify the more subtle expression of the disease, and it helps classify lesions into categories keyed to different treatment strategies.

Agar↗
PubMed2005

Evaluation of internal adaptation in ceramic and composite resin inlays by silicon replica technique.

This study was aimed at investigating the internal adaptation of a ceramic (Ceramco II) and two composite resin inlay materials (SureFil and 3M Filtek Z 250) using silicon replica technique as an indicator. Forty-five standard mesial-occlusal-distal (MOD) cavities were prepared into brass moulds by using computer numerically controlled system. Inlays were prepared according to manufacturers' instructions with indirect methods. Replicas of the prepared cavities and inlays were produced with a polyvinyl siloxane material (Elite H-D). The spaces between inlays and cavities were filled by different coloured light-body polyvinyl siloxane material. Two parallel slices (mesio-distally) were obtained from the replicas with a sharp blade. Different coloured polyvinyl siloxane material thickness between cavity and inlay was measured at seven points (mesial, occlusal and distal). The data were evaluated with anova and Tukey's honestly significantly different (HSD) statistical tests. In the SureFil and Ceramco II groups, the sizes of the contraction gaps at mesial and distal gingival floors were greater than that of the occlusal marginal walls. In comparison of gap formation at occlusal regions, while the 3M composite group showed highest gap values (204.33 +/- 75.45 microm), the Ceramco II group revealed the lowest (141.17 +/- 23.66 microm) (P < 0.05). At the gingival floors, gap formation of Ceramco II group was the highest (227.08 +/- 51.95 microm). Neither the 3M Filtek Z250 nor SureFil group showed any statistical difference between gap values of their self-occlusal and gingival floors (P > 0.05). In conclusion, our results showed that ceramic inlays did not confer any big advantage for internal adaptation over the composite inlays.

Ceramics↗
PubMed1985

Replica techniques for in vivo studies of tooth surfaces and prosthetic materials.

In order to obtain a replica technique suitable for a complete or segments of a dental arch two different impression materials were combined with two epoxy resin model materials. The models were examined and photographed in an optical microscope and a scanning electron microscope. No systematic differences were found between the used combinations of materials except a tendency towards greater contraction of one of the model materials. The A-silicone impression materials combined with one of the epoxy resin material seemed to be the easiest to handle and to give the best models.

Calcium Sulfate↗
PubMed1990

A replica technique for extracting precipitates from zirconium alloys for transmission electron microscopy analysis.

A reliable two-stage carbon replica technique has been developed to extract precipitates from zirconium alloys. Using this technique, all precipitating phases can be extracted from Zircaloy-2, Zr-Cr-Fe, and Zr-Nb-Fe alloys. Precipitate identification using EDS X-ray analysis and convergent beam electron diffraction was greatly facilitated in comparison to thin foils. In addition, the sensitivity for the detection of trace elements in particles was increased using extraction replicas. The chemical compositions of the precipitates as determined from both replica and thin foils were in excellent agreement.

Alloys↗
PubMed1994

Three-dimensional distributions of desmin and vimentin in cultured hamster cardiomyocytes using the immunogold deep-etching replica technique.

The distributions of desmin and vimentin intermediate filaments in cultured hamster heart cells were examined by immunofluorescent microscopy and an immunogold deep-etching replica technique in combination with electron microscopy. Fluorescent studies showed the overall staining patterns of the myocytes as well as the fibroblasts. Monoclonal antibodies (Da, D3) to desmin showed punctate staining for the myocytes, while polyclonal desmin (pD) stained in a filamentous pattern. Fibroblasts stained strongly with monoclonal anti-vimentin (Va), but did not stain with the desmin probes. Deep-etched immunogold studies confirmed at the ultrastructural level that monoclonal anti-desmin antibodies stain individual intermediate filaments in an intermittent pattern. Monoclonal (D3) antibody stained the intermediate filaments heavily and continuously at the cell peripheries, while it stained intermittently in the cell body, similar to the Da monoclonal. Monoclonal anti-vimentin stained only intermediate filaments in fibroblasts. Our studies show a heterogeneity of staining within the cultured heart cells when various anti-desmin and anti-vimentin antibodies are used.

Animals↗
PubMed1987

Cytological and immunohistochemical study of the limbal form of vernal keratoconjunctivitis by the replica technique.

The cellular composition of the inflammatory infiltrate present in 13 patients with the limbal form of vernal keratoconjunctivitis was examined in the conjunctival scrapings and the limbic replicas by means of Giemsa stain and immunohistochemistry. Conjunctival scrapings showed the presence of mast cells, lymphocytes, plasma cells, polymorphonuclear leucocytes, and very few basophils in all the specimens. Eosinophils were present in only four scrapings. The superficial epithelium of the limbic lesion and the adjacent cornea and conjunctiva was studied by the replica technique. The limbic lesion area showed the presence of necrotic epithelial cells mixed with inflammatory cells, including eosinophils, mast cells, lymphocytes, plasma cells, and polymorphonuclear leucocytes and very few basophils. Most of the inflammatory cells were HLA-DR+. Many OKT6+ cells were present, indicating the presence of Langerhans cells. T-lymphocytes including a few helper/inducer cells and many suppressor/cytotoxic cells, were detected in the infiltrate. In addition many B-lymphocytes were observed. These findings suggest that other immune mechanisms in addition to type 1 reaction are involved in the pathogenesis of the disease.

Adolescent↗
PubMed1985

Use of a replica technique to isolate muscle cell lines defective in expressing the acetylcholine receptor.

We have isolated genetic variants of the C2 muscle cell line that are defective in expressing the acetylcholine receptor (AcChoR). Because the AcChoR is expressed only after C2 myoblasts have fused to form myotubes, we employed a replica technique to detect the variants. This technique yields two copies of each clone, one of which can be used for screening and the other, as a source of dividing cells. In a screening of about 10,000 clones derived from mutagenized cells, we found 2 that fused normally and expressed normal levels of acetylcholinesterase but had reduced amounts of AcChoR on their surface. One of these also had a reduced level of intracellular AcChoR, but, in the other, the amount of intracellular AcChoR was 5-fold higher than normal. Several variants were found that failed to fuse and had reduced levels of both AcChoR and acetylcholinesterase. Though we relied on 125I-labeled alpha-bungarotoxin to distinguish wild-type from deficient clones, we found that an antiserum to the AcChoR, followed by a biotinylated second antibody and a horseradish peroxidase-avidin complex, could also be used. Therefore, it should be possible to obtain muscle cell variants defective in the expression of a variety of proteins for which specific antibodies are available.

Animals↗
PubMed1989

Dentine hypersensitivity. The development and evaluation of a replica technique to study sensitive and non-sensitive cervical dentine.

Studies of extracted teeth have shown that teeth exhibiting dentine hypersensitivity have larger numbers of widened dentinal tubules at the dentine surface compared to non-sensitive teeth. Many compounds used in the treatment of dentine hypersensitivity are thought to achieve therapeutic benefit by tubule occlusion, but there has been almost no attempt to prove such action in vivo. These studies systematically determined whether the dentine surface could be evaluated non-invasively, by a scanning electron microscopic replica technique. Employing a silicone rubber impression method in vitro, the surface detail of dentine could be accurately replicated, with surface scratches, tubules and intratubular structures on the original reproduced on the replica. With attention to method, similar accuracy was achieved in vivo, particularly when tubules were open on the dentine surfaces of the original. The method would appear useful for the study of the dentine surface in cases of dentine hypersensitivity and could prove the first objective method of studying the effects of treatment agents used in the treatment of this painful condition.

Acid Etching, Dental↗