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PubMedDate not supplied

Comparative quantitative and qualitative assessment of the marginal adaptation and apposition of bonded amalgam restorations using luting glass ionomer and 4-META adhesive liner under a scanning electron microscope. An in vitro study.

The present invitro study was conducted to assess the marginal adaptation and apposition of amalgam restorations bonded to tooth structure, using freshly mixed luting glass ionomer cement (type 1) and compared with the much documented material--Amalgam bond (4-META). Twelve freshly extracted human premolar teeth were used and class V cavities were prepared on the buccal and lingual surfaces of twelve teeth for the experimental groups. Buccal cavities (class V) were prepared on twelve other teeth for the control group. In the control, two coats of cavity varnish was applied as the liner. The experimental groups were lined with freshly mixed luting glass ionomer in twelve buccal cavities and amalgam bond adhesive liner in twelve lingual cavities. The amalgam was then condensed before the liner sets in all the cavities. The teeth were sectioned and mounted on aluminum stubs and then placed in the scanning electron microscope and were observed. The results of the study showed that marginal interface gaps were higher with luting glass ionomer and cavity varnish than with amalgam bond as the liner. The results were statistically not significant. All the three groups were effected by the severe thermal stresses introduced by the microscopy with the glass ionomer cement suffering the worst. The present investigation confirms that glass ionomer cement (type 1) can be effectively used as a bonding agent between amalgam and the tooth when it is painted onto the cavity walls after which the amalgam is condensed immediately, prior to its setting. Its ability to bond amalgam to the tooth structure with minimal gaps is comparable to that of amalgam bond.

Acrylic Resins↗

PubMed1989

The effect of transfusion of fresh whole blood versus platelet concentrates after cardiac operations. A scanning electron microscope study of platelet aggregation on extracellular matrix.

To evaluate the effect of fresh whole blood transfusion versus platelet concentrates transfusion on platelet aggregation after cardiac operations, 24 patients were randomized to receive either one unit of fresh whole blood (12 patients) or 10 platelet units (12 patients) after cardiopulmonary bypass. Platelet aggregation on extracellular matrix, platelet count, and mean platelet volume were studied preoperatively, at termination of cardiopulmonary bypass, after protamine administration, and after the transfusion of fresh whole blood or after transfusion of each two platelet units. Extracellular matrix produced by cultured bovine corneal cells closely resembles the vascular subendothelial basal lamina, and is an ideal in vitro model in the study of platelet interaction with the subendothelium. Platelet aggregation on extracellular matrix, studied by a scanning electron microscope, was graded from 1 to 4, wherein grade 1 represents nonactivated platelets and grade 4 a mature platelet aggregate. With this grading system, the two groups were similar in preoperative values (3.3 +/- 0.9 versus 3.7 +/- 0.4) and values after cardiopulmonary bypass (1.5 +/- 1.0 in both groups). One unit of fresh whole blood restored platelet aggregation on extracellular matrix to preoperative status (3.0 +/- 1.0), whereas eight platelet units were needed for the same result (3.2 +/- 0.8). One unit of fresh whole blood increased platelet count in a manner similar to that achieved by six platelet units and increased mean platelet volume to a level higher than that achieved by 10 platelet units. These results suggest that the effect of one unit of fresh whole blood on platelet aggregation after cardiopulmonary bypass is at least equal, if not superior, to the effect of 8 to 10 platelet units.

Adult↗

PubMed1994

A preliminary report on a method for studying the permeability of expanded polytetrafluoroethylene membrane to bacteria in vitro: a scanning electron microscopic and histological study.

The technique of guided tissue regeneration using expanded polytetrafluoroethylene (ePTFE) membranes has been shown to be effective in implant dentistry (bony defects, extremely thin alveolar ridges, and implants placed in fresh extraction sockets). One of the drawbacks associated with the use of membranes is their premature exposure with consequent bacterial contamination. The aim of this study was to examine the possibility that oral bacteria migrate through the occlusive portion of ePTFE membranes and to determine the time needed for microorganisms to pass from the outer surface to the inner surface of the membranes. A removable acrylic device was adapted to the molar-premolar region of one quadrant of the jaws in each of three volunteers. Five cylindrical teflon chambers were glued to the buccal aspect of each device. The chambers were divided into two rooms separated by the inner portion of a ePTFE membrane. The outer room was open to the oral cavity allowing plaque accumulation; the inner room was isolated from the oral cavity by the ePTFE membrane. One of the 5 chambers was completely closed and used as control. The test period lasted for 4 weeks. Every week, one chamber was removed from each device and processed for scanning electron microscopic and histologic examinations. Our study showed the possibility that oral bacteria may contaminate ePTFE membranes exposed to the oral cavity. One specimen showed partial bacterial penetration after 2 and 3 weeks, but after 4 weeks, all membrane specimens demonstrated bacterial contamination.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

[Observation of corneal endothelial cells in modified mid-term preservation by scanning electronic microscope].

PURPOSE: To observe the ultramicroscopic structure of corneal endothelium in modified mid-term preservation. METHODS: Eyes of 4 New Zealand rabbits were enucleated. The 4 right eyes and additional 6 human eyes (as experiment group) were treated as follows: Aqueous was drawn off and replaced with equal volume of C3F8 air, then the whole eye was preserved in wet chamber at 4 degrees C, with 2 rabbit eyes being preserved for 7 days. 1 for 10 days and 1 for 14 days, and 6 human eyes for 0, 3, 5, 7, 10 and 14 days respectively. Corneas with 1 mm scleral ring of the 4 rabbit eyes (control group) were derived and preserved in Optisol nutrients at 4 degrees C for the same period of time. Corneas of all eyes were examined by scanning electronic microscope. RESULTS: For rabbit eyes, slight edema was found in the cornea preserved for 7 days, and loss of surface microvilli and cell lysis were found in those preserved for 10 and 14 days. For human eyes, no significant change was found in cornea preserved for 7 days, and different changes were found in those preserved longer. CONCLUSION: No significant change was found in cornea endothelium preserved by this method for 7 days.

Animals↗

PubMed2005

[The effect of matrix metalloproteinase-1 on root surface dentin matrix: a scanning electron microscope observation].

OBJECTIVE: To observe the effect of matrix metalloproteinase-1 (MMP-1) from human host on degradation of dentin organic matrix of root dentin. METHODS: The freshly extracted caries-free impacted teeth were selected. Teeth were cut transversely under the enamel-cementum junction into dentin sections with a thickness of about 5 mm. Then all sections with removal of cementum, pulp and predentin were randomly divided into four groups. In the first group, dentin sections were demineralized with acid solution for 21 days, and then incubated with MMP-1 solution for 7 days; the second group were only treated with acid solution for 21 days; the third group were only attacked by MMP-1 solution for 7 days; and the fourth group were untreated as a control. Then all sections were dehydrated in ascending strength of alcohol, critically dried, coated with platinum, and then observed under scanning electron microscope(SEM). RESULTS: The dentin sections of root surface attacked by acid and MMP-1 showed that demineralization of dentin mineral and degradation of dentin matrix fibrae synchronously happened. The dentin matrix fibrae wasn't degradated in the groups treated with acid or MMP-1. CONCLUSION: The proteinases from human host may play an important role in the development of root surface caries. MMP-1 may distinctly degradate the organic matrix of demineralized dentin.

Dental Cementum↗

PubMed1996

Light and scan electron microscopic analysis of cyclops syndrome: etiopathogenic hypothesis and technical solutions.

The loss of range of motion after anterior cruciate ligament (ACL) reconstruction is one of the most common and most challenging complications of this kind of surgery. Recently, an intercondylar notch fibrous proliferation, called cyclops syndrome because of its arthroscopic appearance, has been identified as one of the specific causes of loss of extension. The incidence of cyclops syndrome is 2%-4% [17, 18], but there is still no understanding of its etiology. We speculate on the etiology and suggest some technical solutions to reduce this complication. In 180 patients submitted to arthroscopic ACL reconstruction with patellar tendon, we observed in 4 cases a fibrous nodule adherent to the neoligament that caused a loss of extension between 12 degrees and 17 degrees. In all cases, arthroscopic removal of this nodule solved completely the loss of articular motion. The nodules were subjected to light and scanning electron microscope evaluation. We observed numerous, newly formed vessels in all 4 nodules. These vessels were made up of hyperplastic and hypertrophic cells and were surrounded by bundles of disorganized fibrous tissue. No inflammatory cells or bone or cartilaginous tissue was observed. We hypothesize a microtraumatic genesis for cyclops syndrome. Repeated microtraumas expose the graft collagen fibers, which can lead to productive inflammatory process and thence to the formation of the cyclops nodule. We suggest some technical solutions to avoid graft impingement with the notch and with the tibial bone tunnel.

Anterior Cruciate Ligament↗

PubMed2000

Cryo-scanning electron microscopic study on freezing behavior of xylem ray parenchyma cells in hardwood species

Differential thermal analysis (DTA) has indicated that xylem ray parenchyma cells (XRPCs) of hardwood species adapt to freezing of apoplastic water either by deep supercooling or by extracellular freezing, depending upon the species. DTA studies indicated that moderately cold hardy hardwood species exhibiting deep supercooling in the XRPCs were limited in latitudinal distribution within the -40 degrees C isotherm, while very hardy hardwood species exhibiting extracellular freezing could distribute in colder areas beyond the -40 degrees C isotherm. Predictions based on the results of DTA, however, indicate that XRPCs exhibiting extracellular freezing may appear not only in very hardy woody species native to cold areas beyond the -40 degrees C isotherm but also in less hardy hardwood species native to tropical and subtropical zones as well as in a small number of moderately hardy hardwood species native to warm temperate zones. Cryo-scanning electron microscopic (cryo-SEM) studies on the freezing behavior of XRPCs have revealed some errors in DTA. These errors are originated mainly due to the overlap between exotherms produced by freezing of water in apoplastic spaces (high temperature exotherms, HTEs) and exotherms produced by freezing of intracellular water of XRPCs by breakdown of deep supercooling (low temperature exotherms, LTEs), as well as to the shortage of LTEs produced by intracellular freezing of XRPCs. In addition, DTA results are significantly affected by cooling rates employed. Further, cryo-SEM observations, which revealed the true freezing behavior of XRPCs, changed the previous knowledge of freezing behavior of XRPCs that had been obtained by freeze-substitution and transmission electron microscopic studies. Cryo-SEM results, in association with results obtained from DTA that were reconfirmed or changed by observation using a cryo-SEM, revealed a clear tendency of the freezing behavior of XRPCs in hardwood species to change with changes in the temperature in the growing conditions, including both latitudinal and seasonal temperature changes. In latitudinal temperature changes, XRPCs in less hardy hardwood species native to tropical and subtropical zones exhibited deep supercooling to -10 degrees C, XRPCs in moderately hardy hardwood species native to temperate zones exhibited a gradual increase in the supercooling ability to -40 degrees C from warm toward cool temperate zones, and XRPCs in very hardy hardwood species native to boreal forests exhibited extracellular freezing via an intermediate form of freezing behavior between deep supercooling and extracellular freezing. In seasonal temperature changes, XRPCs in hardwood species native to temperate zones changed their supercooling ability from a relatively low degree in summer to a high degree in winter. XRPCs in hardwood species native to boreal forests changed their freezing behavior from deep supercooling to -10 degrees C in summer to extracellular freezing in winter. These results indicate that the freezing behavior of XRPCs in hardwood species tends to shift gradually from supercooling of -10 degrees C, to a gradual increase in the deep supercooling ability to -40 degrees C or less, and finally to extracellular freezing as a result of cold acclimation in response to both latitudinal and seasonal temperature changes. It is thought that these temperature-dependent changes in the freezing behavior of XRPCs in hardwood species are mainly controlled by changes in cell wall properties, although no distinct changes were detected by electron microscopic observations in cell wall organization between hardwood species or between seasons. Evidence of temperature-dependent changes in the freezing behavior of XRPCs in hardwood species provided by the results of studies using a cryo-SEM has indicated the need for further investigation to clarify cold acclimation-induced cell wall changes at the sub-electron microscopic level in order to understand the mechanisms of freezing adaptation.

Journal Article↗

PubMed2002

Scanning electron microscope study of the effects of soft drinks on etched and sealed enamel.

The purpose of this study was to determine the effects of cola and other acidic drinks on etched tooth enamel in a simulated oral environment. The test beverages were cola, orange soda, lemon soda, and sparkling mineral water. Sixty extracted premolars were divided into an experimental group (n = 40) and a control group (n = 20). Half of the buccal surface of each tooth in the experimental group was coated with wax. The teeth were etched for 60 seconds with 37% phosphoric acid, and half of the teeth were also bonded. The experimental group was further divided into 4 subgroups of 5 teeth each, and each subgroup was exposed to 1 of the test beverages in a thermocycling apparatus. The apparatus was designed to keep the teeth in artificial saliva for 2 hours and in the soft drink at room temperature for 15 minutes. This procedure was performed 3 times a day for 5 days. The control group was also divided into 4 subgroups of 5 teeth each. Half of the buccal surface of each tooth in 2 subgroups was coated with wax, and the teeth in the other 2 were left uncoated. One waxed and 1 unwaxed subgroup were then etched, and the other waxed and unwaxed subgroups were etched and bonded. The waxed subgroups were stored in artificial saliva for 5 days, and the unwaxed subgroups were examined without further exposure to liquids. Surfaces exposed to acidic soft drinks were compared with control surfaces under a scanning electron microscope. Defect zone borders were observed between the exposed areas and the wax-coated areas of teeth in the experimental groups, especially the subgroups exposed to cola, orange soda, and lime soda. Fewer defect zones were observed on teeth exposed to sparkling mineral water. The results indicate that acidic soft drinks cause enamel demineralization on etched tooth surfaces.

Acid Etching, Dental↗

PubMed1997

[Age-related development of the arrangement of connective tissue fibers in the lamina propria of the human vocal folds--scanning electron microscopic examination with digestion method].

The lamina propria of the human vocal fold consists of a superficial, intermediate, and deep layer. This stratified structure is thought to facilitate phonation. Each layer has different physical properties based on different alignment and distribution of collagen and elastic fibers. In the present study, developmental changes in vocal fold structure were studied in human fetuses, infants, and children, with special reference to the pattern of distribution of collagen and elastic fibers. Vocal fold specimens were obtained at autopsy from 5 fetuses, 7 neonates, 3 infants, 3 children at the age of 1 year, 3 children at 3 years, 3 children at 5 years, 3 children at 12 years, and 5 subjects at ages ranging from 15 to 22 years. Prior to the examination of collagen fibers, elastic fibers and cells were dissolved with 10% sodium hydroxide treatment. Prior to the examination of elastic fibers, collagen fibers and cells were dissolved by treatment with 90% formic acid. The specimens were then dehydrated, dried, ion-coated with platinum, and examined with a scanning electron microscope. In fetuses and infants, thin, coiled fibers were found distributed densely in the anterior, posterior, and deep parts of the lamina propria, while irregular thick fibers were sparsely seen in the superficial layer of the vocal fold. In children aged 1 to 3 years, the dense fibers in the deep part decreased, and the longitudinal fibers in the superficial layer increased. In children at 5 years of age, longitudinal collagen and elastic fibers were noted in all of the layers of the vocal fold. The distribution of fibers was uniform irrespective of the depth. At 12 years of age, thin, coiled fibers were noted in the superficial layer, while thin, irregular fibers were found in the deep layer. At 17 years, differentiation of the superficial and deep layers was more evident. In male subjects after adolescence the curvature of curly collagen fibers decreased, and the diameter of fibers increased. The present findings suggest that the development of the vocal fold in childhood occurs in two steps. In the first step, dense fibers in the anterior, posterior, and deep parts of the lamina propria found in fetuses and infants shift to the anterior and posterior ends of the vocal fold, between which longitudinal fibers appear. During this step only simple phonation is possible. In the second step, differentiation of the superficial and deep layers occurs, and the stratified structure of the vocal fold appears in the teens. This step is probably related to the complicated modality of phonation in this age group. In males, the development of the vocal fold is completed after changes in collagen fibers during the mutation.

Adolescent↗

PubMed1997

[Scanning electron microscopic studies on mucosal coating by barium mixtures].

The purpose of this study was to observe and evaluate mucosal coating by barium mixtures using electron microscopy. Specimens from the ileum of two pigs, about 50cm in length from the terminal ileum, were divided into 3 groups with different in concentrations and additives of barium mixture. The 50cm length of ileum was cut into 10cm long pieces. Four specimens from each group were evaluated by double contrast study for coating by the barium layer. Then the specimen was frozen with liquid nitrogen solution, and fixed. Afterward, the specimen was cut into about 1cm sections, fixed again, dehydrated, dried, and observed by scanning electron microscopy (SM). In the double contrast study, the differences in barium coating were correlated with the concentration of barium sulphate. The scanning electron microscopic findings were correlated with those of the double contrast study. The various additives in the barium mixture did not cause any distinctive differences. Although barium particles have been studied by electron microscopy, barium mixture coating state on the mucosa of biological materials has not been reported. In conclusion, a correlation of the coated barium layer on double contrast study and the images of scanning electron microscopy was observed using pig ileum specimens.

Animals↗

PubMed1988

Surface morphology of the human ciliary body during prenatal development. A scanning electron microscopic study.

The development of the ciliary body was examined by scanning electron microscopy in human embryos and fetuses with a gestation age of 9.5 to 24 weeks. During this period it was possible to follow up the main morphogenetical events, beginning with the appearance of the first radial folds up to the occurrence of ciliary processes with a rather adultlike arrangement. The ciliary processes observed during week 24 differed from those of the adult eye only by their dimensions and the lack of surface infoldings. A primitive pars plana could only be identified during week 24. The morphological basis for aqueous humor production is discussed.

Ciliary Body↗

PubMed2006

Compensation of the shadowing error in three-dimensional imaging with a multiple detector scanning electron microscope.

A method for three-dimensional quantitative surface characterization for scanning electron microscopy is presented. The method used a quadruple scintillator detector developed by us. A surface reconstruction algorithm was performed by special software, with new algorithms for error compensation. Among these errors, detector shadowing was of particular importance. This was due to the disturbance in integration continuity when one or more detectors was screened from the flow of electrons. Several methods for the reduction of this error have been proposed and tested by us. The methods were based on software processing of complementary information, such as unshadowed detector signals, shadow depth and modified integration schemes.

Journal Article↗

PubMed2005

Effect of graded doses of Momordica charantia seed extract on rat sperm: scanning electron microscope study.

Morphological changes in sperm of albino rats observed under scanning electron microscopy illustrate the disturbance in the plasma membrane as well as in the acrosomal membrane on treatment with effect of graded doses of alcohol seed extract from Momordica charantia. Considerable changes in the shape and size of the sperm head were observed, with the middle region of the sperm head being slightly constricted dorsoventrally. Most sperm appeared morphologically abnormal in the mid-region of the tail, with formation of a balloon-like cytoplasmic droplet. The results of this study suggest that such effects may have resulted from a general disturbance in proteins and an alteration in the cauda epididymal milieu, probably due to androgen deficiency consequent to the anti-androgenic property of Momordica charantia seeds.

Acrosome↗

PubMed1983

Surface structures and osteoclasts of mouse parietal bones: a light and scanning electron microscopic study.

The resorption surface caused by osteoclasts are identified by scanning electron microscopy (SEM), but the morphological interrelation between these resorption surfaces and Howship's lacunae observed by light microscopy remains obscure, and little evidence showing that the distribution and structures of the resorption surface change according to the function of osteoclasts is available. To understand the relationship between the function of osteoclasts and the morphological evidence of bone resorption, surface structures of the parietal bones in mice, newborn to adult, were studied by SEM. The osteoclasts on the inner surface of the calvaria are considered to be involved in the growth of the skull. The outer surface of the parietal bone was smooth, whereas the inner surface consisted of both smooth and rough areas. The rough areas were usually much larger than Howship's lacunae, which are generally thought to be of osteoclast size. These areas were composed of small and shallow concavities with oval or polygonal outlines. The borders between adjacent concavities appeared as ridges. The rough areas were very wide in the growing skull and osteoclasts were scattered on these wide rough areas. The osteoclasts were much larger than the concavities in the rough areas. During the growth of the skull, the proportion of rough areas occupying the inner surface changed parallel to the number of osteoclasts, which varied in correspondence with the growth rate of the skull. The maximum value of the proportion was ab out 60% at 1 week of age. The findings suggest that the osteoclasts resorb the bone by moving along its surface, forming small concavities and leaving rough areas larger than Howship's lacunae of osteoclast size. Furthermore, they suggest that the size and distribution of the rough areas and the morphological features of the concavities in the rough areas vary depending upon the activities of the osteoclasts.

Animals↗

PubMed2001

The distribution of intratubular dentine in equine incisors: a scanning electron microscopic study.

The distribution of intratubular (peritubular) dentine was studied by scanning electron microscopy in 12 equine incisor teeth. High levels of intratubular dentine were found in the peripheral regions of the dentine. In these areas, a marked asymmetry occurred, as intratubular dentine was predominantly deposited onto the side of the dentinal tubular walls nearest to the dentino-enamel junction. The quantity and asymmetry of intratubular dentine were reduced towards the centre of the tooth. The significance of these variations in the amount and distribution of intratubular dentine between the different dentinal regions is discussed.

Animals↗

PubMed1986

The effect of peritoneal exudate on peritoneal morphology in experimental acute pancreatitis. A histologic and scanning electron microscopic study.

Changes in peritoneal morphology were examined histologically and by scanning electron microscopy during porcine acute hemorrhagic (n = 8) and edematous (n = 9) pancreatitis and after intraperitoneal installation of hemorrhagic pancreatitis-associated peritoneal exudate in healthy piglets (n = 3). In all experimental groups peritoneal inflammatory changes with mesothelial damage were evident already 1 h after the induction of the disease, and increased with time. Hemorrhagic pancreatitis caused desquamation of mesothelial cells and denudation of the basal membrane. Intraperitoneal installation of hemorrhagic pancreatitis-associated peritoneal exudate in healthy piglets caused similar changes, whereas the changes in edematous pancreatitis were much less extensive. Peritoneal exudate accumulating in the peritoneal cavity during hemorrhagic pancreatitis caused early chemical peritonitis characterized by severe inflammation of the peritoneum with destruction of the mesothelial cell layer, leading to denudation of the underlying connective tissue. The significance of these changes in the pathophysiology of acute fulminant pancreatitis remains to be further studied.

Acute Disease↗

PubMed1988

[Scanning electron microscopic studies of the microbial colonization of slow sand filters].

Using scanning electron microscopy (SEM), we studied the periphyton on the filter material of slow sand filters (SSF)--main basins--from the water-works in Geisecke/Ruhr. Table 1 presents information about the quantitative vertical distribution of the filter material with its size and shape, water-storage, nutrient content and the presence of bacteria. The proportion of microbial growth to microbial content was high with 80% found in the upper and about 70% in the lower part of the filter body. Larger sand particles supported proportionally higher populations than did small grains. Depressions were well populated. Heavier microbial concentrations resulted in attachment and colonization on exposed grain surfaces. Only some microorganisms adhered through slime-nets and stalks, and no sample showed any general or special mechanisms. The photographic reproduction of the effects was difficult, because of the amount of adherent organic and inorganic matter as well as the different topographic surfaces of the grains. Therefore we have not attempted a quantitative evaluation. 3 plates with SEM micrographs show the locations of colonizing bacteria on sand grains and organisms and their mode of attachment.

Bacteria↗

PubMed1987

Scanning electron microscopic observations on differentiation and maintenance of photoreceptor cells in vitro.

Scanning electron microscopy was performed on cell cultures of embryonic and post-hatch chick retinas co-cultured with optic lobe neurons or in medium that had been pre-conditioned with optic lobe cells. The culture medium consisted of Eagles Basal Medium supplemented with glucose, fetal calf serum, glutamine and bicarbonate. Application of colchicine (5 micrograms/ml) to the cultures, encouraged the dissociation of retinal cell rosettes and optic lobe neuron aggregates, thereby allowing us to examine differentiation of isolated photoreceptor cells. Over time, developing photoreceptor cells gradually took on the morphological characteristics of rods and cones in the post-hatch chick: cells were polarized having a single neurite on one end of the cell and inner and outer segment-like structures on the other end. Developing cone cells elaborated an oil droplet and filopodial-like processes at the apical end of the inner segment. The latter may correspond to the calyceal processes which normally envelop the basal 1/3 of the outer segment. The sequence of events noted in vitro parallel those previously reported in vivo.

Animals↗