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PubMed1982

Pathological studies on calcification of the intervertebral discs.

Calcified deposits in the intervertebral discs of 35 cadavers microradiographically appeared as linear of flake-like densities composed of calcium pyrophosphate dihydrate (CPPD) crystals and as multiple punctates possibly composed of dicalcium phosphate dihydrate (DCPD) crystals. Calcium deposits were found in 57% of the cadavers by microradiography and 63% by light microscopy, without known metabolic or familial history related to articular chondrocalcinosis. By scanning electron microscopy, CPPD crystals were mainly rod-like, rectangular and cuboid and were about 4 to 10 mu in length while DCPD crystals were prismatic and about 20 to 60 microns in length.

Adolescent↗
PubMed1981

[Hyperostosis of the skull (author's transl)].

X-ray findings and the result of microradiographic examinations of hyperostotic processes of the skull (Osteomas, Meningioma, Fibrous Dysplasia, Morbus Paget) are described. The films permit a reliable diagnosis statement only in a few cases, because similar findings can be seen in different diseases. Microradiographic investigations demonstrate the microstructure of the tissue of hyperostotic processes. There are no specific findings typical for one disease alone, but there are qualitative and quantitative variations in the different diseases mentioned above. Microradiography gives information about morphology and dynamics in the transformation of the calvarium in the observed pathologic conditions.

Diagnosis, Differential↗
PubMed1995

De/remineralization from sodium fluoride dentifrices.

PURPOSE: To test the demineralization/remineralization effects of sodium fluoride dentifrices using an in situ single-section crown model system. MATERIALS AND METHODS: A fluoride dose response was evaluated using 0, 1100 and 2800 ppm F-, along with the effects of an enhanced fluoride delivery system (polyampholyte-NaF). The single-section crown model was employed with supervised toothbrushing twice a day. At the end of each 1-month study leg, sections were removed and replaced with new sections for the next leg. Both before and after the double-blind, crossover portion of the study, sections were evaluated by polarized light microscopy and microradiography. The change in mineral content of the enamel and root lesions was analyzed by ANOVA with a Waller-Duncan K-Ratio Test post hoc. RESULTS: The placebo dentifrice group showed a loss of mineral and was statistically different from all groups. The fluoride dentifrices showed increasing amounts of enamel mineral gain, with increasing fluoride concentration. The polyampholyte-NaF delivery system with 1100 ppm F- was equivalent to the 2800 ppm F- dentifrice. Root lesions gave similar rank-order results although all treatments showed demineralization or mineral loss.

Adult↗
PubMed1994

Three-dimensional structure of two different lymphatic spaces in rat testis, and the route of flow fluxes of their lymphatic fluids.

In addition to the collecting vessels, two initial lymphatic spaces were observed with light and electron microscopes. In the deep parenchyma, the peritubular lymphatic spaces surrounding the tubules were observed as polygonal piles after a corrosion casting to the testis. They were joined to the adjacent piles through fenestrae to form a loose spongiform structure. In the superficial parenchyma, the peritubular lymphatic spaces communicated to the subtunical lymphatic space on one side. The subtunical lymphatic spaces anastomosed to each other through small bypasses to form a rich network. Near the mediastinum, the peritubular lymphatic spaces bifurcated and narrowed on another side. Microradiography demonstrated two fluxes of the intratesticular lymphatic fluids; fast and slow flows. The fast flow was observed as a shaded line running into the subtunical lymphatic spaces immediately after injection of the contrast media. It remained 1 or 2 minutes and then disappeared. In contrast, the slow flux was observed as a spongiform shade shifting from the anteroposterial quadrant to the posterosuperior portion of the testis. Seven to 15 minutes were needed for the contrast media to reach near the mediastinum. Both lymphatic spaces are functionally discussed with relation to the two different fluxes of the lymphatic fluids.

Animals↗
PubMed1994

The crystalline structure of pancreatic calculi.

The present study was carried out to investigate the ultrastructure and composition of crystals of pancreatic calculi. Microradiography showed that they were irregularly mineralized with radial or stratified zones of low mineralization. The crystals were identified as calcite composed of CaCO3 in X-ray and electron diffraction studies. Scanning electron microscopy (SEM) revealed that the calculi consist of aggregations of rhombohedral, fang-shaped, botryoidal, foliaceous, and plate-shaped crystals. Some of them showed signs of partial dissolution on their surface. Transmission electron microscopy (TEM) showed crystals of various sizes and shapes either solitary or in clumps. The direct measurement of crystalline lattice intervals obtained from each crystal was 0.386 nm in accordance with the diffraction data. Exocrine pancreatic cell debris are present in pancreatic calculus matrices.

Calculi↗
PubMed1993

Human cellular mixed stratified cementum: a tissue with alternating layers of acellular extrinsic- and cellular intrinsic fiber cementum.

Following the first description of the formal genesis of acellular extrinsic- and cellular intrinsic fiber cementum on growing human teeth, the present paper introduces cellular mixed stratified cementum as a particular tissue. Based on a large and diverse material (human premolars and molars) that was examined by various methods, such as microradiography, light microscopy using transmitted and polarized light, and scanning- and transmission-electron microscopy, the composition and structure of this type of cementum is described. Cellular mixed stratified cementum covers the apex, the apical third of the roots or more, and the furcational aspects of human teeth. With all methods employed, it was shown that this tissue consists in principle of acellular extrinsic- and cellular intrinsic fiber cementum, i.e. two major types of cementum that alternate or are in irregular sequences deposited upon one another. The dynamics of this layering and the fact, that, temporarily, root surfaces may remain unsupported by Sharpey's fibers as a consequence of this layering, are discussed.

Adolescent↗
PubMed1996

Quality control of bioprosthetic heart valves by means of holographic interferometry.

BACKGROUND AND AIMS OF THE STUDY: Limited durability of porcine bioprostheses is mainly caused by the progressive development of calcification. We tested the hypothesis that hidden tissue anomalies or unfavorable stress concentrations of commercially available bioprostheses may lead to later calcification and dysfunction. Application of holographic interferometry for non-destructive testing of biological heart valves enables a full-field analysis of heart valves and reveals deformation irregularities of valve tissue. MATERIAL AND METHODS: We developed an accelerated calcification protocol for bioprosthetic heart valves including an accelerated pulsatile valve tester for simultaneous testing of 10 heart valves under identical conditions and a rapid synthetic calcification fluid containing a final Ca x P of 130 (mg/dl)2 in barbital buffer solution. Ten porcine bioprostheses (St. Jude Medical, Bioimplant) were assessed by holographic interferometry and subjected to the pulsatile accelerated calcification process. Distribution and amount of calcification was evaluated by microradiography after 12 x 10(6) and 19 x 10(6) cycles, respectively. Areas of irregular fringe patterns detected by holography as well as areas of calcification were calculated and compared using a personal computer. RESULTS: All tested bioprostheses had localized or extended areas with holographic irregularities and the accelerated valve testing protocol resulted in even macroscopically visible calcifications at various sites. Comparative analysis of the obtained microradiographs revealed that 74.2% +/- 6.0% of calcified leaflet areas lay within the previously detected holographic anomalies. CONCLUSIONS: Our first results show a strong correlation between holographic anomalies and calcification of porcine bioprostheses. We conclude that suitable methods for evaluation and quality control of bioprosthetic heart valves are available and seem to be predictive with regard to valve calcification.

Aortic Valve↗
PubMed1997

A new in vitro test method for calcification of bioprosthetic heart valves.

To investigate the calcification behavior of different bioprosthetic heart valves and verify possible hypotheses of the etiology of valve calcification, an accelerated pulse tester for bioprostheses was developed, whereby up to ten valves can be tested under identical test conditions. Each valve was mounted in a separate compartment on a piston and cyclically moved through a calcifying solution at frequencies of up to 800/min at 37 degrees C: An appropriate calcifying solution was evaluated by incubation tests of bovine and porcine tissue. Calcification was confirmed by measuring Ca and phosphate depletion by atomic absorption spectroscopy, von Kossa staining, EDAX, and microradiography. The first tests were successfully carried out on porcine valves that had been nondestructively assessed for tissue/stress anomalies by holographic interferometry prior to the calcification test. The tests showed that 75% of irregular fringe pattern areas corresponded to the calcification areas.

Animals↗
PubMed1996

[Constant composition study on kinetics of enamel demineralization].

The aim of this work was to investigate the kinetic behaviour of whole enamel demineralization compared with that of powder enamel. Constant composition technique was used to maintain a constant undersaturation degree with respect to hydroxyapatite in the demineralizing solutions. The demineralizing processes were monitored by recording the volume of adding titrant solution. Finally, sections were measured for lesion depth by microradiography, and blocks were tested for microhardness. The results showed that demineralization of enamel powder nearly completed within 40 minutes, while demineralization of whole enamel was much slower and with a constant rate within the experimental time. It was also found there were significant increases of concentrations of calcium and phosphate in solutions during the first 40 hours of whole enamel demineralization. It suggests that the kinetic behaviour of whole enamel demineralization is different from that of powder enamel, which is not only due to the unique transport process in whole tissue, but also possible due to a different phase transformation before and after formation of a surface layer.

Calcium↗
PubMed1996

Effect of age on physiologic and mechanically stressed rat alveolar bone: a cytologic and histochemical study.

The effect of age on physiologic and mechanically stressed rat alveolar bone was assessed with special focus on bone formation and resorption in maxillary molar sections of 1-, 4-, 9-, 16-, and 24-month-old male Fischer rats. Tetracycline- and calcein-labeled undecalcified sections were used for observation by confocal laser scanning microscopy and contact microradiography. The localization of osteoclasts and the morphological change of osteoblasts were observed on decalcified sections. Mechanical stress was applied by an orthodontic elastic inserted between the first and second maxillary molars for 7 days. Results showed that bone-formative activity of osteoblasts and bone-resorptive activity of osteoclasts declined with age around the maxillary molar section of physiologic rat alveolar bone. However, results of mechanically stressed rat alveolar bone revealed no evidence of numerical difference in number, size, and activity of osteoclasts and osteoblasts among the ages, suggesting that mechanical stress provokes a higher activity of osteoblasts and osteoclasts similarly in both adult and younger rat alveolar bone.

Age Factors↗
PubMed1996

Effect of a specially formulated remineralizing solution on the remineralizing capacity of saliva.

The present study was carried out to assess whether the remineralization of artificial caries like lesion by artificial saliva can be improved by daily 5 minute treatment in a specially formulated remineralizing solution containing Ca, P, Zn, Sr, F. Extracted human premolars were dipped for 24 hours in artificial saliva and subsequently daily for 5 minutes in the remineralizing solution for 3 weeks. Lesions were assessed using transverse microradiography, electron probe microanalysis (EPMA) and scanning electron microscope (SEM). The results showed that remineralization by specially formulated solutions repair the enamel lesion and enhances the salivary remineralizing potential.

Bicuspid↗
PubMed1998

Studies on fluoridated toothpicks.

The aim of this thesis was to evaluate the wooden toothpick as a vehicle for the delivery of fluoride to the approximal area. After two minutes use in vivo, the release of fluoride from the pointed section of a toothpick impregnated in 4% NaF was estimated to 0.15 mg. Toothpicks produced similar or somewhat higher fluoride concentrations in the approximal area compared with other fluoride-containing products, like dentifrice, mouthrinse solution and tablet. The mean fluoride concentration in an approximal area treated for two minutes with a toothpick impregnated in 4% NaF was around 11 mM/l. Toothpicks impregnated in 4% NaF, 8% SnF2 or 2% chlorhexidine had an effect on the proportion of mutans streptococci and on the decline of pH in dental plaque, but it was small and only of short duration. The recolonization of mutans streptococci was, however, slower after using the SnF2- and chlorhexidine-impregnated toothpicks than after using the NaF- and non-impregnated toothpicks. The effect of fluoridated toothpicks on the degree of de- and remineralization of enamel and dentine was measured using transversal microradiography in an in situ study. Four weeks' use of toothpicks, especially of NaF-impregnated toothpicks, reduced the degree of demineralization of enamel and dentine at approximal sites. Secondary ion mass spectrometry was also used to determine the fluoride content in the outer surface of dentine, which increased more than 10 times after using fluoride toothpicks compared with non-impregnated toothpicks. In a second in situ study, 4% NaF-, 2% chlorhexidine- and non-impregnated toothpicks had a similar effect on sound and demineralized enamel and on demineralized dentine. However, the NaF toothpicks were superior in terms of their effect on sound dentine. The effect on mutans streptococci and plaque-pH, on the other hand, was the same for all three types of toothpicks. The main conclusion from this thesis is that the wooden toothpick is a suitable vehicle for the delivery of fluoride to the approximal area.

Anti-Infective Agents, Local↗
PubMedDate not supplied

In vitro enamel effects of a resin-modified glass ionomer: fluoride uptake and resistance to demineralization.

PURPOSE: The purpose of this study was to determine the in vitro effects of a resin-modified glass-ionomer restorative material on human enamel. METHODS: Enamel specimens were restored with Photac-Fil, a resin-modified glass ionomer; Ketac-Fil, an autopolymerizing glass ionomer and silver amalgam. The samples were pH cycled and then subjected to an artificial caries challenge. Specimens were evaluated by fluoride microdrill biopsy and quantitative microradiography at 1, 2, and 3 mm from restorations. Data on fluoride content, lesion depth, and mineral content were analyzed by one-way ANOVA, Student's t test, Neuman-Keuls procedure (multiple [pairwise] comparison), and Pearson's product-moment correlation tests. RESULTS: There were significant differences in fluoride uptake, lesion depth, and mineral density between groups. Significant correlational relationships were also determined. CONCLUSION: This study demonstrates that Photac-Fil and Ketac-Fil prevent in-vitro demineralization of enamel and suggests different mechanisms of action for each material.

Analysis of Variance↗
PubMed1996

Resorption of, and bone formation from, new beta-tricalcium phosphate-monocalcium phosphate cements: an in vivo study.

Hard cylinders (4.7 x 10 mm) of two kinds of beta-tricalcium phosphate-monocalcium phosphate monohydrate-calcium sulfate hemihydrate (beta-TCP-MCPM-CSH) cements with and without beta-TCP granules (500-1000 microns) were implanted into holes drilled in rabbit femoral condyles for up to 16 weeks. Empty cavities were used as control. Cement resorption and new bone formation in the cylinders were evaluated with contact microradiography and quantified through an automatic image analysis system. At 4 weeks, both kinds of cement cylinders were surrounded by new bone. At 8 weeks, except for beta-TCP granules, both cement cylinders were almost completely resorbed and replaced by bone tissue. At 16 weeks the bone in the cavities of both cements recovered a trabecular pattern, but only the bone trabeculae in the initial cavity of the cement with beta-TCP granules became thick and mature. However, the cavities of the empty control were still empty and large. These results show that the beta-TCP-MCPM-CSH cements stimulate bone formation and are rapidly replaced by bone tissue. When added with nonresorbable beta-TCP granules, this cement maintains bone formation for a longer time.

Animals↗
PubMed1996

Bone-bonding behavior of plasma-sprayed coatings of BioglassR, AW-glass ceramic, and tricalcium phosphate on titanium alloy.

The bone-bonding behavior of three kinds of bioactive ceramics coated on titanium alloy by the plasma-spray technique was investigated. Titanium alloy (Ti-6A1-4V) coated with BioglassR (45S5), apatite-wollastonite containing glass ceramic (AW), or beta-tricalcium phosphate (TCP) was prepared, and rectangular specimens were implanted into the tibial bones of mature male rabbits, which were sacrificed 8 or 24 weeks after implantation. The tibiae containing the implants were dissected out and subjected to detachment tests to measure the failure load. The bone-implant interface was investigated by Giemsa surface staining, contact microradiography, and scanning electron microscopy-electron probe microanalysis (SEM-EPMA). Eight weeks after implantation, the failure loads for implants coated with BioglassR, AW, and TCP were 1.04 +/- 0.94, 2.03 +/- 1.17, and 3.91 +/- 1.51 kg, respectively, and 24 weeks after implantation, the respective failure loads were 2.72 +/- 1.33, 2.39 +/- 1.30, and 4.23 +/- 1.34 kg. Failure loads of AW- and TCP-coated implants did not increase significantly with time. After the detachment test, breakage of the coating layer was observed. Bioactive ceramics can act as stimulants that induce bonding between bone and metal implants. However, failure load of metal implants coated with the bioactive ceramics was lower than that of bulk AW or TCP. It appears impossible to obtain a higher failure load using a bioactive-ceramic coating on titanium alloy. Histologically, the coating layer was found to become detached from the metal implant and the bone tissue bonded to the coating layer. SEM-EPMA observation revealed breakage of the coating layer, although bonding between bone and the coating layer was evident. A Ca-P-rich layer was observed at the interface between bone and the AW coating, and a Ca-P-rich and a Si-rich layer were observed at the interface between bone and the BioglassR coating. For clinical application, it would seem better to use coated metal implants for short-term implantation. However, there is a possibility of breakage of the coating layer because of both dissolution of the bioactive ceramic and mechanical weakness at the interface between the coating layer and the metal implant.

Alloys↗
PubMed1996

Bone bonding ability of an apatite-coated polymer produced using a biomimetic method: a mechanical and histological study in vivo.

A 20-microns thick apatite layer was coated onto polyethersulfone (PES) rectangular plates by soaking them in simulated body fluid containing CaO-SiO2 based glass powder. Coated and uncoated PES plates (10 x 15 x 1.5 mm) were implanted in the tibiae of rabbits, which were sacrificed 8, 16, and 30 weeks thereafter, and the samples were examined histologically using contact microradiography (CMR), Giemsa surface staining, and a scanning electron microscope connected to an electron probe microanalyzer (SEM-EPMA). The tensile failure loads at the bone/implant interfaces were determined using the detaching test. The histological examinations showed excellent bone apposition on coated PES and the sign of degradation of the apatite layer at remodeling lacunae. The apatite layer underwent complete resorption and was replaced by bone in most areas of the bone/implant interface after 30 weeks. Bone did not bond directly to uncoated PES after each follow-up period. The failure loads between bone and coated PES at 8, 16, and 30 weeks after implantation were 1.7 +/- 0.35, 2.36 +/- 0.53, and 1.45 +/- 0.48 kg, respectively. Those between bone and uncoated PES were nearly 0 kg at each postimplantation period. Failure during the detaching test occurred at the bone/apatite interface or near it after 8 weeks. After 16 weeks, it usually occurred at the apatite/ PES interface or near it, and occasionally in the middle of the apatite layer. The apatite layer was hardly detected at the failured interface after 30 weeks. In this study, an apatite-coated PES produced using a biomimetic method was demonstrated to bond directly to bone without any intervening soft tissue, which indicates that this material possesses excellent bioactivity.

Animals↗
PubMed1997

Bonding of chemically treated titanium implants to bone.

A study was undertaken in rabbit tibiae to determine the effects of chemical treatments and/or surface-induced bonelike apatite on the bone-bonding ability of titanium (Ti) implants. Smooth-surfaced plates (10 x 10 x 2 mm) of pure Ti, alkalil- and heat-treated Ti, and bonelike apatite-formed Ti after the treatments were implanted into the tibial metaphyses of mature rabbits. The tibiae containing the implants were harvested at 4, 8, and 16 weeks after implantation and subjected to a tensile testing and histologic evaluation. Biomechanical results showed that both treated implants exhibited significantly higher failure loads compared with untreated Ti implants at all time periods. Histologic examination by Giemsa surface staining, contact microradiography (CMR), and scanning electron microscopy (SEM) in backscatter mode revealed that both treated Ti implants directly bonded to bone tissue during the early postimplantation period, whereas untreated Ti implants formed direct contact with the bone only at 16 weeks. SEM-electron-probe microanalysis (EPMA) examination showed a Ca-P-rich layer at the interface between the treated implants and bone, although the Ca-P-rich layer was not detected on the surface of untreated implants during observation periods. The results of this study suggest that chemical treatments may accelerate the bone-bonding behavior of titanium implants and enhance the strength of bone-implant bonding by inducing a bioactive surface layer on Ti implants.

Animals↗
PubMed2000

Bonding of alkali- and heat-treated tantalum implants to bone.

Alkali- and heat-treated tantalum (Ta) has been shown to bond to bone. The purpose of this study was to investigate the effects of chemical treatments on the bone-bonding ability of tantalum implants in rabbit tibiae. Miyazaki et al. reported in vitro that alkali- and heat-treated tantalum had an apatite forming ability in an acellular simulated body fluid (SBF). In this study, smooth-surfaced rectangular plates (15 x 10 x 2 mm) of pure tantalum and treated tantalum were prepared. The plates were implanted transcortically into the proximal metaphyses of bilateral rabbit tibiae, alkali- and heat-treated plates for one limb and untreated plates for the contralateral limb, which served as a paired control. Bone bonding at the bone/implant interface was evaluated by tensile testing and undecalcified histological examination, at 8 and 16 weeks after implantation. The treated implants showed weak bonding to bone at 8 weeks, and exhibited significantly higher tensile failure loads compared with untreated tantalum implants at 16 weeks. The untreated implants showed almost no bonding, even at 16 weeks. Histological examination by Giemsa surface staining, contact microradiography (CMR), and scanning electron microscopy (SEM) revealed that treated tantalum implants bonded directly to bone tissue. In contrast, the untreated tantalum implants had a intervening fibrous tissue layer between the bone and the plate and did not bond to bone at 8 and 16 weeks. It is clear from these results that alkali and heat treatment induce the bone-bonding ability of tantalum. This new bioactive tantalum should be an effective material for weight-bearing and bone-bonding orthopedic devices.

Alkalies↗