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PubMed1975

The effect of a low-calcium diet in lactating rats; observations on the rapid development and repair of osteoporosis.

Female rats were given a low-calcium diet (0.05%) during the last three weeks of the lactating period, followed by a normal diet (1.03% calcium) during the first three weeks after lactation. The resulting bone loss and its recovery were studied by means of microradiography, tetracycline-uptake, quantitative estimation of the cortical area of cross-sections from the femoral midshaft, and estimation of total body calcium. The cortical area in the femoral midshaft fell to 46% of its original value during depletion, and then rose to 78% during the first three weeks after weaning. Total body calcium fell from 1.12% to 0.60% of body weight and then increased to 0.89%. Removal of bone occurred mainly in the spongiosa and on the endosteal side of the cortex. Subsequently, new bone was laid down on the endosteal side, but also to some extent on the periosteal side of the cortex. The mineral density of this new bone was low. During the recovery phase resorption cavities within the cortex were filled in a concentric manner as in Haversian remodeling. Neither this feature nor the low mineral density of bone are normally present in the rat.

Animals↗

PubMed2004

[Growth and differentiation factor 5 (GDF-5) composite improves the healing of necrosis of the femoral head in a sheep model. Analysis of an animal model].

MATERIALS AND METHODS: After creation of necrosis in 23 sheep, the composites were implanted in half of the animals. The animals were sacrificed 6 and 12 weeks after implantation and the femora were harvested. The specimens were investigated by microradiography, computed tomography, and histologically. RESULTS: The GDF-5 composites were effective in the necrosis model. Osseous regeneration of the necrosis and the drill track were accelerated and enhanced by the composites. In treated animals the necrosis was nearly healed and the drill track was filled with bone after 12 weeks. In the control group the track was partially filled with fibrous tissue and necrotic lesions were still present. Specific side effects of the growth factor or the matrix were not documented. This was documented by histological scoring and CT investigation. DISCUSSION: The application of an absorbable GDF-5 composite in combination with a core decompression procedure may enhance the healing of devitalized bone defects and is a promising approach for further studies.

Animals↗

PubMed2000

Microstructural analysis of severe bone lesions in seven thalassemic patients treated with deferoxamine.

Osteochondrodystrophic lesions, mainly affecting long bone metaphyses, can be radiologically evident in homozygotic thalassemic patients treated with deferoxamine, and their incidence rate varies among authors. The clinical and radiological appearance of these lesions is described in the literature, but microstructural data are still lacking. The aim of our research was to evaluate the microstructure of five tibial biopsy specimens from thalassemic patients with bone lesions (5 cases out of 180 patients followed for the last 10 years, i.e., 2.8%) and two bone biopsy specimens from thalassemic patients with no radiological alteration of the long bones. As control, bone tissue taken from autoptic tibiae of two subjects with no skeletal pathology was used. Using microradiography and X-ray diffraction (XRD), we found a reduced and irregular mineralization of the bone (compared with controls) in thalassemic subjects. Bone tissue microhardness was also significantly reduced. Nevertheless, bone apatite lattice was unaltered and no 'foreign' crystallographic phase was recorded by XRD. In conclusion, all the patients shared a similar picture of abnormal bone, even with no radiological evidence of lesion.

Adolescent↗

PubMed2005

Effects of fixation and decalcification on the immunohistochemical localization of bone matrix proteins in fresh-frozen bone sections.

To examine the stability of bone matrix proteins for crystal dislocation, the immunolocalization of type I collagen, bone sialoprotein, and osteopontin was investigated during different stages of fixation and decalcification. Four-week-old rat femurs were rapidly frozen, and were sectioned without fixation or decalcification. Thereafter, following or bypassing fixation in 4% paraformaldehyde, these sections were decalcified in 5% EDTA for 0-5 min. Before decalcification, marked radiopacity of bone matrix was observed in contact microradiography (CMR) images, and electron probe microanalysis (EPMA) demonstrated intense localization for phosphorus and calcium. In fixed and unfixed sections without decalcification, immunolocalization of bone matrix proteins were almost restricted to osteoid. After 1 min of decalcification, reduced radiopacity was apparent in the CMR images, and less phosphorus and calcium was observed by EPMA, which completely disappeared by 5 min decalcification. After 3-5 min of decalcification, unfixed sections showed that these proteins were immunolocalized in bone matrix, but were not detectable in osteoid. However, fixed sections demonstrated that these were found in both bone matrix and osteoid. The present findings suggest that bone matrix proteins are embedded in calcified matrix which is separated from the aqueous environment and that they hardly move, probably due to firm bonding with each other. In contrast, matrix proteins in osteoid are subject to loss after decalcification because they may be bound to scattered apatite crystals, not to each other.

Animals↗

PubMed2004

Fluoride-induced alterations of enamel structure: an experimental study in the miniature pig.

We studied the structural changes in the enamel of mandibular third molars of miniature pigs administered a daily oral dose of 2 mg NaF (approximately 0.9 mg of fluoride) per kg body weight (added to the feed) for 1 year. The treatment period covered most of the secretory stage and the entire post-secretory stage of amelogenesis of the M(3). The enamel of the molars from the fluoride-fed pigs appeared opaque and chalky, and the erupted portions were stained brown. The underlying histopathological change was a pronounced subsurface hypomineralization of the enamel beneath a thin surface rim of higher mineral content. This enamel hypomineralization was attributed to a fluoride-induced impairment of the process of enamel maturation. The most conspicuous finding in the fluorotic enamel was the presence of numerous pit-type hypoplastic defects, denoting a marked fluoride-induced disturbance also of the secretory stage of amelogenesis. Microradiography and scanning electron microscopy revealed an enhanced incremental pattern in the outer enamel of the fluorotic molars. Typically, the bottom of larger hypoplastic defects was underlain by a broad, grossly accentuated incremental line. Occurrence of larger hypoplasias was further associated with the presence of aprismatic enamel, the formation of which was attributed to a loss of the prism-forming (distal) portion of the Tomes' processes of secretory ameloblasts. The findings in the miniature pigs closely parallel earlier observations on fluorotic enamel of free-ranging deer and wild boar from fluoride-polluted areas.

Administration, Oral↗

PubMed2006

In vitro quantitative light-induced fluorescence to measure changes in enamel mineralization.

A sensitive, quantitative method for investigating changes in enamel mineralization of specimens subjected to in vitro or in situ experimentation is presented. The fluorescence-detecting instrument integrates a Xenon arc light source and an object positioning stage, which makes it particularly suitable for the nondestructive assessment of demineralized or remineralized enamel. We demonstrate the ability of in vitro quantitative light-induced fluorescence (QLF) to quantify changes in mineralization of bovine enamel discs that had been exposed in vitro to a demineralizing gel (n=36) or biofilm-mediated demineralization challenges (n=10), or were carried in situ by three volunteers during a 10-day experiment (n=12). Further experiments show the technique's value for monitoring the extent of remineralization in 36 specimens exposed in vitro to oral multispecies biofilms and document the repeatability of in vitro QLF measurements (n=10) under standardized assay conditions. The validity of the method is illustrated by comparison with transversal microradiography (TMR), the invasive current gold standard for assessing experimental changes in enamel mineralization. Ten discs with 22 measurement areas for comparison demonstrated a positive correlation between TMR and QLF (r=0.82). Filling a technological gap, this QLF system is a promising tool to assay in vitro nondestructively localized changes in mineralization of enamel specimens.

Analysis of Variance↗

PubMed2003

[Osseous defect regeneration using autogenous bone alone or combined with Biogran or Algipore with and without added thrombocytes. A microradiologic evaluation].

In addition to autogenous bone, a variety of bone substitute materials is used to regenerate bony defects. The aim of the study was to evaluate the reossification of critical size defects in the os frontale of adult pigs ( n=16) with microradiography. The defects were filled randomly with autogenous bone or the bone substitute materials Algipore and Biogran each combined with a defined quantity of autogenous bone. Additionally, platelet-rich plasma (PRP) was added in defined quantities (0.5 ml) in two different concentrations (4-fold and 6.5-fold). At 2, 4, 12, and 26 weeks four animals were sacrificed and the osseous regeneration documented by quantitative evaluation of the microradiographic findings. Microradiographic results in the autogenous bone group showed an earlier PRP concentration-dependent mineralization. Over the whole observation period the peak value of autogenous bone as filler alone could not be reached in both PRP groups. Using Algipore, no accelerated effect of mineralization however could be observed. In our study, Biogran proved to be a defect filler only partially suitable for bony defect healing, no matter whether PRP was added or not.

Alginates↗

PubMed1983

The histology of sclerotic human root dentine.

Studies by optical microscopy, microradiography and SEM suggested that sclerosis is the result of occlusion of the dentinal tubules by a mineral substance with a refractive index similar to that of the rest of the dentine. Translucence appeared before the majority of the tubules were completely occluded. The deposition of the occluding mineral took place initially in individual tubules or in groups of tubules. The occluding material and the peritubular dentine were almost indistinguishable under SEM. Both were smooth and densely mineralized. The process of deposition of occluding mineral appeared to be more like that of in-vitro mineralization and thus different from that of peritubular dentine.

Adolescent↗

PubMed1984

Microradiographic and electron microscopic observations of the enamel-covered dentine in rat molars.

The enamel-covered primary and secondary coronal dentine in the molars of 90-day-old and 360-day-old rats was examined using microradiography. Some preparations were subsequently examined by transmission and scanning electron microscopy (SEM). Fractured dentine surfaces and methacrylate casts of the tubular system in the primary dentine were also examined with SEM. No microradiographic evidence of a hypermineralized peritubular matrix, such as that seen in man and other species, was seen in either young or old rats. Transmission and SEM confirmed the microradiographic findings. The tubule obliteration and extensive intra-luminal mineral deposits which have been reported in the enamel-free coronal dentine of the rat molar were not seen in the enamel-covered coronal dentine but some evidence of tubule obliteration was seen in the secondary dentine.

Animals↗

PubMed1985

Effect of time, degree of saturation, pH and acid concentration of buffer solutions on the rate of in-vitro demineralization of human enamel.

The rate of demineralization of the artificial caries-like process was measured using two methods. The rate calculated from microradiography of the demineralized enamel appeared to be equal to the one calculated from calcium and phosphate analysis of the demineralizing buffer. In small volumes of demineralizing solution, the rate of demineralization decreased with time, due to the increase in saturation of the solution during the demineralization of the enamel. With increasing saturation, with respect to hydroxyapatite, and with increasing pH the rate of demineralization decreased. Increasing acid concentration had a marked influence only at the lower concentrations; a further increase had no effect on the rate of demineralization.

Buffers↗

PubMed1989

A morphometric and quantitative microradiographic study of dental tissues in the hypopituitary dwarf mouse.

In transverse sections the areas of enamel, dentine and pulp were determined using image analysis morphometry, and the mineralization levels of enamel, dentine and alveolar bone using quantitative microradiography and a microphotometric-microdensitometric technique. There were significant differences in the ratios of dentine to pulp area, and in the enamel to total area in the incisors from dwarf and normal animals. The mean dentine to pulp ratio for dwarf incisors was more than six times greater than in normal incisors. There was also a significantly greater variation in the dentine to pulp ratio in dwarfs, which was attributed to their greater variation in pulp size. Values for mineral density of enamel, dentine and bone were similar to those found by other investigators. For example, for normal specimens, the mean mineral density of outer enamel was 2.84 g/cm3 (SD = 0.38), percentage mineralization 92%; outer labial dentine was 1.64 g/cm3 (SD = 0.15), percentage mineralization 52%; and alveolar bone was 1.53 g/cm3 (SD = 0.13), percentage mineralization 49%. The variation in mineralization within each tissue confirmed previous work in rodents. There was a consistent trend for mineralization levels of all hard tissues in the dwarf sample to be less than in the normal sample but the difference was not statistically significant for any one tissue.

Alveolar Process↗

PubMed1990

Effects of single doses of 1-hydroxyethylidene-1,1-bisphosphonate on the mineralizing front of rat incisor enamel: a microradiographic and scanning electron microscopic study.

The effects of a single dose of HEBP were examined by injecting rats subcutaneously with various doses (0.5, 1, 2.5, 5 and 10 mg P/kg body wt) and killing them either 2 or 9 days after injection. The maxillary incisors were processed for microradiography and the mandibular incisors for scanning electron microscopy after enzymatic digestion of the enamel organ remains. All doses resulted in a hypomineralized incremental band corresponding to the position of the mineralizing front at the time of injection. At 5 and 10 mg P/kg body wt, a hypomineralized lesion was found throughout the whole thickness of the enamel in an area which corresponded to the stage of late enamel secretion at the time of injection. The surface layer covering this lesion was elevated or disrupted. By scanning electron microscopy, there were three different types of lesions along the enamel surface: a "demarcation groove" corresponding to the initial enamel formation at the time of injection; an "area containing mineral globules" and a "bright band" corresponding to the stages of late secretory and final enamel formation, respectively, at the time of injection. A single injection of HEBP thus interferes with different stages of enamel formation. The findings may be explained as of the physico-chemical effects of HEBP on the mineral phase alone, but a direct effect of the drug on ameloblast function cannot be excluded.

Amelogenesis↗

PubMed1993

Effect of fluoride incorporation into human dental enamel on its demineralization in vitro.

Coronal surfaces of extracted human teeth were ground to a depth of about 1 mm and then cut in half labiolingually. One half was used as a control; the other half was exposed, for 3 days, to a fluoride-enriching buffer (0.1 mol/l lactic acid, 19.7 mmol/l CaCl2, 10.8 mmol/l KH2PO4, 3 mmol/l NaN3; pH adjusted to 4.68 with KOH) having fluoride concentrations from 0.0002 to 2.2 parts/10(6). This exposure resulted in an uptake of fluoride by the enamel to a depth of 2 microns without any apparent demineralization. The fluoride uptake was proportional to the F concentration of the enriching solution, reaching concentrations of about 8000 parts/10(6) within the first micrometre of enamel exposed to the highest F concentration; the controls had uniform F concentrations not exceeding 50 parts/10(6) along the 2.5 microns of enamel depth sampled. Thin sections (140-160 microns) were cut perpendicularly to the lingual surface, coated with protective resin except for a window about 1 mm long on the ground lingual surface, and exposed to a demineralizing buffer. The mineral losses of the sections were followed over 5 days by microradiography and image analysis. Fluoride enrichment resulted in reduced demineralization and the reduction was inversely related to the enamel fluoride content. The controls displayed a uniform erosion of the surface enamel whereas all the treatments below 1.5 parts/10(6) in the enriching solutions developed typical subsurface 'lesions'. The mineral content of the surface layer increased with increasing time of exposure to the demineralizing buffer.(ABSTRACT TRUNCATED AT 250 WORDS)

Buffers↗

PubMed1986

Selenium-induced cataract--a correlation of dry mass content and light scattering.

Selenium-induced cataracts in young rats were used to compare light scattering and dry mass concentration along the lens axis. Selenium-treated rats and control rats were examined 1, 2, 4 and 6 days after subcutaneous injection of selenium or 0.9% NaCl. The development of nuclear cataract was followed with a Scheimpflug slit-lamp camera. Light-scattering was determined by densitometry of the negatives taken by the Scheimpflug camera. Dry mass concentration was determined by quantitative microradiography of the extracted lenses. Increasing light scatter was seen from day 2 to day 6. The dry mass concentration, however, was not changed until day 6. Two distinct zones were found surrounding the center of the nucleus, one with increased and one with decreased dry mass. The rapid changes in dry mass concentration were probably caused by shifts in water distribution within the lens. Similar zones of hydration have also been found in human senile nuclear cataract. Selenium-induced cataract in the rat is discussed in relation to human nuclear cataract.

Animals↗

PubMed1978

A microangiographic study of vascular changes in replanted and autotransplanted teeth of young dogs.

The purpose of the present investigation was to study the revascularization process of the pulp of replanted and autotransplanted teeth with incomplete root development in dogs. A barium-sulfate injection method combined with contact microradiography was used. Ingrowth of apparently new vessels was seen during the first postoperative days. After 10 days, visible vessels were seen in the apical half of the pulp, and after 30 days, in the whole pulp. Branches and apparently also anastomoses between pulpal vessels were seen after 10 days but were especially numerous after 30 days. One hundred eighty days postoperatively, only one of fifteen teeth was devoid of visible vessels, indicating pulpal necrosis. Thirteen of the remaining fourteen teeth exhibited visible vessels throughout the entire length of the pulp. It seems, therefore, that replanted and autotransplanted teeth with open apices have a high potential for repair. The revascularization of the pulp appeared to occur mainly by ingrowth of new vessels. In some instances, however, anastomoses seemed to form to pre-existing vessels in the pulp.

Animals↗

PubMed1983

Dentinogenesis imperfecta with dens in dente.

An uncommon case of dentinogenesis imperfecta with dens in dente was studied by light microscopy, microradiography, and electron-microprobe analysis. Numerous canals and cellular inclusions were found in the coronal portion of the dentin where the tubules were sparse and irregularly distributed. In the radicular portion of the molar, large canals ran parallel to each other down to the apical region. The cementum was thinner and the Tomes granular layer greater in amount than usual. A dens in dente occurred in the radicular portion of the molar. It was located in a cavity and consisted of a mineralized cap of enamel, a spherical dentinal mass, and cellular cementum, located outside the cavity and in the "cervical" portion of the dens in dente.

Adolescent↗

PubMed1988

Structural deformities of deciduous teeth in patients with hypophosphatemic vitamin D-resistant rickets.

Structural deformities of deciduous teeth from patients with hypophosphatemic vitamin D-resistant rickets (HVDRR) (1 male and 2 female patients) were examined by means of transmitted light microscopy, contact microradiography, and x-ray microanalysis. Freshly extracted teeth were fixed in formalin and subsequently hemisected longitudinally through the midline. One half was prepared for ground sections and the other half for decalcified sections. Neither gross nor microscopic abnormalities were present in enamel of patients with HVDRR. The concentration of calcium and phosphorus and the calcium/phosphorus ratio of the enamel of patients with HVDRR were nearly equal to those of normal teeth, although the degree of radiopacity was less in HVDRR. On the other hand, numerous microscopic abnormalities in the dentin of patients with HVDRR were found, such as interglobular dentin, wide predentin zones, and tubular defects. The concentration of phosphorus in the dentin of a patient with familial HVDRR was extremely low. Furthermore, formation of reparative dentin was observed at the pulp horn of teeth in patients with HVDRR that had been subjected to definite attrition at the corresponding dentin site.

Calcium↗

PubMed1993

Enamel ultrastructure and protein content in X-linked amelogenesis imperfecta.

X-linked amelogenesis imperfecta has been proven in a number of families to be linked to or involve a variety of mutations in the X chromosome amelogenin gene. The purpose of this study was to characterize the enamel ultrastructure and enamel protein in a kindred affected by X-linked amelogenesis imperfecta. Exfoliated primary teeth were obtained from two related persons (one male, one female) who had X-linked amelogenesis imperfecta with marked hypoplasia. Normal enamel (age and sex matched) was used as the control for all analyses. The teeth were evaluated using light microscopy, scanning electron microscopy, and microradiography. The enamel of the heterozygous female was hypoplastic and rough with marked surface depressions. Enamel beneath these depressions was poorly organized and lacked a prismatic structure. The affected male had very thin enamel (approximately 40 microns) that also lacked an organized structure. Enamel protein from the teeth of the heterozygous female and the control was characterized using amino acid analysis. The protein content of the enamel of the female with amelogenesis imperfecta was 0.40% (N = 1) whereas the control enamel ranged from 0.17% to 0.45% (N = 4; mean = 0.34%). This study indicates that although the enamel in both the male and female with X-linked amelogenesis imperfecta displayed marked structural abnormalities the enamel protein was similar in quantity and amino acid composition for normal and X-linked amelogenesis imperfecta (female) enamel.(ABSTRACT TRUNCATED AT 250 WORDS)

Amelogenesis Imperfecta↗