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PubMed1989

Patho-morphological study of the supplemental groove.

The following results have been obtained in consequence of patho-morphological examination regarding the supplemental groove. 1. Light microscopic observation of cross-sectioned supplemental grooves revealed that most of them were shallow in the form of plate or bowl. Some of the supplemental grooves had contents not described in the past and the structure of the contents was not clear under a light microscope. The contents were found in 22% of the supplemental grooves examined. 2. The contents in supplemental grooves which were confirmed under a light microscope were found to consist of enamel itself when examined by means of an electron microscope. Microhardness measurements of this enamel showed less than one third the values of normal enamel. By means of microradiography, it was established that radiolucency of this enamel was, for the most part, much higher than normal enamel. 3. It was ascertained that enamel with low hardness and high radiolucency constitutes the contents of supplemental grooves. Judging from its tissue properties, the contents were believed to be susceptible to attack by caries. This view was supported by the results of an investigation of caries sites in supplemental grooves.

Dental Caries Susceptibility↗
PubMed1989

[Anomalies of enamel formation in subjects with maxillary clefts].

A structural and ultrastructural study of teeth located in the vicinity of maxillary cleft and teeth located outside the cleft region, was made in 12 cases, using correlated light microscopy, microradiography and SEM. All teeth directly involved in cleft process presented gross hypoplasia of the crown where the enamel surface was hypomineralized. Globular calcified masses of different radiodensity were seen on the hypomineralized enamel surface. The teeth located outside the cleft region presented less pronounced anomalies constituted by isolated or group microhypoplasia on hypomineralized enamel. The observation of enamel pearl was not pathognomonic of maxillary cleft.

Cleft Lip↗
PubMed1989

The influence of fluoride on in vitro remineralization of bovine enamel.

Remineralization experiments using bovine enamel were carried out with 2 ppm fluoride or no fluoride added to the remineralizing solutions. The group without fluoride showed (quantitative microradiography) significantly more remineralization in the first 50 microns of the lesion than the fluoride group. It is suggested that fluoride may inhibit remineralization.

Animals↗
PubMedDate not supplied

Bone formation and remodeling after symmetric and asymmetric physeal distraction.

Bone formation after symmetric and asymmetric physeal distraction was studied in growing sheep. After gradual distraction by external fixation, separation of the growth plate occurred. Fluorescence microscopy, microradiography, and histomorphometric methods were used to study neometaphysis formation. The bone was formed from the inner layer of the periosteum to encircle the distraction area, where the osteogenesis occurred according to the collagen bundles. At consolidation, the distraction area was composed of lamellar trabecular and partly woven bone. The bone trabeculae in the distraction area were thicker than in the control radius. After asymmetric physeal distraction, spontaneous correction of the formed angulation occurred through remodeling and asymmetric physeal growth. Although local physeal changes were noted histologically, enchondral growth usually continued after distraction.

Animals↗
PubMed1988

Fluoride uptake and inhibition of intra-oral demineralization, following the application of varnishes with different concentrations of fluoride.

The relationship between the amount of fluoride acquired by human enamel after varnish application and the resulting inhibition demineralization of is presented and discussed. Intact human enamel was pretreated with Fluor Protector varnishes with differing fluoride contents (0.7; 0.1; 0.05 and 0 wt% F-) for 24 hours. In a first experiment the amount of fluoride acquired after application was determined. In a second experiment the pretreated enamel was stored intra-orally under constant plaque coverage, in order to create a substantial demineralization challenge. The protection against demineralization, induced by the various varnishes was determined four months after varnish application using microradiography. Under the cariogenic conditions created in this study, the fluoride containing varnishes induced a protection of 53-75%. Although the amount of fluoride uptake was strongly related to the fluoride content in the varnishes, no statistically significant difference in demineralization inhibition between the varnishes was observed. SEM investigation of the enamel lesions revealed globular precipitates inside the fluoridated enamel, presumably consisting of calcium fluoride-like material. The present study indicates that the fluoride content in Fluor Protector varnishes can be decreased without reducing its ability to inhibit demineralization.

Dental Caries↗
PubMed1988

Bone vitality in the cat's irradiated jaw. Histological study.

The vitality of the mandible in cats was studied from two to 15 months after irradiation. Dose of 80 Gy in three days was delivered using three hairpin shape iridium-192 wires surrounding the mandibula. The osseous vitality was assessed from the percentages of lacunae inhabited by osteocytes (IL). The results are compared with those obtained by microradiography. At two months, a small reduction of vitality is already observed, it becomes progressively more important. At one year, vitality is recovered nearly fully in the ventral part of the mandibula, mainly at the level of the alveolar crest. Vitality remains reduced in the dorsal part. Microradiographic lesions appear more slowly; they are apparent at six months.

Animals↗
PubMed1988

Effects of lesion size and location on equine articular cartilage repair.

The mechanisms and completeness of equine articular cartilage repair were studied in ten horses over a nine month period. Large (15 mm square) and small (5 mm square) full-thickness lesions were made in weight bearing and nonweight bearing areas of the radiocarpal, middle carpal and femoropatellar joints. The horses were euthanized in groups of two 1, 2.5, 4, 5 and 9 months later. Gross pathology, microradiography, and histopathology were used to evaluate qualitative aspects of articular repair. Computer assisted microdensitometry of safranin-O stained cartilage sections was used to quantitate cartilage matrix proteoglycan levels. Structural repair had occurred in most small defects at the end of nine months by a combination of matrix flow and extrinsic repair mechanisms. Elaboration of matrix proteoglycans was not complete at this time. Statistically better healing occurred in small weight bearing lesions, compared to large or nonweight bearing lesions. Synovial and perichondrial pannus interfered with healing of osteochondral defects that were adjacent to the cranial rim of the third carpal bone. Clinical and experimental experience suggests that these lesions are unlikely to heal, whereas similar lesions in the radiocarpal and femoropatellar joints had satisfactory outcomes. Observations made in this study support the use of early postoperative ambulation, passive flexion of operated joints, and recuperative periods of up to a year for large cartilage defects.

Analysis of Variance↗
PubMedDate not supplied

Bone mass determination from microradiographs by computer-assisted videodensitometry. I. Methodology.

The mass of hard-tissue specimens is assessed by optimised microradiography followed by computer-assisted videodensitometry. Radiographs are produced with 27 kV roentgen radiation, filtered through 0.5 to 1 mm of aluminium, on high-resolution glass plates. Aluminium step wedges are used for density calibration, the result being expressed as 'aluminium equivalent mass'. The plates are subjected to digital image analysis by an operator in interaction with a computer-based image processor, a television camera being used for image input. The program stored in the computer provides calibration of geometry and--via the step wedge images--of densitometry, background adjustment, etc. Measurement takes place by integration over the specimen-image area. No assumptions being needed concerning a specific attenuation model, the errors stemming from the common presumption of exponential attenuation are eliminated. Density profiles or maps of mass distribution are readily obtained from the computer. From measurements of aluminium phantom samples, the total random error (coefficient of variation) was determined at 1.8 per cent, the microradiographic and videodensitometric procedures contributing 1.6 per cent and 0.9 per cent, respectively, whereas the systematic error was negligible. Since specimens need not be sectioned, this method does not interfere with subsequent histologic preparation.

Bone and Bones↗
PubMed1987

Mineralization disturbances in the deciduous teeth of children with so called minimal brain dysfunction.

Exfoliated deciduous teeth from 14 children with so called Minimal Brain Dysfunction (MBD) and from 14 age-matched comparison children without MBD were collected and ground sections prepared. The sections were analysed by means of polarized light and microradiography. The enamel in ground sections of deciduous teeth from children with MBD showed a wider neonatal line than normal. The prenatal enamel showed a slight tendency to an increase in the degree of porosity, and the overall severe pathology was more common in the MBD group than in the comparison group.

Attention Deficit Disorder with Hyperactivity↗
PubMed1987

Electron microprobe and microradiographic studies of carious enamel lesions covered with dental calculus.

From a large number of posterior teeth with arrested natural carious lesions some 0.56 percent were found to have arrested approximal lesions with a superficial layer of calculus. The lesions were examined using quantitative microradiography for mineral content and by electron microprobe analysis for Ca, Na, Cl, Mg and P. The conditions in the plaque, which caused the formation of calculus, might also be expected to cause a remineralization of the lesions. However, the lesions examined were found to have a low mineral content in their body, and moreover, had a lower Na/Ca ratio and a higher Cl/Ca ratio than sound enamel; these are characteristics also found in carious lesions not covered with dental calculus. On the assumption that the lesions developed before any plaque calcification occurred, it is concluded that conditions which favour the calcification of plaque do not favour the remineralization of carious lesions in vivo. As only 0.5% of the carious lesions in extracted teeth were covered with calculus, it must be admitted that consecutive periods of lesion formation followed by calculus formation on the same tooth face are rare.

Adult↗
PubMed1987

Mineral distributions in enamel after in vivo de- and remineralization.

Plates of human enamel were demineralized under plaque in 18 participants. The subjects were randomly allocated to 3 groups consuming 0, 1 or 2 filled chocolate products (FCP) in between meals daily for periods of 4 weeks. Subsequently, the specimens were remineralized in vivo for 9 weeks, with or without the consumption of an FCP. The mineral distribution was assessed by means of microradiography. Special emphasis was placed on the type of mineral distribution. The results showed that: 1) significantly more enamel samples demineralized in vivo with a surface layer covering the lesion, when FCP's were eaten in between meals. The ranking of the number of samples with a surface layer was 0 FCP less than 1 FCP less than 2 FCP. 2) The amount of mineral lost during demineralization was not statistically different between 0 and 1 FCP. There is a difference between 0 and 2 FCP. 3) There was no difference in surface layer thickness or mineral content in the surface layer of 0, 1 or 2 FCP consumption in the demineralization experiment. 4) After 9 weeks a substantial remineralization occurred. There was no difference in remineralization between the 0 and 1 FCP group. 5) No difference in the percentage remineralization was found between mineral distributions with or without a surface layer.

Cacao↗
PubMed1986

Histologic and microradiographic analysis of a revised porous-coated anatomic (PCA) patellar component. A case report.

A retrieved uncemented, porous-coated human patellar component was evaluated histologically and microradiographically. The metal portion of the component and porous coating were made of cobalt--chromium-based alloy. Because of adhesive capsulitis and inadequate knee flexion, the patient had revision surgery 11 months after the original total knee arthroplasty. Clinically, the device was not grossly loose. Contact microradiography of the porous material showed no calcified tissue ingrowth. Undecalcified histologic sections demonstrated only fibrous tissue ingrowth, with obvious bone-resorptive activity as well as numerous multinucleated giant cells adjacent to the porous metal.

Bone and Bones↗
PubMed1986

The inhibition of demineralization of human enamel after fluoride varnish application as a function of the fluoride content. An in vitro study under constant composition demineralizing conditions.

The inhibiting effect of a 24 hours application of a fluoridated varnish with various fluoride contents on demineralization of human sound enamel was evaluated in vitro. The varnishes used had the same polyurethane base (Fluor Protector) and contained 0.7; 0.1; 0.05 and 0 wt% fluoride, resp. A constant composition technique was used to demineralize varnished and non-varnished specimens at a pH of 5 for periods upto 2 weeks. Microhardness measurements were carried out after several time intervals to follow mineral loss in time longitudinally. At the end of each experimental run microradiography was carried out to investigate 1) lesion type, 2) lesion depth and 3) mineral loss. It is shown in this study that the fluoride releasing varnishes applied on the enamel for 24 hours can inhibit demineralization completely. No demineralization inhibition with the 0% fluoride varnish application was observed.

Decalcification Technique↗
PubMed1985

Advanced osteitis fibrosa cystica in the absence of phalangeal subperiosteal resorption. A case report and review of the literature.

A case of primary hyperparathyroidism with advanced osteitis fibrosa cystica but without any subperiosteal phalangeal bone resorption is described. A review of this unusual radiological feature is presented. High-detail magnification radiography (microradiography) is advocated for the early diagnosis of bony defects in hyperparathyroidism.

Bone Resorption↗
PubMed1975

Symphysial changes in rheumatoid arthritis. A microradiographical and histological study.

Autopsied pubic symphyses of 10 male and 10 female non-rheumatoid subjects and of 11 subjects with RA were studied. Osteo-arthritic changes were common in all elderly symphyses. This caused changes in the structure of the end plates and trabeculae. Some non-rheumatoid samples showed changes suggestive of erosion, but no evidence of inflammation. At microradiography the erosions seen in rheumatoid symphyses differed from the controls due to a lack of reactive sclerosis in the surrounding bone, although true inflammation was seen histologically in only two cases.

Adult↗
PubMed1984

[The mineral phase of Malherbe's calcifying tumor].

The mineral phase of a calcified tumour of Malherbe (pilomatrixoma) was studied using microradiography, chemical analysis and X-ray diffraction. It was compared with the mineral phase of a piece of human mandibular bone from a matched subject with respect to age and sex. The main part of the mineral phase of the pilomatrixoma belonged to the biological apatite system; an additional whitlockite phase was found. In the homogeneous areas of the tumour, the radioopacity was similar to that of bone.

Calcium↗
PubMed1981

[Demonstration of bone tissue in the axial skeleton of a chondrichthian: the dogfish (Scyliorhinus canicula)].

Dogfish vertebra have been studied by means of an undecalcified hard tissue method, including microradiography and tetracycline labelling. The transversal section of Dogfish vertebra shows a centrum and two couples of neural and hemal arches. The mineralized area consists of a narrow but continuous band, just against the perichondrium, formed by chondrocytes that participate in the surrounding matrix mineralization. The neural arches appear quite different: the upper parts contain hypertrophied cartilage and, close to it, the inner zones are formed by a crescent-shaped lamellar bone containing osteoblasts and osteocytes. A tetracycline label of these two types of hard tissue reveals a globular calcification with calcospherites and Liesegang rings, at the level of calcified cartilage and a strong and linear label of the inner border of the osseous tissue. The presence of osseous tissue in Elasmobranch endoskeleton is discussed in relation to, on one hand the evolution of the Gnathostomes skeleton and on an other hand the endocrinological point of view of calcium metabolism regulation in this group.

Animals↗
PubMed1982

Comments on the porosity of human tooth enamel.

The porous nature of surface and sub-surface enamel undergoing the final stages of maturation has been observed on unerupted, partly-erupted, and fully-erupted human teeth, using polarized light microscopy, microradiography, and scanning electron microscopy. Maturation deficiency of developmental origin can be distinguished from early carious lesions with polarized light by the absence of a well-circumscribed "dark" zone.

Dental Enamel↗