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PubMed1989

Structural and ultrastructural study of the teeth in a suspected case of pseudohypoparathyroidism.

Two premolars removed from a 14 year old girl, with suspicion of pseudohypoparathyroidism (PHP) have been studied, using several of the correlated techniques applied to the study of calcified tissues (light microscopy, microradiography and scanning electron microscopy). Enamel gross and micro hypoplasia, hypomineralization of the enamel surface and dentin hypocalcification were similar to dental abnormalities observed in pseudohypoparathyroidism. Microradiography showed for the first time calcifications present in blood vessels of the dental pulp. Light microscopy and SEM revealed dystrophic globular calcifications within enamel hypoplastic pits. Cemental changes consisting of hypoplasia, aplasia, localized hyperplasia and cementicules were described for the first time. It is suggested that enamel, dentine and pulp abnormalities observed in the present case might be pathognomonic of PHP.

Adolescent↗

PubMed1988

Bone tissue interface.

High resolution microradiography and multiple fluorochrome labeling are definitive histological methods for assessing the mechanism and timing of osseous healing, maturation, and adaptation. Two fundamental types of bone interface have been described for endosseous dental implants: (1) fibro-osseous integration ("pseudo-periodontal ligament") and (2) rigid osseous fixation ("osseointegration"). No definitive bone interface studies with modern physiological methods have been reported for fibro-osseous integration. Rigid osseous fixation has been investigated in cortical bone implantation sites. The initial healing reaction involves predominantly bone modeling at the periosteal and endosteal surfaces, i.e., a woven bone callus fills with lamellae by the process of lamellar compaction. Nonvital osseous interface and adjacent compacta are replaced by bone remodeling (turnover). As assessed with high resolution microradiography, "clinically successful" specimens had less than half of the intraosseous interface in direct contact with bone. Extrapolation from animal data suggests that endosseous implants can be provisionally loaded at about 18 weeks, but full maturation of the interface requires approximately one year.

Animals↗

PubMed1987

[Structure, ultrastructure and microanalysis of the enamel of teeth near maxillary clefts].

Teeth located in the vicinity of cleft palate were studied using correlated light microscopy, microradiography, SEM, TEM and microanalysis. Structural, ultrastructural and chemical abnormalities were found in enamel. The enamel surface presented micro and gross hypoplasia, associated with hypomineralization. Microradiography showed the antenatal enamel to be more mineralized than postnatal enamel. Microanalysis showed the Ca/P ratio measured at the enamel surface to be higher in the teeth associated with cleft palate, compared with controls. The Ca/P value was due to a Ca increase and a P decrease in the enamel surface. The Ca increase was correlated with a decrease in Mg, supporting the hypothesis of a Mg/Ca substitution in the apatitic structure.

Adolescent↗

PubMed1993

Hematogeneous pulmonary metastasis. An experimental study using VX-2 carcinoma in rabbits.

The purpose of this study was to develop an experimental model of pulmonary metastases using VX-2 tumor, and to describe sequential radiologic and pathologic findings with special attention to the interstitial changes around the metastatic nodules. Through ear veins of 25 rabbits, VX-2 tumor cell suspension was injected with 0.8-mm scalp needles. Chest radiographs were taken every other day after tumor injection. The rabbits were sacrificed at scheduled times from 3 to 30 days after tumor injection. The inflated and fixed lungs were examined with visual inspection, low-kV radiography, high resolution CT (HRCT), microradiography of the sliced lung and with histopathologic studies. Hematogeneous pulmonary metastases occurred in 24 of 25 rabbits. In addition to the metastatic nodules, perinodular and peribronchovascular infiltrations were seen on low-kV radiography, HRCT, microradiography and histologic studies.

Animals↗

PubMed1975

Correspondence of silver nitrate staining patterns in decalcified bone withe the microradiographic image.

A procedure for differential staining of decalcified bone with silver nitrate showed major histological features which appeared to correspond closely to microradiographic images. The extent to which this is actually the case was investigated directly by preparing microradiographs of ground sections of baboon and dog radii and then decalcifying and staining the same sections. The many detailed similarities indicate that this staining procedure is a useful adjunct to microradiography. Thus, poorly mineralized osteons or layers of circumferential lamellae are darker stained by silver nitrate, and the variably mineralized layers of circumferential lamellae are closely duplicated by light and dark bands in the stained sections. These similarities imply that there is a relationship between the mineral density of bone and some condition of the organic matrix which is probably related to maturation changes in the collagen.

Age Factors↗

PubMed1975

The effect of strontium, cobalt and fluoride on rat incisor enamel formation.

This investigation examined ultrastructurally the entire period of development of alterations in formative ameloblasts and the enamel which they produce following injection with fluoride, strontium, and cobalt ions. Rats injected with these ions were sacrificed at intervals of 1, 2, 4, 8, 16, 24 and 48 hours to elucidate the sequence and detail of cytologic and cell product alterations which occur. Undecalcified sections of rat incisor teeth were studied using electron microscopy and microradiography. All three ions initially produced disturbances in cell morphology and enamel formation consisting of dark globules, vacuoles, and pooling of stippled material on the enamel surface. While a period of decreased crystal formation occurred after injection with all three ions, only cobalt responses included a period of apparently complete absence of crystal formation. The hypermineralized layers occurring in the altered enamel are attributed to changes in the rate of enamel matrix formation and duration of its exposure to tissue fluids. Morphologic changes in Tomes' process were observed at the time of formation of abnormel following injection of all three ions. These observations are compared with previous studies of altered enamel formation and analyzed with the goal of learning more about the mechanisms of amelogenesis.

Ameloblasts↗

PubMed2001

Fractal analysis of lumbar vertebral cancellous bone architecture.

Osteoporosis is characterized by bone mineral density (BMD) decreasing and spongy bone rearrangement with consequent loss of elasticity and increased bone fragility. Quantitative computed tomography (QCT) quantifies bone mineral content but does not describe spongy architecture. Analysis of trabecular pattern may provide additional information to evaluate osteoporosis. The aim of this study was to determine whether the fractal analysis of the microradiography of lumbar vertebrae provides a reliable assessment of bone texture, which correlates with the BMD. The lumbar segment of the spine was removed from 22 cadavers with no history of back pain and examined with standard x-ray, traditional tomography, and quantitative computed tomography to measure BMD. The fractal dimension, which quantifies the image fractal complexity, was calculated on microradiographs of axial sections of the fourth lumbar vertebra to determine its characteristic spongy network. The relationship between the values of the BMD and those of the fractal dimension was evaluated by linear regression and a statistically significant correlation (R = 0.96) was found. These findings suggest that the application of fractal analysis to radiological analyses can provide valuable information on the trabecular pattern of vertebrae. Thus, fractal dimensions of trabecular bone structure should be considered as a supplement to BMD evaluation in the assessment of osteoporosis.

Adult↗

PubMed1995

Effect of self-reinforced polyglycolide membranes on cortical bone: an experimental study on rats.

A self-reinforced polyglycolide (SR-PGA) membrane has been developed recently by our research group and testing of it begun. To study the behavior of this membrane and its effect on cortical bone, 93 Wistar rats were operated on. SR-PGA membrane was applied around the rats' femoral diaphyses, either over the periosteum or directly over the bone, after periosteal stripping. In a control group no membrane was applied, but the femoral periosteum was stripped away. The rats were sacrificed 1, 3, 6, 12, 24, and 30 weeks postoperatively. Radiology, histology, oxytetracycline fluorescence labeling, microradiography, and planimetry were used to determine the outcome. A fibrous tissue capsule had formed around and replaced the membrane. SR-PGA membrane had a positive effect on new bone formation. Callus was frequently seen proximally and distally to the implant. Periosteal thickening occurred whether or not SR-PGA membrane was used. PGA fibers decreased in number and diameter continuously until they vanished by 30 weeks. No infections or adverse reactions were encountered. Accordingly, SR-PGA membrane is considered to be biocompatible and applicable in the treatment of cortical bone lesions such as comminuted fractures and defects.

Animals↗

PubMed1987

The evaluation of a biphasic calcium phosphate ceramic for use in grafting long-bone diaphyseal defects.

The effectiveness of a sintered hydroxyapatite-tricalcium phosphate (HA-TCP) ceramic in bridging large diaphyseal defects in the canine ulna was studied. One-hundred percent morselized HA-TCP, a 50:50 mixture of morselized HA-TCP, and autogenous cancellous bone, and 100% autogenous cancellous bone were used to bridge 2.5-cm defects in the left ulnae of three groups of six dogs each. At 24 weeks the ulnae were explanted and studied by radiography, microradiography, mechanical testing, and histology. Pure HA/TCP was not osteoinductive, and four of six ulnae in this group progressed to a fibrous nonunion. The HA/TCP-cancellous bone mixture and pure cancellous bone were approximately equal in effect, leading to good callus formation at 4 weeks and strong bony union by 24 weeks, with no evidence of bioincompatibility. Morselized HA/TCP promises to be useful as a graft extender when mixed with autogenous cancellous bone.

Animals↗

PubMed2002

Effects of Er:YAG laser irradiation on human dentin: polarizing microscopic, light microscopic and microradiographic observations, and FT-IR analysis.

BACKGROUND AND OBJECTIVES: The effects of Er:YAG laser irradiation on dentin have not been sufficiently investigated. The purpose of this study was to investigate the effects of Er:YAG laser irradiation on dentin. STUDY DESIGN/MATERIALS AND METHODS: After cavities were prepared using Er:YAG laser irradiation or rotary cutting instruments, histological observations of cavity-floor dentin utilizing polarizing microscopy, microradiography and light microscopy, and analysis of composition of cavity-floor dentin using Fourier-transformed (FT-IR) spectrometry were conducted. RESULTS: In the laser-treated side, a deeply stained basophilic layer was observed. The number of odontoblastic processes present was obviously less in the laser-treated side than in the bur-treated side. FT-IR analysis revealed that compared to the bur-treated side, a broad background peak at around 1,600 cm(-1) was present. CONCLUSIONS: Er:YAG laser irradiation might have denatured the organic materials of dentin.

Basophils↗

PubMed2005

Measurement of the severity of natural smooth surface (interproximal) caries lesions with polarization sensitive optical coherence tomography.

BACKGROUND AND OBJECTIVES: Previous studies have demonstrated that polarization sensitive optical coherence tomography (PS-OCT) can be used to image early dental caries. The purpose of this study was to compare the measured reflectivity of natural caries lesions found on smooth surfaces (interproximal lesions) with the mineral loss measured using digital microradiography (DM) in order to determine if PS-OCT can be used as a non-destructive method to measure the severity of dental decay and resolve the internal structure of caries lesions. MATERIALS AND METHODS: A PS-OCT system operating at 1,310 nm was used to acquire polarization resolved images of natural white spot lesions and pigmented lesions on the smooth surfaces of extracted teeth. The integrated reflectivity from lesion areas was compared to polarized light microscopic images (PLM) and to the integrated mineral loss from the same lesion area measured using high resolution DM. RESULTS: The frequently complex internal structure of caries lesions could be resolved with PS-OCT. Such structural information is potentially useful for determining whether or not the lesion is active and progressing or whether it has become arrested and remineralized and does not require intervention. There was a strong correlation between the integrated mineral loss of the caries lesions measured using DM and the integrated reflectivity in the perpendicular polarization axis of the PS-OCT system. CONCLUSIONS: The integrated reflectivity in the perpendicular polarization channel can be used to represent the severity of demineralization in natural early caries lesions. Therefore, PS-OCT has considerable potential as a non-destructive clinical probe of early caries lesions to assess their severity, monitor their progression over-time and potentially assess lesion activity.

Dental Caries↗

PubMed1992

Drift barriers in the postcartilaginous development of the mammalian otic capsule.

Postcartilaginous development of the otic capsule was studied in undecalcified histological material from rabbits following sequential fluorochromic time labeling of mineralizing tissues, using combined microradiography, fluorescence microscopy and osteoid staining. Early fetal bone formation was monitored by labelling of the experimental animals in utero. In contrast to the normal pattern of drift movements displayed by long bones and extracapsular cranial bone, capsular bone inside a zone immediately surrounding the perilymphatic space developed as a separate functional unit in which growth and modeling was absent. Bone tissue behavior appeared to depend on its spatial relation to the membranous labyrinth rather than histological characteristics. These findings suggest the role of inner ear tissues as a functional matrix in control of capsular bone dynamics beyond fetal life.

Animals↗

PubMed1979

Fibrous dysplasia in the light of new diagnostic methods.

Various screening tests provide a detailed representation of fibrous dysplasia: thermography, scintigraphy, computer tomography, scanning electron microscopy, X-ray microanalysis, microradiography and fluorescence microscopy. The stationary nature of clinical and X-ray findings contrasts with the intensive structural changes that occur. The above-mentioned methods are examined with regard to differential diagnosis.

Adolescent↗

PubMed1990

Bone formation in porous implants of delrin and commercially pure titanium.

Clinicians have been using implants made by titanium or delrin with varying results. In this study dividable implants, bone growth chambers (BGC), of titanium and delrin were inserted into the rabbit tibia. The ingrowth of hard tissue into a canal in the implant was evaluated after 3 weeks by microradiography and numerically determined by computer analysis. Results showed that bone ingrowth into titanium implants was significantly larger than into delrin implants (P less than 0.005). The possible reasons for this are discussed.

Animals↗

PubMed1983

The osseous structure of the carpal groove.

Transverse osseous structure of the carpal groove was studied using serial sections and microradiography. The width and area of the carpal groove were measured in x-ray films of each section. The wrist and carpal region was divided into six levels: 1) radio-ulnar joint level, 2) proximal level of the carpal bones, 3) intermediate level of carpal bones, 4) distal level of carpal bones, 5) the first C-M joint level, and 6) bases of the metacarpal bone level. The width of the carpal groove averaged 32 mm at the inlet and became narrower toward the outlet. Both inlet and outlet areas were small, the largest area was observed at the middle part. Although the carpal bones did not support the body weight, a remnant of the trajectorial architecture of the trabeculae was observed.

Carpal Bones↗

PubMed1983

Metaphyseal pattern: uniqueness of this structure in growing bones originating from cartilaginous anlage. A microradiographic study.

Microradiographic examination of metaphyses in long and short tubular growing bones allowed detection of a repetitive, clearly defined pattern of three adjacent zones; the latter are successively formed by the mineralization of cartilaginous longitudinal intercolumnar septa and by the subsequent apposition of other mineralized tissues concurrently with resorption. Consequently, each zone of the metaphysis includes mineralized tissues of various compositions and ages, identifiable by their different mineralization densities. Microradiography of pieces of the growing skeleton in several animal species shows that the same organization is not only present in long and short tubular bones but also in many other such as the pelvis and scapula, cuboid bones like the calcaneum and talus, and cartilaginous bones at the base of the skull. This suggests that there is no difference between the osteogenesis pattern of these bones and tubular ones. The problem of identifying the factors generating such metaphyseal organization is raised.

Animals↗

PubMed1984

The influence of dihydroxylated vitamin D metabolites on bone formation in the chick.

The ability of 1,25(OH)2D3 and of 24,25(OH)2D3 to prevent or to heal rickets in chicks was evaluated by studies of plasma biochemistry, growth plate histology, bone morphometry and microradiography, and bone mineralization. 1,25(OH)2D3 at a dose of 100 ng/day produced fewest abnormalities compared with vitamin D3-treated control chicks. Bone growth was slightly greater than vitamin D3-treated controls in chicks given a lower dose of this metabolite; the reverse was observed in chicks given a higher dose. 24,25(OH)2D3 was less effective than 1,25(OH)2D3 in preventing rickets even at doses as high as 400 ng/day. Treatment of rachitic chicks with doses of 24,25(OH)2D3 up to 300 ng/day produced no healing effect on the bone lesions, in marked contrast to the beneficial effects observed with 1,25(OH)2D3.

Animals↗

PubMed1975

Effect of long-term administration of fluoride on physico-chemical properties of the rat incisor enamel.

Rats were maintained on drinking water containing different amounts of fluoride (0, 9, 23 45, 68, and 113 ppm) for 70 days. Physico-chemical properties of the incisor enamel were examined after fluoride administration, using contact microradiography, histochemistry, and microhardness tests. The tooth enamel formed during high fluoride exposure showed marked hypocalcification. Much of organic substance in the enamel seemed to have been retained. In addition, the microhardness of enamel showed a marked decrease. These changes were most prominent in the outer region of enamel and were proportional to the concentration of fluoride administered. Such changes following fluoride administration indicated inhibition of enamel maturation, i.e., an inhibition of the progressive depposition of minerals and/or in inhibition of organic matrix withdrawal by ameloblasts. Enamel seemed more affected by fluoride than dentine.

Animals↗