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At least 487 records · Page 27Linked to original sources
PubMed2000

Effect of acid-etching on remineralization of enamel white spot lesions.

This in vitro study aimed at investigating whether full remineralization would occur in white spot lesions when the surface porosity was increased by acid-etching. The effect of fluoride was also investigated. Enamel blocks with in vitro produced white spot lesions were used. Group A was exposed to a remineralizing solution only. In group B, the lesions were etched with 35% phosphoric acid for 30 s, then treated as in group A. Group C was treated as group A + daily treatment with a fluoride toothpaste slurry (1,000 ppm) for 5 min. Group D was treated as group B + the daily fluoride treatment of group C. The remineralization was measured weekly with Quantitative Light-induced Fluorescence during the experimental period. After 10 weeks of remineralization, mineral profiles were assessed with transverse microradiography. The enamel fluorescence was partly regained. There were significant differences in the lesion depth, mineral content at the surface layer, and integrated mineral loss between the groups. Addition of fluoride accelerated the remineralization only in the beginning; in later stages the process leveled out and even reached a plateau in all the groups. It was concluded that full remineralization was not achieved by etching, by the addition of fluoride, nor by the combination of both treatments in this in vitro study.

Acid Etching, Dental↗
PubMed2004

In vitro quantification of white spot enamel lesions adjacent to fixed orthodontic appliances using quantitative light-induced fluorescence and DIAGNOdent.

The aims of this in vitro study were 2-fold: 1) to evaluate two fluorescence methods (DIAGNOdent and QLF (quantitative light-induced fluorescence)) for quantification of white spot lesions adjacent to fixed orthodontic appliances; and 2) to determine the inter-observer agreement of the DIAGNOdent and QLF methods for quantification of incipient enamel lesions adjacent to fixed orthodontic appliances. Forty-one premolar teeth with visually sound smooth surfaces or visually white spot enamel lesions were included in the study. Orthodontic brackets were fixed adjacent to the lesions, thus simulating the position of fixed appliances during orthodontic treatment. All teeth were measured using both the DIAGNOdent and QLF methods. Of the 41 teeth, 20 smooth surfaces were randomly selected and analyzed by 4 operators using both DIAGNOdent and QLF. The teeth were sectioned into 300-microm-thick slices using a water-cooled diamond saw and the slices manually ground to 80-100 microm thickness. Histopathology and transverse microradiography were performed to provide the gold standards for verification of lesion depth and mineral loss, respectively. The Spearman rank correlation coefficients between lesion depth determined by histopathology and the DIAGNOdent and QLF were 0.76 and 0.82, respectively, whereas the Pearson correlation coefficients between mineral loss and the two methods were 0.64 and 0.84, respectively. Inter-observer agreement was found to be 0.80 and 0.93 for DIAGNOdent and QLF, respectively. In conclusion, QLF may be a suitable method for quantifying incipient carious lesions adjacent to fixed orthodontic appliances.

Bicuspid↗
PubMedDate not supplied

A microradiographic study of nephrons in mercuric chloride-induced acute renal failure in the rabbit.

Microradiography of nephrons was performed on glutaraldehyde-perfusion-fixed kidneys from rabbits injected with mercuric chloride. Kidneys were studied at intervals after injection of the toxin and compared with controls. All mercury-injected animals developed acute renal failure, determined by a rise in serum creatinine. At 6 hours, small filling defects were seen in proximal straight tubules, arising from the wall, and by 24 hours, widespread tubular obstruction was noted. By 12 hours, dilatation of Bowman's space and compression of the glomerular tuft were seen. At 18 hours, preferential channels in the glomerular capillary loops were found, and by 24 hours, there was paraglomerular shunting. No changes were noted in afferent or efferent arterioles. These findings may be related to the decreased glomerular filtration rate seen in acute nephrotoxic renal failure and suggest a role for tubular obstruction in the pathophysiology of this disorder.

Acute Kidney Injury↗
PubMed1991

The healing of facial bone fractures by the process of secondary union.

The mechanism of healing of facial bone fractures was investigated in a rabbit model. Twelve New Zealand white rabbits underwent surgically induced fractures of the right infraorbital rim and fracture ostectomies (4 to 5 mm) of the left infraorbital rim. Animals were sacrificed 2, 4, and 8 weeks postfracture. Bone, including periosteum, obtained from each fracture or fracture osteoctomy site was divided longitudinally for hematoxylin and eosin staining, fluorescent microscopy, microangiography, and microradiography. Sequential fluorochrome labels of oxytetracycline (30 mg/kg), alizarin complexone (30 mg/kg), DCAF (20 mg/kg), and xylenol orange (90 mg/kg) were administered 24 hours preoperatively and at 1, 2, 4, and 8 weeks postfracture. All fracture and fracture ostectomy sites demonstrated vascular ingrowth, mineralization, and woven bone formation by 2 to 4 weeks postoperatively, beginning with a cartilage precursor. Subsequently, the woven bone was replaced with remodeled lamellar bone, resulting in complete bony healing by 8 weeks postoperatively. These steps were substantiated by microscopic, microradiographic, and radiologic examination of the specimens. This study demonstrates that fractures of the facial bones in a rabbit model heal by a process of new bone formation that resembles secondary union in endochondral bones.

Animals↗
PubMed1995

Tricalcium phosphate and osteogenin: a bioactive onlay bone graft substitute.

The disadvantages of autogenous bone grafts has prompted a search for a dependable onlay bone graft substitute. A combination of tricalcium phosphate, a resorbable ceramic, and osteogenin, an osteoinductive protein, was evaluated as an onlay bone graft substitute in a rabbit calvarial model. Twenty-eight tricalcium phosphate implants (15 mm diameter x 5 mm; pore size, 100-200 microns) were divided into experimental and control groups and placed on the frontal bone of 14 adult New Zealand White rabbits. In the experimental animals, 185 micrograms of osteogenin was added to each implant. In the control animals, the implants were placed untreated. Implants were harvested at intervals of 1, 3, and 6 months, and evaluated using hematoxylin and eosin histology, microradiography, and histomorphometric scanning electron microscope backscatter image analysis. At 1 month there was minimal bone ingrowth and little tricalcium phosphate resorption in both the osteogenin-treated and control implants. At 3 months, both the osteogenin-treated and control implants showed a modest increase in bone ingrowth (8.85 percent versus 5.87 percent) and decrease in tricalcium phosphate (32.86 percent versus 37.08 percent). At 6 months, however, the osteogenin-treated implants showed a statistically significant increase in bone ingrowth (22.33 percent versus 6.96 percent; p = 0.000) and decrease in tricalcium phosphate (27.25 percent versus 37.80 percent; p = 0.004) compared with the control implants. The bone within the control implants was mostly woven at 6 months, whereas the osteogenin-treated implants contained predominantly mature lamellar bone with well-differentiated marrow. All implants maintained their original volume at each time interval studied. The tricalcium phosphate/osteogenin composite, having the advantage of maintaining its volume and being replaced by new bone as the tricalcium phosphate resorbs, may be applicable clinically as an onlay bone graft substitute.

Animals↗
PubMed2004

Orbital floor reconstruction using calcium phosphate cement paste: an animal study.

Orbital floor defects were created in 10 New Zealand white rabbits and were reconstructed using an injectable calcium phosphate paste. These animals were euthanized at 2, 4, 8, and 12 months after implantation and were examined for biocompatibility and osteoconductivity. Grossly, implants were found to be adherent to the floor and covered with fibrous tissues. There was no sign of infection, extrusion, or migration of implant within the orbit and maxilla. The orbital floor was completely restored. Histological examination showed active new bone formation that encroached within the implant and gradually increased in density with time. Maxillary mucosa and glands were likewise reconstituted. Thin fibrovascular tissues were seen on top of and within the surface of the implant, and few to slight inflammatory cells were seen. Microradiography showed direct apposition between the new bone and the implant. These findings compare favorably with previously published reports on the biocompatibility and osteoconductivity of calcium phosphate cement. The authors believe that, together with ease of use and structural integrity, calcium phosphate paste can be useful in orbital floor reconstruction.

Animals↗
PubMed2005

Characterization of a new rat model of experimental combined neurotrauma.

Traumatic brain injury (TBI) is present in two-thirds of patients with multiple injuries and in one-third combined with injuries of the extremities. Studies on interactive effects between central and peripheral injuries are scarce due to the absence of clinically relevant models. To meet the demand for "more-hit" models, an experimental model of combined neurotrauma (CNT) incorporating a standardized TBI via lateral fluid percussion (LFP) together with a peripheral bone fracture, i.e., tibia fracture, is introduced. Sprague-Dawley rats were randomized to four experimental groups: controls (n = 10), animals with TBI (n = 30), animals with tibia fracture (n = 30), and animals with CNT (n = 30). Morphological aspects of brain and bone injury were analyzed via standard histopathological procedures and x-ray. Trauma-induced neuromotor dysfunction was assessed using a standardized neuroscore. For interactive effects between injuries, we studied the extent and temporal pattern of circulating interleukin 6 (IL-6) levels via immunoassay and callus formation at fracture sites by means of microradiography. LFP produced an ipsilateral lesion with cortical contusion, hemorrhage, mass shift, and neuronal cell loss (adjacent cortex and hippocampus CA-2/-3), along with contralateral neuromotor dysfunction. X-rays confirmed complete fractures in the middle of the bone shaft. The type of injury (P < 0.001) and time (P = 0.022) were significantly associated with increased IL-6 levels. CNT produced the highest IL-6 plasma levels with a maximum peak at 6 h after trauma (P < 0.001). Similarly, callus formation at fracture sites in CNT was significantly increased versus fracture only (P < 0,01). The CNT model mimics a variety of clinically relevant features known from human multiple injury, including TBI, and offers novel approaches for investigation of interactive mechanisms and therapeutic approaches.

Animals↗
PubMed2003

Multiple microscopy modalities applied to a sea urchin tooth fragment.

Two synchrotron X-ray microscopy methods, phase-contrast microradiography (the propagation method) and absorption microCT (high-resolution computed tomography or microtomography), and laser-scanning confocal microscopy (visible wavelength) were used to study a fragment of the keel of a tooth of the sea urchin Lytechinus variegatus. Stripes observed in the phase-contrast images of the fragment were also seen in confocal micrographs. MicroCT showed that the stripes were due to two parallel planar arrays of low-absorption channels within the bulk of the keel. In the phase microradiographs, maximum contrast stripes appear when a channel image from one row coincides with a channel image from the second row; otherwise, contrast is minimal. Long channels do not appear to have been observed previously in keels of sea urchin teeth.

Animals↗
PubMed1985

Developments in contact X-ray microscopy in biomedical research.

Contact X-ray microscopy (microradiography) is a method of studying the microstructure of biological tissue. These techniques have been used to study the historadiological details of human breast tissue and sections of human ear ossicles. X-ray microscopy can also be used to demonstrate variations in structural densities seen in histological specimens including the detection of microcalcification. A modification of existing apparatus is described which has resulted in improved image-contrast and detail. The ability of X-rays to penetrate relatively thick sections of tissue makes it an ideal method for studying the morphology of biological structures, particularly in calcified tissue. The tissues may be further examined by conventional histology, elemental analysis, etc. The technique has a complementary role to alternative methods of tissue microscopy.

Breast↗
PubMed1980

The in vitro effect of a glass ionomer cement on dentine and enamel walls. An electron probe and microradiographic study.

Glass ionomer cement (ASPA) was inserted in unconditioned class V cavities or in contact with polished ground surfaces of enamel and dentine in twelve teeth. Ground sections of all teeth were examined by microradiography, and four of the sections submitted to electron probe microanalysis. A narrow outer zone of increased radiopacity in the dentine walls was explained by a 5--10% increase of Ca and P. In some sections this zone covered a partly demineralized subsurface zone. The concentrations of F and Al in enamel and dentine were similar to or approximately 0.3% and 1.5%, respectively, decreasing to less than 0.1% at a distance of 16--80 microns (F) and 8--24 microns (A) from the surface. Both F and Al penetrated deeper into the dentine than into the enamel. Decreased Zn values, sometimes concomitant with increased Ca, P and Mg values, were in some instances observed in an outer narrow zone of the dentine walls. It is assumed that like silicate cement, glass ionomer cement must have anticariogenic properties, due to uptake of F and Al in cavity walls.

Calcium↗
PubMed1994

Segmental trends in cancellous bone structure in the thoracolumbar spine: histological and radiological comparisons.

Segmental variations in vertebral body cancellous bone architecture throughout the thoracolumbar spine were examined using histomorphometry and microradiography, and compared to bone mass measured using dual energy X-ray absorptiometry. In six human vertebral columns (T1 to L5) bone mineral content (BMC) and bone mineral density (BMD) of each vertebral body was determined in the lateral projection. Sagittal plane cancellous bone architecture was assessed from two-dimensional surface stained images and microradiographs of two 1 mm thick sections at each vertebral level. Computer-assisted image analysis was used to measure the total bone area (TBA), mean trabecular width (MTW) and trabecular number (TbN) from the stained images, and the skeletonized network length (SNL) from the radiographic images. Consistent segmental trends were observed for all structural parameters across the six columns examined. Higher TBA and TbN values were observed in the upper thoracic segments and decreased caudally. The MTW was relatively constant in the thoracic vertebrae before increasing in the lumbar spine. Pooled correlations between TBA and the bone density measurements were poor (BMC: r = 0.17, BMD: r = 0.25), while the TBA and SNL were only moderately correlated (r = 0.42). In conclusion, histomorphometric and radiological measurements appear to provide different information about cancellous bone structure. Bone structure is poorly correlated to integral measurements of bone mass. The consistent segmental variations in bone architecture appear to reflect a skeletal response to the relative extent of habitually applied loads in different regions of the spine.

Absorptiometry, Photon↗
PubMed1988

X-ray microscopy of the prostate gland.

A technique is described for investigating the internal structure of the prostate gland (including calcification) by projection X-ray microscopy (microradiography). The results show that the technique can be used in conjunction with the corresponding histological preparations to complement the examination of the prostate gland by demonstrating tissue density and the structure and location of microcalcification less than 5 microns in diameter.

Humans↗
PubMed1990

Origin and structure of benign prostatic hyperplasia.

The development of microradiography of the prostate gland has provided a new approach to investigating the origin and structure of benign hyperplasia. It has demonstrated that benign prostatic hyperplasia is usually microadenomatous in structure, although reticular types do occur. It originates at the lateral boundary of the periurethral muscle in the position of the transitional zone. In contrast, stromal nodules are homogeneous and amorphous in structure and develop at the site of the short straight urethral ducts within the periurethral muscle.

Adolescent↗
PubMedDate not supplied

The radiographic and histologic appearance of controlled surgical manipulation of the equine periosteum.

This study documented the normal histologic features of the equine metacarpal and metatarsal periosteum and characterized its osteogenic response to surgical manipulation. Two periosteal flaps were elevated from the dorsomedial matacarpal and metatarsal diaphysis in each of three limbs of four yearling and four adult lightbreed horses. The superficial metacarpal cortex under the flap was resected with a bone chisel in one-half of the horses and was undisturbed in the remainder. One periosteal flap in each limb was excised and the other flap was replaced and secured by sutures. All limbs in the horses were radiographed at regular intervals postoperatively. Horses were killed either 30 or 120 days after surgery. Periosteal bone production occurred only at treatment sites of young horses treated by periosteal flap replacement and was limited to approximately 50% of these sites, as determined by radiography and microradiography. Cortical abrasion resulted in an increased incidence of bone production in the periosteum adjacent to the flap perimeter. The histologic features of the periosteum were similar to those reported in other species; young horses had active osteogenesis referable to appositional growth and adults had an inactive periosteum. Histologically, osteogenesis induced by surgery resembled accentuated appositional growth in both yearlings and adults. In the horse, the cambial (osteogenic) layer is included in sharply elevated periosteal flaps. It should be removed in surgical procedures where bone production is to be avoided, and preserved where osteogenesis is desired.

Animals↗
PubMed1975

Morphology of salivary calculi. The distribution of the inorganic component.

Different hypotheses concerning the pathogenesis of salivary calculi have been postulated on the basis of their morphology. In the present study, microradiography of plane-polished ground sections of a number of salivary calculi has shown that the morphology of salivary calculi varies considerably. The commonly accepted concept that salivary calculi emanate from an inorganic nucleus, which then successively grows by the apposition of alternating shells of organic and inorganic substances, could not be established by this study, as the microradiographs show that the distribution of mineral elements varied extensively from one calculus to another. Thus, whereas some calculi exhibited a lamellar structure, others consisted largely of homogeneous, irregular layers of alternatively high and low mineral content. The lamellar structure also showed great variation, extending in some cases over the entire diameter of the calculus. Some calculi lacked the lamination in their peripheral parts whereas, in others, lamination occurred only in the most peripheral zone. The structure of the central portions also showed a varied configuration. The calculi were often built up around one or more mineralized nuclei, often centrally located, while in some cases a mineralized nucleus was lacking. This report discusses some of the significant factors in the great variation in morphological features and therefore also in the pathogenesis of salivary calculi.

Humans↗
PubMed1983

The detection and prevalence of reactive and physiologic sclerotic dentin, reparative dentin and dead tracts beneath various types of dental lesions according to tooth surface and age.

The pulpo-dentinal complex responds to external injuries with dentin sclerosis (DS), dead tracts (DT), or reparative dentin (RD). This investigation correlates the prevalence of these responses with age, sex, type and surface location of tooth lesions (caries, restorations, attrition, abrasion and erosion) utilizing ground sections, microradiographs and decalcified paraffin-embedded tooth sections treated with the Pollak trichrome stains (270 teeth from 113 patients). The main response to caries, restorations and erosion was DS, followed by RD and DT. DS, RD and DT occurred equally in any tooth, on any tooth surface and even beneath the same lesion. DS did not necessarily prevent RD. Root and furcation DS and RD in the floor of the pulp chamber and root canals were unrelated to particular lesions but did relate to increasing age. Root DS extended from apical to cervical area with increasing age. Beneath caries and restorations DS and RD were more prevalent in males, but DT was more prevalent in females. Pollak staining of decalcified paraffin sections for DS was approximately 80% as accurate as ground sections and microradiography. In pulp studies, where the result is contrary to previous experience, the Pollak stains reveal whether DS has decreased dentin permeability.

Adolescent↗
PubMed1985

The black layer on the teeth of betel chewers: a light microscopic, microradiographic and electronmicroscopic study.

Ten teeth of betel chewing P'wo Karen, a hilltribe group of northern Thailand, were available for this morphologic study. The structural composition of the black layer on these teeth was studied by light microscopy, microradiography and by electronmicroscopy. Principally, the black layer on the teeth of betel chewers was identical with subgingival calculus which had been colored by specific polyphenols contained in the betel nut. However, a pellicle-like layer forming initially on enamel crystals was also observed. From the morphologic aspect of the black layer a specific anticariogenic property cannot be attested. Further studies on the chemical composition of this black layer may elucidate its probable anticariogenic and its carcinogenic properties relative to oral submucous fibrosis.

Areca↗
PubMed1988

Local infusion of prostaglandin E1 stimulates mandibular bone formation in vivo.

The maintenance of alveolar bone is a major clinical objective in dentistry. This is particularly difficult following such local inflammatory episodes as those of periodontitis or the loss of dentition (residual ridge resorption). We present evidence from beagle dogs that local infusion of prostaglandin E1 (PGE) for 3 weeks at doses of 500 to 2000 micrograms per week produces a dramatic, localized formation of alveolar bone in the mandible which exhibits a normal lamellar architecture and mineralization pattern when evaluated by fluorescence microscopy and microradiography. Whether this newly formed bone becomes functionally integrated into the skeleton and can replace bone lost from surgical resections or trauma remains to be established. Nevertheless, these data indicate that predictable local osteogenesis may eventually be produced by infusions of PGE.

Alprostadil↗