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PubMed1991

Histological changes in the nasal ventral conchae of piglets infected with Bordetella bronchiseptica.

Piglets infected intranasally with Bordetella bronchiseptica were injected with two fluorochrome markers. Transverse sections of undecalcified nasal conchae (cut between the third incisor and the third premolar teeth) were examined by microradiography and fluorescence microscopy; surface-stained sections were evaluated by light microscopy. The fluorescent surface of the nasal ventral conchae from the infected piglets was increased as compared with the controls. This was due to an increased amount of fluorescent mineralization fronts as well as to the presence of abnormal fluorescent areas within trabeculae. Trabecular mineral content of the microradiographs was irregular and varied from hypo- to hypermineralized. When compared with the corresponding surface-stained sections, no correlation could be made between the mineral content and the type of tissue. These findings suggest that an increased number of osteoblasts which secrete prebone matrix but are modified so that mineralization does not occur normally.

Animals↗

PubMed1991

In vivo study of fluoride chewing gum for the remineralization of human root lesions.

The purpose of this study was to study the efficacy of a fluoride-containing chewing gum (0.1 mg F/stick chewed 5 x/day) in the remineralization of artificial caries lesions in abraded root surfaces compared to sorbitol-containing chewing gum and a no gum control group in vivo. Root specimens were cut from human root surfaces and polished. The specimens were demineralized in a buffered lactate solution with low concentration of fluoride in order to preserve an intact surface layer. Six healthy subjects wore mandibular Hawley-type appliances containing up to fourteen slabs for each of one control and two experimental periods. The experimental protocol included chewing five pieces of gums per day and brushing with fluoride-free dentifrice for each 21 days period. All three regimens were analyzed for fluoride uptake and microradiography. The results indicate that fluoride-containing chewing gum has a highly significant fluoride uptake and remineralization compared to sorbitol gum and control regimens, suggesting that fluoride chewing gum may provide another vehicle for fluoride delivery.

Chewing Gum↗

PubMed1991

[Calcium fluoride or not? That is the question!].

The relative cariostatic effect of fluoride as fluorapatite, calcium fluoride-like material, loosely bound fluoride or KOH-soluble fluoride is debated. The present study was carried out to investigate this further in an intraoral caries model. Pair of premolars extracted for orthodontic reasons were used. Enamel from one tooth of each pair was used as controls (untreated). Two slabs were cut from the enamel of the other contralateral premolar. These slabs were treated with 2% NaF for 24 h. One slab was then treated with 1 mol/L KOH for 24 h to remove all loosely bound fluoride. The slabs treated with 2% NaF and then 1 mol/L KOH would contain the KOH-insoluble fluoride. Those treated with only 2% NaF would, in addition, contain KOH-soluble fluoride. Each slab, control, KOH-insoluble F and KOH-soluble and insoluble F, was mounted on different upper removable appliances. The slabs were covered with orthodontic banding material, allowing space for plaque accumulation. Five individuals wore the appliances in 3 separate 4-week periods. The slabs were analyzed by quantitative microradiography. The average mineral loss (delta Z) was 1680 +/- 1000 vol% z microns in the control teeth, 620 +/- 76 vol% . microns in the KOH-soluble and insoluble F teeth and 2167 +/- 1278 vol% . microns in the KOH-insoluble F teeth. The average lesion depths were 90 +/- 41 microns in the control teeth, 35.3 +/- 5.5 microns in the KOH-soluble F teeth and 88 +/- 35 microns in the KOH-insoluble F teeth. It was concluded that only KOH-soluble fluoride reduced mineral loss and lesion depths significantly compared with the untreated teeth.

Calcium Fluoride↗

PubMed1991

[Clinical and histological evaluation of implantation of a microporous resin in periodontitis. Report of a case after 13 months].

A patient with adult periodontitis was treated for a 2 and 3-walled intrabony lesion on tooth n degrees 27. After scaling and root planing, the defect was surgically exposed and filled with a micro-porous resin. Following healing, there was a reduction in pocket depth as a result of gingival recession and a gain in probing attachment levels. This was confirmed 13 months post-operatively by clinical observation on re-entry. A biopsy of the treated site was taken at that time and undecalcified sections were studied by light microscopy and microradiography. New bone formation was noted inside and on the surface of the resin granules and at a distance from the particles. From a clinical and histologic point of view, the material seemed to be well tolerated by the host.

Adult↗

PubMed1991

[Behavior of vascularization during hepatic regeneration].

In this work, out of 185 rats 120 underwent hepatectomy of 70%. Studies carried out by microradiography and Spalteholz transparence method prove that during the first days after hepatectomy the ratio hepatic parenchyma/vascular texture is increased; this fact comes to be maximal four days after, becoming stabilized toward ten days after. Studies done by Ibas I imaging analyzer in hepatic sections of rats which underwent hepatectomy as compared to those which underwent laparatomy only, show that ratio LCV-LCV, as well as areas and area form of hepatic sanguineous vessels are changing, in the first ones, in a rhythmical way including two phases of greater activity. These variations are evolved, in a different way, in the central zone than in the peripherical one of liver. We try to relate these facts to vascular and humoural theories which explain hepatic regeneration.

Animals↗

PubMed1990

Effect of two sodium fluoride dentifrices on fluoride uptake and remineralization in situ.

Two dentifrices containing 1100 ppm F from sodium fluoride in silica bases were compared to a placebo dentifrice in an in situ remineralization and fluoride uptake study. Fifteen subjects brushed artificially-formed caries lesions in 60 thin enamel sections and 30 enamel blocks with each dentifrice in a double-blind, randomized, cross-over study design. Analysis of the thin sections by quantitative microradiography before and after exposure to toothbrushing showed that the fluoride dentifrices produced 18.3% and 7.1% remineralization whereas use of the placebo resulted in 10.3% demineralization. The differences between all three dentifrices were statistically significant. Fluoride concentrations at the surface of the lesion increased from approximately 700 ppm F in untreated specimens to approximately 1800 ppm F in specimens treated with either of the two fluoride dentifrices. These data suggest that formulation differences may affect the anticaries activity of a dentifrice without being reflected by fluoride deposition.

Humans↗

PubMed1990

Features of the cerebral vascular pattern that predict vulnerability to perfusion or oxygenation deficiency: an anatomic study.

In an ongoing study of brain microvasculature in humans at autopsy, we had the opportunity to analyze the overall scheme of this vascular supply. The native endothelial membrane enzyme, alkaline phosphatase, is used to precipitate black lead sulfide salt in the vessel wall, rendering the brain microvasculature visible by both light microscopy and microradiography. There are six distinct patterns of intraparenchymal afferent blood supply to the supratentorial brain: short arterioles from a single source (e.g., those in the cortex); short- to intermediate-length arterioles, single source (anterior two-thirds of the corpus callosum); short- to intermediate length arterioles and arteries, dual source (subcortical U fibers); intermediate-length arterioles and arteries, triple source (extreme/external capsule and claustrum); long arteries and arterioles, single source (centrum semiovale); and large, long muscular arteries, single source (thalamus and basal ganglia). The nature of this arrangement offers some protection to certain regions of the cerebrum from circulatory challenges such as hypotension, while leaving other areas vulnerable. The distal arterioles supplying two of these protected regions, the U-fiber area and the extreme/external capsule and claustrum area, also exhibit the feature of interdigitation, which can offer additional collateral potential from one arteriolar territory to the next. Aging, hypertension, diabetes mellitus, and atherosclerosis can have a significant impact on brain microcirculation. The way in which vascular patterns dictate the distribution of these effects is discussed. The ability to stain the cerebral microvessels and demonstrate the finer points of their patterns in sections and microradiographs has enabled us to resolve some long-standing questions about vascular connections and directions.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1990

The effect of a single dose of 1-hydroxyethylidene-1, 1-bisphosphonate (HEBP) on secretory ameloblasts and enamel formation in rat incisors.

The present experiment was undertaken in order to study how HEBP affects secretory ameloblasts and the mineralizing front of rat incisor enamel resulting in the formation of a hypomineralized incremental band. Rats were given a single subcutaneous injection of 10 mg/kg body weight of HEBP and sacrificed at intervals ranging from 1 hour to 9 days. The incisors were specially prepared for microradiography, scanning electron microscopy, and light and transmission electron microscopy. The microradiographical examination 9 days after injection revealed a distinct incremental band of hypomineralization from the amelo-dentinal junction to the outer enamel surface. The overall rod pattern and mineral distribution within the enamel was otherwise normal. Under light microscopy the ameloblasts exhibited an increase in vacuoles and dark granules in the supranuclear cytoplasm 2-12 hours after injection. At 12 hours a total disarray of the mineralizing front was evident and confirmed by SEM. However, 24 hours after injection a normal structure of the mineralizing front was regained. Ultrastructurally the organelles of the ameloblasts showed no changes from normal at any time interval. However, 2 hours after injection multivesicular bodies appeared frequently in the Tomes' processes and crystal density had diminished in the interrod enamel. At 8 hours a proteinaceous matrixdevoid of crystals was accumulating corresponding to interrod growth regions, whereas no obvious changes were recorded at the rod growth regions. At 12 hours the newly formed interrod enamel was thin and without crystals in some places. In such areas a granular, less-dense matrix was found and a band of small swellings of the interrod enamel was evident most likely corresponding to the time of injection. After 24 hours the cells and the mineralizing front appeared normal except in the interrod growth regions where the cell processes were still separated by wide intercellular spaces in which crystals were occasionally found in a fine granular matrix. These observations are discussed with particular reference on the known physico-chemical effects of HEBP on mineral formation. A possible direct cellular effect on the ameloblasts should be studied using radioautography and immunocytological techniques.

Ameloblasts↗

PubMed1990

[Experimental study on the healing processes after the immediate reconstruction of maxillary bone defect--fresh autogenous iliac bone graft].

This study was designed to investigate the healing processes of fresh autogenous bone grafted from iliac to maxillary bone defect, which was an artificial oro-antro fistula and covered with submucosal flap made by ckeek mucosa. The experiments were carried out in vivo on adult mongrel dogs ranging 7,14,30,90,180 and 360 days postoperatively. Radiographic and histological investigations were made to evaluate details, further study has made by means of X-ray contact microradiography (CMR), tetracycline (TC) labeling and angiographic images. Results 1. Radiographic findings, the grafted bone remained unchanged until 14 days postoperatively. The bone bridge formation between host and grafted bone was completed after 30 days in all of the cases. Bone resorption can be observed at 90 days postoperatively, which were as much as one second or one third of grafted. But thereafter there were no changes on the grafting bone area, that is to say, bone resorption ceased and stabilised. 2. Histological findings, inflammatory changes can be mainly observed at the early postoperative stages. And osteoclasts and new bone formation can be observed along the host bone. On 14th postoperative day, all of the grafted bone cells turned to necrosis. Osteoclasts and the new bone formation were observed in that area. 30th postoperative day, new bone formation made connector between host and grafted bone area. And medullary cavity of the grafted bone was filled with fibrous connective tissue, new bone formation and bone resorption occurred at the same spot. On 90th day old grafted bone was scattered like an island among new bones. In 180 days, grafted area was nearly normal maxilla. 3. 7th postoperative day, inflammatory changes can be mainly observed on the mucosal bed of the grafted bone, those diminished in 14 days. It was completely changed to dense fibrous connective tissue. 4. Angiographic images, vascularization to medullary cavity of the grafted bone started on 7 days. In 14 days, vascularization filled about half of the grafted bone. Vascularization was also observed a little in cortical bone. It was completed throughout the entire grafted bone in 30 days and it connected with the host bone. In 180 days, the grafting bone was nearly normal angiographic image. 5. Contact microradiogram, the new bone formation was partially observed in the host bone in 7 days. In 14 days, the bone bridges formation started. It was almost completed in 30 days after transplantation. In 180 days, it was entirely completed. 6. Tetracycline labeling, the host bone was labelled weakly in the early postoperative stages.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1990

[Markers of osteoporosis in clinical practice].

For the assessment of the degree of osteoporosis progression of use are, besides biochemical and histological investigations, also photodensitometry, microradiography and radiological examinations. The last of them are easily available and cheap and they are recommended for screening examinations. Using the cortico-diaphyseal index determined by an own method and the Singh index it was found that atrophy of the spongy bone is not parallel in conditions regarded as pathological. The simultaneous use of both indices makes possible an easy, simple and rapid assessment of the degree of bone atrophy providing a possibility of introducing prophylactic and therapeutic management.

Adult↗

PubMed1990

Preliminary studies of mineralization during distraction osteogenesis.

Distraction osteogenesis by the Ilizarov method was performed on 20 dogs. Mineralization at the site of the left tibial metaphyseal lengthening was measured by weekly quantitative computer tomography (QCT) using the contralateral tibia as a control. Four dogs each were killed on Days 7, 14, 21, and 28 of distraction in order to correlate QCT with microradiology, nondecalcified histology, quantitative calcium analysis, and scanning electron microscopy. It was consistently found that intramembranous ossification proceeded centripetally from each corticotomy surface toward the central fibrous interzone. Bone columns crystallized along longitudinally oriented collagen bundles, expanding circumferentially to surrounding bundles. As the distraction gap increased, the bone columns increased in length and in diameter, while the fibrous interzone remained about 4 mm long. Histologically, the bone columns resembled stalagmites and stalactites, as seen by microradiography and scanning electron microscopy, that projected from each corticotomy surface toward the center. These cones reached maximum diameters of 150-200 mu at the corticotomy surfaces. Radiodensity (QCT) increased gradually from the central fibrous interzone toward each corticotomy surface. Mineral density, as determined by calcium quantification, reflected the microscopic geometry and radiographic polarity.

Animals↗

PubMed1978

Tibial dyschondroplasia (osteochondrosis) in the turkey. A morphologic investigation.

Sixty-seven Broadbreasted White Turkeys, 4 to 137 days old, were included in the investigation. Some were normal, while others were limping, and some had bowed legs. Immediately after destruction of the birds, the arteries of the legs were injected with Colorpaque, using a technique introduced by the author. The proximal part of one or both tibiae were examined radiographically, macroscopically, and microscopically. The microscopic examination included histology, microangiography, and microradiography. The normal development and morphology of the proximal tibia is presented. Thereafter an account is given of development and morphology of the tibia with dyschondroplastic lesions (retained cartilages). It was found that 39 of the 67 birds had some degree of tibial dyschondroplasia. The retained cartilage was seen in the posteromedial part of the proximal tibial metaphysis. The growth plate both of the normal and abnormal birds consisted of 3 layers of cells in order from the epiphysis--the one of proliferating cells, the one of transitional cells, and the one of hypertrophied cells. A main feature in tibial dyschondroplasia is accumulation of transitional cells, which do not have a vascular supply. By microangiographic means it was possible to demonstrate that the retained cartilage is surrounded by numerous vessels, which apparently cannot get into the cartilage. The reason for the loss of normal differentiation of the cartilage cells and concomitant disturbance of the endochondral ossification is obscure. It is speculated that changes on an ultrastructural and biochemical level are responsible for the pathologic condition. When the retained cartilage reaches a certain size, degenerative changes, necrosis, and fissures occur. Complete healing of the lesion was not seen in any of the birds, but partial disappearance of the proximal or distal part of the retained cartilage took place in some birds. It was concluded that the present investigation has shed light on the development and morphology of tibial dyschondroplasia, but it has also brought forward a number of questions about etiology. There seems to be good reason to believe that dyschondroplasia in the turkey is of similar nature as dyschondroplasia in broilers and osteochondrosis in domestic mammals.

Animals↗

PubMed1990

Backscattered electron imaging of partially-demineralized enamel.

Backscattered electron (BE) microscopy is being used increasingly as a technique to study the dissolution of dental enamel because of its high resolution and relatively easy sample preparation. Subsurface details such as striae of Retzius, cross-striations and prism microstructure have been observed with a resolution better than 0.1 micrometers using this technique. Since BE images of demineralized enamel appear very similar to microradiography images, it is tempting to interpret them in a similar fashion. We attempt to show that the interpretation of BE images is not straightforward because enamel is not a homogeneous one-phase material, but a two-component composite material consisting of variable amounts of apatite mineral and organic matter. During re- and demineralization, other calcium phosphate phases may precipitate to further complicate the interpretation of the images. BE images of partially demineralized enamel are affected by local variations in the protein/mineral ratio and also by the reprecipitation of other calcium phosphate phases. BE images are not mineral density maps, but are mean atomic number maps.

Dental Enamel↗

PubMed1990

[New bone formation following implantation of various hydroxyapatite ceramics. Animal experiment with bore hole models of the sheep tibia].

The aim of this study was to measure new bone formation after implantation of hydroxylapatite ceramic materials compared with autogenous and allogenous cancellous bone implantations. Eight standardised bore holes, each 6 mm in diameter, were drilled in the left medial tibia of each of seven merino sheep. Seven of these holes were filled with hydroxylapatite ceramic materials: Bio-Oss, Pyrost, autogenous and deep frozen allogenous spongiosa in various sequences. The empty hole was used for comparison. Results were evaluated after fluorescent marking with calcein green 6 weeks postoperatively. The extent of new bone formation was determined by means of fluorescence microscopy, microradiography and histological sections and quantified by means of an automatic surface-measuring programme. Whilst implantation of autogenous spongiosa resulted in almost complete slicing of the defect, the holes filled with hydroxylapatite ceramic materials showed no significant difference from the empty defect. We conclude that this purely inorganic material cannot stimulate new bone formation.

Animals↗

PubMed1990

Scanning and transmission electron microscopy, and electron probe analysis of the interface between implants and host bone. Osseo-coalescence versus osseo-integration.

Bioinert materials (e.g., alumina implants) and bioactive ceramics (e.g., calcium phosphate ceramics, glass-ceramics) are now extensively used in dentistry. However, the physico-chemical interactions at the interfaces between the implant and the host bone are poorly understood. The purpose of this study was to define the interactions at these interfaces using a combination of analytical techniques: light microscopy, scanning and transmission electron microscopy, electron probe microanalysis, X-ray microradiography, X-ray diffraction, and infrared spectroscopy. Bioinert (pure titanium) and bioactive materials (hydroxyapatite, beta-tricalcium phosphate and biphasic calcium phosphate) were implanted in dogs, and the implants, recovered after various periods of implantation, were analyzed. The results demonstrated the following: the bioactive materials interact with the biological fluid and the living tissues in a specific manner. This process includes biodissolution/biodegradation, apatite crystal precipitation, and bone formation on the implant surface at the expense of the material. The results are discussed according to the limitations of the analytical techniques used. The medical and chemical word coalescence is suggested to describe the specific interactions of bioactive materials and interaction for the phenomenon of physical contact of the bioinert materials with the host bone.

Animals↗

PubMed1989

[Ultrastructural changes induced in rat ameloblasts and enamel by NaF administration, especially the stages of transition and maturation].

Single subcutaneous injections of sodium fluoride (84 mg/kg NaF) were administered to male Wistar rats weighing 100 g each. After 6, 12, and 24 hours and then after 2 and 5 days, the animals were fixed by perfusion with a mixture of 2.5% glutaraldehyde and 2.0% paraformaldehyde; and their upper incisors were subjected to optical microscopy, microradiography, and electron microscopy. 1. Changes in ameloblasts in the matrix-formation stage: Large vacuoles and dark globules, which frequently appeared to be stacked within the cell, could be seen in the distal one-third of the ameloblast 6 hours after NaF injection. These globules and vacuoles disappeared 24 hours after injection. Distortion of the Tomes' processes and separation of the ameloblasts from the enamel surface too could be seen. The separated areas gradually expanded to form cystic cavities, which developed toward the end of the formation stage of amelogenesis. But these cavities never extended to ameloblasts in the transitional stage. 2. Changes in ameloblasts in the transitional stage: Transitional ameloblasts may be divided into 2 stages: the early transitional stage, during which the proximal portion of the Tomes' process persists, and the late transitional stage, during which all trace of the Tomes' process has disappeared and a basement membrane-like structure has been produced. The appearances of ameloblasts in these two stages altered after NaF injection. In the early transitional stage, 6 hours after the injection, large vacuoles and dark globules appeared in the distal portion of the cell. Similar to vacuoles appearing during the matrix-formation stage, these vacuoles and globules disappeared 24 hours after injection. Traces of the Tomes' process, however, persisted and assumed an irregular, wavy form. The adjacent enamel adapted to and interdigitated with the cel surfaces without a structure resembling the basement membrane. NaF injection caused slight changes in the late transitional stage: small vacuoles appeared at the distal ends of the cell and disappeared 24 hours later. 3. Changes in the ameloblasts in the enamel-maturation stage: Six hours after the injection, small vacuoles appeared at the distal portion of the cell close to the striated border which was poorly developed. These vacuoles disappeared, and the striated border resumed its usual features 24 hours after the injection. 4. Changes in the enamel: In the forming enamel, a calciotraumatic line consisting of hypermineralized and hypomineralized layers could be seen. Another hypermineralized line appeared at the enamel surface adjacent to the transitional stage. Electron microscopy showed that this hypermineralized layer consisted of crowded, disoriented, needle-shaped crystals.

Ameloblasts↗

PubMed1989

[Experimental studies of healing process on compound blocks of hydroxyapatite (HAP) particles and tricalcium phosphate (TCP) powder implantation in rabbit mandible--comparison of HAP/TCP ratios and plastic methods].

Bone substitutes consisting in 2 mold-poured compound blocks of HAP:TCP (mixing ratio 1:1) and HAP:TCP (mixing ratio 3:1) and one compound block (mixing ratio 1:1) prepared in a rubber press were implanted in defective areas in rabbit mandibles. The conditions under which the implants were made were identical in all cases. Histological studies and contact microradiography performed on ossification of the surfaces and surroundings of each block, ossification maturation, and the absorptive process of TCP and the extent to which it was replaced by new bone produced the following results. 1. At one week after surgery, new bone had grown along the surfaces of the blocks. It remained in tight contact with the block surfaces as it matured. These findings make it clear that the blocks are superior in terms of biocompatibility and osteoconduction. 2. In the course of time, in the 2 mold-poured compound blocks, the hydrated parts of alpha-TCP, which was a binder, were absorbed and replaced by new bone. At forty eight weeks after surgery, new bone had grown into the pores of the HAP particles to form a bone-HAP composite. 3. Even as late as forty eight weeks after surgery, some of the hydrated parts of alpha-TCP remained unabsorbed; and mold-poured compound blocks (mixing ratio 1:1) retained their shapes. On the other hand, in the mold-poured compound blocks (mixing ratio 3:1), the hydrated parts of alpha-TCP were almost absorbed and replaced by new bone in forty eight weeks after surgery. Amounts of the binder alpha-TCP present appeared to cause differences in biological reactions. 4. In the case of compound blocks of HAP:TCP (mixing ratio 1:1) formed in a rubber press, the binder was beta-TCP. Because of its high sintering properties and great density, absorption and ossification were gradual; and the blocks retained their complete original forms even in forty eight weeks after surgery. 5. Past reports have claimed that beta-TCP is absorbed in the initial stage. But, as is clear from experiments with compound blocks formed by means of a rubber press, even when the binder is beta-TCP in all cases, absorption speed differs depending on the mold used. 6. These results indicate that compound blocks of HAP and TCP used as artificial substitute bone materials have excellent properties of biocompatibility, osteoconduction, and plasticity. In addition, however, they make it clear that, owing to differences in absorption of the binder, ossification speed, and dynamic properties from block to block, it is essential to use the mold that properly suits conditions prevailing in the defective area.

Animals↗

PubMed1989

Simulation of natural enamel caries in vitro with methylcellulose acid gels: effect of addition of calcium and phosphate ions.

A modified acid gel technique for producing caries-like lesions in dental enamel has been developed. The decalcifying medium consists of a 10% (w/v) methylcellulose gel acidified with 0.1 M lactic acid-sodium lactate at pH 4.5 and having a hydroxyapatite content of 0.05% (w/v). This medium can produce caries-like lesions in vitro at a slow rate, which are indistinguishable from natural enamel caries when examined by polarised light microscopy and contact microradiography.

Adolescent↗