ELECTRON OPTICAL AND X-RAY DIFFRACTION STUDIES OF THE ORGANIZATION OF THE INORGANIC CRYSTALS IN EMBRYONIC BOVINE ENAMEL.
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Animals↗
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Results for “Decalcification Technique”
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[Rational simplified plastic embedding with polymethacrylate for non-decalcified bone sections].
A exact judgment of bone and bone marrow tissue is based on an undecalcified treatment technique by means of plastics embedding and hard section microtomy. All hitherto existing routine techniques of plastics embedding of bone tissue used monomeres of methakrylate with addition of so-called emollient substances for polymerisation. Disadvantages of a stronger shrinking of the polymerisation product and uncontrolled, not always avoidable accelerations of the polymerisation process which have an essentially negative influence on the histological results should thus be avoided. A very exact observance of the treatment steps is here necessary. In the further development of our embedding method we turned to the polymethacrylates. The polymerisation adhesive Kalloplast R used in industry proved as the most suitable initial substance for the new method. The yielded results lie in a considerable shortening and further simplification of the embedding technique. The results are always well reproducible. Undesirable shrinking or polymerisation artefacts with impairment of the histological results do no more appear.
Bone and Bones↗
Normal histology of the nasal cavity and application of special techniques.
There are three major epithelial types in the nasal mucosa, in addition to numerous accessory structures, some of which are species specific. Without careful and consistent processing of the nose tissue, histopathologic assessment of lesions in the nasal cavity may be compromised. While formalin fixation may be used for routine review of the nasal cavity, Bouin's fixation provides better histologic detail and fewer artifacts. Decalcification is not recommended for nasal tissues to be examined by transmission electron microscopy because of the detrimental effect of decalcifying solutions on sensory cells. Three levels of the nasal cavity may be used for routine histologic review of the nasal cavity, but four or five levels may be more appropriate for certain studies.
Acetates↗
Comparative SEM study on the effect of different demineralization methods with tetracycline HCl on healthy root surfaces.
Periodontal regeneration through the use of root demineralization received a lot of interest in periodontology. Topical application of acid to dentin surfaces produced a zone of demineralization, exposing dentin collagen fibrils and opening dentin tubules. In this study, the in vitro effects of different tetracycline HCl application techniques were investigated. According to the results of this SEM study, it may be desirable to apply tetracycline HCl using burnishing technique to expose maximum intertubular fibrils and for the tubular openings. However, this technique should be studied when placed in an in vivo system.
Acid Etching, Dental↗
Ridge preservation utilizing an acellular dermal allograft and demineralized freeze-dried bone allograft: Part I. A report of 2 cases.
Alveolar ridge deformities are usually the result of trauma, periodontal disease, surgical insult, or developmental defects. Preventing ridge collapse with the extraction of maxillary anterior teeth is vital to an esthetic restorative result. Several techniques are available to prevent ridge collapse. In these case presentations, ridge preservation was achieved utilizing an acellular dermal matrix as a barrier membrane with a demineralized freeze-dried bone allograft. This report demonstrated an acceptable esthetic result with no loss of ridge height or width. Soft tissue dimensions were also preserved. The two graft materials were well accepted by the body and healing was rapid and without significant discomfort. The technique illustrated provides the surgeon with another option to prevent ridge collapse and ultimately improve esthetics.
Adult↗
Ridge preservation utilizing an acellular dermal allograft and demineralized freeze-dried bone allograft: Part II. Immediate endosseous implant placement.
When maxillary anterior teeth are extracted, subsequent ridge collapse can significantly compromise esthetics. Preservation of an adequate volume of bone is vital to successful implant placement. Ridge preservation achieved utilizing an acellular dermal matrix as a barrier membrane with a demineralized freeze-dried bone allograft has been previously reported. In this case presentation, guided bone regeneration was achieved around an immediate endosseous implant when this same technique was used. As in the previous case reports, this technique demonstrated an acceptable esthetic result with virtually no loss of ridge height or width. Soft tissue dimensions were also preserved. Both the hard and soft tissue grafts were well accepted by the body and healing was rapid and without significant discomfort. This surgical technique provides the clinician with an option to provide immediate implant therapy when primary closure cannot be achieved.
Adult↗
[Treatment of nonunion in childhood by allogeneic decalcified bone graft].
OBJECTIVE: To investigate the effect of allogeneic decalcified bone graft in the treatment of nonunion in children. METHODS: From April 1990 to September 1997, 17 children with nonunion were adopted in this study. Among them, there were 10 boys and 7 girls, the age ranged from 2 to 13 years. The allogeneic decalcified bone graft taken from fresh corpse by aseptic manipulation were used to repair 3 cases of congenital nonunion and 14 cases of acquired nonunion. RESULTS: All cases were followed up 2 to 9 years after operation, 9 cases were cured successfully and 7 cases were cured after twice operations. One case of congenital pseudoarthrosis of the tibia was operated twice and there were callus grown half years after the second operation, but reoccurred after one year. Although there were 1.5 cm to 3 cm shortening deformity of extremity including another 2 cases of congenital pseudoarthrosis of the tibia and 5 cases of nonunion caused by chronic osteomyelitis, the function of joint was normal. CONCLUSION: Treatment of nonunion in children by allogeneic decalcified bone graft is a valuable technique in clinical practice. It is characterised by high capacity of osteoinduction, low antigenicity, rapid bony union, plentiful source of bone graft and convenient utilization.
Adolescent↗
A DEMINERALIZATION PROCEDURE FOR ENZYMATIC HISTOCHEMICAL USE: A QUANTITATIVE SUCCINIC DEHYDROGENASE ASSAY.
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Acid Phosphatase↗
Transparent tooth model system. An aid in the study of root canal anatomy.
Clearing techniques of tooth have long since been advocated in the demonstration of root canal anatomy. We have compared the efficacy of various clearing agents such as Xylene, Benzene, Methyl salicylate and Eugenol, using 40 maxillary second premolars as experimental subjects. We have further tried to select a suitable dye for the demonstration of root canal anatomy and have compared the efficacy of various mounting media such as D.P.X. medium, Canada balsam and Commercial plastic dissolved in benzene, in preserving the cleared state. Results of our study indicate that Eugenol is a superior clearing agent and that oil-based dyes are better suited for root canal demonstration. Canada balsam is the most effective mounting media and D.P.X. medium has been found to serve both as a clearing agent and as a mounting media. We have introduced a miniature museum jar technique, for preserving the transparency permanently. The Transparent Tooth Model System presented here, thus serves as a much simpler tool, in the study of root canal anatomy, three dimensionally.
Benzene↗
Dimensional changes of demineralized human dentine during preparation for scanning electron microscopy.
Dentine rods measuring approx. 0.7 x 0.7 x 5.0mm were prepared from the crowns of extracted human third molars. The specimens were demineralized in 0.5 M EDTA (pH 7.0) for 3 days and their volume measured with a digital micrometer under a dissecting microscope. The specimens were randomly assigned to experimental groups and were chemically dehydrated in acetone. Next they were dried using either hexamethyldisilazane, Peldri II, or critical-point drying techniques. The dimensions of the specimens were measured again after each step and the changes in volume were expressed as a percentage of the original demineralized volume. The effects of fixing the specimens in 10% buffered formalin before dehydration with acetone were also investigated for every drying procedure. Dehydration in acetone caused a small but significant reduction in the volume of demineralized formalin-fixed specimens but unfixed specimens did not change significantly. In general, all three drying procedures caused some shrinkage in demineralized dentine specimens. Unfixed specimens exhibited a volumetric shrinkage of approx. 15-20% after drying with any of the methods. Fixed specimens shrank more than unfixed specimens after drying (25-35%). Regardless of the drying technique, the specimens shrank a further 10-20% when measured in the vacuum chamber of the scanning electron microscope. Among the three drying techniques employed, hexamethyldisilazane seems to be a very useful alternative to critical-point drying for the preparation of dentine specimens for scanning electron microscopy.
Acid Etching, Dental↗
Bone induction using demineralized bone in the rabbit femur: a long-term study.
While traditional bone grafting is the standard for replacement of segmental bony defects, alternative options (avoiding morbidity of autologous grafts) are attractive and continue to be sought. This study attempted to determine whether demineralized bone powder could be used reliably to replace a significant bony deficit at a weight-bearing site. The long-term functional characteristics of this induced bone were analyzed to determine whether it maintained its strength and shape and reacted normally to physiologic stress over an extended period of time (12 months). In 55 New Zealand White rabbits, a 1-cm length of femur was removed (approximately 20 percent of the total length of the rabbit femur). The femur was then reconstructed with a titanium mandibular plate, leaving the gap intact. In 38 of the animals, this gap was filled with demineralized bone powder in an attempt to induce bone to form across the defect. In group 1 (n = 23), the mandibular plate remained in place for the duration of the study (12 months). In group 2 (n = 15), the plate was removed 8 weeks after placement of the demineralized bone powder, and the animals were followed for an additional 12 months. In group 3 (n = 10), nothing was placed within the bony gap. In group 4 (n = 7), the gap was repaired with autologous bone graft. All the animals that received demineralized bone powder completely filled the osteotomy gap with new bone within 6 to 8 weeks after implantation. None of control group 3 formed bone across the gap (p < 0.001). Eighty-six percent of control group 4 (autologous bone graft) successfully formed bone across the osteotomy gap. In addition, 90 percent of control group 3 had hardware failure within 8 weeks after surgery compared with 0 percent (0 of 38) of the group that received demineralized bone powder (p < 0.001). In group 1, analysis after 12 months revealed that the bone formed ultimately became thin and easily fractured, most likely because of shielding from stress loading by the mandibular plate. In contrast, in group 2 (in which the plate was removed after 8 weeks), the bone remodeled and hypertrophied in response to the physiologic stress of weight bearing and at the end of the 12-month period was essentially identical to normal femur. In certain circumstances, reconstruction of bony defects using bone-induction techniques may be as good as autologous bone grafting, with the advantage of limiting the donor-site morbidity for the patient.
Animals↗
Evaluation of guided tissue regeneration in interproximal defects. (II). Membrane and bone versus membrane alone.
This study clinically evaluates the use of expanded polytetrafluoroethylene (ePTFE) membranes with or without the addition of decalcified freezedried bone allograft (DFDBA) in the treatment of interproximal intraosseous defects. 25 patients (26 paired defects) diagnosed with advanced periodontitis and having at least 2 bilateral interproximal probing depths of > or = 6 mm participated in the study. After the hygiene phase, measurements were made to determine soft tissue recession, pocket depth, and clinical attachment levels. Defects from each pair were randomly treated with either ePTFE alone (control), or ePTFE+DFDBA (experimental). Measurements were made during the surgery to determine crestal resorption, defect resolution and defect fill. Membranes were removed at 4 to 6 weeks. At 6 months, the soft and hard tissue measurements (surgical reentry) were repeated. Both groups showed statistically significant improvement when compared to baseline (p < 0.001), but no difference was determined between groups. Control sites showed a 50% bone fill and experimental sites had 54% bone fill. The defect resolution changes were also similar between control and experimental groups, respectively (80%, 74%). For this short-term study, it was concluded that either technique was beneficial for the treatment of intraosseous defects. Other studies are needed to assess the long-term stability of the improvements rendered by these treatments.
Adult↗
[A new application of plastination in bone histology].
The plastination techniques originally developed for macroscopy can be modified for the preparation of plastinated sections for microscopy. Particularly good penetration of the specimen during preparation of the histological section is obtained, when the techniques described for freeze substitution, degreasing and forced impregnation with resin are employed. The different types of polymers are compared to determine the particular advantages and disadvantages of each. The sectioning technique and the use of histological stains are described for both undecalcified and decalcified bones. The modified Spalteholz technique with decalcification of sections and second plastination procedure for the preparation of transparent decalcified bone sections is described. This makes it possible to produce plane parallel standardized sections for morphometric examination of the vascular structure of the bone. The possible uses of the plastination for the histological examination procedures currently in use, such as fluorescence microscopy, microangiography and microradiography, are shown. The relative values of different microangiographic techniques have been determined for the first time by means of further developments of the Spalteholz and plastination techniques, because they have provided the possibility of standardizing sections. Thus, the plastination technique appears to be especially useful for the examination of microscopic specimens.
Animals↗
A clinical evaluation of an allograft combined with a bioabsorbable membrane versus an alloplast/allograft composite graft combined with a bioabsorbable membrane. 100 consecutively treated cases.
The purpose of this study was to evaluate and compare the clinical effectiveness of 2 surgical techniques in treating periodontal defects. Both techniques involved tetracycline treatment of a root planed root, grafting the osseous defect with a bone graft, and placement of a bioabsorbable membrane. In group A, the bone graft was a mix of demineralized freeze-dried allograft, tetracycline, and porous hydroxyapatite and in group B, the bone graft was a mix of demineralized freeze-dried allograft and tetracycline. There was a statistically significant increase in recession (group A, 0.7 mm; group B, 0.6 mm), decreases in probing depth (group A, 6.1 mm; group B, 5.6 mm), and gains in attachment levels (group A, 5.4 mm; group B, 5.0 mm). There were no statistically significant differences between the results for either group. The defects associated with furcations and those that were not associated with furcations had similar results, except for the percent attachment gain. Smoking and age (> or =60 years old) could not be associated with results. Defects with > or =10 mm probing depths (PD) had greater PD reductions (group A, 7.7 mm; group B, 7.1) and attachment gains (group A, 6.6 mm; group B, 6.4 mm) than the defects with probing depths less than 10 mm (probing reduction group A, 4.8 mm; group B, 4.5 mm; attachment gain group A, 4.4 mm; group B, 4.0 mm). Both surgical procedures improved the clinical situation. However, neither technique seemed to offer a statistical advantage over the other. The inclusion of porous hydroxyapatite did not improve or diminish the results.
Adult↗
Periosteal activation and root demineralization associated with the horizontal sliding flap.
A sliding flap technique for covering denuded root associated with periosteal activation and root demineralization "in situ" was described. The possible biological mechanisms involved were discussed. Two clinical cases were presented illustrating the successful results that can be achieved.
Acid Etching, Dental↗
Treatment of a human transosseous mandibular defect by guided bone regeneration.
The treatment of through-and-through human periapical lesions by barrier membrane techniques has not been reported in the periodontal literature. However, periodontists frequently perform this treatment. The authors present a case that demonstrates radiopacity after regeneration surgery of a human periapical transosseous mandibular defect, suggesting local bone regeneration. The surgical technique performed in this case was based on the principles of guided bone regeneration using a demineralized freeze-dried bone membrane (DFDBM). The bone membrane acted as an efficient barrier that excluded the nonosteogenic tissue. Radiographic findings demonstrated bone fill after 8 months.
Bone Regeneration↗
A technique for the removal of junctional epithelium from the epithelial attachment.
A technique utilizing sodium deoxycholate to remove junctional epithelial cells from the epithelial attachment zone is described. Light and electron micrographs show a similarity in size and appearance between the extracellular attachment substance in controls and the extracellular substance which remains on cementum previously in contact with junctional epithelium.
Animals↗
Clinical evaluation of the use of decalcified freeze-dried bone allograft with guided tissue regeneration in the treatment of molar furcation invasions.
The purpose of this study is to evaluate the potential of decalcified freeze-dried bone allograft (DFDBA) combined with a barrier material in the treatment of human molar furcation defects (experimental) as compared to the barrier technique alone (control). Fifteen pairs of Class II or III furcation invasion defects comprised the study group. Measurements with calibrated periodontal probes were made to determine soft tissue recession, probing depth, and attachment levels. Defects from each pair were randomly selected to be treated with an expanded polytetrafluoroethylene membrane (e-PTFE) and DFDBA or the membrane alone. Additional measurements were made during surgery to determine crestal resorption, and vertical and horizontal open probing attachment. The membrane was removed 4 to 6 weeks post-insertion. Six months post-treatment, each site was surgically reentered and measurements repeated. Following either treatment, recession was minimal with statistically significant improvement in probing depth reduction and clinical attachment level gain favoring the combined technique. Hard tissue changes were comparable for alveolar crestal resorption, however, there was a distinct difference, statistically, for both horizontal and vertical bone repair favoring the use of the demineralized bone graft in combination with the e-PTFE membrane.
Bone Transplantation↗