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At least 145 records · Page 8Linked to original sources
PubMed1983

Quantitative microradiography of cortical bone in disuse osteoporosis following fracture fixation.

Stainless steel (elastic modulus 210 GN/m2) and carbon fibre reinforced epoxy resin (elastic modulus 65 GN/m2) plates have been attached to intact femora in cats and the development of disuse osteoporosis assessed by microdensitometric methods after 8 months. The bone adjacent to the stainless steel plate showed evidence of considerable demineralization, both uniformly throughout a section and especially at certain focal points. A noticeable, but much smaller amount of osteoporosis developed adjacent to the composite plate. Various methods of presenting quantitative micro-densitometric data are used.

Animals↗
PubMed2004

Quantitative analysis of the impact of the organic matrix on the fluoride effect on erosion progression in human dentine using longitudinal microradiography.

After an initial demineralisation, an intensive fluoridation is capable of inhibiting the erosive mineral loss in dentine completely, which might be related to the presence of the exposed organic dentine matrix. Aim of the present study was, therefore, to evaluate whether fluoride is also effective when the organic material is removed. The study was a cyclic de- and remineralisation model over 5 days in vitro. Samples from human coronal dentine were demineralised with citric acid (pH 2.3; 6 x 10 min per day) and intermittently stored in a remineralisation solution. Groups (n = 25 each) were defined as follows: Group 1: erosion only, no fluoridation; Group 2: erosion, alternately fluoridation with toothpaste (NaF; 0.15% F-; 3 x 5 min per day), mouthrinse (Olaflur/SnF2; 0.025 F-; 3 x 5 min per day) and gel (Olaflur/NaF; 1.25% F-; at Days 1 and 3 instead of one toothpaste application); Group 3: erosion and fluoridation as Group 2, organic material was continuously removed with collagenase (from Clostridium Histolyticum type VII, 100 U/ml) added to the remineralisation solution. Mineral content was monitored daily using longitudinal microradiogaphy. After fluoridation in the presence of collagenase, a linear increase in mineral loss (73.3 +/- 17.6 microm at Day 5) was observed, which significantly (P < or = 0.001) exceeded that of the control group (45.9 +/- 14.3 microm at Day 5). After fluoridation in the absence of collagenase, mineral loss ceased after the 2nd day (12.2 +/- 10.2 microm at Day 5) and was significantly lower compared to Groups 1 and 3 (P < or = 0.001). The results indicate that the dentine matrix is essential for the effectiveness of fluoride in dental erosion.

Cariostatic Agents↗
PubMed1999

Correlation of transversal microradiography and microhardness on in situ-induced demineralization in irradiated and nonirradiated human dental enamel.

The objective was to evaluate whether a correlation exists between microhardness (MH) and transversal microradiographical (TMR) data for in situ-induced caries lesions in irradiated and nonirradiated human enamel. Enamel specimens were prepared from the lingual and buccal surfaces of 20 freshly extracted, caries-free third molars. The surfaces were polished (4000 grit). Either the lingual or the buccal specimen of each tooth was irradiated with 60 Gy; the other sample was not irradiated. Two irradiated and two nonirradiated specimens were inserted into both buccal aspects of each of five intraoral mandibular appliances. The appliances were worn by five persons for 6 weeks day and night. One side was brushed daily with a fluoride-free toothpaste; on the other side, dental plaque was allowed to grow. Individual oral hygiene was performed without any fluorides. During meals, the appliance was stored in 10% sucrose solution. Then the enamel specimens were cut perpendicular to their oral surface. The cut surface was polished (4000 grit) and the Knoop hardness number (KHN) was measured across the lesions, at 25, 50 and 75 microm from the oral surface. After MH testing the samples were polished again, thereby reducing the surface by about 10 microm. Subsequently, the slabs were ground to a thickness of 90 microm, and studied by means of TMR. Mineral loss was calculated with dedicated software at the locations corresponding to the MH testing. A total of 120 paired data was submitted to linear-regression analysis. Neither MH nor TMR showed significant differences between irradiated and nonirradiated enamel lesions. A linear relation was found between square root of KHN and the mineral volume percent. In naturally induced caries lesions, MH values can be converted to mineral volume percent using the equation [21.19 + 3.66 x square root of KHN]. This equation fits the data with a reliable correlation coefficient (r2=0.915).

Adult↗
PubMed1980

Applicability of macro- and microradiography in diagnosis of malignant neoplasms infiltrating the jaw bones.

The subject of this paper is the evaluation of the applicability of structural jaw and mandible radiograms in diagnosing malignant neoplastic processes infiltrating the osseous tissue. The material studied comprised 20 patients treated surgically due to neoplasms of the faciocranium. The group investigated consisted of 17 males, aged 35--65 years and three females 45--60 years old. The most numerous group of neoplasms was composed of cancers: 18 patients; the remaining two were fibrosarcomas. For structural radiographs fine grained films and folialess cassettes were used, with soft X-rays being applied for irradiating the preparations. The radiograms were prepared by means of X-ray apparatus with a small focal lamp with a diameter of 0.3 mm, and with the point-focal apparatus. On the basis of analyses covering 24 macroradiograms and 71 microradiograms, criteria for estimating the malignant infiltration of the bone were established. The possibility of practical applicability of these investigations during intraoperative evaluation of the clinically suspicious bone segments has been emphasized.

Adult↗
PubMed1995

Evaluation of bone density using cutting resistance measurements and microradiography: an in vitro study in pig ribs.

A method using cutting resistance measurements during low-speed threading for identification of various bone densities has been evaluated with regard to its precision and potential. Pig ribs were used as test samples. Differing hand pressure, minor deviation (5 degrees) from a vertical tapping direction and individual threading did not reveal any significant differences in cutting resistance values. After implants were inserted into the threaded canals, the total bone as well as trabecular and compact bone areas surrounding the implants were calculated via a computer program and using microradiographs of the bone test samples. The outcome of the cutting resistance measurements was compared with that of the microradiographic technique, and good agreement was observed between the two procedures in the ability to identify bone density. Therefore, cutting resistance measurements may in the future also be used to clinically identify bone qualities in jaws.

Animals↗
PubMed1981

Scanning X-ray microradiography of a section of a carious lesion in dental enamel.

A scanning X-ray microradiographic system is described with which it is possible to measure the X-ray absorption in a 1 mm X 1mm area of a section in about 27h at a resolution of 20 micrometers with a reproducibility of about +/- 1.5%. This system has advantages over photographic methods for certain quantitative investigations. The results can be presented in various forms including contour maps and half-tone pictures and this is illustrated with a radiograph of a section of a carious lesion in dental enamel.

Dental Caries↗