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  • 2000-2004  (2)
  • Key words  (1)
  • Key words Ultrasound  (1)
  • 1
    ISSN: 1436-3771
    Keywords: Key words Ultrasound ; Radiation caries ; Head and neck neoplasm ; Radiotherapy ; Modulus of elasticity ; Enamel ; Dentine ; In vitro ; In vivo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Ultrasound transmission velocity (UTV) in isotropic material as a measure for the modulus of elasticity was correlated to mechanical properties. Changes in micromechanical properties of radiated teeth and influence of the oral cavity were to be evaluated nondestructively. UTV was measured in extracted teeth after 36 Gy and 62 Gy of in situ (enorally, with no contact to the oral cavity) and in vitro irradiation. Relative to controls, teeth subjected to 62 Gy in vivo showed higher UTV values for dentine and enamel. Sound teeth irradiated with 60 Gy in situ also showed higher UTV values for enamel, whereas dentine values were not significantly different from those of control. The mechanical properties of teeth irradiated in vitro were affected only after high experimental doses of up to 500 Gy. The difference between in vivo and in vitro mechanical properties may be due to radioxerostomia-induced damages as well as the status of dentine vitality. This supports the concept of direct radiation-induced damage in synergy with radioxerostomia-induced caries.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1434-3940
    Keywords: Schlüsselwörter ; Kalziumphosphatkeramiken ; Spezifische Oberfläche ; Knochenersatzmaterialien ; Poren ; Hydroxylapatit ; Key words ; Calciumphosphate ceramics ; Specific surface area ; Bone regeneration materials ; Pores ; Hydroxyapatite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: The surface area and the microporosity of bone regeneration materials influence their chemical and ¶biological properties. Therefore, the size of the specific surface area and the distribution of the pore diameters (pores 〈 1 μm) of bone regeneration materials were analyzed within this study. The analyzed hydroxyapatites were of synthetic, bovine, and phytotroph origin. The tricalcium phosphates and the bioglasses included only synthetic materials. The gas adsorption of each specimen was analyzed using a volumetric N2/Kr system (ASAP 2010, Micromeritics). Additionally, for materials with a specific surface area (〉 2 m2/g) the pore size distribution was evaluated by the BJH-method. Two of the ¶materials evaluated astonishingly large dimensions of the specific surface area (BioOss 79.7 m2/g, Algipore new 14.6 m2/g). A medium ¶surface area was found for Algipore old (4.9 m2/g) and Interpore200 ¶(2.64 m2/g). All other included materials showed only small sizes of the specific surface area (Ceros80 ¶1.8 m2/g, Ceros82 1.31 m2/g, Cerasorb 1.2 m2/g, Biobase 0.7 m2/g, Endobone 0.7 m2/g, Perioglas 0.6 m2/g, Allotropat50 0.23 m2/g, Biogran ¶0.2 m2/g). The materials with large and medium sizes of the specific surface area evaluated the following pore diameters: BioOss 2–50 nm, Algipore new 2–100 nm, Algipore old 5–50 nm, Interpore200 2–100 nm. Pore sizes less than 2 nm were not found in relevant numbers. The materials BioOss, old and new Algipore, and Interpore200 contain a large interconnecting mesopore system (diameter 〈 1 μm). For the materials Biobase, Endobone, Perioglas, Allotropat 50, and Biogran this cannot be assumed. The materials Ceros80, Ceros82, and Cerasorb evaluated a specific surface area between those and might include only a small part of these interconnecting pores. An influence of the interconnecting porosity and the different sizes of the specific surface areas on the biological behavior of the bone regeneration materials can be suggested.
    Notes: Fragestellung: Die Oberfläche sowie die Mikro- und Mesoporosität von Knochenersatzmaterialien beeinflussen deren chemische und biologische Eigenschaften. Daher wurden in dieser Untersuchung die Größe der spezifischen Oberfläche sowie die Verteilung der Porendurchmesser (Poren 〈 1 μm) in Knochenersatzmaterialien bestimmt. Material und Methode: Die untersuchten Hydroxylapatite waren synthetischen, bovinen und phytotrophen Ursprungs. Die Trikalziumphosphate und die Biogläser umfassten nur rein synthetische Materialien. ¶Die Gasadsorptionsuntersuchung je einer Probe erfolgte mit Hilfe eines volumetrischen N 2 -Kr-Systems (ASAP 2010, Micromeritics). Zusätzlich wurde für Materialien mit spezifischen Oberflächen ¶〉 2 m 2 /g die Porengrößenverteilung nach der BJH-Methode ermittelt. Ergebnisse: 1. Spezifische Oberfläche: 2 der Materialien zeigten eine auffallend große spezifische Oberfläche (BioOss 79,7 m 2 /g, Algipore neu 14,6 m 2 /g). Eine mittlere Oberfläche zeigten Algipore alt (4,9 m 2 /g) und Interpore 200 (2,64 m 2 /g). Die übrigen Materialien zeigten nur kleine Oberflächen (Ceros 80 1,8 m 2 /g, Ceros 82 ¶1,31 m 2 /g, Cerasorb 1,2 m 2 /g, Biobase 0,7 m 2 /g, Endobone 0,7 m 2 /g, Perioglas 0,6 m 2 /g, Allotropat 50 0,2 m 2 /g, Biogran 0,2 m 2 /g). 2. Häufigkeitsverteilung des Porendurchmessers: Die Materialien mit großen und mittleren spezifischen Oberflächen zeigten folgende Porendurchmesser: BioOss 2–50 nm, Algipore neu 2–¶100 nm, Algipore alt 5–50 nm, Interpore 200 2–100 nm. Porengrößen 〈 2 nm fanden sich kaum. Schlussfolgerungen: Die Materialien BioOss, Algipore alt und neu und Interpore 200 haben ein großes interkonnektierendes Mesoporensystem (Durchmesser 〈 1 μm). Für die Materialien Biobase, Endobone, Perioglas, Allotropat 50 und Biogran ist dies nicht anzunehmen. Die Materialien Ceros 80, Ceros 82 und Cerasorb zeigen eine dazwischen liegende spezifische Oberflächengröße und weisen einen mäßigen Anteil von solchen interkonnektierenden Poren auf. Ein Einfluss der interkonnektierenden Porosität und der deutlich unterschiedlichen spezifischen Oberflächen auf das Verhalten der Knochenersatzmaterialien in vivo ist nahe liegend.
    Type of Medium: Electronic Resource
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