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  • 1
    Electronic Resource
    Electronic Resource
    The mineralization of mantle dentine and of circumpulpal dentine in the rat: an ultrastructural and element-analytical study (1997)
    Springer
    Anatomy and embryology 195 (1997), S. 289-297 
    Details
    ISSN: 1432-0568
    Keywords: Key words Mineralization ; Dentine ; Ultrastructure ; Elementanalysis ; Collagen fibrils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The purpose of this study was to compare the biomineralization of circumpulpal dentine with that of mantle dentine by ultrastructural and element-analytical techniques. Forty upper second molar germs of 10-day-old albino rats were cryofixed in liquid nitrogen-cooled propane and embedded in resin after freeze drying. Semithin dry sections were cut for analyzing the calcium and phosphorus concentration in initial mantle dentine, at the mineralization front of circumpulpal dentine, in the middle region of circumpulpal dentine and in mantle dentine peripheral to circumpulpal dentine. For the morphological evaluation of mineral deposits we compared ultrathin and unstained sections of cryofixed molars with chemically fixed molars. For both dentine types it was found that they develop via identical steps of mineral formation at collagen fibrils and non-collagenous matrix molecules. In circumpulpal dentine no globular mineral protrusions along the mineralization front (i.e. calcospherites) and no indications of interglobular dentine at the transition from circumpulpal dentine to mantle dentine were present. The von Korff fibres were not only visible in mantle dentine but also in circumpulpal dentine. Matrix vesicles were present only during the formation of an initial coherent layer of mantle dentine and could not be observed during successive formation of mantle dentine and circumpulpal dentine. The element-analytical data did not demonstrate any difference in the mineral content between the two dentine types. Therefore, we conclude that mantle dentine and circumpulpal dentine in the rat molar possess a high degree of structural and chemical similarity and that only the extent of terminal branching of the odontoblast processes gives an approximate estimation of the thickness of mantle dentine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004290050048
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  • 2
    Electronic Resource
    Electronic Resource
    Sutural mineralization of rat calvaria characterized by atomic-force microscopy and transmission electron microscopy (1998)
    Springer
    Cell & tissue research 294 (1998), S. 93-97 
    Details
    ISSN: 1432-0878
    Keywords: Key words Calvaria ; Mineralization ; Calcium ; Phosphorus ; Apatite ; Atomic-force microscopy ; Transmission electron microscopy ; Rat (Sprague Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The application of transmission electron microscopy (TEM) and atomic-force microscopy (AFM) aid the acquisition of detailed structural information on the process of hard tissue formation. The sutural mineralization of rat calvaria is taken as a model for a collagen-related mineralization system. After cryofixation or chemical fixation an anhydrous tissue preparation technique with no staining procedures is used. The atomic-force microscope and the transmission electron microscope are used for structural analysis of the mineralizing region of the sutural tissue. With the application of AFM the collagen macroperiod is shown to be well represented in the unmineralized sutural tissue. At the mineralization front the collagen fibrils are found to be thickened and to change to a characteristic stacked platelet structure. Using TEM the macroperiod is faintly visible before mineral crystallites have formed and is more prominent after the apatite crystallization has started in the fibrils. In this step a needle-like structure of the newly formed apatitic crystals is visible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051159
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  • 3
    Electronic Resource
    Electronic Resource
    Mineralization during matrix-vesicle-mediated mantle dentine formation in molars of albino rats: a microanalytical and ultrastructural study (1996)
    Springer
    Cell & tissue research 284 (1996), S. 223-230 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Mineralization ; Matrix vesicles ; Dentine ; Ultrastructure ; Element analysis ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The purpose of this study was to elucidate the mineralization process of mantle dentine by ultrastructural and element-analytical investigation of matrix vesicles and successive stages. Upper second molars of albino rats were cryofixed and embedded in resin after freeze drying. Semithin dry sections were prepared for analyzing the calcium and phosphorus concentrations in the mineralized matrix vesicles or noduli, larger mineralized islands, and the mantle dentine. For ultrastructural studies, it was necessary to reduce section contact with hydrous fluids to a minimum in order to avoid preparation artifacts. The first mineral deposits were recognized as dot-like formations both in the interior of matrix vesicles and in association with the inner vesicle membrane. This indicated the existence of mineral nucleating sites located both at the inner membrane and at calcium-phosphate-binding macromolecules in the interior of the matrix vesicles. A significantly higher mineral content was found in mineralized matrix vesicles than in the mineralized extravesicular regions of the mineralized islands, suggesting the existence of a rapidly and densely mineralizing matrix in the matrix vesicles. A significant increase in mineral content per volume proceeding from the mineralized islands to mantle dentine suggested a further increase in the density of mineral.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050582
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  • 4
    Electronic Resource
    Electronic Resource
    Morphologische Ergebnisse zur Anwendbarkeit eines gepulsten Kryptonfluorid-Excimerlasers im Rahmen der Schmelzkonditionierung (1991)
    Springer
    Journal of orofacial orthopedics 52 (1991), S. 315-321 
    Details
    ISSN: 1615-6714
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Although there have been many advances in the field of acid etching, major problems still present. For the most part, these are the unpredictability of the effects of etching, the lack of control of the depth of etching over the long term, and the development of enamel fractures occurring on debonding. The aim of this study was to investigate the morphological effects of enamel conditioning using a pulsed krypton fluoride excimer laser (wavelength 248 nm). Scanning electron microscopic examination revealed a surface similar to that produced by peripheral etching; no signs of thermal damage were to be seen. The requirements that have to be met by a modern laser considered as a possible alternative to conventional acid etching, are discussed.
    Notes: Zusammenfassung Trotz vieler Fortschritte auf dem Gebiet der Säure-Ätz-Technik sind wesentliche Probleme bisher nicht gelöst worden. Die Hauptaspekte dieses Problemkreises sind das nicht vorhersagbare Ätzmuster, die unkontrollierbare Langzeittiefenwirkung sowie die Entstehung von Schmelzausrissen aufgrund einer nicht definierbaren Bruchfläche bei Bracketabnahme. Ziel der vorliegenden Studie ist es, morphologische Ergebnisse der Schmelzkonditionierung bei Verwendung eines gepulsten Kryptonfluorid-Excimerlasers (248 nm) vorzustellen. Die rasterelektronenmikroskopische Untersuchung zeigte ein dem peripheren Säure-Ätz-Tup ähnelndes Oberflächenrelief. Zeichen einer Hitzeentwicklung wurden nicht gefunden. Die Anforderungen an ein modernes Lasersystem, das zu einer möglichen Alternative der konventionellen Säure-Ätz-Technik werden könnte, werden diskutiert.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02166628
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  • 5
    Electronic Resource
    Electronic Resource
    Elementanalytische und quantitativ-morphometrische Bestimmung von Kunststoffresten und Schmelzausrissen nach der Abnahme von Metallbrackets (1992)
    Springer
    Journal of orofacial orthopedics 53 (1992), S. 99-105 
    Details
    ISSN: 1615-6714
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary A number of clincal and experimental studies were performed to assess the quality of the enameladhesive-bracket bond. The aim was to present a combined method that enables the investigator both to examine the surface of metal brackets quantitative-morphometrically and to detect the presence of enamel particles. To this end, 38 metal brackets were examined in the scanning electron microscope. An EDAX-detecting unit was used to analyze morphologically conspicuous structures and identified them as enamel particles. The extent of adhesive remnants and enamel particles was quantified using the image analysis system IBAS. In 24 brackets (53%) bonding adhesive residue was found on the bracket base. In 18 brackets (47%) enamel particles were identified on the adhesive-bearing brackets. This method is easier to carry our and enables a more accurate quantification of enamel particles than the Adhesive Remnant Index. Since it can be applied universally to examine recommended improvements to adhesive technique it facilitates their assessment.
    Notes: Zusammenfassung Un die Güte des Verbundsystems Schmelz-Adhäsivkunststoff-Bracket zu beurteilen, werden verschie dene klinische und experimentelle. Untersuchungen durchgeführt. Ziel der vorliegenden Studie ist die Vorstellung einer kombinierten Methode, die es ermöglicht, die Basis von Metallbrackets nach der Bracketabnahme sowohl quantitativ-morphometrisch auf Adhäsivreste zu untersuchen als auch möglicherweise vorliegende Schmelzpartikel nachzuweisen. Es wurden 38 Metallbrackets rasterelektronenmikroskopisch untersucht Morphologisch auffällige Strukturen wurden mit einer angeschlossenen Mikrosonde analysiert und als Schmelzpartikel identifiziert. Die Flächenanteile der Adhäsivreste bzw. der Schmelzpartikel wurden mit einem rechnergestützten Bildanalysesystem bestimmt Bei 24 Brackets (63%) fanden sich Adhäsivreste auf der Bracketbasis. Bei 18 Brackets (47%) ließen sich Schmelzpartikel auf der adhäsivbedeckten Bracketbasis nachweisen. Das vorgestellte Verfahren ist einfach durchführbar und gestaftet eine gegenüber einem Index zur Quantifizierung von Kunststoffresten (Adhesive Remnant Index) genauere Bestimmung von Schntelzpartikeln. Da es zur experimentellen Überprüfung empfohlener Verbesserungsansätze in der Klebetechnik universell anwendbar ist, erleichtert es deren Beurteilung.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02164644
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Low-dose-Computertomographie des Kieferknochens in der präimplantologischen Diagnostik (1998)
    Springer
    Mund-, Kiefer- und Gesichtschirurgie 2 (1998), S. 188-193 
    Details
    ISSN: 1434-3940
    Keywords: Schlüsselwörter Dentale Implantologie ; Computertomographie ; Genauigkeit ; Strahlendosis ; Key words Dental implants ; Computed tomography ; Radiation dose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Absorbed radiation doses delivered by computed tomography and panoramic radiography were measured in 16 anatomic sites using a head and neck phantom and thermoluminescent dosimetry. The recommended kilovoltage and scan time for dental scanning was reduced step by step, rating the quality of the low-dose scans. A reduction of up to 76% could be achieved without loss of diagnostic accuracy. Measured absorbed radiation dose ranges from 0.30 mGy (thyroid) to 29 mGy (skin) at 187,5 mAs and 1.0 mm-slices (25 mm scanning distance for maxilla, 30 mm for mandible). After reduction to 45 mAs, 0.07 mGy (thyroid) to 6.9 mGy (skin) was measured. Distance measurements on human jaw specimens were compared with corresponding CT image measurements. Average deviation was 0.1– 0.3 mm. A dose reduction of 75% had no effect on the results. However, the doses of CT-scans reduced by 76% exceed by an average factor of 10 the doses of conventional panoramic radiography. Therefore, CT should be reserved for the planning of complex implant treatment in the direct vicinity of the maxillar sinus and nerves and for multiple implant insertion.
    Notes: Die Energiedosis der Spiralcomputertomographie sowie des Orthopantomogramms (OPG) wurde an 16 Positionen im Kopfbereich mit Hilfe von Thermolumineszenzdosimetern und eines Phantomkopfs bestimmt. Die vom Hersteller des Computertomographen empfohlene Röhrenleistung für eine dentale CT wurde schrittweise reduziert. Eine Verminderung der Strahlenbelastung um 76% wurde ohne Verlust an diagnostischer Information erreicht. Die gemessene Energiedosis der Computertomographie betrug 0,30 mGy (Schilddrüse) bis 29 mGy (Hautoberfläche im Strahlengang) bei 187,5 mAs und 1-mm-Schichten (25 mm Scanstrecke im Oberkiefer, 30 mm im Unterkiefer). Bei Reduzierung auf 45 mAs wurden 0,07 mGy (Schilddrüse) bis 6,9 mGy (Hautoberfläche) gemessen. Längenmessungen an gesägten Kieferpräparaten wurden mit korrespondierenden CT-Messungen an einer Workstation verglichen. Die durchschnittliche Meßungenauigkeit betrug hierbei 0,1–0,3 mm. Die Dosisreduzierung der CT um ca. 76% hatte keinen Einfluß auf die Längenmeßgenauigkeit. Allerdings liegen die Energiedosen der um 76% dosisreduzierten CT-Scans noch durchschnittlich um den Faktor 10 über der Energiedosis eines Orthopantomogramms. Die Computertomographie sollte daher der Planung komplexer Implantatversorgungen in Kieferhöhlen- oder Nervennähe sowie multipler Implantationen vorbehalten bleiben.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100060050057
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    Paper (German National Licenses)
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