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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Analytical chemistry 28 (1956), S. 706-714 
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Analytical chemistry 29 (1957), S. 1177-1178 
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Al0.5In0.5P/Ga0.5In0.5P superlattice structures have been investigated as multiquantum barriers (MQB) in 630 nm band laser diodes in order to reduce thermal current losses. By inserting an optimized MQB, we have succeeded in improving both threshold currents and characteristic temperatures of such devices. However, the optimized dimensions of the MQB found experimentally deviated strongly from those predicted theoretically, indicating that the commonly used theoretical description assuming effective mass approximation, electron wave interference, and using transfer matrix calculation is not adequate. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Industrial & engineering chemistry 35 (1943), S. 346-348 
    ISSN: 1520-5045
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1437-1596
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Law
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1436-3771
    Keywords: Key words Dentine ; enamel junction ; Odontoblast processes ; Dentinal tubules ; Confocal laser scanning microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The translucency of teeth allows the non-destructive subsurface visualisation of their microstructure by confocal laser scanning microscopy (CLSM) at a level of about 150 μm below the surface. The dentine–enamel junction (DEJ) is accessible only directly adjacent to the cervix of the tooth. Therefore teeth have to be sectioned for studying marginal areas of the dental hard tissue. The potential of the technique for (pseudo) three-dimensional visualisation allows the study of an array of individual confocal images, the interpretation of which is similar to that of macroscopic tomographs (CT-scan, MRI). Additionally, the extended focus mode yields the overlay of individual confocal images in the form of a two-dimensional projection. This mode of operation proved to be particularly suited for the visualisation of odontoblast processes in their whole extension. The three-dimensional junction between enamel and dentine, the branches of the odontoblast processes and their interactions with the DEJ is demonstrable by CLSM without staining or other procedures of sample preparation. The direct microscopic comparison between samples, either fresh or kept in a humid chamber, and Technovit-embedded sample blocks gives evidence that the risk of artefacts by sample storage or by the embedding procedure is minimal. The tomographs limited to subsurface areas of the tissue also exclude mechanical surface artefacts due to grinding or cutting.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Clinical oral investigations 2 (1998), S. 73-76 
    ISSN: 1436-3771
    Keywords: Key words Inferior alveolar nerve ; Complications ; Endodontic treatment ; Surgical therapy ; Apicectomia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Overextension of filling material into the mandibular canal after root treatment in the lower jaw is a rare but serious complication. Mechanical compression, chemical neurotoxicity and local infection may cause irreversible nerve damage. A report on 11 patients with neurological complaints of the inferior alveolar nerve after endodontic treatment is summarised. The neurological findings are dominated by hypaesthesia and dysaesthesia. Half of the patients reported pain. Hyperaesthesia is found much more rarely. Nearly all the patients had a combination of one or more symptoms. Initial X-rays showed root filling material in the area of the mandibular canal. Nine cases were treated with apicectomy and decompression of the nerve; in two cases, extraction of the tooth was necessary. Only one patient reported persistent pain after surgery. If neurological complaints appear after root filling in the lower jaw, a nerve injury due to root filling material should be ruled out. In cases of overfilling, immediate apicectomy and decompression of the nerve with conservation of the tooth is often the treatment of choice; the tooth may be preserved and the best chance of avoiding permanent nerve damage is provided.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Mund-, Kiefer- und Gesichtschirurgie 2 (1998), S. 141-145 
    ISSN: 1434-3940
    Keywords: Schlüsselwörter Konfokale Laser-Scanning-Mikroskopie ; Knochen ; Histotomographie ; Key words Confocal laser scanning microscopy ; Bone ; Histotomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Objectives: Fixation (formalin), decalcification (sections) or mechanical treatment (grinding) all bear the risk of artifacts occurring during hard-tissue histology. Because studies on the etiology of pathological changes mostly focus on subclinical lesions, artifacts can simulate early changes or even be superimposed on existing changes. The objective of this study was to determine how artifacts can be reduced. Material and methods: In confocal laser scanning microscopy (CLSM) a focused laser beam scans the surface of the specimens and penetrates into the tissue. The intensity of the remitted light is recorded. The confocal effect is due to an extremely small aperture (pinhole), excluding light from out-of-focus planes of the sample. By stepwise movement of the object table, a tomographic series of tomographic images is obtained. Sound cortical bone samples of the lower jaw (n = 20) were studied by light microscopy and by CLSM, visualizing identical areas of a ground sectioned sample after H & E staining. Additionally, embedded and fresh blocks of tissue of the same bone sample were studied histotomographically in the CLSM. Results: (1) Light microscopic micromorphology of cortical bone can be visualized adequately in the CLSM; (2) many structures that can be visualized by light microscopy only after special staining (e.g., osteozyte processes) can be visualized by the CLSM using sample blocks without pretreatment. Conclusion: (1) Nondestructive subsurface histotomography by CLSM totally excludes mechanical artifacts; (2) physicochemical artifacts can be handled more easily because fresh samples can be studied; (3) pseudo-three-dimensional imaging allows histological interpretation of the tissue that is equivalent to macroscopic tomographic techniques (CT, MRT).
    Notes: Durch Fixierung (Formalin), Entkalkung (Schnitte) oder mechanische Bearbeitung (Schliffe) besteht bei der Hartgewebshistologie das Risiko physikalisch-chemischer oder mechanischer Artefakte. Da Studien zur Ätiopathogenese pathologischer Veränderungen meist auf subklinische Läsionen zielen, besteht die Gefahr, daß Artefakte frühe Veränderungen vortäuschen oder vorhandene überdecken. Es wird der Frage einer artefaktminimierten Histologie nachgegangen. Bei der konfokalen Laser-Scanning-Mikroskopie (CLSM) rastert ein monochromatischer Laserstrahl über die Probenoberfläche und dringt in das Gewebe ein. Die Intensität der remittierten Strahlung wird in einem Detektor gemessen. Durch eine konfokale Blende (pinhole) erreicht nur Laserlicht aus einer extrem dünnen In-Fokus-Ebene den Detektor, so daß schrittweises Bewegen des Objekttischs eine tomographische Serie von Einzelbildern visualisiert. Gesunde kortikale Knochenproben des Unterkiefers (n = 20) wurden durchlichtmikroskopisch und im CLSM untersucht: Dabei wurden identische Probenareale an Dünnschliffen nach HE-Färbung visualisiert. Außerdem wurden eingebettete und frische Gewebeblöcke derselben Knochenproben im CLSM histotomographiert. Als Ergebnisse wurden gefunden: 1. Lichtmikroskopische Mikromorphologie kortikalen Knochens ist im CLSM valide visualisierbar. 2. Viele lichtmikroskopisch erst nach Spezialfärbungen darstellbare Strukturen (z.B. Osteozytenfortsätze) können im CLSM an Probenblöcken ohne Vorbereitung mikroskopiert werden. Hieraus können folgende Schlußfolgerungen gezogen werden: 1. Die zerstörungsfreie Histotomographie des CLSM unter der Probenoberfläche vermeidet mechanische Artefakte völlig. 2. Physikalisch-chemische Artefakte werden kontrollierbar, da auch frische Proben mikroskopiert werden können. 3. Die pseudo-dreidimensionale Darstellung erlaubt eine histologische Gewebeinterpretation, die makroskopischen Schichtbildverfahren (CT, MRT) vergleichbar ist.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Mund-, Kiefer- und Gesichtschirurgie 3 (1999), S. 12-16 
    ISSN: 1434-3940
    Keywords: Schlüsselwörter Gaumennahterweiterung ; Distraktionsosteogenese ; Osteotomie ; Atemwegsdiagnostik ; Reflexionsakustische Meßverfahren ; Key words Rapid palatal expansion ; Acoustic impedance tests ; Distraction osteogenesis ; Airway diagnosis ; Maxillary surgery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Objective: To investigate nasal airway changes through transverse maxillary distraction osteogenesis by means of an objective, reliable, non-invasive investigation technique with special attention to nasal valve changes and widening of the posterior maxilla. Patients and intervention: Eight patients with a severe maxillary transversal deficit underwent surgically assisted rapid palatal expansion in local or general anesthesia. Before and after the distraction process, a transnasal series of acoustic measurements of nasal airway profile was performed under topical decongestion. Nasal volume was calculated by integration of the area profile. The cross-sectional area of the nasal valve was also determined. Results: A significant enlargement of nasal volume was recorded in all patients (P 〈 0.01: Wilcoxon signed rank test). The average increase measured 5 cm3 (23%). The increase in volume was recorded in all parts of the nasal cavity, indicating complete maxillary expansion even in the posterior segment. The nasal valve area raised from 0.56 to 0.70 cm2 (P 〈 0.01). Six out of eight patients reported striking improvement of nasal patency after maxillary distraction. Conclusion: Besides correction of the maxillary arch deformity, rapid palatal expansion contributes to improved nasal patency by resolving nasal valve constriction. Significant widening of the posterior nasal cavity was achieved, indicating a translational pattern of maxillary movement, although the pterygomaxillary junction was not touched in the osteotomy.
    Notes: Fragestellung: In dieser Untersuchung sollten die Auswirkungen der transversalen Distraktion des Oberkiefers auf den nasalen Atemweg durch ein nichtinvasives Untersuchungsverfahren beschrieben werden. Es wird damit untersucht, ob die chirurgische Gaumennahterweiterung eine Weitung auch der posterioren Oberkieferbasis erreicht und durch Vergrößerung des Nasenklappenquerschnitts eine Normalisierung der nasalen Ventilation gelingen kann. Material und Methode: Bei 8 Patienten mit hochgradigem Schmalkiefer wurde eine transversale Distraktion des Oberkiefers vorgenommen. Vor der Osteotomie und nach Abschluß der Distraktion wurde das Querschnittprofil des nasalen Atemwegs unter lokaler Schleimhautabschwellung reflexionsakustisch bestimmt. Nasenvolumina und Querschnittsfläche der Nasenklappe wurden berechnet. Ergebnisse: Bei sämtlichen Patienten konnte eine signifikante Zunahme des Nasenvolumens nachgewiesen werden (p 〈 0,01: Wilcoxon-Paardifferenzentest), im Mittel vergrößerte sich das Nasenvolumen um 5 cm 3 . Die Weitung betraf gleichermaßen den vorderen, den mittleren und den hinteren Nasenabschnitt. Der Querschnitt der Nasenklappe vergrößerte sich signifikant (p 〈 0,01) von 0,56 cm 2 auf 0,7 cm 2 . 6 von 8 Patienten berichteten über eine deutliche subjektive Verbesserung der Nasenatmung. Schlußfolgerung: Neben der Weitung des Zahnbogens schafft die chirurgisch unterstütze Gaumennahterweiterung anatomische Voraussetzungen zur Verbesserung der Nasenatmung am ehesten durch eine Erweiterung der Nasenklappe. Auch ohne Osteotomie der Sutura pterygomaxillaris kann eine signifikante Vergrößerung des posterioren Nasenvolumens erreicht werden. Daher ist eine Translationskomponente des Segmenttransports anzunehmen.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Mund-, Kiefer- und Gesichtschirurgie 3 (1999), S. S125 
    ISSN: 1434-3940
    Keywords: Schlüsselwörter Enossale Implantate ; Mundhöhlenkarzinom ; Implantologische Rehabilitation ; Strahlentherapie ; Key words Dental implants ; Oral and oropharyngeal carcinoma ; Implant-supported prosthodontic rehabilitation ; Radiotherapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary A comparative study was carried out of 276 Brånemark fixtures in the irradiated and nonirradiated anterior mandible with a mean follow-up period of 58.2 months. Postoperative radiotherapy with 60 Gy and 100% isodose for the anterior mandible using a 6-MV linear accelerator, conventional fractioning, and a split-course technique was administered in the irradiated patient group. HBO therapy was not applied. A statistical difference in the 5-year success rate between the irradiated and nonirradiated group was not found. Nevertheless, a significantly higher rate of perioperative soft tissue complications at implant insertion was seen in the irradiated group. The statistical analysis showed no significance for sex, interval between radiation and implant insertion (with a minimun of 10 months), or type of periimplant soft tissue (regional vs. flap). The prognosis for implants in the irradiated mandible was, however, statistically improved (n = 0.0035) when the healing period was longer than 4 months. Mobile periimplant soft tissue proved to be the main problem regardless of radiation load. Late complications have not been observed so far. The available results and clinical studies support a positive assessment of the regenerative potential of the irradiated mandible with regard to osteointegration of endosseous implants. A preceding radiotherapy up to 60 Gy should therefore not be considered as a contraindication for an implant/prosthetic rehabilitation.
    Notes: Zusammenfassung Die vergleichende Untersuchung bezieht sich auf 276 Brånemark-Fixturen im bestrahlten und nicht bestrahlten originären anterioren Unterkiefer bei einer mittleren Verweildauer von 58,2 Monaten. Bei den bestrahlten Patienten war eine postoperative Radiotherapie mit 60 Gy mit einer 100%-Isodose für den anterioren Unterkiefer unter Verwendung eines Linearbeschleunigers (6 MV) bei konventioneller Fraktionierung und Split-course-Technik erfolgt. Eine begleitende Therapie mit hyperbarem Sauerstoff hatte nicht stattgefunden. Eine statistische Differenz für die 5-Jahres-Erfolgsrate zwischen der bestrahlten und nicht bestrahlten Gruppe war nicht nachweisbar. Dennoch zeigte sich für den strahlenbelasteten Unterkiefer eine deutlich höhere Rate an perioperativen Weichteilkomplikationen bei der Implantatinsertion. Die univariate Analyse wies keine Signifikanz für das Geschlecht, das Intervall zwischen Bestrahlung und Implantation (bei einem Mindestintervall von 10 Monaten) sowie die Art des periimplantaren Weichgewebes (ortsständig vs. Lappenersatz) nach. Die Prognose der Implantate im bestrahlten Unterkiefer war jedoch bei Verlängerung der Einheilphase über 4 Monate hinaus statistisch günstiger (p = 0,0035). Als vorrangiges Problem ohne Bezug zu einer etwaigen Strahlenbelastung erwies sich das mobile periimplantäre Weichteillager. Spätkomplikationen sind bislang nicht aufgetreten. Die vorliegenden Ergebnisse und klinischen Studien geben Veranlassung zu einer positiven Einschätzung des regenerativen Potentials des bestrahlten Unterkiefers hinsichtlich einer Osseointegration enossaler Implantate. Eine vorangehende Strahlentherapie bis 60 Gy kann daher nicht mehr als absolute Kontraindikation für eine implantologisch-prothetische Rehabilitation gelten.
    Type of Medium: Electronic Resource
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