PubMed ID (PMID): 23457898Pages 271-286, Language: English, GermanKaeppler, Gabriele / Mast, Gerson
The aim of this study was to identify specific indications for dental cone-beam computed tomography (CBCT) in the field of oral and maxillofacial surgery. To this end, we compared the efficacy of CBCT to that of panoramic radiography, the standard imaging modality, for the evaluation of different surgical questions in the oral and maxillofacial region. Dental CBCT proved to be particularly useful in cases where visualization of a second plane is necessary for implant planning or for pre-surgical evaluation of retained and displaced teeth posing a risk to adjacent structures. It is also indicated for precise localization of luxated teeth and dental implants dislocated into surrounding areas, localization of the mandibular canal to assess its anatomical relationship to overfilled root canal filling materials, assessment of the extent of osseous lesions, and evaluation of patients with suspected mandibular or condylar fractures. The main advantages of CBCT are reduction of the risks of surgery due to the free selection of imaging planes, mandibular canal marking, 1:1 magnification, and the ability to use DICOM data in other implant or surgical planning software. Adequate user experience is important for proper evaluation of dental CBCT scans, as is the diagnosis of incidental findings falling into areas not primarily related to dentistry and therefore requiring additional investigation.
Keywords: Dental cone-beam computed tomography, dental volume tomography, oral and maxillofacial surgery, cone beam CT, volume CT
PubMed ID (PMID): 23457899Pages 287-296, Language: English, GermanNeller, Heiner / Geibel, Margrit-Ann
Purpose: To test for differences in image quality between 3D volumetric datasets acquired by cone beam computed tomography (CBCT) with and without simulation of head motion by visual analysis of individual image sections and by comparison of scan-based distance and Hounsfield unit (HU) measurements.
Materials and Methods: A total of 200 volumetric datasets were acquired with and without remote-controlled, simulated movement of a human cadaver head using the KaVo 3D eXam CBCT system.
Results: The "Landscape 8 x 8 cm Slide" mode provided a sufficient field of view at a low radiation dose. All datasets showed reproducible results. Our analysis showed that the level of image quality and image detail increased with increasing resolution. Linear distance measurements and HU measurements in the cone beam CT scans acquired without simulation of head motion were absolutely comparable to those obtained with head motion simulation.
Conclusions: There is no practical difference in image quality between CBCT scans acquired with and without head motion if no long-term change in head position occurs during the acquisition process. Slight head movement has no clinically relevant effect on the geometric accuracy or visual image quality of cone beam CT scans.
Keywords: Cone beam computed tomography, motion artifact, head motion, distance measurement, Hounsfield unit, image quality
PubMed ID (PMID): 23457900Pages 297-314, Language: English, GermanHugger, Sybille / Schindler, Hans J. / Kordaß, Bernd / Hugger, Alfons
Based on a comprehensive computerized literature search supplemented by a specific manual search of the literature, the present review article focuses on concrete aspects of the application of surface electromyography (EMG) for evaluation of the masticatory muscles in general and of the masseter and anterior temporal muscles in particular, and presents the current base of knowledge on the clinical relevance of surface EMG in dental applications. In the first stage of the review, publications from the year 2000 or later reporting the results of controlled clinical trials (randomized as far as available) of patients with craniomandibular or temporomandibular disorders (TMD) were analyzed. Data from the selected publications were systematically compiled and divided into subject areas as follows: Resting activity, maximal and sub-maximal voluntary contraction, symmetry of EMG activity, and fatigue effects; EMG activity during mastication, factors (including pain) that affect EMG activity, and the impact of adjusting static and dynamic occlusal relationships; Effects of occlusal splints and other occlusal treatments. Surface electromyography is in principle a suitable tool for neuromuscular function analysis in the field of dentistry. If used according to the specific recommendations and in conjunction with a thorough and conscientious clinical history and physical examination, surface EMG measurements can provide objective, documentable, valid, and reproducible data on the functional condition of the masticatory muscles of an individual patient.
Keywords: electromyography, review, chewing, masticatory muscles, fatigue, maximal voluntary contraction, symmetry, resting activity, splint therapy, oral rehabilitation
PubMed ID (PMID): 23457901Pages 315-326, Language: English, GermanCook, Kevin T. / Fasbinder, Dennis J.
Studienzweck: Das Anfertigen intraoraler Digitalaufnahmen bildet einen wesentlichen Schritt bei der Herstellung von passgenauen Cerec-Kronen. Gegenstand der vorliegenden Studie war die Rand- und Innenpassung von Cerec-Keramikkronen, die unter Anwendung verschiedener Kameras, Pudermaterialien und Sequenzen der Bilderfassung hergestellt wurden.
Material und Methode: Es wurde ein Typodontmodell für eine Vollkeramikkrone am präparierten Zahn 26 in Polyvinylsiloxan abgeformt. Auf dieser Basis erfolgte anschließend die Herstellung eines Meistermodells aus Epoxidharz. Um eine gleichmäßig reflektierende Oberfläche zu erhalten, wurde entweder durch eine mechanische Sprühvorrichtung ein Titanoxidpuder oder aber ein Aerosol-Kontrastspray appliziert. Die Bildaufnahmen zur Herstellung der Kronen erfolgten mit der Infrarot-Laserkamera (RedCam) des Systems Cerec 3 oder der LED-Kamera (BlueCam) des Systems Cerec AC. Dabei wurden drei verschiedene Sequenzen der Bilderfassung angewendet. Zur Herstellung der Kronen in den einzelnen Prüfgruppen diente ein Cerec AC mit V3.80- Software. Die Kronen wurden aus Blöcken des Typs IPS Empress CAD gefräst, Rand- und Innenpassung der Kronen mit einem Messmikroskop bei 20-facher Vergrößerung auf dem Meistermodell der Präparation beurteilt. Die Datenauswertung erfolgte per Zweiweg-Varianzanalyse.
Ergebnisse: Die Prüfgruppen zeigten keine signifikanten Unterschiede im Randschluss oder in der Passung der axialen und okklusalen Kronenränder (p < 0,05).
Schlussfolgerung: Die ausgewerteten Varianten zur Herstellung der Cerec-Keramikkronen in CAD/CAM-Technik umfassten 1) eine Infrarot- oder eine LED-Kamera (Red- Cam/BlueCam), 2) Titandioxidpuder oder ein Aerosol- Kontrastspray sowie 3) unterschiedliche Bilderfassungssequenzen für die Präparation und die Nachbarzähne. Innerhalb der Einschränkungen dieser In-vitro-Studie zeigten die Kronen in den Prüfgruppen keine signifikanten Unterschiede hinsichtlich der Rand- und Innenpassung.
Keywords: CAD/CAM, Cerec, vollkeramischer Zahnersatz, Randpassung, Innenpassung