International Journal of Computerized Dentistry, 04/2012

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

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

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

Purpose: The intraoral recording of digital images is a critical component of fabricating accurate Cerec restorations. This study evaluated the marginal fit and internal adaptation of Cerec ceramic crowns fabricated using different cameras, alternative powdering materials, and multiple image capture sequences. Materials and Methods: A master epoxy resin model was fabricated using a polyvinylsiloxane (PVS) impression of a typodont with an all-ceramic crown preparation on tooth 14. A titanium dioxide powder/mechanical sprayer and an aerosol contrast spray were used to create a uniformly reflective surface. An infrared laser Cerec 3/RedCam unit and LED Cerec AC/BlueCam unit were used to record images for crown fabrication. Three different image capture sequences were performed to record the data. Crowns were made for each test group using a Cerec AC unit with V3.80 software. The crowns were milled from blocks of IPS EmpressCAD. Marginal fit and internal adaptation of the crowns to the master model of the preparation was assessed with a measuring microscope at 20X. The data was analyzed using a two-way ANOVA. Results: No significant differences were found in the marginal fit, axial wall adaptation, or occlusal wall adaptation between any of the test groups (p 0.05). Conclusion: Within the confines of this in vitro study, there were no significant differences between the marginal fit and internal adaptation of Cerec CAD/CAM ceramic crowns fabricated with: 1) the infrared laser camera (RedCam) and the LED camera (BlueCam), 2) titanium dioxide powder or aerosol contrast spray, or 3) multiple imaging sequences for recording the preparation and adjacent teeth. Keywords: CAD/CAM, Cerec, all-ceramic, marginal fit, internal adaptation