Artifacts In Magnetic Resonance Imaging and Computed Tomography Caused By Dental Materials

BACKGROUND: Artifacts caused by dental restorations, such as dental crowns, dental fillings and orthodontic appliances, are a common problem in MRI and CT scans of the head and neck. The aim of this in-vitro study was to identify and evaluate the artifacts produced by different dental restoration materials in CT and MRI images. METHODS: Test samples of 44 materials (Metal and Non-Metal) commonly used in dental restorations were fabricated and embedded with reference specimens in gelatin moulds. MRI imaging of 1.5T and CT scan were performed on the samples and evaluated in two dimensions. Artifact size and distortions were measured using a digital image analysis software. RESULTS: In MRI, 13 out of 44 materials produced artifacts, while in CT 41 out of 44 materials showed artifacts. Artifacts produced in both MRI and CT images were categorized according to the size of the artifact. SIGNIFICANCE: Metal based restoration materials had strong influence on CT and less artifacts in MRI images. Rare earth elements such as Ytterbium trifluoride found in composites caused artifacts in both MRI and CT. Recognizing these findings would help dental materials manufacturers and developers to produce materials which can cause less artifacts in MRI and CT images

Increasing general dentists’ provision of care to child patients through changes in the undergraduate pediatric dentistry program

Reduced caries rates and an increased percentage of children with dental insurance have made it more difficult for dental schools to provide undergraduates with sufficient numbers of pediatric dental patients requiring restorative procedures. This may result in graduates who are not competent and are reluctant to treat children after graduation. To ensure the quality of the undergraduate clinical training program, the Division of Pediatric Dentistry at the University of Manitoba changed from a comprehensive-based clinic to a block system in 1998–99. Specific communities with limited access to dental care (neighboring core area schools and Hutterite colonies) were specifically targeted as potential sources for child patients. This format increased the exposure of students to patient management as well as to complex pediatric dentistry procedures. To assess the learning experiences before and after the changes to the clinical pediatric dentistry program, sixty general dentists who had graduated from the University of Manitoba were randomly selected using the Manitoba Dental Association Directory. Surveys were sent to twenty general dentists who graduated in each of the following years: 1993, 2000, and 2002. Forty-five dentists responded, fifteen from each of the three surveyed classes. Dentists who graduated after the changes to the program (2000, 2002) reported that they performed a greater number of complex pediatric dentistry procedures and treated more toddler and preschool children than the group that graduated before the changes (1993). Referrals to pediatric dentistry specialists were higher in the 1993 group than in the 2000 and 2002 groups. In conclusion, an adequate pool of pediatric patients is critical to provide dental students with sufficient learning experiences. The dentists who graduated from the program after the changes were implemented are providing more comprehensive treatment to younger children.Predrag-Charles Lekic, Natalie Sanche, Olva Odlum, Johann deVries and William A. Wiltshir

An ex vivo study exploring the diagnostic potential of \ub9H magnetic resonance spectroscopy in squamous cell carcinoma of the head and neck region

NRC publication: Ye

Maximum intensity projection of cranial computed tomography data for dental identification

Dental radiographs play the major role in the identification of victims in mass casualties besides DNA. Under circumstances such as those caused by the recent tsunami in Asia, it is nearly impossible to document the entire dentition using conventional x-rays as it would be too time consuming. Multislice computed tomography can be used to scan the dentition of a deceased within minutes, and the postprocessing software allows visualization of the data adapted to every possible antemortem x-ray for identification. We introduce the maximum intensity projection of cranial computed tomography data for the purpose of dental identification exemplarily in a case of a burned corpse. As transportable CT scanners already exist, these could be used to support the disaster victim identification teams in the field