Evaluation of radiation exposure with Tru-Align intraoral rectangular collimation system using OSL dosimeters.

A pilot study to compare radiation exposure with the Tru-Align rectangular collimation system to round collimation exposures was undertaken. Radiation exposure at various points within the cross sections of the collimators and entrance, intraoral and exit dose measurements were measured using InLight OSL dosimeters. Overall dose reduction with the use of the rectangular collimation system was estimated by taking into account the ratios of collimator openings and the average radiation exposure at the measurement points. Use of the Tru-Align system resulted in an average radiation exposure within the perimeter of the projected outline of the rectangular collimator of 36.1 mR, compared to 148.5 mR with the round collimator. Our calculations indicate a dose reduction by a factor of approximately 3.2 in the case of the Tru-Align system compared to round collimation. The Tru-Align system was easy to use, but in some situations failed to allow Xray coverage of the entire surface of the image receptor, leading to cone cuts.

Guidelines for oral and maxillofacial imaging: COVID-19 considerations.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus causing the current coronavirus disease 2019 (COVID-19) pandemic, is not only highly infectious but can induce serious outcomes in vulnerable individuals including dental patients and dental health care personnel (DHCPs). Responses to COVID-19 have been published by the Centers for Disease Control and Prevention and the American Dental Association, but a more specific response is required for the safe practice of oral and maxillofacial radiology. We aim to review the current knowledge of how the disease threatens patients and DHCPs and how to determine which patients are likely to be SARS-CoV-2 infected; consider how the use of personal protective equipment and infection control measures based on current best practices and science can reduce the risk of disease transmission during radiologic procedures; and examine how intraoral radiography, with its potentially greater risk of spreading the disease, might be replaced by extraoral radiographic techniques for certain diagnostic tasks. This is complemented by a flowchart that can be displayed in all dental offices.

Genomic organization and allelic expression of UBE3A in chicken.

UBE3A, the gene associated with Angelman syndrome, is part of a cluster of genes in the human chromosome 15q11-q13/mouse chromosome 7C region, that is subject to genomic imprinting. In human and mouse brain, UBE3A is expressed predominantly from the maternal allele, and the paternal allele is silenced. A current model concerning the evolution of genomic imprinting, the parental conflict hypothesis, posits that this epigenetic phenomenon is restricted to eutherian mammals. It has been recently reported, however, that several chicken orthologues of mammalian imprinted loci display DNA replication asynchrony, a property of imprinted genes. A separate group also reported monoallelic expression of chicken IGF2 in developing chicken embryos. These observations could suggest that genomic imprinting may occur in chicken. We have assembled the predicted mRNA consensus sequence for the chicken UBE3A gene using published ESTs. We report a high degree of homology with the human UBE3A at the nucleotide and protein levels, as well as a highly conserved genomic organization. Biallelic expression of UBE3A is observed in embryonic chicken brain and limb, indicating that UBE3A is not subject to genomic imprinting in chicken.

Generation of intra-oral-like images from cone beam computed tomography volumes for dental forensic image comparison.

UNLABELLED: Identification of unknown individuals using dental comparison is well established in the forensic setting. The identification technique can be time and resource consuming if many individuals need to be identified at once. Medical CT (MDCT) for dental profiling has had limited success, mostly due to artifact from metal-containing dental restorations and implants. DESCRIPTION: The authors describe a CBCT reformatting technique that creates images, which closely approximate conventional dental images. METHOD: Using a i-CAT Platinum CBCT unit and standard issue i-CAT Vision software, a protocol is developed to reproducibly and reliably reformat CBCT volumes. The reformatted images are presented with conventional digital images from the same anatomic area for comparison. CONCLUSION: The authors conclude that images derived from CBCT volumes following this protocol are similar enough to conventional dental radiographs to allow for dental forensic comparison/identification and that CBCT offers a superior option over MDCT for this purpose.

Evolution of a humanitarian dental mission to Madagascar from 1999 to 2008.

In this article, we report on the evolution of a series of dental outreach missions sponsored by Stony Brook University to remote areas of Madagascar over a nine-year period. The project evolved from one dental resident performing only dental extractions in 1999 to a team comprised of two dentists, six third-year dental students, and two dental assistants performing dental restorations, extractions, and endodontic procedures using digital radiographic equipment in 2008. The ability during the latest mission to utilize digital radiography in remote areas lacking running water, electricity, and dental facilities significantly enhanced the range and efficacy of dental procedures. This long-term project offered senior dental students and residents from Stony Brook University's School of Dental Medicine an educationally valuable opportunity to engage in international dental outreach and to make a significant contribution to the improvement of oral health in the underserved rural communities of Madagascar.

Comparison of the efficacy and technical accuracy of different rectangular collimators for intraoral radiography.

OBJECTIVE: The objective of this study was to compare the operating efficiency and technical accuracy of 3 different rectangular collimators. STUDY DESIGN: A full-mouth intraoral radiographic series excluding central incisor views were taken on training manikins by 2 groups of undergraduate dental and dental hygiene students. Three types of rectangular collimator were used: Type I ("free-hand"), Type II (mechanical interlocking), and Type III (magnetic collimator). Eighteen students exposed one side of the manikin with a Type I collimator and the other side with a Type II. Another 15 students exposed the manikin with Type I and Type III respectively. Type I is currently used for teaching and patient care at our institution and was considered as the control to which both Types II and III were compared. The time necessary to perform the procedure, subjective user friendliness, and the number of technique errors (placement, projection, and cone cut errors) were assessed. The Student t test or signed rank test was used to determine statistical difference (P

Pilot study: digital subtraction radiography as a tool to assess alveolar bone changes in periodontitis patients under treatment with subantimicrobial doses of doxycycline.

BACKGROUND: Subtle changes in marginal alveolar bone level can be demonstrated using digital subtraction of sequential radiographs. OBJECTIVE: We aimed to evaluate the practical application of geometrically corrected digital subtraction in a clinical study of alveolar bone response to a drug previously shown to inhibit alveolar bone loss. STUDY DESIGN: Selected periapical radiographs were acquired with projective standardization of patients with clinical marginal alveolar bone loss. Subsequently, patients received a 6-month regimen of subantimicrobial doxycycline or placebo. Standardized radiographs of the same alveolar regions were acquired after 3 and 6 months, and baseline radiographs were subtracted from these images. RESULTS: Blinded digital subtraction analysis indicated various levels of marginal bone gain in 3 of the 6 patients in the experimental group, whereas in 3 of the 5 placebo patients the method showed bone loss. CONCLUSION: These results suggest that geometrically corrected digital subtraction possibly agrees with clinical predictors of bone loss severity.