Can modifying shielding,field of view,and exposure settings make the effective dose of a cone-beam computed tomography comparable to traditional radiographs used for orthodontic diagnosis?

ObjectivesTo analyze the effect of changes in exposure settings, field of view (FOV), and shielding on radiation to an adult and child phantom from cone-beam computed tomography (CBCT) imaging compared to panoramic and lateral cephalometric radiographs.Materials and MethodsThe effective dose to an adult and child anthropomorphic phantom by the CS 9300 using various scan protocols was recorded. Absorbed radiation was measured with optically stimulated luminescence dosimeters and effective dose calculated using 2007 International Commission on Radiological Protection tissue weighting factors. Scan protocols included different FOVs, voxel sizes, and standard versus low-dose protocols. Radiation shielding was used when it did not interfere with FOV. Panoramic and lateral cephalometric radiographs were taken with the Orthophos SL.ResultsEven with shielding, smaller FOVs, and increased voxel sizes, the effective dose of standard CBCT scans was higher than panoramic and lateral cephalometric radiographs. A shielded limited FOV standard scan combined with a lateral cephalometric radiograph resulted in a lower dose (P < .001) than a full FOV standard scan. Low-dose shielded scans resulted in significant dose reductions to the adult (P < .05) and child (P < .001) phantoms compared to the respective panoramic and lateral cephalometric radiographs combined. Image quality analysis was not possible with radiation equivalent phantoms.ConclusionsUnlike standard CBCTs, shielded low-dose CBCT protocols in the CS 9300 have lower effective doses than conventional radiographs for adult and child phantoms. If high resolution and cranial base visualization are necessary, combining a shielded LFOV standard exposure with a cephalometric radiograph is recommended.     

Association between students' dental admission test scores and performance on comprehensive clinical exams

This study examined the association between Dental Admission Test (DAT) scores and the comprehensive exams conducted at Harvard School of Dental Medicine. The authors hypothesized that students who scored high on the DAT would also perform well on the comprehensive examinations. Sixty-six students from the graduating classes of 2005 and 2006 were included. The outcome variable of interest was the final composite grade obtained by the students in the three comprehensive examinations. The main independent variable of interest was the individual component scores on the DAT. Multivariable logistic regression analysis using the maximum likelihood methods was used to examine the association between comprehensive exam grades and DAT scores. Effects of age, gender, and race/ethnicity were adjusted in the regression models. On the first comprehensive examination, seventeen students obtained an Honors grade, while thirteen did so on the second comprehensive examination and fifteen on the third comprehensive examination. None of the DAT component scores were significantly associated with Honors grades on the first comprehensive examination. On the second comprehensive examination, quantitative reasoning scores (OR=2.48, 95 percent CI=1.09-5.68, p=0.03) and total science scores (OR=14.17, 95 percent CI=1.89-106.80, p=0.01) were significantly associated with Honors grades. Reading comprehension score was associated with increased odds of obtaining Honors grade on the third comprehensive examination (OR=1.81, 95 percent CI=1.13-2.92, p=0.01). Students who scored well on the quantitative reasoning, total science, and reading comprehension sections of the DAT had higher odds of receiving an Honors grade on the second and third comprehensive examinations. These factors may be associated with the problem-solving/critical thinking components in the school's PBL curriculum.     

Interleukin‐1 Gene Polymorphisms and Chronic Periodontitis in Adult Whites: A Systematic Review and Meta‐Analysis

Background: Interleukin‐1 (IL‐1) gene polymorphisms have been associated with increased levels of inflammatory mediators and several inflammatory diseases. Periodontitis is a bacterially induced chronic inflammatory disease that destroys the connective tissues and bone that support the teeth, affects substantial numbers of adults, and has been implicated as a contributing factor in systemic diseases. IL‐1 gene polymorphisms, most prominently IL1A (?889), IL1A (+4845), and IL1B (+3954), have been associated with chronic periodontitis (CP) in whites. Since the first report, ≥125 studies have examined IL‐1 gene variation in relation to periodontal disease. These studies have produced mixed findings in diverse periodontal phenotypes and in different ethnic groups. One previous meta‐analysis has been published on this topic and supported an association between IL‐1 genes and periodontitis, but considerable doubt remains about the patient populations in which the association may be of clinical relevance. Methods: A systematic review and meta‐analysis was conducted in an attempt to clarify whether IL‐1 gene variants were associated with well‐defined clinical phenotypes of CP in white patients. Study inclusion criteria focused on the analytic framework originally proposed for the IL‐1 genetic effect in which overexpression of inflammatory mediators is hypothesized to result in more severe periodontitis in response to a bacterial challenge. Results: Twenty‐seven studies were included in the qualitative analysis. Nineteen studies yielded significant associations between carriage of the minor IL‐1 alleles and periodontitis. The meta‐analysis, based on 13 qualifying studies, found significant effects for the two individual gene variations (IL1A odds ratio [OR] = 1.48; IL1B OR = 1.54) and for a composite genotype that combines minor alleles at each locus (OR = 1.51). Statistically significant heterogeneity was found that could not be explained, but there was no indication of publication bias. Conclusion: This review and meta‐analysis show that IL1A and IL1B genetic variations are significant contributors to CP in whites.