Alan G. Lurie

Imaging of the temporomandibular joint: a position paper of the American Academy of Oral and Maxillofacial Radiology.

Various imaging techniques for the temporomandibular joint are discussed with respect to uses, strengths, and limitations. An imaging protocol is outlined for evaluating patients with a wide variety of temporomandibular joint related signs and symptoms.

Dosimetry and cost of imaging osseointegrated implants with film-based and computed tomography

Thermoluminescent dosimeters were used to measure radiation doses at craniofacial sites in a tissue-equivalent phantom during film-based multidirectional tomography with the Tomax Ultrascan (Incubation Industries, Ivyland, Pa.) and during computed tomography with the Elscint Excel 2400 (Elscint Corp., Tel Aviv, Israel). Mean absorbed doses for presurgical mandibular and maxillary canine and molar implant assessments were converted to equivalent doses, which were then multiplied by published weighting factors and summed to give effective doses. The computed tomography device consistently delivered higher doses than the Tomax Ultrascan to all anatomic locations; the differences were most pronounced when only one or two implant sites were evaluated. The reasons for the dose disparities are considered both anatomically and procedurally. A survey of examination cost revealed film-based multidirectional tomography to be less expensive than computed tomography.

Subtraction radiology demonstrates crestal bone loss in experimentally induced marginal periodontitis.

The potential diagnostic usefulness of subtraction radiology in dentistry was evaluated by means of an experimental model of marginal periodontitis in cynomolgus monkeys. Beam-guiding, field-limiting, intraoral radiographic instruments were modified to allow construction of appliances which yielded repeatable superimposable radiographic images during the course of a 16-week study. Marginal periodontitis was induced in monkeys by means of circumferential silk sutures tied around mandibular second molar and second premolar cementoenamel junctions, and serial radiographs were taken at weekly intervals for 16 weeks. Control subtraction masks were made from pretreatment radiographs, and bone loss was evaluated by means of elapsed-time films to give the subtraction prints. The subtraction films clearly showed increasing bone loss with time and were produced easily with size O dental films. This technique appears to have considerable potential usefulness in the evaluation of bone-density changes in experimental models of dental diseases as well as in the clinical setting.

Dependence of the Mutation Spectrum in a Shuttle Plasmid Replicated in Human Lymphoblasts on Dose of Gamma Radiation

The frequencies and types of mutations induced in the target gene, supF-tRNA, of the shuttle vector pZ189 were analysed following the replication of the gamma-irradiated plasmid in the human lymphoblastoid cell line, GM606. The mutation frequency measured in progeny of unirradiated pZ189 was 1.02 x 10(-4), increasing to 17.5 x 10(-4) at 1000 cGy, and to 63.4 x 10(-4) at 5000 cGy, approximately 17- and 62-fold over background levels, respectively. Simultaneously, the number of plasmids capable of replicating in Escherichia coli decreased with increasing radiation dose to 4% of the control value at 5000 cGy. Electrophoresis of the irradiated DNA showed a correlation between increases in mutation frequency and decreases in plasmid survival, and the formation of open-circular and linear DNA. The majority of the spontaneous (69.8%) and induced mutations (85.7%) at 1000 and 79.4% at 5000 cGy) were base substitutions and were generally of similar types among all groups. However, changes at 2500 (12.7%) and 5000 cGy (13.2%) involving A:T base pairs were greater than those in unirradiated controls (3.4%) or those at 1000 cGy (2.0%). This increase in A:T base pair mutations could be a result of reduced repair fidelity when the DNA is extensively damaged by high doses of ionizing radiation.

Radionuclide bone imaging in the surgical treatment planning of odontogenic keratocysts

Locally aggressive benign lesions of the jaws, such as odontogenic keratocysts and ameloblastomas, require complete excision in view of the high incidence of recurrence after incomplete surgical removal. Because of the limitations of conventional radiology as the sole technique for determining the extent of these lesions, the use of 99m-technetium-labeled bone-imaging agents is suggested. This method of defining the location of surgical margins is based on the agents sensitivity as an indicator of subtle changes in bone metabolism. A case of an unusually large recurrent odontogenic keratocyst is presented in which the planning of the surgical procedure was predicated on the results of a bone scan of the jaws in addition to conventional radiology. This diagnostic procedure, especially when used in conjunction with conventional radiology, appears to be of considerable value in defining the extent of a variety of oral-maxillofacial bony lesions.

The Image Gently in Dentistry campaign: promotion of responsible use of maxillofacial radiology in dentistry for children

© 2014 Published by Elsevier Inc. The Image Gently in Dentistry campaign to be launched in September 2014 is a specific initiative of the Alliance for Radiation Safety in Pediatric Imaging, supported by organized dentistry and dental education as well as many dental specialty organizations. The objective of the campaign is to change practice by increasing awareness of the opportunities to improve radiation protection when imaging children in dental practices. Six practical steps are provided that underline the principle that one size does not fit all, especially when it comes to using radiography during pediatric dental procedures. When we image children, let us image gently: More is often not better.

The Effects of Age on Radiation Resistance and Oxidative Stress in Adult Drosophila melanogaster

Abstract Parashar, V., Frankel, S., Lurie, A. G. and Rogina, B. The Effects of Age on Radiation Resistance and Oxidative Stress in Adult Drosophila melanogaster. Radiat. Res. 169, 707–711 (2008). Drosophila melanogaster (fruit fly) is a well-established model organism for genetic studies of development and aging. We examined the effects of lethal ionizing radiation on male and female adult Drosophila of different ages, using doses of radiation from 200 to 1500 Gy. Fifty percent lethality 2 days postirradiation (LD50/2) in wild-type 1-day-old adult fruit flies was ∼1238 Gy for males and 1339 Gy for females. We observed a significant age-dependent decline in the radiation resistance of both males and females. Radiation damage is postulated to occur by the generation of oxygen radicals. An age-related decline in the ability of flies to resist an agent that induces oxygen radicals, paraquat, was observed when comparing 10- and 20-day adults. Female flies are more resistant to paraquat than male flies. Oxidative stress mediated by paraquat was additive with sublethal exposures to radiation in young adults. Therefore, the ability to repair the damage caused by oxygen radicals seems to decline with the age of the flies. Because Drosophila adults are largely post-mitotic, our data suggest that adult Drosophila melanogaster can serve as an excellent model to study the factors responsible for radiation resistance in post-mitotic tissue and age-dependent changes in this resistance.

Enhancement of DMBA tumorigenesis in hamster cheek pouch epithelium by repeated exposures to low-level X radiation.

Duplicate studies were conducted to determine the effects of repeated exposures to low-level X radiation on the incidence, volume, and latent period of DMBA-induced neoplasms in Syrian hamster cheek pouch epithelium. Doses employed were 0.05 ml of 0.1% 7,12-dimethylbenz[a]anthracene (DMBA) in mineral oil twice weekly for 10 weeks and 20-R head and neck X radiation once weekly for 17 weeks. Animals received either radiation alone, DMBA alone, or simultaneous radiation + DMBA beginning together. Appropriate controls were performed. Radiation alone did not result in any detectable pathology. In one study, the incidence (68 vs 40%) and volumes of tumors were significantly greater in animals receiving radiation + DMBA than in animals receiving DMBA alone. The latent period for earliest tumor appearance was shorter in animals receiving radiation + DMBA than in animals receiving DMBA alone (9 weeks vs 24 weeks). In the repeat study, increased tumor incidence in the radiation + DMBA group was again observed, but ...

Mutation spectrum in γ-irradiated shuttle vector replicated in ataxia-telangiectasia lymphoblasts

Cells from ataxia-telangiectasia (AT) patients are hypersensitive to the lethal effects of ionizing radiation. To assess radiation mutagenesis in these cells, the SV40-based shuttle vector, pZ189, was used to analyze gamma-ray-induced mutations following the plasmids replication in AT lymphoblasts. Progenies from the AT line GM2783 exposed to 50 Gy showed a mutation frequency of 7.6 x 10(-3), 63-fold over background; surviving plasmids were 3.4% of control. Both values were essentially the same as those of irradiated plasmids replicated in a normal lymphoblast line, GM606. In addition, pZ189 exposed to 25 Gy of gamma radiation and replicated in another normal lymphoblast line and in cells of two additional AT lymphoblast lines showed similar mutation frequencies and percentages of surviving plasmids. Qualitative comparison of plasmid mutations from AT and normal cells showed no significant differences, indicating that the damaged DNA was repaired with similar fidelity in AT and normal cells. These studies suggest that there is no correlation between the enhanced sensitivity of AT cells to killing by ionizing radiation and gamma-radiation-induced mutagenesis of plasmid DNA processed in these cells.

Cone beam CT analysis of Haller cells: prevalence and clinical significance.

OBJECTIVES Haller cells are anterior ethmoid air cells located in the medial orbital floor immediately lateral to the maxillary infundibulum. The purpose of this study was to demonstrate the prevalence and relationship between the existence and size of these cells with ipsilateral maxillary sinusitis and orbital floor dehiscence as visualized on cone beam CT (CBCT) images. METHODS CBCT image volumes of 50 patients were retrieved and analysed. All CBCT images were acquired with a 9-inch field of view scan. χ(2) and Cochran-Mantel-Haenszel tests were used for statistical analysis of the obtained data, and p-values of <0.05 were considered to be statistically significant. RESULTS There was no statistically significant association between the existence and size of Haller cells and maxillary sinusitis. There was a significant association between Haller cells and orbital floor dehiscence. CONCLUSIONS The explanation of maxillary sinusitis on the basis of mechanical obstruction is unlikely. This study provides evidence for the usefulness of CBCT scan in delineation of the sinonasal anatomy.