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Biomedical subjects

Allan G Farman

Publications and source records attributed to Allan G Farman.

At least 19 recordsLinked to original sources
PubMed2006

Correlation between carotid area calcifications and periodontitis: a retrospective study of digital panoramic radiographic findings in pretreatment cancer patients.

OBJECTIVES: The objective of this study was to examine the prevalence of carotid area calcifications retrospectively detected on digital panoramic radiographs of pretreatment cancer subjects, and to correlate the finding of such calcifications with radiographic evidence of periodontal bone loss in the same subjects. STUDY DESIGN: Digital panoramic radiographs of 201 subjects were evaluated for calcifications projected in the carotid artery bifurcation area as well as for alveolar bone loss as a result of periodontal disease. Inclusion criteria were unobscured carotid artery bifurcation regions bilaterally and sufficient index teeth present with a definable cemento-enamel junction and alveolar crest. Radiographs were independently observed for carotid area calcifications and for periodontal status. Image enhancements permitted for detection of calcifications projected in the carotid area included window/level, inverse, and emboss. Periodontal measurements were made on index teeth using proprietary imaging software and a mouse-driven measurement algorithm. A 3-factor analysis of variance was performed with 3 between-subjects comparisons. Percentage of bone loss was the dependent variable. Independent variables were age, subject sex, and the presence or absence of carotid area calcifications. RESULTS: Differences measured in percentage of bone loss between sexes were not statistically significant. While bone loss did increase with age, comparison of the mean bone loss of each age category revealed no statistical significance. There was a highly significant correlation between carotid artery area calcifications visible on panoramic radiographs and percent alveolar bone loss. Radiographs showing unilateral and bilateral calcifications had a mean percent bone loss of 24.2% +/- 12.6% and 25.7% +/- 13.0% respectively, compared to those with no calcification at 10.4% +/- 9.9%. CONCLUSIONS: Nearly 1 in 4 subjects in this study evidenced calcifications projected in the carotid bifurcation region. The finding of such calcifications was significantly related to the calculated percentage of alveolar bone loss.

Age Factors↗
PubMed2006

Cone beam computed tomographic findings in refractory chronic suppurative osteomyelitis of the mandible.

AIMS: To report the imaging features of osteomyelitis of the mandible in various two-dimensional multiplanar and three-dimensional reformations using cone beam computed tomography (CBCT). METHODS: The images were 12-bit DICOM files acquired with a 10cm field of view and voxel resolution of 0.4mm. Two-dimensional multiplanar reformatted reconstructions included coronal, "panoramic" (variable thickness), and serial cross-sections. Three-dimensional reconstructions included surface renderings. Images were presented to referring oral and maxillofacial surgeons in "real time" immediately after acquisition. RESULTS: The features of mandibular osteomyelitis seen on CBCT included: a peripheral sclerotic rim, cortical layering (involucrum), central loss of trabecular pattern with internal round radiolucent resorptive tracts, minimal jaw expansion, and reduction of the alveolar cortex. Sequestra were occasionally evident. The history and presentation of each case on CBCT were consistent with osteomyelitis of the mandible; however, the clinical differential diagnosis in each case had included malignancy. The definitive diagnosis was confirmed by histological examination of biopsy specimens. Two of the three cases were patients who had been treated with bisphosphonates. CONCLUSION: CBCT facilitated comprehensive and dynamic imaging of the jaws based on surgical consultation, rather than inflexible imaging protocols. CBCT images guided operative planning.

Aged↗
PubMed2006

Effects of imaging system and exposure on accurate detection of the second mesio-buccal canal in maxillary molar teeth.

OBJECTIVES: The objectives of this study were to determine observer ability to detect the second mesio-buccal canal (MB2) in maxillary molars using analog film, CMOS, and photostimulable phosphor x-ray detectors across a wide range of radiation exposures and to determine the optimal exposures for these modalities accurately detecting presence of the MB2. RESEARCH DESIGN: Using 6 experimental models with 2 maxillary molars in each, images were generated with the 3 detector modalities at nominal x-ray beam angulations of 0 degrees and 10 degrees across a range of radiation exposures. Observers independently assessed presence of the MB2 in images presented in random order. Horizontal root sections were then evaluated to determine true MB2 presence. RESULTS: For single images at optimal exposures, the correct number of mesiobuccal canals could be identified 55% of the time for CMOS (RVG 6000), 44% of the time for analog x-ray film (InSight), and 39% of the time for photostimulable phosphor (DenOptix). Statistically significant differences were observed between the imaging modalities (chi2 = 23.4, crucial value = 5.99, P < or = .05). RVG 6000 CMOS outperformed both DenOptix photostimulable phosphor (z score = -5.5) and InSight analog direct exposure x-ray film (z score = 4). Exposure affected the rate of accuracy for MB2 detection across the exposure range tested for RVG 6000 and for film, but not to any appreciable degree for DenOptix. CONCLUSIONS: The CMOS detector (RVG-6000) performed best for evaluating presence of the MB2. This was the only modality to exceed 50% reliability with optimal exposure when single images were considered.

Dental Pulp Cavity↗
PubMed2006

Development of imaging selection criteria and procedures should precede cephalometric assessment with cone-beam computed tomography.

Cone-beam computed tomography (CBCT) systems for craniofacial imaging are now available from several manufacturers. CBCT potentially provides opportunities for 3-dimensional cephalometrics in orthodontic assessment of bony landmarks and air-bounded surfaces such as the facial skin. Two-dimensional cephalogram simulation could facilitate the transfer of growth projections from existing data sets as a starting point for use of a new 3-dimensional paradigm. Three methods are described to simulate conventional 2-dimensional cephalograms from CBCT images and volumetric data sets. However, certain precautions are required to assure that selection criteria and imaging parameters guarantee a radiation dose that is as low as reasonably achievable.

Algorithms↗
PubMed2006

A Cochrane systematic review finds no evidence to support the use of antibiotics for pain relief in irreversible pulpitis.

The Cochrane Systematic Review promotes evidence-based outcomes studies. The review summarized here was conducted in an attempt to achieve reliable evidence concerning the effectiveness, or otherwise, of prescribing antibiotics for patients having irreversible pulpitis. A competent search strategy was developed and used across several databases including MEDLINE to identify randomized controlled trials for inclusion. Assessment of methodological quality was based on criteria defined by The Cochrane Collaboration. Clinical outcome, expressed in terms of pain relief, was examined. There was a relative dearth of research providing a high level of evidence. Only one methodologically sound trial was found that compared pain relief with systemic antibiotic/analgesic treatment against a placebo/analgesic combination during the acute preoperative phase of irreversible pulpitis. Although the selected study used a relatively small, low-powered sample, it did provide some evidence that there is no significant difference in pain relief for patients with untreated irreversible pulpitis who received antibiotics versus those who did not. These findings increase the rationale to investigate the teaching of safe and effective antibiotic prescribing in endodontics and to advance the development of appropriate evidence-based clinical guidelines.

Adult↗
PubMed2006

Clinical applications of cone-beam computed tomography in dental practice.

Cone-beam computed tomography (CBCT) systems have been designed for imaging hard tissues of the maxillofacial region. CBCT is capable of providing sub-millimetre resolution in images of high diagnostic quality, with short scanning times (10-70 seconds) and radiation dosages reportedly up to 15 times lower than those of conventional CT scans. Increasing availability of this technology provides the dental clinician with an imaging modality capable of providing a 3-dimensional representation of the maxillofacial skeleton with minimal distortion. This article provides an overview of currently available maxillofacial CBCT systems and reviews the specific application of various CBCT display modes to clinical dental practice.

Cephalometry↗
PubMed2005

Effects of scintillator on the detective quantum efficiency (DQE) of a digital imaging system.

OBJECTIVE: To compare the effects of scintillator on the detective quantum efficiency (DQE) of a charge-coupled device (CCD) digital intraoral radiographic system. STUDY DESIGN: Three screens composed of 3 different scintillator materials, namely europium-doped lutetium oxide (Lu2(O3):Eu3+), transparent optical ceramic (TOC), thallium-doped cesium iodide (CsI:Tl; CsI), and terbium-doped gadolinium oxysulfide (Gd2(O2)S:Tb; GOS) were compared, in turn, in combination with a CCD detector having square pixels with height and width dimensions of 19.5 microm. DQE was investigated using the slanted-slit-derived MTF and surrogate signal-to-noise ratio (SNR) measurements derived from calculations of the mean and standard deviations from the mean pixel values of multiple random patches from various uniform exposures. An Irix x-ray generator operated at 70 kVp and 8 mA, with a nominal focal spot size of 0.7 mm and 2.5 mm Al equivalent filtration, was used in making all exposures. RESULTS: Using TOC, the peak DQE was 62% at 5 cycles/mm. For CsI, the peak DQE was 22% at 2 cycles/mm. With GOS, the peak DQE was 10% at 1 cycle/mm. CONCLUSION: Under identical experimental settings, TOC consistently resulted in higher DQE than CsI and commercially available GOS scintillators combined with the same high-resolution solid-state detector.

Algorithms↗
PubMed2005

Applying DICOM to dentistry.

There are more than 160,000 dentists licensed in the United States. For the dental patient, the dentist is both radiologist and treating clinician. The American Dental Association (ADA) has been a member of the Digital Imaging and Communication in Medicine (DICOM) Standard Committee since 1996. DICOM v.3 provides image object definitions for digital transmission radiography (Dx) with special categorization for intraoral projections (Io), and it also provides for color photography used in dentistry. Digital dental radiographs include transmission images of the head and jaws, pantomography, tomography and cone-beam computed tomography. In 2000, the ADA resolved to strive for interoperability of digital dental images, using the DICOM Standard as the backbone of the effort. ADA Working Group 12.1 was tasked with development of specifications and also with educating the dental profession concerning digital image interoperability. DICOM-related interoperability demonstrations are now a part of the ADA Annual Congress, in the form of seminar and as a noncommercial exhibit.

American Dental Association↗
PubMed2005

Accuracy of linear temporomandibular joint measurements with cone beam computed tomography and digital cephalometric radiography.

INTRODUCTION: Cone beam computed tomography (CBCT) is making headway into imaging for orthodontics. The purpose of this study was to define CBCT multi-planar reformatted projections for temporomandibular joint (TMJ) examination and compare the accuracy of linear measurements of the TMJ and related structures from these projections with similar measurements made with conventional cephalograms and with the anatomic truth. METHODS: Linear dimensions between 11 anatomical sites were measured with a digital caliper to assess the anatomic truth for 25 dry human skulls. The skulls were imaged with iCAT (Xoran Technologies, Ann Arbor, Mich/Imaging Sciences International, Hatfield, Pa) CBCT, and cephalograms were made in all 3 orthogonal planes (lateral cephalometric [LC], posteroanterior [PA], and submentovertex [SMV]) acquired with photostimulable phosphor plates. Linear measurements were made on 7 custom CBCT reconstructions and the digital cephalograms. Modality means and the natural log of the standard deviations were compared post hoc against the actual dimensions by using analysis of variance with the Dunnett t test. Significance was set at P < .05. RESULTS: All CBCT measurements were accurate; however, 3 of 5 LC measurements, 4 of 5 PA measurements, and 4 of 6 SMV measurements varied significantly from the truth. Intraobserver CBCT measurements were highly reliable compared with anatomic truth and significantly more reliable than measurements made from LC, PA, and SMV images. CONCLUSIONS: Custom oblique multi-planar reformatted reconstructions with iCAT CBCT provide accurate and reliable linear measurements of mandibular and TMJ dimensions.

Analysis of Variance↗
PubMed2005

A comparison of 18 different x-ray detectors currently used in dentistry.

PURPOSE: There has been a proliferation of available dental x-ray detectors over the recent past. The purpose of this short technical report is to provide a basic comparison of spatial resolution, contrast perceptibility, and relative exposure latitudes of 18 current dental x-ray detectors, including solid-state systems (CCD and CMOS), photostimulable phosphors, and analog film. METHODS: Spatial resolution was measured using a 0.025 mm Pb phantom test grid with a measurement range from 1.5 to 20 lp/mm. For contrast perceptibility, a 7-mm thick aluminum perceptibility test device with wells of 0.1-0.9 mm depth at 0.1 mm intervals and 1 defect of 1.5 mm was used. The relative exposure latitude was determined by expert consensus using clear discrimination of the enamel-dentin junction as the lower limit and pixel blooming or unacceptable levels of cervical burnout as the upper limit. RESULTS: The highest spatial resolution was found with Kodak InSight film, RVG-ui (CCD), and RVG 6000 (CMOS) detectors, each of which achieved 20 lp/mm, followed by the Planmeca Dixi2 v3 at > or =16 lp/mm. Contrast resolution was at least to 0.2 mm through 7 mm aluminum for all 18 detectors, with the best results being found for the Visualix HDI, RVG-ui, RVG 5000, and RVG 6000 detectors and the Schick CDR wired and wireless systems. The greatest exposure ranges were found with photostimulable phosphors and the Kodak RVG 6000 and RVG 5000 detectors. CONCLUSIONS: Most current x-ray detectors generally perform well in terms of spatial and contrast resolutions, and in terms of exposure latitude. These findings were independent of the modality applied.

Contrast Media↗