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PubMed1999

Assessment of image quality in dental radiography, part 2: optimum exposure conditions for detection of small mass changes in 6 intraoral radiography systems.

OBJECTIVE: The purpose of this study was to compare 2 film systems and several digital intraoral systems with regard to visual image quality through use of a test phantom developed for this purpose. STUDY DESIGN: The detectors used for digital imaging were as follows: Computed Dental Radiography (CDR), Digora, Dixel, and Sens-A-Ray without scintillator layer. Two types of digital images were prepared for the observer performance test: one with original gray scales and another with contrast enhancement. Images with and without enhancement from the 4 systems were displayed to 7 observers. The change in the average number of perceptible holes was plotted against exposure, and modified perceptibility curves were created and compared with curves for the film systems. The exposure level at which the maximum number of holes was perceived was defined to be optimum. The optimum exposure levels were determined for each digital system and compared with that of the film systems. At the optimum exposure, the average maximum numbers of perceptible holes in each digital system with and without contrast enhancement were compared with the maximum numbers for the film systems. The minimum exposure levels were determined to be those at which the number of perceptible holes exceeded the number for film, and the possibility of exposure reduction was evaluated. RESULTS: All digital systems except the Digora system showed lower optimum exposures than E-speed film. In all digital images without enhancement, however, the maximum number of perceptible holes was significantly lower than that for the film systems at that exposure. With contrast enhancement, all digital systems except the Sens-A-Ray system showed visibility superior to that of the film systems. With the CDR, Digora, and Dixel systems, exposures could be further reduced by a considerable amount, with greater retention of information than was associated with film. CONCLUSIONS: Our results strongly suggest that digital systems, if properly used, can exceed film systems in the detection of small mass changes.

Contrast Media↗

PubMed1987

Dental radiography: efficacy in the assessment of intraosseous lesions of the face and jaws in asymptomatic patients.

In this investigation the efficacy of dental radiography for the detection of occult intraosseous lesions of the face and jaws was evaluated. An analysis of 30 million health insurance records indicated that the period prevalence of malignant lesions was less than 5 cases/million/year, and for benign lesions approximately 100 cases/million/year. Data from a controlled observer-performance study showed that radiographic sensitivities ranged between 50% and 80%. The cost per true-positive finding was estimated to be +8.6 million per malignant case and +430,000 per benign case. An assessment of the dosimetric literature indicated that the benefits of radiographic screening as a means for early detection of a malignancy appear to be counterbalanced by the risk of causing a radiation-induced malignancy. Taken together, these data demonstrate that dental radiography is not efficacious for the purpose of detecting occult lesions.

Costs and Cost Analysis↗

PubMed1980

A leaded apron for use in panoramic dental radiography.

The leaded aprons currently available for use during dental radiography do not protect the thyroid gland from radiation. Conventional aprons may produce artifacts when used with panoramic dental x-ray units. This study measures the dose reduction obtained with an experimental leaded apron designed for use with panoramic dental x-ray units. Skin exposures measured at the thyroid and at the sternum were reduced with the use of the apron. Films produced during the study were free from apron artifacts.

Adult↗

PubMed1986

Clinical efficacy of dental radiography in the detection of dental caries and periodontal diseases.

This article reports the ability of dental radiographs to correctly detect evidence of dental caries and periodontal disease (sensitivity) and to correctly establish the absence of these diseases (specificity). The analysis used a unique data set that was collected as part of the Veterans Administration Dental Longitudinal Study in Boston. Periapical, panoramic, and posterior bitewing radiographs were independently compared with a consensus radiographic standard of all three radiographs read simultaneously. Findings showed that the sensitivities of all three radiographs to detect dental caries were lower than expected, at approximately 60%, whereas the sensitivities to detect evidence of periodontal disease averaged approximately 85%. Panoramic radiographs were substantially less sensitive for detecting dental caries than periapical and posterior bitewing radiographs, but no difference between these modalities was observed in the analysis of sensitivity to periodontal disease. The proportion of false-negative and false-positive readings from dental radiographs was substantial and requires further investigation.

Adult↗

PubMed1989

Thyroid dose distribution in dental radiography.

The anatomic position and proven radiosensitivity of the thyroid gland make it an organ of concern in dental radiography. A calibrated thermoluminescent dosimetry system was used to investigate the absorbed dose (microGy) to the thyroid gland resultant from a minimum irradiated volume, intraoral full-mouth radiography technique with the use of rectangular collimation with a lead-backed image receptor, and conventional panoramic radiography performed with front and rear lead aprons. Use of the minimum irradiated volume technique resulted in a significantly decreased absorbed dose over the entire thyroid region ranging from 100% to 350% (p less than 0.05). Because this intraoral technique results in radiographs with greater image quality and also exposes the thyroid gland to less radiation than the panoramic, this technique may be an alternative to the panoramic procedure.

Equipment Design↗

PubMed1996

Observer differentiation of proximal enamel mechanical defects versus natural proximal dental caries with computed dental radiography.

OBJECTIVES: Various models have been used to study the accuracy of imaging systems for detection of dental caries. This study compares the ability of dentists to detect mechanically created defects versus natural dental caries cavitations on the proximal surfaces of extracted teeth with Computed Dental Radiography (Schick Industries, Long Island City, N.Y.). Detection rates are investigated according to lesion depth to permit comparisons to be made between studies in the literature with other mechanical defects or natural caries models. Discrimination of natural caries versus artificial defects with Computed Dental Radiography is also compared with a previous report that used standard dental film. STUDY DESIGN: Fifty-two extracted molar and premolar teeth were mounted into representative sets of maxillary and mandibular posterior arches for bite-wing radiography. There were 16 proximal surfaces with natural caries and 28 proximal surfaces with mechanical defects. An optical bench was used to ensure constant beam geometry. A 1.8 cm acrylic soft tissue equivalent attenuator was placed in front of the receptor. Thirty dentists acted independently as observers to differentiate between sound proximal tooth surfaces, natural dental caries, and mechanical defects. Evaluation of intra- and interobserver variability was made with use of the kappa statistic. The Zelen test of odds ratios was used to test for homogeneity, and the Mantel-Haenszel analysis plus stratified logistic regression were used for inference about the common odds ratio. Significance was set at p < 0.05. RESULTS AND CONCLUSIONS: Ignoring stipulation of cavity type, detection was 74% for mechanical defects and 67% for natural caries. The odds of detecting a mechanical defect were 1.40 times the odds of finding natural dental caries cavitation of the same depth. Lesion depth did influence the probability of correctly identifying the presence of a lesion; the odds of identifying cavitation increased 1.41 times with every 0.1 mm increase in lesion depth. Correct designation of lesion type was 1.42 times more likely with mechanical defects than with natural caries (p = 0.003). Intraobserver (kappa = 0.65) and interobserver (kappa = 0.43) agreements were fair to good. Discrimination between natural and artificial lesions was less with the Computed Dental Radiography than that found in our previous study with standard direct emulsion x-ray film.

Bicuspid↗

PubMed1998

Dental radiography after age 25 years, amalgam fillings and tumours of the central nervous system.

The aim of the study was to investigate the importance of diagnostic dental radiography and amalgam fillings as risk factors for tumours of the central nervous system (CNS). This population-based case-control study included subjects aged 25-74 years, living in the catchment area of the Neurosurgery Department of Uppsala University Hospital in Sweden. A total of 192 cases of glioma, 99 cases of meningioma and 42 cases of acoustic neurinoma were identified between 1987 and 1990. A control group of 343 subjects was matched on age, gender and parish. Information about dental exposure was obtained by a self-administered questionnaire and from dental records. For those who had a dental radiography at least once a year after age 25 years, a relative risk of 2.1 (95% confidence interval (CI) 1.0-4.3) was seen for meningioma, while for other subgroups of CNS tumours the relative risk was close to unity. No association was observed between the number of amalgam fillings and CNS tumours. In conclusion, there was no clear evidence that dental radiography or amalgam fillings is related to the development of tumours of the CNS.

Adult↗

PubMed1986

The effects of beam quality and optical density on image quality in dental radiography.

The literature relating to the choice of beam quality in dental radiography is reviewed. Twenty observers were asked to select radiographs of a test object at different beam qualities and densities. The same observers were asked to identify numbers of circular areas of small density differences in zones of high and low density. Subjectively, the observers favored radiographs produced with lower beam energies; 90 kVp aluminum filtration and 3.5 mm was least popular, and 70 kVp with 2.5 mm aluminum was most popular. Objectively, there was little difference in the success of identification between the beams of different energies. Masking of radiographs improved success apart from the low density zones in less exposed radiographs. Little evidence has been found within the range investigated for selecting one beam quality over another, other than subjective preference. However, low beam energies should be avoided because of reduced emulsion sensitivity.

Densitometry↗

PubMed1990

Problems associated with veterinary dental radiography.

Veterinarians have been radiographing animal skulls for many years, but sophisticated dentistry was not widely used until the 1970s. Elevated awareness of veterinary dental techniques has led to the need for producing accurate radiographic images of the teeth and periodontal structures. Many problems arise for the clinician who treats small animals who has, before this time, radiographed the skull of dogs and cats solely for the purpose of assessing neoplastic, infectious, or traumatic disease of the mandible, maxilla, or calvarium and now desires to perform dental radiography. This chapter will describe the advantages and disadvantages of some of the more common types of radiographic equipment and supplies, discuss extraoral and intraoral radiographic positioning and technique, identify anatomic landmarks and diagnostic features of intraoral radiography, and offer suggestions concerning the art of using dental radiography in veterinary practice.

Animals↗

PubMed2004