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[The use of a thyroid collar for intraoral radiography].

OBJECTIVE: To determine whether a thyroid collar is a reasonable measure to reduce patient exposure from intraoral radiography (cost benefit analysis). DESIGN: In the thyroid gland of a Rando phantom dose measurements were carried out to determine the effect of a thyroid collar during intraoral radiography. SETTING: Department of Oral Radiology at ACTA, Amsterdam. METHODS: Dose measurements were carried out using LTDs. The average absorbed dose to the thyroid gland with and without thyroid collar from intraoral radiography was compared using an analysis of variance. RESULTS: For periapical radiographs the equivalent dose to the thyroid gland was significantly lower (p < 0.05) when a thyroid collar was used. For bitewing radiography there were no significant effects of the thyroid collar (p > 0.05). The cost benefit analysis showed that it takes more than 40 years before the benefits of a thyroid collar exceed the costs. CONCLUSION: Collective use of thyroid collars therefore does not seem to be a reasonable measure to optimize radiological protection during intraoral radiography.

Cost-Benefit Analysis↗

Approximal caries diagnosis in epidemiological studies: transillumination or bitewing radiographs?

The aim of this study was to compare the results obtained by transillumination and bitewing radiography in the diagnosis of caries affecting approximal surfaces of molar and premolar teeth for epidemiological surveys. 3960 posterior approximal surfaces on the right side of 330 patients aged 5 to 35 years were examined using a transillumination probe with a 1.5 mm diameters light source (Oralum, Rocky Mountain, Denver, Colorado) and bitewing radiographs using a portable dental apparatus (Elin, Wien, 60kV, 15mA. Transillumination detected 89% of the carious lesions reaching dentine diagnosed on radiographs and no statistically significant differences were observed in the diagnosis yield of the two systems. However, transillumination detected only 45% of these lesions diagnosed from bitewings as being confined to the enamel. Transillumination also made it possible to detect approximal caries into dentine in teeth covered by orthodontic bands. Thus comparative study gives experimental support to the use of transillumination in large epidemiological studies. The transillumination method is however not suitable for epidemiological trials including caries confined to the enamel.

Adolescent↗

Inter-relationships between bone mineral content measures. Dual energy radiography (DER) and bitewing radiographs (BWX).

In vitro periodontal alveolar bone mineral content (BMC) measurements obtained with dual-energy radiography (DER) were compared with assessments based on bitewing radiographs (BWX). In addition, in patients, the relationship between bitewing and several postcranial dual-energy-radiographic measures were evaluated. Dual-energy-radiographic and bitewing measurements were made on 2 cadaver mandibles initially and after 2 incremental bone reductions at 4 sites. Rank-order correlations between dual-energy-radiographic and bitewing measures for the 4 sites ranged from 0.7 to 1.00. Bitewing measures indicated true bone loss with a sensitivity of 1.00. For patients, correlations between bitewing measures and dual-energy-radiographic scans suggested the strongest relationships were in the distal sections of the radius and ulna and in the intertrochanteric and Ward's areas of the femur. Correlations, in the 0.5-0.6 range, were not statistically significant (p > 0.05), but were quite robust considering the small sample size and preliminary nature of this investigation. Results suggest that the bitewing measure is sufficiently sensitive to detect clinically meaningful (5% or greater) changes in alveolar BMC and, further, that alveolar bone mineral content may reflect postcranial BMC. The implications of postcranial bone mineral changes being reflected in alveolar bone would enhance both our understanding and treatment of alveolar bone loss. The use of bitewing measures to facilitate identification of patients with postcranial bone loss is discussed.

Absorptiometry, Photon↗

Identification of victims from the M/S Estonia.

With 852 victims from 17 different countries, the sinking of the Estonia was Europe's most severe passenger ferry disaster. The Finnish Disaster Victim Identification (DVI) team identified all 93 victims recovered from the sea within 33 days of the accident as well as victim number 94 found 18 months later. Dental identification was established in 57 cases (60%).

Cause of Death↗

Application of the Third Molar Eruption Predictor to periapical radiographs.

The aim of this study was to test whether the Third Molar Eruption Predictor, developed for panoramic radiographs, can also be applied to periapical radiographs. The Third Molar Eruption Predictor is a transparent device (US patent 5,816,814), not commercially available, and developed for prediction of future eruption or impaction of third molars. The material consisted of periapical radiographs of mandibular third molars taken from the lateral projection without angulation of the central beam. The radiographs taken at the mean age of 20.6 years (SD +/- 1.4 years) were retrospectively available from a four-year follow-up study of third molars carried out at the University of Copenhagen, Denmark. Initially unerupted or partially erupted third molars (n=43) in 28 dental students were analyzed. Clinical statuses of the third molars were available at baseline and four years later. The device was calibrated using the method of simple proportions and Bayes' Decision Theory. The predictions made with the calibrated device were in conformity with the final clinical outcome in 84% of the cases. It was concluded that the Third Molar Eruption Predictor may also be used on periapical radiographs after calibration of the device.

Adult↗

Detection and measurement of approximal radiolucencies by computer-aided image analysis.

Serial standardized bitewing radiography permits monitoring of the development of approximal carious lesions. A quantitative method using image-analysis techniques was developed. Only certain types of hardware proved capable of processing this complex image adequately. A computer-aided, software-driven, TV-based system incorporating an image memory, recursive filtration, and 256 gray-level resolution, which can both detect and measure approximal enamel radiolucencies produced by natural carious lesions, has been developed. The radiolucent boundary is delineated, displayed, and plotted to scale. For the first time, objective values for depth, area, width, perimeter, and "degree of radiolucency" can be automatically derived. Currently the system is seen as a tool in caries research; in the future such systems may have wider applications.

Computers↗

Sens-A-Ray. A new system for direct digital intraoral radiography.

A new system for direct digital intraoral radiography, Sens-A-Ray, is presented. This system is based on a detector with a charge-coupled device that was designed especially for direct exposure to x-ray radiation. The system also includes interface electronics and an IBM AT-compatible personal computer with a digital I/O with frame memory, a super VGA graphics board, a high-resolution monitor, and software for the exposure, capture, storage, and enhancement of images. An external optical mass storage device is used for permanent storage of images in digital format. A video printer may be used to create hard copies. The system produces radiographic images at a significantly lower exposure than required for E-speed intraoral film. Applications of the system are exemplified, and its basic properties are discussed.

Computer Graphics↗

Clinical comparison of two panoramic modalities and posterior bite-wing radiography in the detection of proximal dental caries.

A clinical study was designed to examine whether the Philips OrthOralix SD (Gendex Dental Systems, Monza, Italy) orthogonal panoramic projection could improve diagnostic accuracy over standard projections in the detection of proximal surface caries. Thirty-five sets of radiographs that demonstrated optimal image characteristics were selected. Using a five-point scale, 18 viewers evaluated whether specified lesions were present or absent. Viewer data was then compared with a consensus radiographic assessment of the state of the proximal areas. Receiver operating characteristic curves were generated with the use of a maximum-likelihood method of fit. The area under the receiver operating characteristic curve was used as the index of diagnostic accuracy. The mean receiver operating characteristic areas for orthogonal and standard projection panoramic and bite-wing radiography to detect the presence of proximal dental caries were 0.68 +/- 0.03, 0.69 +/- 0.03, and 0.79 +/- 0.03 respectively. Critical ratio analysis was used to compare the means for all possible pairings of imaging modalities. In overall performance, conventional bite-wing radiographs gave a significantly greater diagnostic yield for proximal caries than the Philips OrthOralix SD orthogonal or standard panoramic modalities (p > 0.05). The orthogonal projection did not improve diagnostic accuracy in the detection of proximal carious lesions compared with the standard projection.

Dental Caries↗

Radiation doses of commonly used dental radiographic surveys.

The purpose of this study was to evaluate and to compare the radiation dose associated with commonly used dental radiographic surveys including the following: (1) 20 film full-mouth survey, (2) bite-wing radiographs, (3) panoramic survey supplemented with bite-wing radiographs and (4) a common orthodontic radiographic survey (a lateral cephlometric radiograph supplemented with a panoramic radiograph). The effects of collimation and faster radiographic film speeds on dose were also investigated. The effective doses to selected anatomic sites were calculated from measured absorbed doses with the use of an improved, tissue-equivalent phantom fitted with lithium fluoride thermoluminescent dosimeters. It was demonstrated that converting from round to rectangular collimation reduced the radiation exposure by a factor of four. A panoramic survey supplemented with bite-wing radiographs uses approximately one third of the radiation exposure needed to expose a full-mouth survey made with E-speed film and rectangular collimation.

Cephalometry↗

An algorithm for ordering pretreatment orthodontic radiographs.

A study was conducted to identify selection criteria for ordering pretreatment orthodontic radiographs. Thirty-nine orthodontists evaluated six test cases. They provided information on the rationale for ordering each specific radiograph and the impact of the radiograph on the diagnosis and treatment plan. Skeletal relationship of the jaws was the most common indication for a radiograph request, followed by root formation/length and molar position or development. Of the radiographs, 16% produced a change in diagnosis, and 20% produced a change in treatment plans. The criteria specified for the radiographs, their impact, and relevant information in the literature were used to develop an algorithm or set of decision rules that, when tested on the six test cases, resulted in a 36% reduction in the total number of radiographs.

Airway Obstruction↗

Validation of a model to evaluate the role of radiographs in the diagnosis and treatment planning of periodontal diseases.

OBJECTIVES: The purposes of this study were (i) to see if an indirect method of design (paper patients) could be developed for study of change affected by radiographs on diagnostic outcome and planned treatment of periodontal patients and (ii) to investigate the effect of the nature of clinical examination on the value of radiographs in reaching a periodontal diagnosis. Paper cases could allow the design of examiner blind studies where repeatability could be assessed. METHODS: 201 patients were assigned to one of four groups and clinically assessed according to group specifications. Radiographs were taken. Periodontal diagnoses and treatment plans were drawn up for each patient with and without radiographic information (real patient). Simulated paper transcriptions were made for each subject and diagnoses and treatment plans were again drawn up (paper patient). RESULTS: For many diagnoses and treatment options assessments were similar for real and paper patients. There was substantial agreement between periodontal diagnoses reached from real and paper assessments (kappa=0.68). Greater differences were seen for extractions and periodontal surgery. Paper assessments better replicated real assessments when more thorough clinical examinations were undertaken. The relatively time efficient Group 2 clinical assessment appeared to perform similarly to the extensive Group 4 clinical assessment. CONCLUSIONS: The model described may be useful for simulating real patients for studies of this nature. The Group 2 assessment appeared to give sufficient clinical information for patient management and may be an appropriate choice for initial diagnosis and treatment planning of periodontal patients.

Anti-Bacterial Agents↗

Smoking may affect the alveolar process dimensions and radiographic bone density in maxillary extraction sites: a prospective study in humans.

PURPOSE: Loss of ridge width and height typically occur after tooth extraction. This study aimed to investigate whether smoking would effect alveolar ridge remodeling after tooth extraction. MATERIALS AND METHODS: Twenty-one individuals (11 nonsmokers, 10 smokers) requiring a nonmolar extraction in the upper jaw were selected. Radiographs were taken 7 and 180 days after surgery, and the following parameters obtained: alveolar process height (AH), alveolar process width (AW), radiographic bone density in the postextraction socket (BDS), and in the pre-existing bone apically (BDPB). RESULTS: Six months after surgery, intragroup analysis showed that both groups presented a significant reduction in AH, while only smokers had a significant reduction in AW, BDS, and BDPB (P < .05). Furthermore, intergroup analysis showed that smokers presented lower BDS (91.45 pixels +/- 26.62 and 59.53 pixels +/- 19.99, for nonsmokers and smokers, respectively; P = .006) and continued to present lower BDPB (129.34 pixels +/- 42.10 and 89.29 pixels +/- 29.96, for nonsmokers and smokers, respectively; P = .023). Additionally, smokers presented a tendency for lower AH and AW than nonsmokers, but this was not statistically significant. CONCLUSION: Within the limits of the present study, smoking may lead to a more significant dimensional reduction of the residual alveolar ridge and postpone postextraction socket healing.

Absorptiometry, Photon↗

Comparative investigation of subjective image quality of digital intraoral radiographs processed with 3 image-processing algorithms.

OBJECTIVE: To evaluate the subjective diagnostic image quality of clinical digital intraoral radiographs processed with 3 different image-processing algorithms. STUDY DESIGN: One hundred digital intraoral radiographs were collected and subsequently processed in 3 sets. In the first set the radiographs were processed for correction for attenuation and visual response. In the second set the radiographs were processed with the same algorithms but with an additional shift in gray levels so that the average brightness of a region of interest was displayed with the mean brightness of the computer monitor. In the third, the radiographs were processed with the default gamma-correction in the Dimaxis program (Planmeca Oy, Helsinki, Finland). The 3 radiographs that were differently processed from the same original were displayed simultaneously on the computer monitor. Ten observers evaluated subjectively all the radiographs according to the portrayal of normal structures under the same viewing conditions. Five of them performed repeated evaluations of 20 of the 100 radiographs 2 months later. RESULTS: The best subjective diagnostic quality was found for the radiographs processed with the new algorithms plus an additional shift in gray levels. Radiographs processed with the new algorithms were preferred when compared with those processed with the default gamma-correction. The differences between the 3 types of radiographs were significant (P <.0001). No significant intraobserver differences were found (P=.5487). CONCLUSION: Radiographs processed for correction for attenuation and visual response might be beneficial in clinical work. Clinical radiographs processed with the new algorithms plus an additional shift in gray levels further improve the subjective impression of normal structures.

Adolescent↗

Image shift of intracoronal pins viewed on bite-wing and panoramic radiographs.

Pins were placed into dentin in molars and premolars in a dried mandible. Panoramic and bite-wing radiographs were obtained, and measurements of the images of pins on these radiographs were compared with measurements of the mandible. The bite-wing radiographs showed little distortion of the relative distance between pins. The panoramic radiographs showed magnification and parallax shift of images of pins; the distance between pins placed mesially and distally in a tooth was magnified maximally at the first molar, decreasing to the third molar. For pins related diagonally in a tooth, the image showed magnification and parallax shift so that the apparent distance between pins placed mesiobuccally and distolingually increased from bicuspid to third molar, whereas distobuccally and mesiolingually placed pins showed the reverse trend. Guidelines are given for the evaluation of bite-wing and panoramic radiographs that can give clinically valuable information about the positions of intracoronal features.

Artifacts↗

Factors influencing the selection of panoramic radiography in general dental practice.

OBJECTIVES: To identify factors influencing dentists' decisions to take panoramic radiographs and to determine dentists' perceptions of the value of panoramic radiographs in the diagnosis of common dental pathologies. METHODS: Questionnaire of dentists with access to panoramic radiography equipment in 22 randomly selected Family Health Service Authorities in England and Wales. Dentists were asked to score 17 factors for their influence upon panoramic use, compare the relative diagnostic value of panoramic and intraoral radiographs for diagnosis of common dental pathologies and state their principal reasons for taking panoramic radiographs. RESULTS: The response rate to the questionnaire was 73.3%. The factors most likely to influence dentists to take a panoramic radiograph were 'planning oral surgery', 'facial trauma', 'periodontal disease', 'heavily restored dentition' and 'patient first attendance'. Dentists' opinions on the diagnostic usefulness of panoramic radiographs were in broad agreement with those in the scientific literature. The main reasons for taking panoramic radiographs were as a 'general screen' and as a 'view for unerupted or impacted teeth'. CONCLUSIONS: There are areas where dentists' prescription of panoramic radiographs is in disagreement with recent guidelines. Successful implementation of these guidelines would be likely to lead to a substantial reduction in the numbers of panoramic radiographs taken by GDPs.

Adult↗

Radiographic localization of unerupted maxillary anterior teeth using the vertical tube shift technique: the history and application of the method with some case reports.

The preferred means of radiographic localization is the parallax method introduced by Clark in 1910. He used 2 periapical radiographs and shifted the tube in the horizontal plane. In 1952, Richards appreciated that a vertical tube shift could also be carried out. No major changes then occurred in the technique until Keur, in Australia, in 1986 replaced the periapical radiographs with occlusal radiographs. This modification enables a greater tube movement and therefore a greater shift of the image of the impacted tooth; it also ensures that the whole of the tooth is captured on the radiograph. For the vertical tube shift, Keur introduced the use of a rotational panoramic radiograph with an occlusal radiograph. In 1987, Southall and Gravely discussed this vertical tube shift combination in the English dental literature, and it is now the preferred combination of radiographs for localizing impacted maxillary anterior teeth. Jacobs introduced this method to the American literature in 1999, but it has yet to gain acceptance in the continental European literature. Jacobs recommended, when using this combination, to routinely increase the vertical angulation for the occlusal radiograph by 10 degrees to achieve a greater image shift. Four case reports are presented in this article. Three have photographs taken at surgical exposure to illustrate how the position of the impacted tooth can be accurately predicted by appropriate interpretation of the radiographs.

Adolescent↗

Updated quality assurance self-assessment exercise in intraoral and panoramic radiography. American Academy of Oral and Maxillofacial Radiology, Radiology Practice Committee.

This updated self-assessment exercise for the dental team by the Radiology Practice Committee of the American Academy of Oral and Maxillofacial Radiology is intended to produce the highest quality diagnostic radiographs while keeping patient exposure as low as is reasonably achievable. To continue to provide the best radiographic services to patients, those involved in dental radiography need to be aware of the latest changes and advances in dental radiography and need to use them in their practice.

Credentialing↗