[The dental radiograph: pitfalls and surprises]. / De tandheelkundige röntgenopname: valkuilen en verrassingen.

Guidelines allow retakes of dental radiographs of up to 10%. In the general practice the percentage of retakes is considerably higher. In intraoral radiography film positioning and faults in directing the collimator are the most common reasons for retakes. The use of film holders and correctly aiming the collimator decrease the risk of failure. In panoramic radiography the positioning of the patient in the x-ray machine and the palatoglossal air space are the main causes of failure of radiographs. A systematic approach, a thorough check of the radiation area for artefacts and the use of the available laser lines decrease the risk of a diagnostically unacceptable radiograph.

Detection of proximal caries in vitro using standard and task-specific enhanced images from a storage phosphor plate system.

Eight dentists evaluated 72 proximal surfaces of premolars with respect to all caries lesions and to lesions into dentine in digital images from a storage phosphor plate system. The images were processed in four different ways: (1) the default algorithm of the standard imaging system (DF); (2) an algorithm correcting for attenuation and visual response (AV), and two proprietary caries-specific enhancement algorithms (3) K1, and (4) K2, respectively. The lesions were validated by histological examination. There were no significant differences in the areas under the receiver operating characteristic curves between differently processed radiographs for the categories of all caries lesions and caries into dentine.

Assessment of metal artefact reduction around dental titanium implants in cone beam CT.

OBJECTIVES: The aim of this study was to investigate if the metal artefact reduction (MAR) tool used in the software of the ORTHOPANTOMOGRAPH(®) OP300 (Instrumentarium Dental, Tuusula, Finland) can improve the gray value levels in post-operative implant scans. METHODS: 20 potential implant sites were selected from 5 edentulous human dry mandibles. Each mandible was scanned by a CBCT scanner, and images were produced under three different conditions: implant sites drilled but no implants inserted, implants inserted without application of MAR and implants inserted with application of MAR. Using Geomagic(®) Studio 2012 (Geomagic, Morrisville, NC) and 3Diagnosys(®) v. 5.3.1 (3Diemme(®) SRL, Cantù, Italy) software, three scans of each mandible were superimposed. The mean gray value of identical regions of bone around the implants was derived for each condition. The differences between gray value measurements at implant sites derived from different conditions were assessed. RESULTS: A significant difference was found between mean gray values from the scans with no implants inserted and with implants inserted (with and without MAR) (p = 0.012). No significant difference was revealed for gray values measured from scans with and without MAR (p = 0.975). CONCLUSIONS: The MAR tool in the software of the ORTHOPANTOMOGRAPH OP300 CBCT scanner does not significantly correct the voxel gray values affected by the metal artefact in the vicinity of an implant in human dry mandibles.

Detection of proximal caries with high-resolution and standard resolution digital radiographic systems.

AIMS: The aim of this study was to: (1) compare the diagnostic accuracy of the high-resolution and standard resolution settings of four digital imaging systems for caries diagnosis and (2) compare the effect on the diagnostic accuracy of reducing the high-resolution image sizes to the standard resolution dimensions, and vice versa. MATERIALS AND METHODS: 90 extracted human premolars were mounted in groups of 5 in plaster blocks, containing 4 test teeth and 1 non-test tooth. Two blocks at a time were placed in a jig to simulate a bitewing radiograph. Radiographs were taken using four digital systems (Planmeca Dixi 2; Gendex Visualix HDI; Dürr Vistascan; Digora Optime), each at two resolution settings. Next, the teeth were sectioned and a total of 65 surfaces were incorporated in the study. Additionally, the bicubic interpolation method was applied to reduce the high-resolution original images and to enlarge the standard resolution images. The original, reduced and enlarged images were randomly shown to five observers in two random sessions. The observers were asked to assess caries depth on a 4-point scale. The observers' scores were compared with the results from a histological examination. Data were analysed using the statistical theory for multivariate discrete data. Cohen's kappa was used to determine the agreement with the gold standard. RESULTS: None of the comparisons between the spatial resolution settings, or the comparisons between increased or reduced image size and the original image sizes, showed significant differences in the probability of caries detection (chi2=26.59, df=26, P approximately 0.50). The four digital systems used in this study differ significantly in the probability of caries detection (chi2=41.55, df=24, P<0.02). Compared with the gold standard, the Gendex Visualix HDI CCD sensor has the highest measure of agreement (kappa=0.31). CONCLUSION: Caries diagnosis does not improve when using high-resolution settings compared with the standard settings. The use of bicubic convolution interpolation for zooming has no detectable effect on caries diagnosis and therefore is recommended to use when enlarging or reducing radiographs. The probability of caries detection, however, was different for the sensor systems of the different manufacturers.

Radiographic examination of the temporomandibular joint using cone beam computed tomography.

Cone beam CT (CBCT) is a new technique for maxillofacial imaging. We describe a reconstruction technique for radiographic examination of the temporomandibular joint (TMJ) using CBCT, and we further present four cases where the technique was employed. The technique provides a complete radiographic investigation of the bony components of the TMJ. The reconstructed images are of high diagnostic quality. The examination time is shorter and the patient dose is lower than that with conventional CT. It may therefore be considered as the imaging technique of choice when investigation of bony changes of the TMJ is the task at hand.

Sensitometric and clinical evaluation of a new F-speed dental X-ray film.

OBJECTIVE: To compare the sensitometric properties, diagnostic efficacy and image quality of the InSight (F-speed) and Ektaspeed Plus (E-speed) dental X-ray films (Kodak Eastman Co, Rochester, USA). METHODS: Characteristic curves were constructed, using manual and automatic processing, in order to compare film speed and average gradient. The diagnostic yield was compared by assessment of endodontic file length. Endodontic files, sizes 10 and 15, were placed at the root apex or 1.5 mm short. The exposure time for the InSight films was 20% lower than that of Ektaspeed Plus. Seven dentists rated the position of file tip using a 5-point confidence scale. ROC data were analysed by means of analysis of variance. The null hypothesis was rejected when P<0.05. In order to compare the image quality, 100 pairs of bitewing radiographs of the left (using Ektaspeed Plus) and the right sides (using InSight) of the same patient were made. Four dentists viewed the radiographs and the data were analysed using Kendall's coefficient of concordance. RESULTS: InSight was faster than Ektaspeed Plus. It was an E-speed film when processed in manual conditions and an F-speed film when processed automatically. The films had comparable average gradient. No significant difference was found in the diagnostic yield using the two films (P=0.648). Two observers showed a significant preference for Ektaspeed Plus. CONCLUSIONS: The first results of the new InSight film are promising: the exposure time can be reduced by 20% in comparison with Ektaspeed Plus at no detriment to diagnostic efficacy.

Radiographic detection of approximal caries: a comparison of dental films and digital imaging systems.

OBJECTIVES: To compare the diagnostic accuracy for the detection of approximal caries of two dental X-ray films, two CCD-based digital systems and two storage phosphor (SP) digital systems. METHODS: Fifty-six surfaces in 56 extracted unrestored premolars were radiographed under standardised conditions using two E-speed dental film, Ektaspeed Plus (Eastman Kodak Co, Rochester, NY, USA) and Dentus M2 Comfort (Agfa-Gevaert, Mortsel, Belgium), two CCD systems, Sidexis (Sirona, Bensheim, Germany) and Visualix (Gendex, Milan, Italy) and two SP systems, Digora (Soredex, Helsinki, Finland) and DenOptix (Gendex, Milano, Italy). The images were assessed by eight observers (four radiologists and four general practitioners). True caries depth was determined by histological examination. True caries depth was subtracted from the values given by the observers and an analysis of variance was performed. The null hypothesis was rejected when P < 0.05. RESULTS: No significant differences were found in diagnostic accuracy with the two dental films and the Sidexis and Digora systems. The depth of the lesion significantly affected observer performance. Caries depth was underestimated. Radiologists performed significantly better than general practitioners whatever the recording system. CONCLUSION: The diagnostic accuracy of digital systems is comparable with that of dental films. The ability of dentists to recognise caries correctly is the main factor contributing to variation in radiographic diagnosis and not the imaging modality.

A radiographic method for measuring radiation dose based on beam quality.

OBJECTIVES: To develop a radiographic method for measuring radiation dose based on beam quality for inexpensive postal surveys of general dental practitioners. METHODS: Different beam qualities were simulated to expose a commercially available film (X-Omat MA 18 x 22.4 cm, Ready Pack, Kodak Pathe, Paris, France). Density and contrast curves were fitted by means of 4th-degree polynomial functions. The curves were used to estimate beam quality (as the first HVL) and radiation dose in air for 22 different dental X-ray machines by means of linear interpolation. These estimations were compared with the measurements obtained with the NERO system and an ionization chamber (paired t-test). RESULTS: No significant differences were found between the radiographic and the conventional methods in determining beam quality and radiation dose. CONCLUSIONS: The radiographic method can be used to determine beam quality and radiation dose of dental X-ray machines from a single exposure. The radiographic method is simple and inexpensive and causes a minimum of disruption to the dental practice.

The effects of developer age on diagnostic accuracy: a study using assessment of endodontic file length.

OBJECTIVES: To examine the effects of developer age on image quality. METHODS: Endodontic files, size 10 and 15, were placed in upper and lower molars and premolars up to the root apex or 1.5 mm short. A series of radiographs were made with each of three film types: Dentus M2 (Agfa-Gevaert, Mortsel, Belgium), Ektaspeed Plus and Ultra-speed (Kodak Eastman Co, Rochester, USA). The films were processed bi-weekly using the same Agfa chemicals (Heraeus Kulzer, Dormagen, Germany) over a 6-week period. An additional set of Dentus M2 films was processed using Periomat chemicals (Dürr Dental, Bietigheim-Bissingen, Germany). The films were viewed by eight dentists who rated the position of the tip of the file using a 5-point confidence scale. ROC data were analysed by means of analysis of variance. Az value was the dependent variable, whereas observer age group was entered as between subject factor. The null hypothesis was rejected when P<0.05. RESULTS: The diagnostic accuracies of the three films were comparable during the first 4 weeks. In the sixth week Ultra-speed was significantly better than the other two films (P=0.046). The Periomat chemicals showed significantly greater consistency than the Agfa chemicals (P=0.004). Developer exhaustion significantly affected the performance of the older observers (P=0.008), especially when Agfa chemicals and file size 10 were used. CONCLUSION: Agfa chemicals older than 4 weeks significantly affect the assessment of endodontic file length. In earlier stages there are no significant differences between the three films tested. Dentus M2 and Ektaspeed Plus films should be used as they require lower exposures.

Mail survey of dental radiographic techniques and radiation doses in Greece.

OBJECTIVES: To measure the entrance dose from periapical radiography in Greece and to determine the relative influence of factors affecting it. METHODS: Special packs, containing a questionnaire, a film (X-Omat MA 18 x 22.4 cm, Ready Pack, Kodak-Pathe, Paris, France) with an attached aluminium stepwedge and a pre-exposed Ektaspeed Plus (Kodak) film, were mailed to 550 randomly selected dental practitioners. The results were tested statistically using an Analysis of Variance (level P < 0.05). RESULTS: Three hundred and sixty-four packs were returned: 311 were complete but in 53 the pre-exposed film had not been developed. The average HVL was 1.4 mm Al 51% of the units had pointed cones and 34% a beam diameter larger than 6 cm. 54% of the dentists used E-speed films. Eighty per cent of the films were inadequately processed. For the total group the average entrance dose was 6.9 mGy (range 0.6-36 mGy), and 6.3 mGy (range 0.6-35 mGy) for the completed packs (n = 311). The radiation dose for the completed packs was significantly influenced by HVL, film speed, length of cone and standard of processing. CONCLUSIONS: HVL, film speed, length of cone and standards of processing influence the entrance dose. Not all of the available measures for reducing radiation dose are commonly practised in Greece. Continuing education programs can help to improve radiation safety for dental patients.

Sensitometric evaluation of four dental X-ray films using five processing solutions.

OBJECTIVES: To compare the sensitometric properties of four dental films: Ektaspeed Plus and Ultra-speed (Kodak Eastman Co, Rochester, USA) and new and previous Dentus M2 (Agfa-Gevaert, Mortsel, Belgium) in five different processing solutions. METHODS: Characteristic curves were constructed for four dental X-ray films using five different processing solutions. All films were processed manually in three sets of chemicals for manual processing: Agfa (Heraeus Kulzer, Dormagen, Germany), Kodak (Kodak-Pathé, Paris, France) and Demat (Viscopac, Athens, Greece) and two sets of chemicals for automatic processing: Dürr XR and Periomat (Dürr Dental, Bietigheim-Bissingen, Germany). Analysis of variance and regression analysis was performed to examine the factors significantly affecting film density. RESULTS: The new Dentus M2 film had comparable gradient, higher speed and lower base-plus-fog than its predecessor. It had comparable speed with Ektaspeed Plus in chemicals for automatic processing. All films had a higher speed and lower gradient when processed in the chemicals for automatic processing. The highest film speed was achieved using Dürr XR chemicals. CONCLUSIONS: The new Agfa Dentus M2 film is an E-speed film and can be considered an alternative to Ektaspeed Plus: both can be recommended for use in dental practice as they contribute to dose reduction.

Effects of developer exhaustion on the sensitometric properties of four dental films.

OBJECTIVES: To examine the effects of exhaustion of five different processing solutions on the sensitometric properties of four dental X-ray films: Ektaspeed Plus and Ultra-speed (Kodak Eastman Co. Rochester, USA) and new and previous Dentus M2 (Agfa-Gevaert, Mortsel, Belgium). METHODS: An aluminum stepwedge was used to construct characteristic curves for the four films. All films were processed manually using three sets of chemicals for manual processing: Agfa (Heraeus Kulzer, Dormagen, Germany), Kodak (Kodak-Pathé, Paris, France) and Demat (Viscopac, Athens, Greece) and two sets for automatic processing: Dürr XR and Periomat (Dürr Dental, Bietigheim-Bissingen, Germany). Film speed and gradient were evaluated until the chemicals were completely exhausted. An analysis of variance was performed separately for each set of chemicals for manual and automatic processing. RESULTS: Ektaspeed Plus was the fastest film in the manual processing solutions. The new Dentus M2 and Ektaspeed Plus films had similar speed using the chemicals for automatic processing. Ultra-speed had the lowest speed in all solutions, but it had the greatest consistency. Exhaustion of the developer caused a comparable decrease in speed of Ektaspeed Plus and the two Dentus M2 films. In fresh chemistry Agfa was the strongest manual processing solution, but it had the highest exhaustion rate. The Dürr XR chemical was stronger than Periomat over the whole test period. CONCLUSIONS: The combination of film and processing solution is an important factor for achieving constant sensitometric properties. Ektaspeed Plus and the new Dentus M2 film should be used in dental practice, as they require lower exposure and have equivalent or superior properties compared with Ultra-speed.

The effect of developer age on the detection of approximal caries using three dental films.

OBJECTIVES: To compare the diagnostic accuracy for the detection of approximal caries of three dental X-ray films using fresh and aged processing chemicals. METHODS: Fifty-six extracted unrestored premolars were radiographed under standardized conditions using the new Dentus M2 (Agfa-Gevaert, Mortsel, Belgium), Ektaspeed Plus and Ultra-speed (Kodak Eastman Co, Rochester, USA) dental films. The films were processed manually using Agfa chemicals (Heraeus Kulzer, Dormagen, Germany). The procedure was repeated once a week until the complete exhaustion of the chemicals (6 weeks). Three independent observers assessed 210 radiographs using the following rating scale: 0 = sound, 1 = enamel lesion; 2 = lesion reaching the ADJ; 3 = dentinal lesion. True caries depth was determined by histological examination (14 sound surfaces, 11 enamel lesions, eight lesions reaching the ADJ and 23 dentinal lesions). True caries depth was subtracted from the values given by the observers and an analysis of variance was performed. The null hypothesis was rejected when P < 0.05. RESULTS: No significant differences were found in the diagnostic accuracy between the three films when using chemicals of up to 3 weeks old (P = 0.056). After the third week, Ultra-speed was significantly better than the other two films (P = 0.012). On average caries depth was underestimated. CONCLUSION: A similar level of diagnostic accuracy for approximal caries is achieved when using the three films. Dentus M2 and Ektaspeed Plus are at present the fastest available films and they should therefore be recommended for clinical practice. Agfa chemicals should be renewed every 3 weeks. Fifty per cent reduction in average gradient is indicative of renewing processing chemicals.