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.

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 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.

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.

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 use of a thyroid collar for intraoral radiography]. / Het gebruik van een loodkraag bij intraorale röntgenopnamen.

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.

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.

In vivo study of approximal caries depth on storage phosphor plate images compared with dental x-ray film.

The aim of this in vivo study was to compare approximal caries depth on storage phosphor plate images to conventional film. A Soredex Digora imaging plate was placed in a film bite-wing positioner behind a Kodak Ektaspeed Plus film package without lead foil. The effect of scattered radiation on film without lead foil with a storage phosphor plate at the back was studied in a separate in vitro experiment. Compared with film protected by lead foil, the film showed higher density, but comparable contrast. For the in vivo study, clinical bite-wing exposures were made with the setup described above, with exposure settings for Ektaspeed Plus film. A four-point scale was chosen for approximal caries depth: 0 = no caries; 1 = caries in enamel; 2 = caries reaching dentino-enamel junction; 3 = caries into dentin. The bite-wing film images were shown to a panel of four experts. Sixty surfaces were selected for observer performance, based on identical scorings of the experts consensus classification. Next, six dentists evaluated both film and storage phosphor plate images with the same four point scale. Analysis of variance revealed a significant observer and image modality effect without an interaction effect. In conclusion, caries depth on storage phosphor plate images was underestimated compared with film-based images.

Dose reduction of two digital sensor systems measuring file lengths.

OBJECTIVE: The aim of this study was to determine the effect of dose reduction on the image quality of two sensor systems with automatic greyscale adjustment. STUDY DESIGN: Two digital sensor systems, Sidexis (Siemens, Bensheim, Germany) and Digora (Soredex, Helsinki, Finland), were tested. The image quality of the systems was determined by comparing lengths of endodontic files (025, 020, 015, and 010 files) and a premolar root in the digital images with lengths on conventional radiographic films. For the experiments the exposure was changed to 100%, 50%, 25%, 12.5%, 6.25%, and 3.125% of that for Ektaspeed films. RESULTS: The lengths of 025 and 020 files and the premolar root in the digital images were comparable with the lengths on films even if the exposure was reduced to 6% of that used for Ektaspeed films. The lengths of 015 files reduced as the exposure was reduced. The lengths of 010 files were significantly shorter than the lengths on films. CONCLUSIONS: With the systems tested, a dose reduction of approximately 95% compared with Ektaspeed films is possible to determine the lengths of a premolar root and 025 and 020 files. For thinner objects a dose reduction is questionable.

[100 years of x-rays: increase in image quality of intra-oral radiographs, decrease in patient exposure]. / 100 jaar röntgenstraling: kwaliteit intra-orale röntgenopnamen toegenomen, stralenbelasting afgenomen.

Comparing a present-day bitewing radiograph with one of the first dental radiographs made immediately after the discovery of the X-rays, we can see how enormously the image quality of dental radiographs has improved. Besides the improved image quality, patient exposure has decreased considerably during the past 100 years. Improvement of image quality and reduction of patient exposure have been brought about by changes of X-ray equipment and radiographic films. These changes, which have led to a better image quality and a decrease of patient exposure during the past 100 years, are discussed in this article.

[Dose distribution in tissues]. / Dosisdistributie in weefsels.

Biological effects of ionising radiation are dependent on the distribution of doses in tissue. In this article parameters influencing the distribution of dose in tissue are discussed with emphasis on intraoral and rotational panoramic radiography. For both examinations the probability to develop stochastic effects is estimated. For intraoral radiography the probability ranges from 0.1 to 0.3 per million exposures and for rotational panoramic radiography from 0.4 to 0.8 per million. For the whole Dutch population the probability to develop stochastic effects is 0-2 persons per year and 0-1 person per year respectively. Dental radiography is therefore justified if further diagnostic information is to be expected and exposure circumstances are optimal.

Risk assessment from bitewing radiography.

The effective dose equivalent and the effective dose from bitewing radiography have been estimated for three different X-ray sets under 10 different exposure conditions using the ICRP 26 (1977) and the ICRP 60 (1990) recommendations. The results of dose measurements in the head and neck with an Alderson Rando phantom and thermoluminescence dosimeters (TLD-100 ribbons) were used (Velders XL et al. Dentomaxillofac Radiol 1991; 20: 161-5). The effective dose equivalent (ICRP 26) was calculated using the salivary glands and brain as remainder organs. The highest effective dose equivalent was 11 microSv for the Philips Oralix 50 unit with a round, pointed cone; the lowest was 2 microSv for the X-ray sets with a rectangular open-ended tube. The highest effective dose using the ICRP 60 weighting factors was 4 microSv for the Oralix 50, the lowest 1 microSv for the X-ray sets with a rectangular open-ended tube. The probability of stochastic effects was calculated as at the most 0.18 x 10(-6) using a nominal probability coefficient of 165 x 10(-4) Sv-1 (ICRP 26); when using the ICRP 60 recommendations (where the nominal probability coefficient for stochastic effects including non-fatal cancer is 730 x 10(-4) Sv-1) the maximum probability was 0.25-0.31 x 10(-6). The maximum probability of fatal cancer induction was calculated as 0.18 x 10(-4) for both fatal probability coefficients, 125 x 10(-4) Sv-1 in ICRP 26 and 500 x 10(-4) Sv-1 in ICRP 60. The calculated probability of the total stochastic effects is nearly twice as high when using the new recommendations, whilst the estimated probability of fatal cancer induction is of the same order of magnitude with both.

Absorbed dose to organs in the head and neck from bitewing radiography.

Dose measurements were carried out to estimate the absorbed dose to organs at risk from bitewing radiography under exposure conditions similar to those found in general dental practice in The Netherlands. The measurements were carried out in the head and neck of a Rando phantom using TLD-100 ribbons. Three different X-ray machines were used simulating 10 different exposure conditions to determine the effects of beam energy, beam size and focus-skin distance on the absorbed dose. The absorbed dose in the primary beam, close to the focal spot, decreased as the beam energy increased, while behind the film plane it increased with the beam energy. Outside the primary beam, at short distances from the skin surface, the absorbed dose decreased as the energy increased, while behind the film plane and at greater distances from the primary beam the absorbed dose increased as the beam energy increased. The absorbed dose was significantly lower for smaller beam sizes and for larger focus-skin distances, independent of beam energy.

[Administration of local anesthesia by dental hygienists. A survey in The Netherlands]. / Lokale anesthesie. Een taak voor de mondhygiënist?

In 1987 100 dental hygienists, members of the Dutch Dental Hygiene Association have received a questionnaire (response: 73%) about administration of local anesthesia. Fifty-five respondents worked in a general practice setting. The results showed that the need for administration of local anesthesia is very limited.