Biomedical subjects

F C van Ginkel

Publications and source records attributed to F C van Ginkel.

At least 19 recordsLinked to original sources

PubMed2003

Comparison of standard and task-specific enhancement of Digora storage phosphor images for approximal caries diagnosis.

OBJECTIVES: To compare approximal caries detection on Digora storage phosphor images pre-enhanced with the automatic "caries-specific Oslo enhancement procedure" ("Oslo-enhanced" method) and storage phosphor images individually enhanced by observers particularly experienced in digital imaging using standard brightness and contrast functions of the Digora system ("Digora-enhanced" method). METHODS: Seven staff members from four oral radiology departments rated 240 approximal surfaces for caries with regard to lesion depth in the inner and outer half of the enamel and dentine, using a 5-point confidence scale. The observations were validated histologically. A receiver operating characteristic (ROC) analysis and an analysis of variance with three dependent variables (observer confidence, observer signed error and observer absolute error) were performed. RESULTS: The most evident difference between the methods as elucidated by the ROC analysis was the highly significant smaller interobserver and intraobserver variance with the Oslo-enhanced method for all but one observer. The methods were not different with regard to average diagnostic accuracy (A(z) values) as tested with paired t-tests, and there was no correlation between A(z) across methods. The method and lesion main effects, as well as the lesion by method interaction effect, were multivariately significant (P<0.001) in favour of the Oslo-enhanced method. On a univariate level, the method main effect was not significant for the absolute observer error (P=0.330). All other univariate effects were significant (P<0.001). CONCLUSIONS: The accuracy of approximal caries detection with Digora storage phosphor images pre-enhanced and images individually enhanced was similar, but interobserver and intraobserver variability improved with the Oslo-enhanced method. Since image manipulation is not performed with the Oslo-enhanced method, the increased speed of the diagnostic procedure combined with the improved observer variability would probably be even more pronounced for the general dental practitioner.

Analysis of Variance↗

PubMed2001

Scanning resolution and the detection of approximal caries.

OBJECTIVE: To determine a proper scanning resolution for digitizing bitewing radiographs in the detection of approximal caries. METHODS: Fifty-two premolars and 48 molars were mounted in blocks and imaged on conventional film (Ektaspeed Plus, Eastman-Kodak, Rochester, NY USA) simulating a bitewing projection. The 15 bitewing radiographs were then scanned with a flatbed scanner at three resolutions 150, 300 and 600 d.p.i. The digitized images were displayed in random order on a high-resolution cathode ray tube monitor. Ten observers assessed the caries status of 200 approximal surfaces. They scored lesion presence on a 5-point confidence scale and depth on a 3-point scale. The observer's scores were compared with the results from a histological examination. Data were analysed using analysis of variance, by calculating signed observer error, absolute observer error and observer confidence. RESULTS: Lesion depth had a significant effect on confidence of lesion recognition. The main effect of resolution and the interaction between resolution and lesion depth were significant. Pair-wise comparison showed a significant difference between resolutions in case of sound surfaces and surfaces with dentinal lesions for absolute error. The confidence increased as the resolution increased but no significant difference was found between 300 and 600 d.p.i. The best score for depth estimation was obtained at the 300 d.p.i. scanning resolution. CONCLUSIONS: When bitewing radiographs are scanned with a flatbed scanner, a resolution of 300 d.p.i. seems the best choice. At this resolution the digital file size is manageable without significant loss of the information necessary for caries diagnosis.

Absorptiometry, Photon↗

PubMed2000

Interaction between noise and file compression and its effect on the recognition of caries in digital imaging.

OBJECTIVES: To determine the interaction between image noise and file compression, with special emphasis on the accuracy of caries diagnosis. METHODS: Fifty-nine bitewing radiographs of patients were taken simultaneously with Ektaspeed Plus (Eastman-Kodak, Rochester, NY, USA) film without lead foil and the Digora storage phosphor system (Soredex, Helsinki, Finland). Three different levels of Gaussian noise were added to the original digital images which were then compressed with JPEG 53. Seven observers evaluated the presence and depth of caries lesions on selected approximal surfaces on a 5-point scale. The results of JPEG 27 compression from a previous study were also included. ROC analysis was used together with multivariate analysis of variance (MANOVA). RESULTS: JPEG 27 and 53 reduced the file size down to 7% and 4.6% of the original respectively. ROC curve analysis showed no significant difference between image conditions (original, JPEG 27, and JPEG 53) at the same noise level. JPEG 27 and 53 had larger Az scores than their original counterparts at the same noise level. However, MANOVA showed that for depth estimation of enamel lesions JPEG 53 resulted in a higher observer error. CONCLUSIONS: Both JPEG 53 and 27 could reduce some of the adverse effect of noise from the image by removing high spatial frequencies. JPEG 53, resulting in a compression ratio of 1:21, does not compromise the diagnostic performance in general. JPEG 53 compression may however affect the ability to detect enamel lesions.

Artifacts↗

PubMed1999

Effect of noise on the compressibility and diagnostic accuracy for caries detection of digital bitewing radiographs.

OBJECTIVES: To determine the effect of noise on the compressibility and the diagnostic accuracy for caries detection of digital bitewing radiographs. METHODS: Bitewing radiographs of patients were obtained with a storage phosphor (Digora, Soredex, Helsinki, Finland) and compressed at different JPEG compression levels (2, 27, 53 and 128). A just noticeable difference study was performed to select a compression level to study the added noise effect. Gaussian noise was added at low, medium, and high levels to both the original and compressed images. Seven observers examined the selected approximal surfaces to identify the caries depth. ROC analysis was performed together with ANOVA at P = 0.05. RESULTS: The compressibility of the images decreased as the noise level increased. ROC analysis revealed no significant difference between the original and compressed images within the same noise level (P > 0.06). With added noise compressed/decompressed images had a higher Az than the corresponding original images. CONCLUSIONS: JPEG compression at level 27 can be used without a significant deterioration in diagnostic accuracy. Compression at this level seemed to reduce the effect of noise to some extent.

Analysis of Variance↗

PubMed1999

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.

Absorptiometry, Photon↗

PubMed1999

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.

Analysis of Variance↗

PubMed1999

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.

Analysis of Variance↗

PubMed1999

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.

Adult↗

PubMed1999

Contribution of jaw muscle size and craniofacial morphology to human bite force magnitude.

The existence of an interaction among bite force magnitude, jaw muscle size (e.g., cross-sectional area, thickness), and craniofacial morphology is widely accepted. Bite force magnitude depends on the size of the jaw muscles and the lever arm lengths of bite force and muscle forces, which in turn are dictated by craniofacial morphology. In this study, the relative contributions of craniofacial morphology and jaw muscle thickness to the bite force magnitude were studied. In 121 adult individuals, both magnitude and direction of the maximal voluntary bite force were registered. Craniofacial dimensions were measured by anthropometrics and from lateral radiographs. The thicknesses of the masseter, temporal, and digastric muscles were registered by ultrasonography. After a factor analysis was applied to the anthropometric and cephalometric dimensions, the correlation between bite force magnitude, on the one hand, and the "craniofacial factors" and jaw muscle thicknesses, on the other, was assessed by stepwise multiple regression. Fifty-eight percent of the bite force variance could be explained. From the jaw muscles, only the thickness of the masseter muscle correlated significantly with bite force magnitude. Bite force magnitude also correlated significantly positively with vertical and transverse facial dimensions and the inclination of the midface, and significantly negatively with mandibular inclination and occlusal plane inclination. The contribution of the masseter muscle to the variation in bite force magnitude was higher than that of the craniofacial factors.

Adolescent↗

PubMed1998

Is short-term neurosensory testing after removal of mandibular third molars efficacious?

OBJECTIVE: The purpose of this study was the validation of two-point discrimination, Semmes-Weinstein, and pinprick tests of possible sensory disturbance of the inferior alveolar nerve after the surgical removal of lower wisdom teeth. STUDY DESIGN: Forty-two patients who had undergone elective unilateral lower wisdom tooth removal and 30 control subjects were given two-point discrimination, Semmes-Weinstein, and pinprick tests bilaterally in the dermatome of the mental nerve. Test results were compared to the patients subjective experiences of sensory disturbance. Statistical analysis was done with multivariate analysis of variance. RESULTS: Untreated sides in patients and test sides in control subjects agreed well for all tests. Five of the 42 patients mentioned sensory disturbance, which was confirmed objectively in 3 (by pinprick and two-point discrimination tests). Testing revealed that 16 of the 42 patients had abnormal pinprick and two-point discrimination tests without subjective sensory disturbance. No abnormal values were found for Semmes-Weinstein tests in any of the patients. Multivariate analysis of variance identified a univariately significant effect of the two-point discrimination test (p = 0.027); all other interactions were multivariately insignificant. CONCLUSION: The value of neurosensory testing after third molar removal is limited because of inconsistency between objective test results and subjective findings.

Adolescent↗

PubMed1998

An evaluation of periapical radiography with a charge-coupled device.

OBJECTIVES: To compare the standards of periapical radiography with a CCD-image receptor with film. METHODS: Three radiography technicians exposed a total of fifty teeth from all areas of the jaws using either size 1 or size 2 film and the Sidexis (Siemens, Bensheim, Germany) direct digital dental radiography system with the appropriate film holders. Image quality was assessed by two dental radiologists for nine individual criteria and overall, on a three-point scale. RESULTS: There was a significant difference between film and sensor exposures (P < 0.014). Six per cent of dental films required retakes compared with 28% with the sensor. CONCLUSION: Periapical radiography with a CCD sensor leads to more errors and thus more retakes than conventional film.

Evaluation Studies as Topic↗

PubMed1998

Effects of calibration and automatic greyscale adjustment on detectability of simulated bone lesions using a storage phosphor system.

OBJECTIVES: To analyse the interaction of calibration, automatic greyscale adjustment and X-ray exposure on the evaluation of simulated bone lesions with the Digora (Orion Corporation Soredex, Helsinki, Finland) storage phosphor system. METHODS: Exposures were made under five conditions based on the exposure time for Ektaspeed Plus film: A-calibration exposure 100%, exposure 100%; B-calibration exposure 100%, exposure 50%; C-calibration exposure 100%, exposure 10%; D-calibration exposure 50%, exposure 50%; E-calibration exposure 10%, exposure 10%. Series of images of artificial bone lesions were created each representing one of the five conditions, with or without automatic greyscale adjustment and including one of two lesion sizes. The series were evaluated by seven expert radiologists. Results were analysed by means of MANOVA statistics. RESULTS: The large lesions were evaluated significantly better than the small lesions (P < 0.011). The two 10% exposure conditions were evaluated significantly worse than the other three (P < 0.029) which had comparable results. Automatic greyscale adjustment had no significant effect (P > 0.253). CONCLUSIONS: The Digora should be calibrated for the highest exposure to be used to optimize the wide latitude. Automatic greyscale adjustment is not useful for the detection of simulated bone lesions.

Bone Diseases↗

PubMed1998

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.

Analysis of Variance↗

PubMed1998

[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↗

PubMed1997

Clinical relevance of third permanent molars in relation to crowding after orthodontic treatment.

OBJECTIVES: The purpose of this study was to determine the relationship between dental crowding and the clinical presence or absence of third permanent molar teeth. METHODS: Ninety-nine patients were analysed before and after orthodontic treatment and at least three years after the end of retention. The sample consisted of four groups: subjects whose third permanent molar teeth had erupted into the mouth, were non-erupted, were extracted, and were congenitally absent. Arch Length Discrepancy, Irregularity Index and observer bias were examined. Multivariate analysis of variance with repeated measurements was used to analyse differences between the four groups. RESULTS: Significant differences in Arch Length Discrepancy during time were shown between the premolar segment and the frontal area. The group with third permanent molar teeth congenitally missing showed a significant higher positive Arch Length Discrepancy in the premolar segment of the upper jaw. No significant differences in Irregularity Index were found between the third molar groups. CONCLUSIONS: It can be concluded that there is no relation between crowding and the presence or absence of third permanent molar teeth.

Adolescent↗

PubMed1997

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.

Dental Caries↗

PubMed1997

Relationships between the orientation and moment arms of the human jaw muscles and normal craniofacial morphology.

It has been suggested that subjects with increased vertical craniofacial dimensions have relatively oblique orientated jaw muscles with a reduced possibility to restrain the vertical component of craniofacial growth. To test this hypothesis, relationships were investigated between the spatial orientation of the jaw muscles and the craniofacial morphology. Computer reconstructions of the external shape of the jaw muscles of 30 adult males with a normal skull were made with the use of serial magnetic resonance imaging (MRI) scans. The orientation of the jaw muscles was defined by a regression line through the centroids of the serial cross-sections. Sagittal and frontal projections of the moment arms of the muscles were measured with respect to the centre of the ipsilateral condyle. Craniofacial morphology was analysed three-dimensionally using lateral head films and coronal MRI scans. The cephalometric data were analysed statistically using regression and factor analyses. Six cephalometric factors with Eigen values higher than 1 were correlated with jaw muscle orientation and moment arm data, using a multiple regression analysis. The anterior face height factor was significantly correlated with the orientation of the jaw opening muscles in the sagittal plane but was not significantly correlated with the orientation of the mandibular elevators. The sagittal moment arms of the mandibular elevators showed significant correlations with the factors describing the gonial angle and the posterior face height. It was concluded that the variation of spatial orientation of the human jaw closing muscles is predominantly associated with the variation of mandibular morphology (expressed by the gonial angle) and the posterior face height. The orientation of the jaw opening muscles shows significant relationships with anterior vertical craniofacial dimensions. The hypothesis that persons with an increased anterior face height have relatively oblique orientated jaw elevators was rejected.

Adult↗

PubMed1997

Estimating distances on direct digital images and conventional radiographs.

Digital images produced by direct sensor systems are much larger than conventional radiographic film images because of monitor resolution and digital image file sizes. This difference in size may introduce difficulties when estimating distances (for example, during endodontic treatment). The aim of this study was to compare observers' estimates of distances on digital images with those of conventional radiographs.

Dental Pulp Cavity↗