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Biomedical subjects

E H Verdonschot

Publications and source records attributed to E H Verdonschot.

At least 55 records · Page 3Linked to original sources
PubMed1995

Opinions and experiences of dental students and faculty concerning computer-assisted learning.

This study assessed the opinions and attitudes of faculty and students concerning the use of computer-assisted learning (CAL) at three different dental schools on two continents (Manchester, U.K.; Nijmegen, The Netherlands; and Lexington, Kentucky, U.S.A.). In each school students and faculty received a questionnaire; faculty by internal mail, students at the end of a lecture. Response rates for students were 76 percent in Manchester, 64 percent in Nijmegen, and 91 percent in Lexington. The respective figures for faculty were: 42 percent, 47 percent, and 39 percent. In all three schools approximately 50 percent of students had a computer at home. Students in Lexington and Manchester seemed to be more advanced in the use of computers for self-instructional learning. Students and faculty in Lexington had more experience with interactive multimedia than did those in Manchester and Nijmegen. In general, Lexington students were somewhat more familiar with computers and CAL than Manchester students, with Nijmegen showing the lowest percentages. Few CAL programs were available at any school, with small numbers of dental students having been exposed to programs involving animation (vision, sound). The majority of students are of the opinion that the use of computers for learning is not impersonal, nor difficult, but challenging and motivating. There is good agreement that if a program is to be bought or developed, it should be a combination of text, images, and sound. It is postulated that concerted action by dental schools is required to realize the potential of CAL in dental education, and that international organizations should give consideration to coordinating this action.

Adult↗
PubMed1995

[Treatment planning. Learning to solve complicated dental problems].

The importance of comprehensive care treatment planning in dental undergraduate and graduate curricula has long been underestimated. With a decreasing prevalence of dental diseases an increasing interest in the subject has been recognized. Comprehensive care treatment planning requires a strategic approach to resolve a patient's problems in a logical sequence and at a a priori estimation of treatment time and costs. The strategy outlined in this work comprises a phasing of the treatment along urgency criteria. Initially, immediate problems are resolved, followed by microbial problems, functional problems, after which a maintenance plan is established. A treatment planning model is introduced to enable students to hold track of the overall treatment plan and to advice students how to address specific dental problems.

Adult↗
PubMed1994

Prediction of the need for bitewing radiography in detecting caries in the primary dentition.

In recent literature some controversy has been reported regarding the prescription of bitewing radiography for caries diagnosis, particularly in children. While the low prevalence of caries justified the decision not to take radiographs, it has also been reported that the benefits of detecting slowly progressing, clinically undetectable lesions could outweigh the "costs" of radiography. It was the aim of this study to investigate whether specific risk factors could predict the presence of additional dentinal lesions (ADL) in the primary dentition on radiographs which could not be detected by visual inspection. Bitewing radiographs were taken in 182 children aged 5 yr. Risk factors for ADL were identified and appropriate rating scales were designed. Sensitivities, specificities and relative risks expressing the relation between scale values and ADL were computed for each of the risk factors and direct and stepwise discriminant analyses were performed. The results indicate that particularly the presence of lactobacilli and mutans streptococci in saliva and the detection of three or more discolored enamel lesions or dentinal lesions were good predictors of ADL. It is suggested that these risk factors be used in the timing of bitewing radiography in children with a primary dentition.

Child, Preschool↗
PubMed1994

Performance of diagnostic systems in occlusal caries detection compared.

Many investigations have been conducted to evaluate existing and new diagnostic systems in the detection of occlusal carious lesions. The performances of these systems are difficult to compare with each other, because of the disadvantages associated with the widely used validity parameters sensitivity and specificity. In this study a meta-analysis was performed to facilitate a comparison between the performances of diagnostic systems which are currently in use in occlusal caries diagnosis. Nine in vitro studies and one in vivo study complied with the selected criteria for inclusion in the analysis. The sensitivity and specificity values obtained from these studies were converted into normal deviate values, and plotted on linearly scaled normal-deviate axes. DZ values, which quantify the performance above chance of a diagnostic test in one single value, were calculated. Averaged DZ values of the diagnostic systems were subsequently compared to each other. The results indicate that electrical resistance measurements and fiber-optic transillumination had a comparatively good, and visual inspection and xeroradiography a poor, performance in occlusal caries diagnosis. All the other radiographic image modalities had intermediate performances.

Contrast Media↗
PubMed1994

Impact of the validator and the validation method on the outcome of occlusal caries diagnosis.

In studies evaluating the performance of caries-diagnostic methods, a validation of the true state of disease is needed. The aim of this study was to evaluate the impact of the validator and the validation system (stereomicroscopy or radiography of tooth sections) on the outcome of diagnostic tests for occlusal caries. The material consisted of 60 extracted third molars which were serially sectioned (500-600 microns thick). Four observers examined the sections by two caries validation methods: stereomicroscopy and film radiography. The presence of caries in the occlusal surfaces of these teeth had previously been recorded by visual inspection and conventional film radiography. The kappa values for interobserver agreement within one validation method ranged from 0.44 to 0.76 for radiography and from 0.47 to 0.60 for microscopy. The intraobserver agreement with the two methods was low (range 0.31-0.49), and by cross-tabulating the data, it was found that the disagreements originated in a consistently deeper lesion score with stereomicroscopy than with radiography by all observers except 1. By use of receiver operating characteristic curve areas, little impact of the validation method was seen when visual inspection was validated (against microscopy mean area = 0.75, against radiography mean area = 0.74). The mean receiver operating characteristic area was higher when diagnostic film radiographs were validated against radiography (0.68) than against microscopy (0.63). The differences between observers within a validation method were larger with microscopy than with radiography. In conclusion, caries validation methods are subject to variability. The outcome of caries--diagnostic tests may be influenced both by the validator and the validation method.

Dental Caries↗
PubMed1994

[Diagnosis of primary caries. Current techniques and their consequences for treatment].

The decline in caries prevalence in The Netherlands has incited dentists to focus their attention to the detection of small carious lesions rather than large cavities. The diagnosis of primary caries is, however, still predominantly being accomplished by the traditional diagnostic methods, used in the high caries prevalence era. Today's appearance and behaviour of caries lesions have led to the situation that incipient enamel lesions, dentinal caries and cavities are frequently missed during routine recall examinations. There is increasing concern with the occurrence of large caries lesions underneath visually intact enamel. These problems have induced diagnostic research aimed at developing and evaluating new caries diagnostic methods and some of them are already used in general practice. Visual inspection and bitewing radiography, however, still constitute the most important methods in the diagnosis of primary caries. The results from these examinations are used to classify an individual's caries risk, to monitor the progression of existing caries lesions, and to aid preventive or restorative treatment decision making.

Dental Caries↗
PubMed1994

[The computer in education. Applications in dentistry].

During the last decade an increased interest in Computer Managed Instruction (CMI) and Computer Assisted Learning (CAL) can be observed among teachers and students in dental education. Both CMI and CAL can be used to manage individualized instruction, to assist students in specific scientific tasks and to master or enhance knowledge and skills. In balancing the pros and cons against each other, it was concluded that CAL should preferably be developed by joint efforts of collaborating Dental Colleges. It is expected that new developments in authoring systems and hardware will encourage the development of courseware.

Computer-Assisted Instruction↗
PubMed1993

Performance of electrical resistance measurements adjunct to visual inspection in the early diagnosis of occlusal caries.

The detection of small carious lesions at occlusal surfaces is a difficult task, particularly in low caries prevalence populations and individuals. The aim of this study was to evaluate the performance of electrical resistance measurements (ERM) in diagnosing small dentinal lesions at one site per occlusal surface in low caries prevalence populations when used adjunct to visual inspection, and to compare the performance of ERM to that of radiographic examination. The occlusal surfaces of 81 third permanent molar teeth extracted from young adolescents were diagnosed by four examiners, who measured the electrical resistance of enamel on a one measurement per surface basis, and furthermore assessed the occlusal surfaces visually and radiographically. The teeth were sectioned for validation by histological examination. The ERM had the highest sensitivity (0.67), and visual inspection had the highest specificity (0.89). ROC analysis showed no statistically significant differences between the performance of the observers when using visual inspection and ERM (z-score test; P > 0.05). One examiner performed statistically significantly better by measuring the electrical resistance of enamel than by radiographic examination (P < 0.05). The average sensitivity and specificity of the three diagnostic systems were used to express the positive and negative predictive values as a function of caries prevalence. At a caries prevalence of 0.2 the negative predictive values for visual inspection, ERM and radiographic examination were 0.88, 0.91 and 0.89, and the positive predictive values were 0.53, 0.48 and 0.42 respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Developments in radiographic caries diagnosis.

The developments that have been taking place in radiographic caries diagnosis, within the context of the changes occurring in both the disease process and the available technology, are reviewed. The decline in caries prevalence seen in many western countries has been accompanied by changes in the pattern and behaviour of lesions. More lesions are now seen on occlusal surfaces, more are concealed (and thus imperceptible to conventional diagnostic techniques), while the average progression rates for approximal lesions have also slowed. Systems employed for caries diagnosis must take account of these changes and the varying needs of users employing different diagnostic thresholds. This paper reviews and discusses developments in: conventional film radiography; xeroradiography; indirect digital imaging (with computer image analysis and subtraction radiography), and direct digital imaging. It is concluded that: for the detection in high caries prevalence groups of both approximal caries (especially small lesions in enamel) and dentinal occlusal lesions in teeth with little or no surface breakdown, radiography is still a significant and reasonably accurate diagnostic method; and that, in spite of the more limited resolution, digital imaging methods seem to perform as well or better than conventional film radiography. Digital systems possess a number of advantages, primarily the possibility for image enhancement and significant dose reduction. It may be predicted that digital imaging techniques will enter the clinical routine in the near future.

Dental Caries↗
PubMed1993

Assessment of diagnostic accuracy in caries detection: an analysis of two methods.

The quality of a diagnostic tool for caries detection is usually evaluated by quantification of observer performance using sensitivity and specificity values calculated from data obtained from ordinal caries depth rating scales. The application of Receiver Operating Characteristic (ROC) analysis has been restricted to the use of confidence rating scales. The aim of this investigation was to study the appropriateness of ROC analysis using caries depth ratings by comparing sensitivity and specificity values to parameters of diagnostic performance obtained by ROC analysis. In two recent reports, sensitivity and specificity values were utilized to express diagnostic accuracy of observer performance from specified caries diagnostic systems. The raw data from these investigations were subjected to ROC analysis in the current study. The results illustrated that ROC analysis, producing estimates of sensitivities for all specificities, yielded more comprehensive measures of diagnostic performance than single values for sensitivity and specificity. In particular, the area under the ROC curve constituted a clearly interpretable parameter representing the quality of diagnostic performance.

Analysis of Variance↗
PubMed1993

Applicability of Receiver Operating Characteristic (ROC) analysis on discrete caries depth ratings.

Accuracy of diagnostic tests for caries detection is frequently evaluated by sensitivity and specificity values obtained from data acquired on an ordinal rating scale which classifies lesions according to the depth in enamel and dentin. The interpretation of these parameters may, however, be difficult. Receiver Operating Characteristic (ROC) analysis, on the other hand, yields an expression for overall diagnostic accuracy in a single parameter, facilitating a comparison of performance of several diagnostic tests. The basis for applying ROC analysis has been that data were collected on a confidence (likelihood) scale. The aim of this preliminary study was to investigate whether the application of ROC analysis would yield as valid parameters for diagnostic accuracy in assessment of approximal caries on a depth rating scale as on a likelihood rating scale. The results demonstrated that the accuracy of observer performance was not influenced by the type of rating scale employed, justifying the application of ROC analysis on discrete caries depth ratings.

Chi-Square Distribution↗
PubMed1992

Effects of digital grey-scale modification on the diagnosis of small approximal carious lesions.

The aim of this study was to evaluate the accuracy of approximal caries diagnosis from digitized radiographs and digitally modified radiographic images, compared with conventional radiography. Twenty bitewing radiographs were digitized and from the digitized radiographs mirror-images were produced, resulting in 40 digital images. The caries progress at three approximal surfaces was graded by 12 dentists from conventional radiographs, digital unmodified images and digitally modified images. The image modifications were derived from the cumulative probability of grey values in the original digital image using one of five probability distributions: uniform, exponential, Rayleigh, hyperbolic cube root and hyperbolic logarithmic. Interobserver agreement was substantial. The unmodified digital images produced sensitivities comparable to radiographs but their specificities were lower. When the diagnostic task was to discriminate between 'caries' and 'no caries', the exponential, hyperbolic cube root and hyperbolic logarithmic modifications and radiographs performed equally well. With the decision cut off between 'dentinal caries' and 'no dentinal caries', the sensitivity of the hyperbolic logarithmic type of modification was statistically significantly superior to that of radiographs, but this modification was also associated with a statistically significant reduction of specificity. It is concluded that in particular the hyperbolic logarithmic modification can be an alternative to conventional radiography in incipient approximal caries diagnosis and restorative decision making.

Color↗
PubMed1992

Performance of some diagnostic systems in examinations for small occlusal carious lesions.

The objective of this study was to compare the performance in occlusal caries diagnosis of various available diagnostic systems when applied to the same teeth. The sample investigated consisted of 13 children for whom 4 premolar and 19 molar teeth were judged to require a sealant. The indication was based on the criteria 'fissure discoloration', 'enamel decalcification' and 'absence of dentinal decay'. For predefined locations within these occlusal fissures a diagnosis was obtained by the following diagnostic systems: clinical examination, examination on fiber-optic transillumination (FOTI), fissure discoloration, electrical resistance measurement, radiographic examination and ratings of fissure morphology. Tooth material was removed until no (more) carious enamel or dentin was left. Two dentists then jointly decided on the status of decay for each of the defined locations within the fissure. These ratings served as the 'gold standard' diagnoses. The electrical resistance measurement with a sensitivity of 0.96 and a specificity of 0.71 was the only diagnostic tool with acceptable performance. Radiographic diagnosis was characterized by a moderate sensitivity and specificity. All other diagnostic systems had either very low sensitivities or very low specificities, or both. The positive predictive value of FOTI examination and the negative predictive value of the electrical resistance measurements were very high, irrespective of the prevalence of occlusal dentinal decay.

Adolescent↗
PubMed1992

Accuracy of visual inspection, fiber-optic transillumination, and various radiographic image modalities for the detection of occlusal caries in extracted non-cavitated teeth.

Occlusal caries lesions may progress into the dentin without this resulting in a macroscopic breakdown of the enamel surface. Imaging methods may therefore be needed to aid in the visual detection of occlusal caries. It was the aim of this study to evaluate diagnostic accuracy in a laboratory set-up of visual inspection (VI), fiber-optic-transillumination (FOTI), conventional radiography (CR), and two digital radiographic image modalities (DRm and DRr) for detection of occlusal caries in clinically non-cavitated teeth. Eighty-one extracted third molars from 18-20-year-old males were assessed by four observers on a five-rank confidence scale by the five methods. Ground sections (500-600 microns) served as validation for true state of disease: 1 = no caries in dentin, 2 = caries just beyond dentino-enamel junction, or 3 = deep dentinal caries, halfway or more to the pulp. ROC analysis was performed on the basis of the confidence rank scale data on two diagnostic thresholds, T1 = caries in dentin (disease state 2+3) and T2 = caries deep in dentin (state 3). On the T1 level, use of the FOTI method gave on average the most accurate diagnosis, closely followed by VI, both performing better than use of radiography. On the T2 level, all five diagnostic methods performed equally well.

Adolescent↗
PubMed1991

Aesthetic properties of three type II glass polyalkenoate (ionomer) cements.

The aesthetic properties of three recently marketed Type II glass polyalkenoate (ionomer) cements were evaluated in a combined laboratory and clinical study. The materials investigated were Fuji Cap II, ChemFil II in capsules and Ketac-fil Aplicap. The aesthetic properties of a glass ionomer restoration were represented by its translucency, the colour match with surrounding enamel and marginal adaptation. The translucency of all shades of the selected glass ionomer cements was measured under laboratory conditions and expressed as the optical density on transillumination. Colour match and marginal adaptation were evaluated in a clinical study. Twenty Class V restorations of each of the three products were placed. After finishing, the marginal adaptation was rated by two clinicians and colour slides of the restoration were made. Five clinicians assessed the colour match of the restorations from colour slides. ChemFil II and Ketac-fil Aplicap shades were considerably more translucent than the Fuji Cap II shades. The colour match of the ChemFil II restorations was significantly better than the Fuji Cap II and Ketac-fil Aplicap restorations. Marginal adaptation was judged excellent for all three products.

Aluminum Silicates↗
PubMed1991

Applicability of an image analysis system in alveolar bone loss measurement.

Clinical and epidemiological studies in the field of periodontics and endodontics often utilize radiographs to monitor or measure the changes in bone structure and density. Periodontal bone loss or gain can be quantified on a radiograph by measurement of the distance between the bottom of the bony pocket and the apical contour of the involved tooth. The objective of this investigation was to study the accuracy of an image analysis system (IAS) to measure changes in height of the interproximal crest on radiographs. Artificial bone lesions were introduced in a dissectioned part of a human mandible. The distances between crest and apices were measured with a micrometer (MM). Radiographs were produced with horizontal and vertical deviations of 10 degrees. The radiographs were digitized and processed by computer. The landmarks in the digital image were enhanced mathematically and by histogram-based thresholding. The depth of the introduced defect was increased 6 times, followed by the measurement procedure. The IAS produced measurements of crown-apex distances with an accuracy of 0.066 to 0.358 mm. Repeated crest height measurements were recorded with an accuracy of 0.112 to 0.184 mm. Both the histogram-based binarization and the ellipse-fitting type of contour detection could be applied precisely. Misangulation errors during radiographic exposure of 10 horizontal or vertical did not statistically significant influence the IAS-measurements. The IAS can be applied in clinical trials and follow-up studies.

Alveolar Bone Loss↗