Biomedical subjects

E H Verdonschot

Publications and source records attributed to E H Verdonschot.

At least 19 recordsLinked to original sources

PubMed1995

Light propagation through teeth containing simulated caries lesions.

The methods currently utilized in dentistry to detect caries lesions have their limitations and alternatives are being investigated. A promising option is tooth transillumination which is based on an increase of light scattering or light absorption in the affected tissue region. In this study transillumination applied to detect approximal caries lesions was investigated using premolar teeth containing simulated caries lesions. Cavities were drilled at the approximal surface and filled with light absorbing and light scattering fluids in different dye and particle concentrations to model successive stages of lesion progress. For light absorbing cavities the extinction as function of the decadic absorption coefficient measured at the occlusal surface could be approximated by the Lambert-Beer law (r = 0.98 +/- 0.01). For light scattering cavities the extinction as a function of the decadic reduced scatter coefficient wad fitted to a straight line (r = 0.98 +/- 0.03) for mu's (lambda = 633 nm) < 1.25 mm-1. For higher reduced decadic scatter coefficients the curves levelled off due to multiple scattering. In addition, the contribution of the dentinal cavity part to the radiance change induced by the total cavity was estimated. For light absorbing cavities illuminated with red light the average contribution was 10.5 (SD 4.2)% and for those illuminated with green light it was 1.4 (SD 0.9)%, indicating that the radiance change caused by a caries lesion is mainly determined by the enamel lesion part.

Biophysical Phenomena↗

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↗

PubMed1991

Approximal caries diagnosis using fiber-optic transillumination: a mathematical adjustment to improve validity.

Several studies were conducted recently to evaluate the use of Fiber-Optic Trans-Illumination (FOTI) in the diagnosis of approximal carious lesions. All these studies utilized radiographic readings to validate the FOTI diagnoses. Other investigations studied the value of radiographic readings using more solid validating techniques, which made it possible to judge the true state of decay, such as histology, cavity preparation and microradiography. In this study, data from both types of studies were used to estimate the validity of FOTI diagnosis of approximal caries relative to the true status of decay through correction for radiographic misclassification. The results indicate that particularly the sensitivity of FOTI diagnosis has yet to be determined.

Dental Caries↗

PubMed1991

Optical quantitation and radiographic diagnosis of incipient approximal caries lesions.

The objectives of this study were to test the applicability of photocell measurements in approximal caries diagnosis and to evaluate the use of radiographs as validating criterion. Forty extracted premolars were selected, and the progression of the approximal lesions was graded clinically and radiographically by three examiners. Each tooth was transilluminated from the occlusal surface, and the throughput of light at the approximal surface was measured by a photocell. Together with clinical examination, the results of microradiographic analysis served as validating criterion in this study. The results indicate that photocell measurements can be useful in the diagnosis of incipient approximal caries lesions. Radiographs have a restricted value as validating criterion in diagnostic studies pertaining to incipient caries.

Bicuspid↗

PubMed1990

A computer-aided image analysis system for area measurement of tooth root surfaces.

The characteristics of a computer-aided Image Analysis System (IAS) to conduct linear and area measurements on tooth root surfaces were investigated. The borders of the features to be measured were extracted from a digitized video image by histogram-based thresholding and binarization. The lengths and square areas were expressed in the number of pixels. The reference-length and area of one pixel were obtained through measurement of the diameter of a metal ball of known diameter in the same digital image. The validity of the IAS was tested using radiographs of teeth containing round metal restorations of known diameter and area. The accuracy of the length measurements ranged from -2.0 to 2.1%, whereas the accuracy of area measurement was between -5.3 and 0.8%. The precision of the IAS to identify the borders of a tooth root surface and to reproducibly calculate its area, expressed in a coefficient of variation, ranges from 0.49 to 4.11%. The results indicate that imaging techniques can be applied to obtain very accurate measurements of tooth root surfaces.

Dental Enamel↗

PubMed1990