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Biomedical subjects

E H Verdonschot

Publications and source records attributed to E H Verdonschot.

At least 37 records · Page 2Linked to original sources
PubMed1998

Marginal integrity and postoperative sensitivity in Class 2 resin composite restorations in vivo.

INTRODUCTION: Problems that may arise in resin composite Class 2 restorations include microleakage and postoperative sensitivity. However, limited in-vivo research is conducted to evaluate these processes. AIM: The aim of this study was to assess postoperative sensitivity, microleakage and the pooling of adhesives in relation to Class 2 box-type composite restorations placed in vivo using various adhesive systems and application techniques. MATERIALS AND METHODS: One hundred and forty-four Class 2 box restorations were placed in the mesial and distal surfaces of 72 premolar teeth in-vivo using one of three combinations of adhesive systems and three filling techniques. After 6 weeks of clinical service postoperative sensitivity was recorded. The teeth were then extracted, immersed in a dye solution and sectioned. Microleakage and pooling of the adhesive was recorded. Statistical analysis involved logistic regression and chi2 tests to identify differences between groups at p < 0.05. RESULTS: Of the 144 restorations, 65 showed minimal cervical leakage in enamel, 5 suffered leakage into dentin and 74 were free of microleakage. No statistically significant differences were found in cervical microleakage between the adhesive systems or between filling procedures. Occlusal microleakage in the enamel was present in 16 of the 160 restorations. Liner Bond 2 restorations leaked significantly more at the occlusal surface (p < 0.05). Pooling of the adhesive was significantly less when PhotoBond was used. No spontaneous postoperative sensitivity was reported. Twenty-eight restorations were sensitive to loading. Postoperative sensitivity was significantly less in patients with Liner Bond 2 restorations. CONCLUSIONS: The adhesive systems used in this study showed minimal leakage into dentin in vivo. Using Liner Bond 2, restorations exhibited more occlusal leakage but were significantly less sensitive to loading.

Adhesives↗
PubMed1998

Surface-specific electrical occlusal caries diagnosis: reproducibility, correlation with histological lesion depth, and tooth type dependence.

Electrical conductance measurements are being used experimentally for occlusal caries detection. Recently, it was suggested to cover the fissure system with a conducting medium, resulting in a surface-specific measurement. It was the aim of this study to determine in vitro the reproducibility of this modified technique for occlusal caries in posterior teeth, to determine for a large study sample the correlation between the electrical measurements and histological lesion depth, and to evaluate the difference between results for premolars and molars. For the reproducibility determination, surface-specific electrical resistance measurements were made using a sample of 68 posterior teeth. Eight operators performed measurements on all teeth, and repeated measurements on 24 teeth. The validity study included the previous sample and the collected samples from two more studies, resulting in a total sample of 325 posterior teeth. One operator had performed electrical resistance measurements on all teeth in the sample. Reproducibility was good: mean Pearson's correlation coefficient 0.89 (+/-0.05) for interexaminer correlation, and 0.86 (+/-0.12) for intra-examiner correlation, using log (resistance) as the result parameter. The correlation coefficient between log(resistance) and histological lesion depth for the large sample was -0.78 for all teeth, -0.64 for premolars, and -0.73 for molars. The regression line for molars was located below the regression line for premolars: at a hypothetical histology score of 2.5 (a dentine caries threshold) the estimated resistance threshold would be 507 kOmega for premolars, and 233 kOmega for molars. Converted to Electronic Caries Monitor (ECM) readings, the difference is about 1.4 on the ECM scale. It was concluded that the in vitro reproducibility of the described surface-specific method for electrical resistance measurement is very good, even for inexperienced operators. The correlation between measurements and histological lesion depth is moderate to good. The method is sensitive to electrode area differences, which will result in different clinical cut-offs for caries diagnosis in premolar and molar teeth.

Bicuspid↗
PubMed1998

[Is there a place for computer-assisted Post-Academic Dental Education (PAOT)? A survey from the period 1998-2008].

OBJECTIVE: To estimate the role of computer-CPED in the Netherlands to the year 2008. DESIGN: Computer-assisted learning is currently employed in many modern undergraduate dental curricula. It could also play an important role in providing continuing professional education in dentistry (CPED) to general dental practitioners. Computer-CPED offers teacher-independent and individualized interaction by distance learning. METHODS: A simulation study was conducted. Entry data were either derived from publications or were estimated. RESULTS: The results indicate that the demand for CPED will exceed the supply by 2002. CONCLUSION: The introduction of Computer CPED may substantially contribute to the supply of CPED-courses in de first decade of the next century. By 2008 about 25% of the CPED-courses could be provided by computer education.

Computer Communication Networks↗
PubMed1998

[Re-restoration decisions].

OBJECTIVE: In this study an attempt was made to explain some of the interobserver variation in re-restoration decision making using. METHOD: A simplified re-restoration case was shown to 22 dentists who were asked what treatment decision they would make, and what factors would play a role in their decision. The treatment decisions were compared to the outcomes of a knowledge-system on re-restoration decision making. RESULTS: The dentists unanimously selected re-restoration as the treatment alternative. Half of the dentists preferred amalgam, and the other half chose composite as restorative material. This variation could be explained almost fully by the dentists' weighs on the factors 'tissue loss during preparation', 'restoration and preservation of the chewing function' and 'prognosis and durability of the restoration'. The knowledge system indicated that more than 80% of the dentists actually should have selected composite resin for a restorative material. CONCLUSIONS: It was concluded that the availability of knowledge and its application can explain variation in re-restoration decisions. Knowledge systems can be used in designing practice guidelines.

Decision Making↗
PubMed1997

Adaptation and radiographic evaluation of four adhesive systems.

OBJECTIVES: The purpose of this study was to compare microleakage, gap formation, thickness of the adhesive layer and its radiographic appearance associated with four adhesive restorative procedures for class I cavities. METHODS: Adhesive systems with easy handling characteristics were selected for the restoration of class I cavities in extracted third molars. Bitewing radiographs were taken of each tooth and four observers were asked to assess the presence of the adhesive layer. Microleakage, gap width and the thickness of the adhesive layer of each restoration were measured upon sectioning of the teeth. RESULTS: Microleakage in the experimental restorations was minimal. The thickness of the adhesive layers and gap formation varied among different adhesive systems. The adhesive system with self-etching primer produced the highest percentage gap-free restorations. Thick adhesive layers could be detected on the radiograph. ROC analysis of the results validates the diagnosis from the radiograph. CONCLUSIONS: The four restorative systems performed well in the prevention of microleakage. The use of a resin modified glass-ionomer cement base did not prevent gap formation compared with the all-etch bonding systems used in this study. The presence of an adhesive layer contributed to the prevention of gap formation, independently of the bonding system used. Thick adhesive layers could be detected on the radiograph.

Acid Etching, Dental↗
PubMed1997

The effect of a multimedia interactive tutorial on learning endodontic problem-solving.

New technology may create additional opportunities for learning in dental education. One of these new features is a multimedia approach, courseware combining sound, text, stills and video with interactive learning. A multimedia program was developed to train dental students and dental practitioners in decision making and problem solving in endodontics. This study compared the effects of the multimedia program with a more traditional approach consisting of written information, without interaction. 28, 4th-year dental students at the University of Kentucky in Lexington, KY, USA were randomly assigned to the multimedia or the text-based groups. They were given a written pre-test using 2 cases of dental pain and were instructed to study independently using either the multimedia program (group A) or the written information (group B). No restrictions were imposed on the amount of time to be invested, and the total study time was recorded for each student. 3 weeks after the pre-test, the students completed the post-test. A total of 18 students completed both the pre-test and the post-test and their scores were included in the final data. Statistical analysis of the average scores using paired t-tests revealed no significant difference between the performance of the students in either group, indicating that the multimedia approach to learning endodontic problem solving may successfully replace traditional learning strategies.

CD-I↗
PubMed1997

Wavelength-dependent fibre-optic transillumination of small approximal caries lesions: the use of a dye, and a comparison to bitewing radiography.

The mere detection of caries lesions is insufficient for optimal treatment decision-making. Hence, the aim of this study was to investigate whether quantitative information about approximal lesion depth can be obtained from a technique based on the wavelength dependency of light propagation and additional use of a dye. Another aim was to compare the diagnostic performance of the optical technique and bitewing radiography. Measurements were performed on 33 extracted premolar teeth. Twelve proximal surfaces had white-spot, and 17 had discoloured small lesions. Four surfaces were sound. The teeth were transilluminated with a single glass fibre at the approximal surface before and after dye application. The occlusal surface was imaged with a CCD camera. Light in the blue and red part of the electromagnetic spectrum was selected using Schott glass filters. Average decadic optical thickness differences, delta bl-rd tau eff, were estimated and plotted as a function of normalised lesion depth, dhist, established from histological validation by two observers. The Spearman rank correlation was rs (delta bl-rd tau eff, dhist) = 0.87 (95% confidence interval, CI: 0.74-0.94). A marked increase in average decadic optical thickness in the blue part of the electromagnetic spectrum, delta dye tau eff, was observed for those lesion that, upon direct visual inspection of the approximal surface, clearly showed dye uptake. Bitewing radiographic depth ratings of two observers were plotted as a function of dhist. The correlations were rs (dRA,1, dhist) = 0.62 (95% CI: 0.34-0.80), rs (dRA,2, dhist) = 0.75 (95% CI: 0.54-0.87), and between the observers rs (dRA,1, dRA,2) = 0.44 (95% CI: 0.10-0.69). The p values of rs (delta bl-rd tau eff, dhist) -rs (dRA1,1, dhist) and rs (delta bl-rd tau eff, dhist) -rs (dRA,2, dhist) were p1 = 0.01 and p2 = 0.08, respectively. It was concluded that quantitative information about lesion depth can be obtained optically. The dye penetrates into only a limited number of caries lesions, in which cases dye uptake is detectable in transillumination geometry. Under laboratory circumstances the optical technique performs as well as bitewing radiography in the diagnosis of small approximal caries lesions.

Bicuspid↗
PubMed1997

Quantitative diagnosis of small approximal caries lesions utilizing wavelength-dependent fiber-optic transillumination.

The instruments clinically available for the diagnosis of approximal caries lesions are inadequate to detect lesions early and quantitatively. The aim of this study was to investigate whether wavelength-dependent light scattering and absorption of carious tissues may be utilized for the quantitative diagnosis of these small approximal caries lesions. Seventeen extracted premolar teeth were transilluminated at an approximal surface with a glass fiber, which transported the light from a halogen light bulb. Seven approximal surfaces contained a naturally developed small white-spot lesion, and 5 surfaces a small discolored lesion. Five teeth were sound. The occlusal surface was imaged with a CCD camera. Light in the blue and red portions of the electromagnetic spectrum was selected by means of Schott glass filters. From the obtained images, average effective decadic optical thickness differences were determined. These were plotted as a function of average mineral loss assessed by means of wavelength-independent microradiography. The correlation coefficient between the average effective decadic optical thickness difference and average mineral loss was r = 0.79 (95% CI: 0.47 ... 0.93). Different sources of variation that influence the observed correlation were defined and quantified. From these measurements, the correlation coefficient between average effective decadic optical thickness difference and "true' average mineral loss was estimated to be r = 0.92 (95% CI: 0.77 ... 0.97). The results indicate that early and, in principle, also quantitative diagnosis of approximal caries lesions is feasible when wavelength-dependent light propagation through carious tissues is utilized.

Dental Caries↗
PubMed1997

[Practice guidelines in dentistry. An insight into the Dutch situation].

Practice guidelines provide opportunities for monitoring and improving dental health care. A survey was conducted among 78 departments at dental societies, scientific dental associations and health care insurance companies in the Netherlands to obtain insight into the number and quality of practice guidelines available. The response rate was 67%. Written materials were analysed and 21 practice guidelines were identified as such. The results of the analysis indicate that many initiatives to construct and implement practice guidelines have been taken. However, these initiatives were insufficiently coordinated and existing guidelines may be subject to improvement. Main improvement would be to demonstrate the validity and reliability of the existing guidelines and, more in general, to provide a sound scientific basis to the development and implementation of practice guidelines.

Data Collection↗
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↗
PubMed1995

Propagation of light through human dental enamel and dentine.

Techniques based on transillumination of teeth with visible light will be a valuable aid in caries diagnosis, if a higher sensitivity than that of the present Foti method is achieved. Therefore, a better understanding of light propagation through teeth is required, and hence it is useful to investigate the propagation of light through sound dental material. In this study the intensities emanating from the surfaces of enamel and dentine bars were measured when these bars were illuminated using a fibre rod transporting the light from a HeNe laser (lambda = 633 nm) as a light source. From the measured intensities, the radiant fluxes emanating from the surfaces were calculated. To account for a directional dependence of these fluxes, optical anisotropy in dental material was investigated by comparing the transmitted light intensity in a direction perpendicular and parallel to the approximal surface of the tooth from which the sample was cut. The mean ratio of the transmitted intensities in perpendicular and parallel direction was 0.86 +/- 0.06 for enamel and 2.88 +/- 0.43 for dentine. In addition, for enamel the asymmetry parameter, g, was estimated. The averaged value was g = 0.68 +/- 0.09. It was concluded that for dentine the optical anisotropy as measured supports the idea that tubules are the predominant cause of scattering in dentine. For enamel the results indicate that the hydroxyapatite crystals contribute significantly to scattering and that the influence of the prism structure on the light propagation is small.

Anisotropy↗
PubMed1995

Electrical conductance and electrode area on sound smooth enamel in extracted teeth.

Electrical conductance measurements are being used experimentally to diagnose caries. Current equipment, e.g. the electronic caries monitor (ECM), uses a probe to scan occlusal fissures. For full-mouth examination this method is rather time-consuming. A method with which only one measurement is needed for an entire (occlusal) surface would be preferable. However, the enlargement of the area being measured will influence the conductance. It was the purpose of this study to investigate the relationship between the electrical conductance of human teeth and the enamel electrode area, and to compare the range of results of surface measurements with those of the scanning method. Twenty-five sound extracted teeth were selected for the study. The reference electrode of the ECM was connected to the roots. The buccal surface was blotted dry, and a coloured dentifrice was syringed in increments onto the surface. After each increment the surface was photographed together with a metric reference, a conductance measurement was performed by holding the ECM probe tip in the dentifrice, and the ECM reading was recorded. For each tooth between 5 and 10 increments were applied and measured. The photographs were digitised and the electrode areas were calculated. A least squares curve fitting procedure yielded a linear relationship between conductance and electrode area (0.88 < or = R2 < or = 1.0, mean R2 = 0.97). For most teeth the threshold for dentinal caries as used for scanning ECM measurements (ECM reading = 6.00) was reached only when the electrode area exceeded 12 mm2. For 6 teeth this conductance was already reached between 5 and 12 mm2.(ABSTRACT TRUNCATED AT 250 WORDS)

Dental Caries↗
PubMed1995

Electrical conductance of fissure enamel in recently erupted molar teeth as related to caries status.

Pit-and-fissure caries lesions contribute greatly to the caries incidence in permanent molar teeth in children. To date, the diagnosis of occlusal caries is still performed mainly by visual inspection, periodically aided by bite-wing radiography. However, in detecting small occlusal carious lesions, these methods perform inadequately, especially in low caries prevalence populations or individuals. The use of electrical conductance measurements (ECMs) has been evaluated to improve the diagnosis of small occlusal carious lesions. The aim of this study was to monitor the electrical conductance of fissure enamel in recently erupted molar teeth and to relate these measurements to the caries status. 50 children aged 5-15 years, having first or second permanent molars that were not exposed to the oral environment for more than 6 months, participated in the study. The diagnostic systems evaluated were visual inspection and ECMs. Following baseline data recording, diagnostic measurements were repeated three times within 18 months. Data were collected at predefined sites in the fissures. 18 months after baseline recording, 179 sites at 60 molar teeth in 27 children were judged to require a sealant based on visual inspection. After removal of carious tissue, two examiners jointly decided on the status of decay as per the criteria: 0 = no caries or caries limited to enamel, and 1 = caries involving dentine. The sensitivity of ECM continued to increase with time after a slight initial dip, whereas the specificity continuously increased after baseline measurements as a result of the decreasing amount of false-positive diagnoses.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Validity of electrical conductance measurements in evaluating the marginal integrity of sealant restorations.

The use of sealants and sealant restorations has increased considerably over the past 10 years, and with it increased the problem of detecting secondary caries and marginal (micro)leakage. It was the purpose of this study to investigate the validity of electrical conductance measurements (ECMs) in diagnosing marginal leakage into dentine of sealants and sealant restorations. Ninety extracted premolar teeth were divided into three groups. Initial ECMs, denoted 'baseline ECMs', were conducted in all three groups by placing the probe tip of an Electronic Caries Monitor in the occlusal fissure which was filled with a dentifrice. The ECMs were divided by the area, yielding ECM/mm2 values. In group A 30 teeth were treated to receive 'nonleaking sealants'. In the 30 teeth of group B a narrow groove was cut at the occlusal surface reaching the dentine and restored by the application of a sealant without etching of the adjacent enamel to create a high probability of marginal leakage. The samples in group C received the same treatment as those in group B, but in this group the enamel was etched to reduce the probability of marginal leakage. The ECMs subsequently conducted were denoted 'sealed/restored ECMs'. Teeth in groups B and C were thermocycled 700 times (4-67 degrees C) to provoke leakage, after which ECMs were conducted (denoted 'ECMs after thermocycling'). The teeth were immersed in fuchsin for 24 h and cut along the fissure system to validate marginal leakage. The electrical conductance decreased significantly from baseline to the sealed/restored stage in all groups (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Bicuspid↗
PubMed1995

Factors involved in validity measurements of diagnostic tests for approximal caries--a meta-analysis.

In this study, a meta-analysis was performed on published validity parameters of visual inspection, radiographic examination and visual inspection upon fibreoptic transillumination (FOTI) in approximal caries diagnosis. It was the objective to investigate the influence of the diagnostic test, the study design and the validation method on reported validity. Sensitivities and specificities reported in the literature were transformed into D2 values, representing the performance of a diagnostic method above chance, or of the observer using it, in a single parameter. Dz values were neither statistically significantly different between visual inspection, radiographic examination and FOTI nor between 'weak' and 'strong' validation methods (p > 0.05). Dz values obtained from in vivo studies were significantly different from those obtained from in vitro studies (p < 0.05), indicating that study design had a significant impact on the measurement of the validity of the evaluated test for approximal caries diagnosis.

Dental Caries↗
PubMed1995

[Bitewing radiographs in dentistry: how frequently are they indicated?].

Bitewing radiographs should be taken on an individual indication. The individual's caries risk is an important factor in determining the frequency of bitewing radiographs and, therefore, a dentist should estimate the individual's caries risk. Given two serial bitewing radiographs, the dentist should be able to distinguish freshly developed caries lesions, which require preventive or restorative treatment, from old remineralized lesions, which do not require any treatment at all. Assessment of caries progression from serial bitewing radiographs should also provide the dentist with information to determine the moment of subsequent bitewing radiographs. Because in many western countries the caries prevalence is quite low, this is a complicated task, since the dentist is expected to carry out the diagnostic and decision making process without errors. The true probability of caries progression was derived and plotted as a function of the time span between two bitewing radiographs. The results indicated that the interval between standardized serial bitewing radiographs should be approximately three years for individuals which run a high risk of developing caries, and four years for individuals with a low caries risk.

Dental Caries↗
PubMed1995

[Towards a system of quality care in dentistry in the Netherlands].

Monitoring and improving the quality of rendered health care in a systematic way has been laid down in Dutch legislation. In Dutch family health care particularly, many initiatives have already been taken to improve the quality of health care utilizing a pre-defined systematic approach. In recent years various groups in The Netherlands took initiatives to maintain and improve quality of care in dentistry. This publication reports on some of the frequently used constructs and the state of the art in The Netherlands. A proposition for the development of a system of quality monitoring and improvement is presented. It is furthermore suggested that all parties involved should collaborate to achieve the joint goal.

Dentistry↗