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J J ten Bosch

Publications and source records attributed to J J ten Bosch.

At least 19 recordsLinked to original sources
PubMed2006

Transversal wavelength-independent microradiography, a method for monitoring caries lesions over time, validated with transversal microradiography.

This paper describes a microradiographic method for measuring mineral concentration in a transversal geometry with thick (< or =3.2 mm) sections: transversal wavelength-independent microradiography (T-WIM). It was tested on bovine enamel and dentin samples in vitro, and the results were validated with those of transversal microradiography (TMR). 48 enamel and 48 dentin samples (3.2 x 3.2 x 1.5 mm) were embedded in acrylic resin, randomly divided into six groups of 8 dentin or 8 enamel samples, and demineralized for 0 (sound control), 1, 2, 3, 4, or 5 weeks. For T-WIM, samples were imaged on film with polychromatic 40-kV Cu X-rays with an Al (0.25 mm)/Ni (0.02 mm) filter together with an aluminium/zinc step wedge. TMR slices (about 80 mum for enamel and about 130 mum for dentine) were subsequently cut from the centre of the samples and subjected to TMR. Microradiographs from both methods were digitized and image analysis software was used to calculate lesion depth and mineral loss. The relations between T-WIM and TMR results for mineral loss (DeltaZ) and lesion depth were nearly linear (r > or = 0.96) for both enamel and dentin. The slopes of the regression lines were between 0.99 and 1.02 except for DeltaZ in dentine, which was 0.89. It was concluded that T-WIM is a suitable method for TMR on thick samples.

Animals↗
PubMed2003

[Lasers in dentistry. Epilogue].

Laser use in the dental clinic requires scientifically demonstrated improvement for patient and/or dentist, easily obtainable equipment, adequate training and safety. These aspects are summarized for all laser applications. Improvement has not been shown for all applications. In the Netherlands manufacturer-independent training is little available. Safety requires care, but not a large investment. Economical aspects include an adequate compensation for the necessary investment. For only a few applications laser treatment leads to decreased cost or time of treatment. However, also increased compensation by insurers or patients may be possible; some patients will be willing to pay more when laser treatment is less unpleasant than traditional treatment or, in the case of diagnosis, leads to better information.

Dental Equipment↗
PubMed2002

[Lasers in dentistry 1. What is special about lasers?].

Diagnosis and treatment with lasers is becoming widely spread in dentistry. This article is an introduction to a series of articles that deal with the many dental applications of lasers. The article contains a summary of presently used lasers. It also describes the pertinent features of laser radiation: parallelism of the beam and narrow line shape in the spectrum of electromagnetic radiation. Finally, it summarizes the relevant processes of interaction of laser radiation with tissue: scattering, absorption, fluorescence and frequency-doubling.

Dental Instruments↗
PubMed2002

[Lasers in dentistry 6. The soft laser].

A soft laser is a low-power laser emitting in the red and near-infrared part of the spectrum. Studies with cell cultures have shown that radiation from a soft laser, when used under proper conditions, promotes cell function and cell proliferation. However, wavelength and dose should be carefully adjusted to an optimum value: too low a dose does not work and neither does a high dose. The dose should be adjusted within an interval of about 10%. In a few animal studies a positive effect on wound healing has been demonstrated, although other studies did not show such an effect. Of the human studies done in the dental field, many do not meet scientific standards because there was no control group or the study was not double-blind. A few studies showed a positive effect but most did not. Perhaps the large variation in results may be explained by the required accuracy of adjustment of the dose, combined with the complicated processes that relate the incident dose to the dose to cells lying on or in tissue. More research, in particular studies in which the dose and wave length are varied systematically, are needed before responsible clinical use can be recommended.

Animals↗
PubMed2001

Quantitative light-induced fluorescence (QLF): a method for assessment of incipient caries lesions.

OBJECTIVES: To review the literature on validation and application of the quantitative light-induced fluorescence (QLF) method for quantitative assessment of early enamel lesions in vivo and in vitro. METHODS: QLF uses light with wavelengths around 405 nm to excite yellow fluorescence at wavelengths above 520 nm. Its diagnostic capacity is based on the mechanism that the intensity of natural fluorescence of a tooth is decreased by scattering due to a caries lesion. The equipment, the data processing and the interaction between equipment and operator are described. RESULTS: The method has been validated by many authors; the results are presented and compared. For artificial lesions, the validation line is curved. For larger mineral losses, the curve is linear with a slope of 10% fluorescence loss corresponding with a mineral loss of 0.15 kg x m(-2). For lesions caused by natural caries, it is tentatively concluded that fluorescence loss is linear to mineral loss with a slope similar to that of artificial lesions. Reliability and reproducibility have been tested in vivo and show interexaminer values of the interclass correlation coefficient, r, of 0.93<r<0.99. Confounding factors are inadequate reconstruction of sound fluorescence values and drying of the lesion before or during measurement. In vivo application showed that statistically significant changes between different preventive regimes could be proven in only 6 months of study time. CONCLUSION: QLF offers a potential tool to reduce the time needed for clinical research. Its objectivity will prove useful in epidemiological surveys. QLF provides visual and quantitative feedback to patients.

Child↗
PubMed2000

Characterization and validation of diagnostic methods.

Diagnosis is defined as the determination of disease, but not as the determination of the signs and symptoms thereof. The use of modern diagnostic methodology in the clinic is hampered by cost considerations and by the still widespread belief that, e.g. caries lesions and periodontal breakdown are irreversible processes that need to be detected and treated invasively as early as possible, their measurement thus being irrelevant. Modern instrumental and quantitative methods allow early detection and introduction of noninvasive preventive measures to control the development of the disease. Such methods are also very beneficial in clinical research as they may describe the speed of progress or regress of disease. In epidemiology, such methods reduce the classical problem of calibration of observers. Repeatability, reproducibility, accuracy and validity are defined as method-characterizing quantities, for which examples are given. To express the validity of quantitative methods compared with a quantitative gold standard, the use of scatter plots and correlation and regression methods is suggested. Validation of a dichotomous method with a dichotomous gold standard in terms of sensitivity and specificity is discussed. To validate a quantitative method with a dichotomous gold standard, the receiver operating characteristic curve is suggested, with the requirement that the cutoff value should be determined in relation to the use of the method. However, preferably a quantitative method should not be reduced to a dichotomous one by using a cutoff value, but instead all available information should be used by the diagnostician. It is argued that the use of a secondary standard instead of the accepted gold standard usually leads to inadequate results, even when the validity of the secondary standard is known. Finally, it is argued that the choice of a gold standard is a matter of reasoning and weighing of arguments and not of following a prescribed procedure.

Calibration↗
PubMed2000

Time-dependent decrease and seasonal variation of the porosity of recently erupted sound dental enamel in vivo.

Recently erupted teeth are more sensitive to dental caries than teeth that have remained free from caries lesions for a few years after eruption. It has been hypothesized that this may be ascribed to differences in enamel porosity. The objective of the present work was to assess the time-dependence of electrical conductance, as an indication of porosity, of occlusal enamel in recently erupted permanent molar teeth. Fifty children aged 5-15 years of age, receiving regular dental care at six-month intervals, participated in the study when their first molar teeth (in 5- to 6-year-olds) or their second molar teeth (in 11- to 15-year-olds) had not been exposed to the oral environment for more than six months. On the first semi-annual check-up after eruption of a first or second molar, baseline diagnostic measurements, i.e., visual inspection and electrical conductance measurements (ECMs), were made at three or four pre-defined sites in the fissures. Subsequently, data collection was repeated every six months for three years. Sites were excluded from ECMs when a caries lesion was observed at a site by visual inspection. After 36 months, there were 257 sites in teeth considered sound upon visual examination. The ECM values of these sound sites showed a clear decrease with time after the first examination. The conductance decreased on average from 0.13 (Momega)(-1) to 0.059 (Momega)(-1). Since the conductance is assumed to be proportional to the porosity of the enamel, the latter decreased by a factor of 2.2 over the 36-month period. The results furthermore indicated a higher conductance for maxillary than for mandibular enamel. Almost all sites in that sample appeared to be in teeth that were observed for the first time during the months September to December. Electrical conductance, and therefore enamel porosity, of the sites showed a periodic variation with season of observation: In the fall, the conductance was higher than in the spring. This implies that a dentist should be more prudent in the fall than in the spring when indicating restorative treatment of an incipient caries lesion.

Adolescent↗
PubMed2000

The real performance of bitewing radiography and fiber-optic transillumination in approximal caries diagnosis.

For both general practitioners and researchers in caries diagnostics, the true validity of available diagnostic techniques is of considerable interest. Yet, for both bitewing radiography and fiber-optic transillumination, this is still not accurately known, nor is it clear which of the two techniques performs best clinically. This study's purpose was to estimate the clinical performance of the two techniques in diagnosing approximal caries lesions in low-caries-prevalence populations. Clinical studies that compare the two techniques were selected from literature. We determined 2 x 2 contingency tables from these studies and calculated one overall contingency table. The cut-off for decay was at dentinal caries. Assuming that erroneous outcomes from both techniques are mutually independent, we expressed diagnostic sensitivity and specificity of the two techniques as functions of the contingency table cell contents, with caries prevalence as the parameter. Because the caries prevalence was unknown, every sensitivity and specificity value was possible. From the conditions that sensitivity, specificity, and caries prevalence are always between one and zero, a limited range of sensitivity and specificity values was obtained. Three situations were examined: Bitewing radiography specificity is 1, fiber-optic transillumination specificity is 1, and both specificities are equal. Under these conditions, the bitewing radiography sensitivity was between 1.00 and 0.71 +/- 0.01, and the fiber-optic transillumination sensitivity was between 0.70 +/- 0.01 and 0.50 +/- 0.02. Both specificities were between 1.00 and 0.99. We concluded that the two techniques have comparable specificities. but that the fiber-optic transillumination sensitivity is significantly lower than that for bitewing radiography.

Dental Caries↗
PubMed1999

Developments in caries diagnosis and their relationship to treatment decisions and quality of care. ORCA Saturday Afternoon Symposium 1997.

This symposium report evaluates the achievements made in caries diagnostic research since the previous symposium held in 1992. The symposium aimed at presenting the state of the art of caries diagnostic methods, on presenting the links between caries diagnosis and subsequent treatment decisions and their effect on the treatment outcomes, particularly the quality of dental care. The variation among dentists in diagnosing (small) caries lesions and in treatment decision making is considerable. This has been explained by the imperfection of caries decision making tests, but also by making incorrect treatment decisions due to incorrect or partial understanding of diagnostic test parameters. Meta-analyses into the performance of caries diagnostic tests revealed that the available quantitative methods are very promising. It was concluded that these methods had high correlations with lesion depth. They were considered suitable to monitor small changes in lesions. Many obstacles have been experienced in attempting to transfer the outcomes of diagnostic research into clinical practice and it was concluded that caries diagnosis researchers should co-operate with manufacturers to introducing valid new diagnostic tools to the market. Main research priorities for the coming 10 years are to conduct cost-effectiveness and cost-utility studies of caries diagnostic tools, to continue to review the performances of diagnostic tests, to transfer diagnostic knowledge and experience to the general practitioners particularly by constructing evidence-based clinical guide-lines, to study the relationship between diagnosis and treatment decision, and to assess the effect of diagnostic and treatment decisions on the outcome of care.

Cost-Benefit Analysis↗
PubMed1998

Optical properties of bovine muscle tissue in vitro; a comparison of methods.

We measured the optical properties of muscular tissue using several methods. Collimated transmission measurements of thin slabs showed spatial anisotropy of the scattering processes. Surface roughness of the sample disables the calculation of the extinction coefficient from these measurements. From angular intensity measurements we found a scattering asymmetry parameter g = 0.96. In fresh samples the optical diffusion constant D depends on the orientation with respect to the longitudinal direction of the muscular cells. From the D values we calculated s' perpendicular to the longitudinal direction as 0.19 mm(-1) (at 543 nm), 0.39 mm(-1) (at 594 nm) and 0.59 mm)(-1) (at 632 nm). The values for D which we measured from samples that were frozen and thawed did not show dependence on orientation. From spectral dependent reflectance measurements we found an oxygenation degree of 0.61 and a reduced scattering coefficient s' = 0.85 mm(-1) around 560 nm.

Animals↗
PubMed1997

Problem solving and problem-solving education in dentistry.

Academic education in dentistry should lead to the capability to solve complex open problems. The student entering university is only familiar with closed problems. Research into the making of a medical diagnosis has shown that novices do so differently than experts. These research results are summarised and are presumed to be transferable to dental diagnosing and treatment planning. Examples of this transfer are given. Until 1 or 2 decades ago, education in problem solving was done only by extensive teacher-student interaction in clinical and scientific work. Presently, this is no longer adequate because of reduction of curriculum time for these activities. Therefore other methods have been developed in many places. These methods include the use of a problem-solving model (heuristic). Based on models in the literature, 3 new models are presented. These are intended for novices that solve a dentally relevant open problem in basic sciences, for novices that solve a clinical dental problem, and for more expert students that solve such a problem. Diagrams and examples are given.

Curriculum↗
PubMed1997

X-ray-induced photoelectron spectroscopy of dentin as a function of duration of Ar(+)-ion etching.

XPS, or ESCA, measures the atomic concentration in the outermost layers of the sample. The surface is often etched with Ar(+)-ions before any measurement. We investigated the role thereof on XPS measurements of root dentin. Nine slices were cut from premolars. Slices were ground or broken. XPS was measured before etching. Six samples were then subjected to Ar(+)-ion etching (10 kV ions, 0.25 microA/mm2). A gold sample was also included. Relative concentrations of N and C decreased with etching time, while O, P, and Ca increased. N and C curves were analyzed assuming a sum of two exponential decays and a final level. On average, tau 1 = 20 sec for C and 17 sec for N. On average, tau 2 = 278 sec for C and 350 sec for N. No differences between differently prepared samples were apparent. The gold sample showed a single decay to noise for C and N, with tau 1 = 8 and 7 sec, respectively. We conclude that two decay processes are present, due to gas removal and to the removal of organic material from the dentin matrix, respectively. Thus, true values can be obtained by extrapolation to t = 0 of only the data obtained by summing the slow decay and the final level.

Acid Etching, Dental↗
PubMed1996

A fiber-optic setup for quantification of root surface demineralization.

A fiber-optic fluorescence observation (FOFO) technique has been developed for the quantification of demineralized root dentin. The method was tested on 40 specimens of in vitro demineralized parts of human root dentin. Fluorescein sodium salt was used as a penetrating dye. The fluorescein sodium salt was excited using light around 465 nm. The fluorescence signal around 527 nm measured for demineralized dentin was corrected for lamp output and then divided by the corrected fluorescence signal for the sound control dentin on the same root, resulting in a FOFO-value. FOFO-values correlate linearly (r = 0.91) with mineral loss measured by transverse microradiography. Therefore, it was concluded that the FOFO-technique provides a good, non-destructive measure of the severeness of in vitro demineralized human root dentin, and is applicable on bulk dentin. Future work on natural lesions in vivo will be needed to investigate the applicability of the technique in a clinical situation.

Adolescent↗
PubMed1996

The influence of mineral loss on the auto-fluorescent behaviour of in vitro demineralised dentine.

The aim of this study is to investigate the influence of demineralisation on the fluorescent properties of dentine. The fluorescence emission at 529 nm due to 515 nm excitation of in vitro demineralised lesions was determined with a micro-Raman spectroscope as a function of location. Results were compared with the mineral loss profiles of the same lesions measured by microradiography. The root surfaces of 6 in vitro demineralised human third molars (lactic acid CMC gel, pH 5; six groups: 0, 4, 7, 14, 18 and 21 days) were used in the experiment. Thin slices of +/- 130 microns were cut perpendicular to the tooth axis. The fluorescence scans corresponded to mineral loss profiles. Confocal microscope images showed increasing fluorescence with increasing mineral loss. From these results it is concluded that this mineral loss causes an increase in auto-fluorescence by a factor of at least 10, therefore the chromophore causing this green fluorescence must be organic in nature. De-quenching or modification of this fluorophore due to the demineralisation process is probably the cause for the increase of the green fluorescence.

Dentin↗
PubMed1996

Dynamics of and diagnostic methods for detecting small carious lesions.

This paper reviews and discusses the dynamics of carious lesions and diagnostic methods for their detection. Summary data are presented on progression rates of differing lesion types with differing initial severity. Among the non-invasive techniques, fibre-optic transillumination, used appropriately, gives the most accurate estimate of posterior approximal dentinal caries. Electrical resistance methods are likely to provide a significant contribution to the diagnosis of occlusal caries in the future. Radiographs remain an important component of the diagnostic armamentarium and may be enhanced by the introduction of direct digital imaging. Problems in appropriate validation must be addressed to ensure that new techniques are correctly evaluated.

Dental Caries↗
PubMed1996

Evaluation of sodium fluorescein for quantitative diagnosis of root caries.

The diagnosis of root caries, in particular the judgment of the activity of a visually observed lesion, is difficult. Quantitative determination of lesion severity would allow the lesion to be monitored with time, so that an indication of lesion activity could be obtained. This paper describes a step in the development of a method that provides such a quantitative determination. Specifically, fluorescein sodium salt is used as a penetrating dye, the subject of study being the relationship between dye concentration and porosity in demineralized root dentin. Fourteen human third molars were demineralized in vitro (lactic acid CMC-gel, pH 5; in each of 6 groups for 4, 7, 11, 14, 18, and 21 days). Fluorescein sodium salt (0.2 g/L) was applied for 2 min. Thin slices (+/- 130 microns) were cut from the root surfaces without water cooling. The dye fluorescence radiance in the demineralized dentin was determined by means of a micro-Raman spectroscope and compared with the mineral loss profiles measured with transverse microradiography (TMR). The TMR data were corrected for the difference in measurement area between the two measurement systems. Corrected TMR profiles were compared with the corresponding fluorescence scans, showing linear correspondence. The correlation coefficient was r = 0.96. We conclude that, after uptake of fluorescein sodium salt for 2 min, the dye concentration in an artificially produced root-surface caries lesion is proportional to the amount of mineral lost from that lesion.

Dentin↗
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↗