Approximal secondary caries lesion progression, a 20-week in situ study.

There is no consensus about the definition and progression of outer and wall lesions in secondary caries. In this study we investigated whether lesion progression is influenced by an adjacent composite restoration and whether wall lesions develop at the composite-tooth interface. In order to study the appearance and progression of approximal primary caries lesions and lesions next to composite restorations, 16 samples were placed in a full denture of each of 8 subjects. Each denture housed 4 restored and 4 unrestored enamel samples and similarly 8 dentin samples. All samples were distributed over 2 sample holders, in each of which 4 approximal spaces were simulated. Every 4 weeks the sample holders were microradiographed using transversal wavelength independent microradiography and lesion depth was measured. At the end of the study, after 20 weeks, the lesion depth of the outer lesions was 0-350 microm for enamel and 0-750 microm for dentin. The estimated difference in progression between secondary and primary lesions (1.1 microm/4 weeks, 95% CI: -9.2 to 11.4 microm) was not statistically significant (p = 0.83). Secondary outer lesions appeared and progressed as primary caries lesions. No clear wall lesions were found next to composite, but they were observed next to acrylic resin.

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.

Reproducibility of electrical caries measurements: a technical problem?

The currently available instrument for electrical detection of occlusal caries lesions [Electronic Caries Monitor (ECM)] uses a site-specific measurement with co-axial air drying. The reproducibility of this method has been reported to be fair to good. It was noticed that the measurement variation of this technique appeared to be non-random. It was the aim of this study to analyse how such a non-random reproducibility pattern arises and whether it could be observed for other operators and ECM models. Analysis of hypothetical measurement pairs showed that the pattern was related to measurements at the high and low end of the measurement range for the instrument. Data sets supplied by other researchers to a varying degree showed signs of a similar non-random pattern. These data sets were acquired at different locations, by different operators and using 3 different ECM models. The frequency distribution of measurements in all cases showed a single or double end-peaked distribution shape. It was concluded that the pattern was a general feature of the measurement method. It was tentatively attributed to several characteristics such as a high value censoring, insufficient probe contact and unpredictable probe contact. A different measurement technique, with an improved probe contact, appears to be advisable.

The influence of drying on quantitative laser fluorescence and optical pathlengths in incipient natural caries lesions.

Drying effects in 14 natural lesions were studied with quantitative light-induced fluorescence and optical pathlength spectroscopy. Results were compared with clinical judgments of the lesion surface and microradiographical characterizations of the lesions. Relative fluorescence and average pathlength decreased as a function of drying time with a decay time ranging from 35.5 to <1 min. Depth and mineral loss correlated with average pathlength total changes (r = -0.79/-0.60, respectively) and poorly with total fluorescence changes (r approximately = 0.3). The decay time of the drying process for the relative fluorescence correlated well with a theoretical model based on water diffusion in lesion and surface layer, but only for large decay times. Clinical judgments could not be related to the surface layer properties or the changes in the average pathlength, but were weakly related to the changes in the relative fluorescence. We conclude that (i) fluorescence effects are mostly due to the screening by the lesion of the fluorescence from the dentin and enamel-dentin junction; (ii) water evaporation in lesions conforms to the diffusion laws only in large lesions with low surface layer penetrability; (iii) the evaporation process is controlled by the surface layer only for small surface penetrabilities (approximately 0.1 vol% microm(-1)).

[Lasers in dentistry. Epilogue]. / Lasers in de tandheelkunde. Nawoord.

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.

Pharmaceutical development of a parenteral lyophilized formulation of the antimetastatic ruthenium complex NAMI-A.

This paper describes the development of a stable pharmaceutical dosage form for NAMI-A, a novel antimetastatic ruthenium complex, for Phase I testing. NAMI-A drug substance was characterized using several spectrometric and chromatographic techniques. In preformulation studies, it was found that NAMI-A in aqueous solution was not stable enough to allow sterilization by moist heat. The effect of several excipients on the stability of the formulation solution was investigated. None of them provided sufficient stability to allow long-term storage of an aqueous solution of NAMI-A. Therefore, a lyophilized product was developed. Five different formulations were prepared and subjected to thermogravimetric (TG) analysis and stability studies at various conditions for 1 year. Minimal degradation during the production process is achieved with a formulation solution of pH 3-4. Of the acids tested, only hydrochloric acid (HCl 0.1 mM) both stabilized the formulation solution and was compatible with the lyophilized product. This product was stable for at least 1 year when stored at -20 degrees C, 25 degrees C/60% relative humidity (RH) and 40 degrees C/75% RH, and was also photostable.

[Lasers in dentistry 6. The soft laser]. / Lasers in de tandheelkunde, 6. De '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.

The limited practical value of color Doppler sonography in the differential diagnosis of men with erectile dysfunction.

From the files of the outpatient urology department 44 men with ED had undergone both psychophysiological diagnostic screening (PDS, VSS, VSS+VIB, ICI+VSS+VIB) and color Doppler sonography testing (CDS, including VSS). PDS was carried out by one medical physiologist, CDS by one urologist. The diagnoses reached could be compared. This study revealed that CDS in ED-patients often resulted in an incorrect diagnosis, that is a presumed vascular abnormality while many such patients demonstrated firm erections under PDS-laboratory test conditions. Thus, it was concluded that CDS as a (first) screening test in ED-patients is of limited value. It was further emphasized that PDS, although giving quite relevant information about possible etiology and therapeutic treatment, is not a necessary first screen. Good history taking, preferably of the man and his partner, is still the basic first screen and quite often offers enough information to make a treatment plan with reasonable likelihood of success.

[Lasers in dentistry 1. What is special about lasers?]. / Lasers in de tandheelkunde 1. Wat is er bijzonder aan 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.

Intracavernous injection during diagnostic screening for erectile dysfunction; five-year experience with over 600 patients.

Psychophysiological diagnostic screening (PDS) was carried out on just over 1000 consecutive patients with erectile dysfunction (ED) during 1995 through 1999. Roughly one-third did not require an intracavernous injection (ICI) because of optimal penile response during visual and tactile penile sexual stimulation. The present article deals with those other patients (n = 609) who required an ICI and completed a 24-hour-postinvestigation questionnaire (PIQ). The two ICI preparations used, prostaglandin and papaverine + fentolamine, were virtually equally effective in the doses applied, with very low and similar percentages of unwanted side effects, for example, prolonged erection. Somatic ED patients displayed the lowest penile responses to ICI, whereas psychogenic ED patients had the highest penile responses. ED patients who also suffered from premature ejaculation (PE) ejaculated significantly more readily during PDS that those without PE. An ICI following an ejaculation/orgasm could lead to an erection presumably sufficient for intromission, which indicates ICI as a therapeutic option for rapid ejaculators. Our elaborate and lengthy PDS procedure, particularly the use of penile vibration as an addition to the visual sexual stimulation, obviates the diagnostic use of the PIQ.

Chemical hydrolysis of DOTAP and DOPE in a liposomal environment.

In this study the hydrolysis kinetics of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) and 1,2-dioleoyltrimethylammoniumpropane (DOTAP) in net neutral DPPC-DOPE (3:1, mol/mol) and cationic DOTAP-DOPE (1:1, mol/mol) liposomes are described. The log k(obs)-pH profile for DOTAP-DOPE liposomes differs markedly from earlier observed hydrolysis profiles: the slope approaches zero in the acidic region and +1 in the alkaline region. The concept of amine-influenced hydrolysis is introduced to explain the lack of pH dependency in the acidic region of the log k(obs)-pH profiles.

Functional analysis of problem behavior in children with mental retardation.

Pediatric nurses are frequently asked to give advice on behavior management. This can become considerably more difficult when the child in question has limited cognitive abilities and communication skills. It is especially complex when the behavior in question involves self-injury or aggression. Frequently used behavior modification strategies such as time-out may actually reinforce the inappropriate behavior in these children by allowing them to escape from an aversive task. Likewise, other common behavior management strategies such as discussion, saying "no," or yelling at the child, may reinforce the inappropriate behavior by providing attention for it. It is sometimes difficult to identify the antecedents of self-injurious or aggressive behavior, making appropriate behavior management plans elusive. However, functional analysis can be used to identify the functions that serve to maintain a child's inappropriate behavior, and may provide a basis for developing and implementing an individualized behavior management plan. The possibility that discomfort from an untreated or undertreated physiologic problem is exacerbating the behavior should not be overlooked.

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

Biodegradable hydrogels based on stereocomplex formation between lactic acid oligomers grafted to dextran.

A novel hydrogel system in which crosslinking is established by stereocomplex formation between lactic acid oligomers of opposite chirality is proposed. To investigate the feasibility of this novel system, we first investigate whether there is an operation window where lactic acid oligomers in either the D- or L-form do not give a crystalline phase, whereas in a blend of the D- and L-form stereocomplex formation occurs. Therefore, D- and L-lactic acid oligomers with different degrees of polymerization (DP) were prepared and analyzed using DSC. It was shown that crystallinity was present in D- or L-oligomers with DP > or = 11. On the other hand, in blends of D- and L-oligomers of lactic acid crystallinity (stereocomplexation) was already observed at a DP > or = 7. In the next step, L- and D-lactic acid oligomers were coupled via their terminal hydroxyl group to dextran, yielding dex-(L)lactate and dex-(D)lactate, respectively. Upon dissolving each product in water separately and mixing the solutions, a hydrogel is formed at room temperature as demonstrated by rheological measurements. The storage modulus of the obtained hydrogel strongly decreased upon heating to 80 degrees C, while it was restored upon cooling to 20 degrees C demonstrating the thermo-reversibility and the physical nature of the cross-links. The storage modulus of the gels depends on the degree of polymerization of the lactate acid grafts and their degree of substitution on dextran. Interestingly, gel formation was favored when one lactic oligomer was coupled via its hydroxyl group whereas the oligomer of opposite chirality was coupled via its carboxylic acid group. This is ascribed to the parallel packing of the oligomers in stereocomplexes.

Physically crosslinked dextran hydrogels by stereocomplex formation of lactic acid oligomers: degradation and protein release behavior.

Hydrogels, physically crosslinked through stereocomplex formation, were obtained by mixing aqueous solutions of dextran with L-lactic acid grafts and dextran with D-lactic acid grafts. Protein-loaded hydrogels were simply prepared by dissolving the protein in these dextran solutions prior to mixing. It was shown that under physiological conditions the gels are fully degradable. When the gels were exposed to an aqueous buffer solution, they first showed a swelling phase in which their weight increased 2-3 times due to absorption of water, followed by a dissolution phase. The degradation time depended on the composition of the hydrogel, i.e., the number of lactate grafts, the length and polydispersity of the grafts and the initial water content, and varied from 1 to 7 days. Most likely, the degradation of the stereocomplex hydrogel started with hydrolysis of the carbonate ester, which links the lactate graft to dextran. The gels showed a release of the entrapped model proteins (IgG and lysozyme) over 6 days and the kinetics depended on the gel characteristics, such as the polydispersity of the lactate grafts and the initial water content. Lysozyme was mainly released by Fickian diffusion, indicating that its hydrodynamic diameter is smaller than the hydrogel mesh size. On the other hand the release of IgG was governed by diffusion as well as swelling/degradation of the hydrogel. Importantly, the proteins were quantitatively released from the gels and with full preservation of the enzymatic activity of lysozyme, emphasizing the protein-friendly preparation method of the protein-loaded stereocomplex hydrogel.

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.