Biomedical subjects

W Geurtsen

Publications and source records attributed to W Geurtsen.

At least 55 records · Page 3Linked to original sources

PubMed1998

Nicotine-induced alterations in human primary periodontal ligament and gingiva fibroblast cultures.

Various in vivo and in vitro investigations have indicated that tobacco smoking as well as the use of smokeless tobacco products may be important risk factors for the development and severity of inflammatory periodontal disease. The purpose of this study was to determine the cytotoxicity of nicotine by means of human primary oral fibroblast cultures and a permanent cell line. The cytotoxicity of nicotine was evaluated by determination of cell growth, cell membrane integrity, protein content, and alterations of the cytoskeleton. Furthermore, recovery following nicotine exposure was assessed by vital staining (trypan blue). Dose-dependent toxic effects of nicotine were measured within a range of 0.48 mM to 62 mM. Growth of fibroblasts was decreased by nicotine concentrations higher than 7.8 mM. Additionally, the protein content was significantly decreased and cell membranes were damaged. Morphological alterations of microtubules and vimentin filaments were observed at concentrations higher than 3.9 mM. Nicotine-exposed cells revealed atypical shapes and vacuoles. The toxic effects of nicotine became irreversible in the range between 10.5 and 15.5 mM, whereas at lower concentrations cells recovered after the withdrawal of nicotine. Our results confirm clinical oberservations regarding the important role of nicotine as a risk factor in the etiology and progression of periodontal disease.

Cells, Cultured↗

PubMed1998

Effect on caries experience of a long-term preventive program for mothers and children starting during pregnancy.

The aim of this three-phase prospective study was to determine the effects of a primary-primary prevention program on the oral health of children. Eighty-six pregnant women from various social backgrounds participated in the first phase of this study. In the second phase (at 3 years of age) 54 of the mother-child couples and in the third phase (at 4 years of age) 47 of the mother-child couples remained. Participants were recalled every 6 months and received individual prophylactic care. The following clinical parameters were assessed at each examination period for mother and child: DMF-S or dmf-s, proximal plaque index, and the salivary level of Streptococcus mutans (Dentocult SM). The control group consisted of 65 (at 3 years of age) and 45 (at 4 years of age) children from various kindergartens. All children in the second phase of the study group revealed a naturally healthy dentition with an API of 0-25% and a salivary S. mutans score of 0 (0-10(3) cfu/ml). In the third phase, only four of the 47 children of the study group showed caries, with a mean dmf-s of 1.5. No S. mutans could be detected in 20 (42.6%) children. Ten (21.3%) children of the study group showed a S. mutans score of > or = 2 (> 10(5) cfu/ml). In contrast, only 53 of the 65 children of the control group (second phase) and 26 of the 45 control children (third phase) revealed a naturally healthy dentition. The remaining 19 children of the control group revealed a mean dmf-s of 7.0 at 4 years of age. In the control group, no S. mutans could be detected in 25 (38.5%) children at 3 years of age whereas 21 (32.3%) children showed a S. mutans score of > or = 2. In the third phase, a salivary S. mutans score of > or = 2 was found in 27 (60%) children of the control group. The statistical comparison between the study and the control groups revealed significant differences for all results determined (P < 0.001). Additionally, all mothers revealed a significant improvement in oral health and a reduction of salivary S. mutans colonization. From our data we conclude that a pre- and postnatal prevention program (primary-primary vs primary prevention) may significantly improve the oral health of mother and child.

Adult↗

PubMed1998

Effects of extraction media upon fluoride release from a resin-modified glass-ionomer cement.

Previous studies have shown that various factors such as ionic composition or pH of the extraction medium may significantly influence leaching of components from restorative materials. Therefore, it was the aim of this investigation to determine the release of fluoride from a resin-modified glass-ionomer cement (GIC) following storage in various extraction media, including an esterase buffer. Specimens of the resin-modified GIC, Fuji II LC, were stored for 144 h in deionized water, acidic buffer (pH 4.2), neutral buffer (pH 7.0), and neutral buffer supplemented with porcine liver esterase. Fluoride release into the various media was measured every 48 h over a 6-day period. In addition, activity of porcine esterase in neutral buffer (artificial saliva) was measured for up to 144 h. The data were statistically evaluated by three-way ANOVA using the Student-Newman-Keuls test (P < 0.05). It was found that esterase activity in neutral artificial saliva decreased during the first 24 h to approximately 40% of the baseline value and then remained constant for up to 6 days. Fluoride release into the various storage media varied significantly (P < 0.05). The highest amounts of fluoride were released into deionized water (30.9 ppm +/- 1.1) and acidic buffer (26.9 ppm +/- 0.7) after 48 h. In addition, significantly more fluoride leached into esterase-containing neutral artificial saliva (6.9 ppm +/- 0.2) than into neutral buffer without enzyme (6.3 ppm +/- 0.2) after 96 h. Our data indicate that fluoride release from the resin-modified GIC investigated may be increased under acidic conditions and by hydrolysis in saliva.

Analysis of Variance↗

PubMed1998

Biocompatibility of various light-curing and one conventional glass-ionomer cement.

The purpose of this study was to determine and to compare the cellular compatibility of modern light-curing (lc) glass-ionomer cements (GICs) to one conventional (co) GIC. The following materials were investigated: Ionoseal (IS, lc) (VOCO, Germany), Vitrebond (VB, lc) (3M, USA), Compoglass (CG, lc) (Vivadent, FL) and Ketac Fil Applicap (KF, co) (ESPE, Germany). From all GICs, equally sized specimens (height 2 mm, diameter 5 mm) were polymerized or set according to the instructions of the manufacturers. Various extracts of all specimens were obtained by subsequent elutions. Human primary fibroblasts of the attached gingiva (HGF) and permanent mouse fibroblasts (3T3) were used for the experiments. HGF and 3T3 cells were exposed to the extracts of all materials for 48 h. Growth inhibition due to cytotoxic effects was determined by staining the cultures with Hoechst 33342 (determination of DNA and cell vitality). It was found that the material CG induced no growth inhibition in any of the assays. Proliferation of HGF was not, or only slightly, inhibited by the extracts of the materials IS and KF, whereas severe alterations were caused by the extracts of the material VB. Growth of 3T3 cells was only moderately or slightly reduced by the extracts of materials IS and KF respectively, but was severely or totally inhibited by all extracts of VB. From our results we conclude that the GIC VB is very cytotoxic and therefore may also induce alterations in vivo. All other investigated GICs revealed excellent (CG), or good (IS, KF) cellular compatibility.

3T3 Cells↗

PubMed1998

Determination of leachable components from four commercial dental composites by gas and liquid chromatography/mass spectrometry.

OBJECTIVES: The purpose of our study was to determine the quality and quantity of leachable residual (co)monomers and additives eluted from various commercial dental composite resins after polymerization. METHODS: Polymerized specimens from four universal hybrid-type composite resins were eluted for 3 days with methanol resp, water. Then all extracts were analysed by gas chromatography/mass spectrometry or liquid chromatography/mass spectrometry using a particle beam interface. RESULTS: In all polymerized composite resin specimens, (co)monomers and various additives as well as contaminants from manufacturing processes were identified. Almost every compound detected in the unpolymerized resins could also be identified in the methanol extracts, but only a few of them were found in the water extracts. From these the co-monomer TEGDMA was extracted in quantities higher than those reported to be cytotoxic in primary human oral fibroblast cultures. CONCLUSIONS: From our results we conclude that the extractable quantities of composite resin components should be minimized, either by reducing the mobility of leachable substances within the set material or by applying less water-soluble components. Furthermore, all ingredients of a dental composite should be declared by the manufacturers, in order to identify those substances in a product which may cause adverse side effects in patients and dental personnel.

4-Aminobenzoic Acid↗

PubMed1998

Erbium:YAG laser application in caries therapy. Evaluation of patient perception and acceptance.

OBJECTIVES: In previous studies it has been demonstrated that the Er:YAG laser can be used to prepare cavities efficiently and without thermal damage to the adjacent dental hard and soft tissues. To investigate the patients' response to Er:YAG laser preparation of teeth, a prospective clinical study was performed in five dental hospitals. METHODS: To evaluate patients' perception and response to cavity preparation a direct comparison was made between conventional mechanical preparation and Er:YAG laser preparation of caries in dental hard tissues. Half of the preparations were completed by the laser alone with standardized parameters, with the other half being mechanically prepared. The sequential order of treatment was randomized, and clinical parameters such as depth and location of the cavities were carefully balanced. A three-score evaluation scheme of patient responses was used: comfortable, uncomfortable, very uncomfortable. In addition the patients were asked to decide which was the more uncomfortable form of treatment and the preferred treatment for future caries therapy. RESULTS: The study included 103 patients with 206 preparations distributed amongst 194 teeth. All teeth gave vital responses (ice test) before and after both types of treatment. The laser treatment was found to be more comfortable than the mechanical treatment, with high statistical significance. During treatment, the need for local anaesthesia was 11% for mechanical preparation compared to 6% during laser application. It was found that 80% of the patients rated the conventional preparation as more uncomfortable than the laser treatment and 82% of the patients indicated that they would prefer the Er:YAG laser preparation for further caries treatment. CONCLUSIONS: The application of the Er:YAG laser system is a more comfortable alternative or adjunctive method to conventional mechanical cavity preparation.

Adult↗

PubMed1998

Cytotoxicity of four root canal sealers in permanent 3T3 cells and primary human periodontal ligament fibroblast cultures.

OBJECTIVES: The purposes of this study were to determine the cytocompatibility of four endodontic sealers and gutta-percha using various extracts and to compare the cellular injuries resulting from these materials in permanent 3T3 monolayers and primary human periodontal ligament fibroblasts. STUDY DESIGN: Set specimens from four sealers (AH26, Apexit, Sealapex, N2) as well as gutta-percha were eluted with cell culture medium for 24 hours, 5 days, 5 days, and 24 hours, respectively. Cytotoxic effects due to these extracts were evaluated by determining proliferation of permanent 3T3 cells and primary human periodontal ligament fibroblasts by means of the fluorochrome propidiumiodide. RESULTS: No statistically significant cellular alterations were induced by gutta-percha and Apexit, whereas various extracts of AH26 and Sealapex caused significant moderate or severe growth inhibition. Severe cellular damage was documented for all extracts of N2, which was statistically significantly different from the other materials in both cell lines (p < 0.05). CONCLUSIONS: Our results confirm that various root canal sealers constantly segregate substances after being exposed to an aqueous environment for extended periods, possibly causing moderate or severe cytotoxic reactions and possibly contributing to failure.

3T3 Cells↗

PubMed1998

Substances released from dental resin composites and glass ionomer cements.

An increasing number of cavities in the primary and permanent dentition is restored with tooth-colored materials, especially dental resin composites or glass ionomer cements. Several investigations have revealed that various components are segregated from different composite filling materials into an aqueous environment after polymerization. Most organic substances can be extracted from a set resin by organic solvents (methanol, tetrahydrofuran, ethanol). Furthermore, in most studies, the co-monomer TEG-DMA has been identified as the main compound released from polymerized resin composites into aqueous media. However, small quantities of the monomers (Bis-GMA, UDMA) and other co-monomers, as well as additives, may also be released into water. Very little data have been published about substances released from various types of glass ionomer cements (GIC), except the liberation of fluoride. Erosion studies have revealed that there is a considerable disintegration of GICs at lower pH-values. However, the nature of the eroded substances has not yet been clarified. Altogether, the data presented in this review indicate that information is comparably scarce for resin composites and GICs in comparison to the rich amount of knowledge concerning amalgams. Therefore, further studies are necessary to determine quality and quantity of substances segregated from resin composites and GICs.

Bisphenol A-Glycidyl Methacrylate↗

PubMed1998

Effects of various resin composite (co)monomers and extracts on two caries-associated micro-organisms in vitro.

Previous studies have shown that extracts of various filling materials, e.g., resin composites, may influence the growth of cariogenic micro-organisms. The purpose of this study was to examine the effects of important resin composite (co)monomers (Bis-GMA, UDMA, TEGDMA, EGDMA) and extracts of two commercial dental composites with similar composition (composite A, Arabesk; composite S, Superlux) on the growth of the two cariogenic bacterial pathogens Streptococcus sobrinus and Lactobacillus acidophilus. It was found that neither the monomers Bis-GMA and UDMA, nor the comonomer EGDMA, nor the extract of composite A influenced the growth of S. sobrinus in the log phase. The comonomer TEGDMA and the extract of composite S were found to stimulate growth in the log phase, but this stimulation was not statistically significant. However, EGDMA, TEGDMA, and the extract of composite S did stimulate the total growth of S. sobrinus. In the assays with L. acidophilus, Bis-GMA, UDMA, and the extract of composite A inhibited the growth in the log phase, whereas TEGDMA stimulated it. Furthermore, EGDMA, TEGDMA, and the extract of composite S stimulated the biomass production of L. acidophilus. We conclude from our results that a release of EGDMA and TEGDMA from resin composites should be avoided due to their growth-stimulating effects on the caries-associated micro-organisms S. sobrinus and L. acidophilus.

Biomass↗

PubMed1998

Residual monomer/additive release and variability in cytotoxicity of light-curing glass-ionomer cements and compomers.

In previous studies, light-cured glass-ionomer cements have been shown to evoke cytotoxic reactions. It was the purpose of this investigation (a) to determine the nature of the ingredients released into an aqueous medium from 2 light-cured glass-ionomer cements (GICs) and 3 compomers; (b) to evaluate the cytotoxicity of these extracts; and (c) to correlate the extent of the cytotoxic effects with eluted substances. Specimens of 2 light-cured GICs and 3 compomers were prepared and extracted in distilled water or cell culture medium for 24 hrs (surface-liquid ratio 42.4 mm2/mL). The aqueous eluates were analyzed by gas chromatography/mass spectrometry (GC/MS). The relative amounts of the components released from various products were compared by means of an internal caffeine standard [%CF]. For evaluation of cytotoxic effects, permanent 3T3 fibroblasts were incubated with medium extracts for 24 hrs. In addition, the ED50 concentration of the photoinitiator diphenyliodoniumchloride (DPICl) was determined. In all extracts, several water-elutable organic substances were found: (Co)monomers (especially HEMA and ethylene glycol compounds), additives (e.g., camphorquinone and diphenyliodoniumchloride), and decomposition products. The extracts of 3 products inhibited cell growth only moderately, whereas the light-cured GIC Vitrebond and the compomer Dyract Cem revealed severe cytotoxic effects. Vitrebond liberated the initiator DPICl, whereas Dyract Cem segregated a relatively high quantity [2966 %CF] of the comonomer TEGDMA in comparison with the other products. The present data show that TEGDMA and DPICl may be regarded as the prime causes for cytotoxic reactions evoked by the investigated light-cured glass-ionomer cements or compomers. Therefore, leaching of these substances should be minimized or prevented.

3T3 Cells↗

PubMed1998

Inorganic polyphosphate in human osteoblast-like cells.

Significant amounts of inorganic polyphosphates and of polyphosphate-degrading exopolyphosphatase activity were detected in human mandibular-derived osteoblast-like cells. The amount of both soluble and insoluble long-chain polyphosphate in unstimulated osteoblast-like cells was higher than in human gingival cells, erythrocytes, peripheral blood mononuclear cells, and human blood plasma. The cellular content of polyphosphate in osteoblast-like cells strongly decreased after a combined treatment of the cells with the stimulators of osteoblast proliferation and differentiation, dexamethasone, beta-glycerophosphate, epidermal growth factor, and ascorbic acid. The amount of soluble long-chain polyphosphate, but not the amount of insoluble long-chain polyphosphate, further decreased after an additional treatment with 1alpha,25-dihydroxyvitamin D3 (1,25(OH)2D3). The decrease in polyphosphate content during treatment with dexamethasone, beta-glycerophosphate, epidermal growth factor, and ascorbic acid was accompanied by a decrease in exopolyphosphatase, pyrophosphatase, and alkaline phosphatase activity. However, additional treatment with 1,25(OH)2D3 resulted in an increase in these enzyme activities. Osteoblast-like cell exopolyphosphatase activity and exopolyphosphatase activity in yeast, rat tissues, and human leukemia cell line HL60 were inhibited by the bisphosphonates etidronate and, to a lesser extent, clodronate and pamidronate. From our results, we assume that inorganic polyphosphate may be involved in modulation of the mineralization process in bone tissue.

Acid Anhydride Hydrolases↗

PubMed1998

Histopathological investigation of gingival tissue from patients with rapidly progressive periodontitis.

In this study, fine structural features of the pocket walls in rapidly progressive periodontitis (RPP) and adult periodontitis (AP) in 20 cases were compared using light and transmission electron microscopy. Gingiva was also obtained from a control group of periodontally healthy teeth. Clinical parameters were assessed in both RPP and AP patients and in controls. Bone destruction and attachment loss were more marked in RPP than in AP. Light microscopical observations of inflamed RPP tissue as compared to AP showed gross histological distortions in the pocket walls. Micro-ridges within the epithelium and large intercellular spaces between the epithelial cells were observed in most RPP biopsies. Epithelial cells surrounding the microclefts and adjacent keratinocytes were found to produce interleukin-1beta (IL-1beta). Prevotella intermedia and Porphyromonas gingivalis were identified in the RPP biopsies using immunohistological methods. These microorganisms were localized outside the epithelium and inside intercellular spaces. Furthermore, the effect of inflammation on the distribution of collagen types I, III, IV, V, and VI in the human gingiva was studied after staining them with antibodies to these proteins. In RPP and AP tissues, the staining was sparse in areas of inflammation and leukocytic infiltration. Collagen type I and III were almost entirely lost at sites of inflammation. Type V and VI collagen antibodies were retained in inflamed areas. Type IV collagen was restricted to basement membrane structures. These observations demonstrated numerous structural features indicative of more pronounced degenerative changes in RPP than in AP.

Adult↗

PubMed1997

Light-microscopical investigation of the distribution of extracellular matrix molecules and calcifications in human dental pulps of various ages.

The distribution of extracellular matrix molecules, especially collagen types I, III, V, and VI, in the extracellular matrix of the connective tissue of human dental pulp of various ages was studied by polarization and indirect immunofluorescence microscopy by using a conventional fluorescence microscope and a confocal laser scanning microscope. Polarization and immunofluorescence microscopy of paraffin sections showed thick fibers of collagen type I, which represented the main component of the connective tissue matrix of the dental pulp. By indirect immunofluorescence, thin fibers and small bundles of collagen type III were determined to be one of the main fibrillar elements present in the dental pulp matrix. Collagen type IV was detected by a clear intense staining of the basement membrane of blood vessels at all ages examined. Collagens type V and VI formed a dense meshwork of thin microfibrils throughout the stroma of the connective tissue of the dental pulp. These fibers were localized around blood vessels and appeared to be enriched in the subodontoblastic layer. Investigations by means of confocal laser scanning microscopy revealed fibers of collagen type VI spiralling between fully differentiated odontoblasts toward the predentin layer. With advancing age, the connective tissue matrix appeared to be condensed and aggregates of thick fiber bundles could be observed. Furthermore, the participation of various collagen types in the composition of pulp stones was shown. These calcifications and diffuse calcifications increased in frequency with advancing age in a statistically significant manner.

Adolescent↗

PubMed1997

Biological aspects of root canal filling materials--histocompatibility,cytotoxicity, and mutagenicity.

In order to minimize the incidence of local and/or systemic side effects, the biocompatibility of all endodontic materials should be investigated by various in vitro and in vivo tests prior to clinical application. The battery of in vitro tests includes determinations of mutagenicity, cytotoxicity, and antibacterial effects. Several reports have shown that paraformaldehyde-containing ZnO-eugenol cements in particular, such as Endomethasone and N2, are antibacterial. On the other hand, it has been found that endodontic materials with strong antimicrobial activity are frequently mutagenic, i.e., primarily those which release formaldehyde. Cell culture tests clearly show significantly different cytocompatibility of the various types of endodontic sealers: in general, formaldehyde-containing ZnO-eugenol cements are classified as highly/extremely cytotoxic, whereas most Ca(OH)2-based sealers are rated as possessing good or excellent cytocompatibility. These results were confirmed by numerous histological studies in vivo. Sealers with inferior biocompatibility, such as formaldehyde-releasing materials, should no longer be applied in practice because safer alternatives are available.

Animals↗

PubMed1997

Proximo-cervical adaptation of Class II-composite restorations after thermocycling: a quantitative and qualitative study.

Sixty caries-free extracted human molars were used to determine the proximo-cervical adaptation and sealing of Class II-composite restorations related to the location of the cavity margins: 1.0 mm or 0.5 mm coronal to the cementum-enamel-junction (CEJ), at the CEJ, and 0.5 mm apical to the CEJ. All cavities were filled with a hybride type composite resin, which was combined at the CEJ and apical to the CEJ with a dentine adhesive in half of the specimens. The proximo-cervical adaptation and sealing was determined before and after thermocycling (TC, 2000 cycles, 5-55 degrees C) by SEM and dye penetration tests. Furthermore, an analysis of the interfaces between the enamel or dentine and the filling material was performed to determine whether or not there is a significant correlation between micromorphological factors of the dental hard tissues (enamel acid etch pattern, dentine resin tag pattern) and the marginal adaptation of the composite restorations. The data were statistically evaluated by means of H-tests (Kruskall-Wallis), U-tests (Mann-Whitney), and Chi2-tests (P < 0.05). It was found that the proximo-cervical adaptation is statistically significant dependent on the position of the margin. 1.0 mm coronal to the CEJ an excellent marginal sealing was found before and after TC, whereas all other groups revealed a significant deterioration of the marginal integrity after TC. Using a dentine adhesive significantly improved the marginal sealing in cavities at the CEJ before and after TC, however the marginal quality was not achieved as in the case of the normally structured enamel 1.0 mm coronal to the CEJ following acid etching. In defects 0.5 mm apical to the CEJ the dentine adhesive only improved the cervical adaptation before TC. The evaluation of the tooth/filling interfaces revealed that there is no statistically significant correlation between the enamel acid etch pattern resp. dentine resin tag pattern and the marginal sealing.

Acid Etching, Dental↗

PubMed1996

Genotoxicity of dental materials.

This study was performed to characterize the (possible) DNA-damaging properties of dental materials and to identify specific compounds that contribute to this genotoxicity. For screening, three tests that assay for different aspects of genotoxicity (i) the bacterial umu-test; (ii) the eucaryotic DNA synthesis inhibition test; and (iii) the in vivo alkaline filter elution technique were chosen. This investigation gives several lines of evidence that most dental materials tested (14 chemical monosubstances present in dental devices and 7 extracts of dental materials) yield 'positive' results in at least one of the genotoxicity tests, however, with effects ranging from 'borderline' to 'strong positive'. The extracts of the widely used dental materials Vitrebond and AH26 elicited clear concentration-related genotoxic responses in all test systems. On the basis of these data and public concern, more attention has to be given to local or systemic complications which may be associated with the use of dental materials.

Animals↗

PubMed1996

Pathohistology of undecalcified primary teeth in vitamin D-resistant rickets: review and report of two cases.

The basic dental defects in vitamin D-resistant rickets seem to be manifested in dentin. Enamel is usually reported to be normal. This histologic examination showed the penetration of microorganisms through the calcified structures of the enamel layer without visible caries. The microorganisms passed through the dentinoenamel junction and invaded dentin, which was characterized by calcospherites and large amounts of interglobular dentin. Furthermore, microorganisms could be detected in dentinal tubules, which were exposed to the oral cavity when enamel was removed. However, large areas of tertiary dentin extended between such tubules and the pulp. These light microscopic results suggest that clinical manifestations, such as, pulp recrosis and periapical lesions (without carious defects) may be caused by the penetration of microorganisms through microclefts of the enamel layer as well as pathologically altered enamel microstructures of affected teeth.

Adult↗

PubMed1995

Immunohistological determination of interleukin-1 beta in inflamed human gingival epithelium.

Interleukin-1 beta (Il-1 beta) is the predominant form of Il-1 produced by monocytes of the blood and by macrophages of various tissues. Human keratinocytes express both Il-1 alpha and Il-1 beta mRNA, but appear to produce mainly Il-1 alpha. The aim of this study was to determine the localization of interleukin-1 beta and interleukin-1 beta receptors in human gingival epithelium by different immunohistochemical methods. The alkaline phosphatase and the immunogold staining technique, as well as fluorescence microscopy, were used to investigate active participation of gingival epithelial cells in the development of periodontitis. Biopsies of human interdental papillae showed some activity of epithelial cells in the production of Il-1 beta. Single cells, clusters or larger areas of the sulcular and oral epithelium appeared to produce Il-1 beta at inflamed sites, and in these areas the normal epithelial structure was disturbed. Epithelial cells grown from the same biopsies appear able to express specific receptor molecules for Il-1 beta under normal culture conditions. It is concluded that gingival keratinocytes might be activated by inflammatory irritants and participate actively in the inflammatory processes.

Cells, Cultured↗