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ABSTRACT: Aim: The study aimed to investigate the effect of a customary fluoride solution, containing sodium fluoride and amine fluoride, on initial biofilm formation on enamel and dentin in situ compared directly to chlorhexidine. Methods: Bovine enamel and dentin specimens were mounted on maxillary splints carried by 9 subjects. After 1 min of pellicle formation, rinses with tap water (control), chlorhexidine (meridol med CHX 0.2%, GABA) and a fluoride mouthrinse (elmex, GABA) were performed for 1 min. Subsequently, the slabs were carried for another 8 h. The adherent bacteria were determined by DAPI staining, live-dead staining and determination of colony-forming units after desorption; glucan formation was visualized with concanavalin A. Additionally, energy-dispersive X-ray spectroscopy (EDX) analysis of the in situ biofilm layers was conducted, and contact angle measurements were performed. Statistical evaluation was performed by means of the Kruskal-Wallis test followed by the Mann-Whitney U test (p < 0.05). Results: In the control group, significantly higher amounts of adherent bacteria were detected on dentin (4.8 × 10(6) ± 5.4 × 10(6) bacteria/cm(2)) than on enamel (1.2 × 10(6) ± 1.5 × 10(6) bacteria/cm(2), DAPI). Chlorhexidine significantly reduced the amount of adherent bacteria (dentin: 2.8 × 10(5) ± 3.4 × 10(5) bacteria/cm(2); enamel: 4.2 × 10(5) ± 8.7 × 10(5) bacteria/cm(2)). Rinses with the fluoride solution also significantly reduced bacterial adherence to dentin (8.1 × 10(5) ± 1.5 × 10(6) bacteria/cm(2)). Fluoride could not be detected by EDX analysis of the biofilms. Fluoride mouthrinsing did not influence the wettability of the pellicle-covered enamel surface. Conclusion: In addition to the reduction of demineralization and antibacterial effects, fluorides inhibit initial biofilm formation on dental hard tissues considerably, especially on dentin.
Caries Research 11/2012; 47(2):150-161. · 2.33 Impact Factor
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ABSTRACT: OBJECTIVES: There is still a great demand for the improvement of oral prophylaxis methods. One repeatedly described approach is rinsing with edible oils. The aim of the present review paper was to analyze the role of lipids in bioadhesion and preventive dentistry. MATERIALS AND METHODS: Despite limited sound scientific data, extensive literature search was performed to illustrate possible effects of lipids in the oral cavity. RESULTS: It is to be assumed that lipophilic components modulate the process of bioadhesion to the oral hard tissues as well as the composition and ultrastructure of the initial oral biofilm or the pellicle, respectively. Thereby, lipids could add hydrophobic characteristics to the tooth surface hampering bacterial colonization and eventually decreasing caries susceptibility. Also, a lipid-enriched pellicle might be more resistant in case of acid exposure and could therefore reduce the erosive mineral loss. Furthermore, anti-inflammatory effects on the oral soft tissues were described. However, there is only limited evidence for these beneficial impacts. Neither the lipid composition of saliva and pellicle nor the interactions of lipids with the initial oral biofilm and the pellicle layer have been investigated adequately until now. CONCLUSION: Edible oils might qualify as mild supplements to conventional strategies for the prevention of caries, erosion, and periodontal diseases but further research is necessary. CLINICAL RELEVANCE: Against the background of current scientific and empirical knowledge, edible oils might be used as oral hygiene supplements but a decisive benefit for the oral health status is questionable.
Clinical Oral Investigations 09/2012; · 2.36 Impact Factor
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ABSTRACT: The purpose of this review is to highlight recent nanotechnological developments for remineralization of incipient caries lesions as well as biomimetic strategies for enamel synthesis based on the application of nanotechnology. Analysis of in vitro data indicates that apatite nanoparticles might be effective in reversing lesion progression in the outer but not in the deeper part of early caries lesions. To control caries-induced demineralization, investigators have developed calcium and phosphate or fluoride ion-releasing nanofillers, enabling resin composites to release ions, if the pH decreases under in vitro conditions. Extensive in vitro investigations of apatite crystallization have been performed to mimic the hierarchical topology of natural enamel. Strategies for formation of highly organized biomineralized structures include oriented aggregation of nanocrystallites or the assembly of apatite nanoparticles mediated by organic scaffolds. Despite all these promising in vitro experiments, the effectiveness of such strategies for the control of demineralization processes as well as for caries therapy still needs validation by clinical studies.
Advances in dental research 09/2012; 24(2):53-7.
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ABSTRACT: OBJECTIVES: The aim of the present study was to investigate different fluorescence-based, two-color viability assays for visualization and quantification of initial bacterial adherence and to establish reliable alternatives to the ethidium bromide staining procedure. MATERIALS AND METHODS: Bacterial colonization was attained in situ on bovine enamel slabs (n = 6 subjects). Five different live/dead assays were investigated (fluorescein diacetate (FDA)/propidium iodide (PI), Syto 9/PI (BacLight®), FDA/Sytox red, Calcein acetoxymethyl (AM)/Sytox red, and carboxyfluorescein diacetate (CFDA)/Sytox red). After 120 min of oral exposure, analysis was performed with an epifluorescence microscope. Validation was carried out, using the colony-forming units for quantification and the transmission electron microscopy for visualization after staining. RESULTS: The average number of bacteria amounted to 2.9 ± 0.8 × 10(4) cm(-2). Quantification with Syto 9/PI and Calcein AM/Sytox red yielded an almost equal distribution of cells (Syto 9/PI 45 % viable, 55 % avital; Calcein AM/Sytox red 52 % viable, 48 % avital). The live/dead ratio of CFDA/Sytox red and FDA/Sytox red was 3:2. An aberrant dispersal was recorded with FDA/PI (viable 34 %, avital 66 %). The TEM analysis indicated that all staining procedures affect the structural integrity of the bacterial cells considerably. CONCLUSION: The following live/dead assays are reliable techniques for differentiation of viable and avital adherent bacteria: BacLight, FDA/Sytox red, Calcein AM/Sytox red, and CFDA/Sytox red. These fluorescence-based techniques are applicable alternatives to toxic and instable conventional assays, such as the staining procedure based on ethidium bromide. CLINICAL RELEVANCE: Differentiation of viable and avital adherent bacteria offers the possibility for reliable evaluation of different mouth rinses, oral medication, and disinfections.
Clinical Oral Investigations 07/2012; · 2.36 Impact Factor
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ABSTRACT: The prevalence of dental erosion is still increasing. A possible preventive approach might be rinsing with edible oils to improve the protective properties of the pellicle layer. This was tested in the present in situ study using safflower oil.
Pellicle formation was carried out in situ on bovine enamel slabs fixed buccally to individual upper jaw splints (6 subjects). After 1 min of pellicle formation subjects rinsed with safflower oil for 10 min, subsequently the samples were exposed in the oral cavity for another 19 min. Enamel slabs without oral exposure and slabs exposed to the oral cavity for 30 min without any rinse served as controls. After pellicle formation in situ, slabs were incubated in HCl (pH 2; 2.3; 3) for 120 s, and kinetics of calcium and phosphate release were measured photometrically (arsenazo III, malachite green). Furthermore, the ultrastructure of the pellicles was evaluated by transmission electron microscopy (TEM).
Pellicle alone reduced erosive calcium and phosphate release significantly at all pH values. Pellicle modification by safflower oil resulted in an enhanced calcium loss at all pH values and caused an enhanced phosphate loss at pH 2.3. TEM indicated scattered accumulation of lipid micelles and irregular vesicle-like structures attached to the oil-treated pellicle layer. Acid etching affected the ultrastructure of the pellicle irrespective of oil rinsing.
The protective properties of the pellicle layer against extensive erosive attacks are limited and mainly determined by pH. The protective effects are modified and reduced by rinses with safflower oil.
Caries Research 07/2012; 46(5):496-506. · 2.33 Impact Factor
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ABSTRACT: OBJECTIVE: The aim of the present study was to investigate the efficacy of a new preparation in dental prophylaxis containing zinc-carbonate hydroxyapatite microclusters (Biorepair) for oral biofilm management. METHODS AND MATERIALS: Initial biofilm formation was carried out in situ with bovine enamel slabs fixed to individual upper jaw splints worn by six subjects. Rinses with the customary preparation as well as with subfractions (hydroxyapatite microclusters in saline solution; liquid phase without particles) were adopted for 1 min in situ after 1 min of pellicle formation, and the bacterial colonization was recorded after 6 h and 12 h, respectively. Rinses with chlorhexidine served as a reference. The adherent microorganisms were quantified and visualized using DAPI staining and live-dead staining (BacLight). Furthermore, the effects on Streptococcus mutans bacteria were tested in vitro (BacLight). RESULTS: Application of the customary preparation and of the separate components distinctly reduced the initial bacterial colonization of the enamel surface in situ as visualized and quantified with all techniques. After 12 h, 1.3 × 10(7) ± 2.0 × 10(7) bacteria/cm² were detected on unrinsed control samples with DAPI staining; 2.4 × 10(6) ± 3.3 × 10(6) after application of Biorepair (12 h after CHX-rinse; 1.3 × 10(5) ± 9.2 × 10(4)). Also, pure hydroxyapatite microclusters in saline solution (2.1 × 10(6) ± 3.0 × 10(6)) as well as the liquid phase without particles (5.1 × 10(5) ± 3.3 × 10(5)) reduced the amount of adherent bacteria. Furthermore, antimicrobial effects on S. mutans were observed in vitro. CONCLUSION: The preparation is an effective compound for biofilm management in the oral cavity due to antiadherent and antibacterial effects. CLINICAL RELEVANCE: The tested mouthrinse seems to be a reasonable amendment for dental prophylaxis.
Clinical Oral Investigations 07/2012; · 2.36 Impact Factor
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ABSTRACT: Different enzyme-containing toothpastes are available on the market. The aim of the present in situ study was to investigate their efficacy for immobilisation of protective enzymes in the pellicle layer.
Pellicle formation took place in situ on bovine enamel slabs fixed to individual upper jaw splints carried by 6 subjects. After pellicle formation for 1 min, brushing was performed for 3 min with the commercially available toothpastes Enzycal, biotène and BioXtra, respectively. Before as well as 0, 20 and 40 min after brushing, samples were removed from the splints and tested for lysozyme, peroxidase and glucoseoxidase activity. The assays for the respective enzyme activities were based on fluorogenic substrates. Separate experiments were conducted for the different enzymes and toothpastes.
Brushing with the toothpastes caused an extensive increase of glucoseoxidase activity in the pellicle, but it was of low tenacity whereas peroxidase activity was enhanced considerably. However, targeted accumulation of lysozyme in the pellicle was not very pronounced. Brushing without toothpaste had no effect on enzyme activities in the acquired pellicle.
Targeted immobilisation of enzymes in the in situ pellicle can be achieved with toothpastes.
Archives of oral biology 07/2010; 55(7):463-9. · 1.65 Impact Factor
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ABSTRACT: Dental caries is a widespread chronic disease caused by glucolytic biofilms. Despite considerable success in prophylaxis, there is still a strong demand for biomimetic biofilm management. Reflections on the abraded, but mostly caries-free teeth observed in prehistoric sculls or omnivorous primates, respectively, offer perspectives for developing new approaches in preventive dentistry. It is hypothesized that nano-sized hydroxylapatite crystallites occur in the oral cavity during extensive physiological wear of the hierarchical structured enamel surface due to dental abrasion and attrition. These nano-scaled apatite enamel crystallites might promote re-mineralization and physiological biofilm management at the tooth surface. Indeed, modern bioinspired nanomaterials in preventive dentistry containing nano-sized hydroxylapatite particles have shown efficacy in reducing oral biofilm formation and yield re-mineralizing effects. Accordingly, they seem to mimic extensive abrasions which do not occur with modern diet.
Medical Hypotheses 12/2009; 74(4):670-2. · 1.39 Impact Factor
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ABSTRACT: Transaminases (AST, aspartate amino transferase; ALT, alanine amino transferase) are relevant enzymes in physiology and pathology of the human organism. The aim of the present in situ study was to demonstrate the presence of these enzymes in the enamel pellicle.
Bovine enamel slabs were fixed on buccal sites of individual upper jaw splints and worn for 3, 30 and 120 min by 5 subjects to allow pellicle formation. The in situ pellicles were tested for AST and ALT. Enzyme activities were measured photometrically via determination of the products pyruvate and oxalacetate using lactate-dehydrogenase and malate-dehydrogenase, respectively.
Enzymatic AST- as well as ALT-activities are present in the acquired pellicle within 3 min. The enzyme activities exposed at the pellicles' surfaces increased slightly with the pellicle formation time (ANOVA, AST: n.s., ALT: p=0.021). However, the two enzymes show considerable intraindividual and interindividual variability. The mean AST-activity of the pellicle amounted to 1.07+/-0.81 mU/cm(2) (ALT 1.18+/-0.52 mU/cm(2)). The ALT-activity of the centrifuged saliva was 26.62+/-11.09 mU/ml (AST 35.98+/-29.35 mU/ml).
AST as well as ALT are present in the in situ pellicle layer and may contribute to the intrinsic maturation of pellicle proteins.
Archives of oral biology 04/2009; 54(5):445-8. · 1.65 Impact Factor
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ABSTRACT: Glucosyltransferases (GTFs) represent a virulence factor of mutans streptococci. The aim of the present in situ study was to investigate the distribution of different GTF-isoforms in the pellicle.
Bovine enamel slabs were fixed on buccal and palatal sites of individual splints worn by five subjects for 30 and 120 min to allow pellicle formation. Pellicle specimens were processed for transmission electron microscopy (TEM) and field emission in-lens scanning electron microscopy (FEI-SEM). Gold-immunolabelling was used for detection of GTF-isoforms B, C and D. Furthermore, glucosyltransferase activity of 3-, 30- and 120-min pellicles was tested via determination of fructose release.
All isoforms of the enzyme were found to be randomly distributed within all layers of the pellicle. In cross-sections (TEM), GTF D was the most abundant isoform. More labelled molecules were detected on buccal sites compared with palatal surfaces, the number of molecules detected increased with time. The amount of GTF B, C and D found on the pellicle surface by FEI-SEM showed no correlation with pellicle formation time or localisation in the oral cavity. Overall, GTF D was detected more frequently on the surface than GTF B and C. All pellicles tested showed GTF-activity.
The study shows for the first time the presence of the GTF-isoforms B, C and D within all layers of the in situ formed pellicle. This emphasises the impact of streptococcal products on the composition of the pellicle and illustrates a mechanism used by bacteria to colonize dental surfaces.
Archives of oral biology 06/2008; 53(11):1003-10. · 1.65 Impact Factor
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ABSTRACT: The acquired enamel pellicle is a proteinaceous layer formed on all solid substrata exposed to the oral cavity. It has been supposed that the pellicle undergoes maturation after protein adsorption. The aim of the present study was to investigate enzyme activities with an impact on intrinsic maturation processes in in situ formed pellicles.
Bovine enamel specimens were exposed to the oral cavity in six subjects to allow in situ pellicle formation over 3, 30 and 120 min. The slabs were fixed on the buccal and palatal surfaces of individual splints fixed with silicone impression material. After rinsing with deionised water, the pellicle samples were tested fluorimetrically for transglutaminase, protease and elastase activity. Phosphatase activities were tested photometrically. Separate samples were used for each of the enzymes tested.
Transglutaminase was detected in in situ pellicle (16.7+/-21.2 mU/cm(2)) as was alkaline phosphatase activity (0.87+/-0.99 mU/cm(2)). For both enzymes, there was no correlation of enzyme activities with time or localisation of pellicle formation. Acidic phosphatase- and protease-activities were not detectable. Only traces of elastase activity were found in 57% of the samples.
Transglutaminase and phosphatase activity are detectable within in situ pellicle. Enzymatic crosslinking and dephosphorylation appear more important for intrinsic maturation of the acquired enamel pellicle than proteolysis.
Archives of Oral Biology 06/2008; 53(5):416-22. · 1.60 Impact Factor
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ABSTRACT: Caries and periodontitis, the most wide-spread oral diseases around the world, are caused by bacterial adherence and biofilm formation onto the natural as well as restored tooth surface. One possible way to prevent the pathogenic consequences of intraoral biofilm formation might be the modification of the tooth surface by application of an anti-adhesive coating that interferes with the bacterial attachment and subsequent bacterial accumulation. The objective of this study was to investigate the effect of an experimental, low surface free energy nano-composite coating material on biofilm formation in situ. For this purpose, an organic/inorganic nano-composite coating (NANOMER, INM, Saarbrücken, Germany) with a surface free energy of 18-20 mJ/m2 was applied to enamel as well as titanium specimens. The nano-composite coated specimens and un-coated controls were attached to removable intraoral splints and carried by volunteers over 24 h in the oral cavity. After intraoral exposure, specimens were processed for transmission electron microscopic analysis. On non-coated enamel and titanium control samples a multi-layer of adherent bacteria was found. In contrast, on nano-composite coated specimens strongly reduced biofilm formation was observed. In most areas of the surface-coated specimens only a 10-20 nm thick electron dense layer of adsorbed salivary proteins with adherent protein agglomerates of 20-80 nm diameter could be detected. In addition, detachment of the adsorbed biofilm from the nano-composite coated surfaces was evident in electron microscopic micrographs. The present investigation provides ultrastructural evidence that it is possible to cover enamel as well as titanium with a nano-composite coating revealing easy-to-clean surface properties that cause reduced biofilm formation and accelerated removal of adherent biofilms under oral conditions.
Journal of Nanoscience and Nanotechnology 01/2008; 7(12):4642-8. · 1.56 Impact Factor
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ABSTRACT: The acquired salivary pellicle has been defined as proteinaceous film free of bacteria. However, due to the large numbers of microorganisms existent in the oral fluids, it is conceivable that adherent bacteria are already present in the initial pellicle. The aim of this in situ study was to visualize and to quantify these bacteria.
Initial biofilm formation was performed on bovine enamel slabs mounted buccally on individual splints and carried in situ by six subjects for 3, 30 and 120 min, respectively. After intraoral exposure, the slabs were rinsed with saline solution and the adherent bacteria were investigated with the following fluorescence microscopic methods: staining with 4',6-diamidino-2-phenylindole (DAPI), staining of vital and nonvital bacteria with fluoresceinediacetate and ethidiumbromide (live/dead staining) and fluorescence in situ hybridization (FISH) of eubacteria and streptococci, respectively. In addition, determination of colony forming units after ultrasonically induced detachment of bacteria was performed.
With all the methods, bacteria were detected in the initial in situ biofilm irrespective of the formation time. The numbers of bacteria revealed high intraindividual and interindividual variability and the microorganisms were distributed randomly in small aggregates. The results of the epifluorescence microscopic techniques corresponded well. The mean number of adherent bacteria detected was in the range of 10-20x10(4)cm(-2).
Already after 3 min, adherent bacteria are present in the initial pellicle. For the first time, DAPI-staining as well as FISH have proven success for visualization of initial intraoral colonization of enamel specimens.
Archives of Oral Biology 12/2007; 52(11):1048-56. · 1.60 Impact Factor
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ABSTRACT: The purpose of this study was to compare the relative amount of low molecular weight salivary proteins in patients with head and neck tumours treated with radiotherapy and healthy subjects. Reverse-phase high-pressure liquid chromatography was used for protein separation. Nine protein fractions (including acidic and basic proline-rich proteins (PRPs), cystatins, histatins and statherin) were identified in saliva from irradiated patients as well as healthy subjects. However, compared with non-irradiated healthy subjects, the fraction of acidic PRPs was significantly reduced in irradiated patients. These data indicate an alteration of the relative amount of low molecular weight salivary proteins in irradiated patients besides the reduction of salivary flow.
Clinical Oral Investigations 04/2006; 10(1):61-5. · 2.36 Impact Factor
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ABSTRACT: The purpose of this study was to investigate the interfacial interaction of tartaric acid with hydroxyapatite and enamel. Hydroxyapatite particles were mixed with 15% (w/v) alcohol-aqueous (1:1) solution of tartaric acid for 72 h. After the mixture, the filtrate was separated from the solid. The filtrate, the solid, hydroxyapatite, and tartaric acid were dried for FTIR and XRD analysis. Enamel disks etched with tartaric acid for 60 s were analyzed by attenuated total reflectance (ATR). Enamel disks etched with 15% tartaric acid for 15, 30, 60, 120 s were analyzed by SEM. FTIR spectra showed carboxylate in the solid and in subtraction spectra. ATR spectra revealed carboxylate on the enamel surfaces. XRD data indicated the formation of calcium tartrate and calcium hydrogen phosphate after the reaction of tartaric acid with hydroxyapatite. SEM observations revealed typical decalcification of the periphery of the enamel rods due tartaric acid etching. It is concluded that tartaric acid can decalcify and chemisorb onto HA simultaneously, hence, tartaric acid could be used as etchant and ingredient of self-etching primers in adhesive dentistry.
Journal of Materials Science Materials in Medicine 10/2005; 16(9):827-31. · 2.32 Impact Factor
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ABSTRACT: The in vivo formed salivary pellicle is composed of an outer globular and a densely structured basal layer. This study developed a method for selective recovering of these pellicle layers from the enamel surface. Two-hour in situ pellicles were formed by intraoral exposure of enamel specimens in two adults. Pellicle-covered enamel specimens were treated either mechanically (scraping with scaler, curette or razor blade, or rubbing with a sponge) or chemically (phosphate buffer, NaCl, NaOCl, CaCl2, NaSCN, urea, tetrahydrofurane, guanidine, SDS, HCl, or EDTA with or without additional ultrasonication). Specimens were processed for transmission electron microscopic analysis to detect pellicle residues remaining on the enamel surface after the different treatments. Most of the chemical treatments caused partial, incomplete removal of the globular layer. Complete removal of the globular layer without disruption of the basal layer was obtained by sponge rubbing or by CaCl2 combined with ultrasonication, whereas scraping caused partial disruption of the basal layer. Removal of the basal layer was observed after treatment with HCl, EDTA, or NaOCl combined with ultrasonication. Electrophoretical analysis of recovered pellicle fractions indicate that combination of sponge-rubbing followed by EDTA treatment can be recommended for stepwise removal of the globular and basal pellicle layers.
Clinical Oral Investigations 04/2005; 9(1):30-7. · 2.36 Impact Factor
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ABSTRACT: Organic layers of salivary biopolymers adsorbed on soft and hard oral tissues, referred to also as salivary pellicle, play a critical role with respect to all surface phenomena taking place in the oral cavity. The initial stages of pellicle formation are of great interest since they determine the ensuing processes of salivary biopolymer adsorption and subsequent adherence of bacteria. In spite of the important physiological role of the pellicle in protecting the enamel surface against short-term acidic attacks, the composition and ultrastructure of the pellicle layer are not yet understood and resolved in detail. The present study utilized atomic force microscopy (AFM), for the first time, to elucidate the morphogenesis and ultrastructural pattern of initial salivary pellicle formation taking place in situ on solid substrates of mica, silicon wafer and graphite. Using tapping mode AFM, salivary pellicles were found in all intraorally exposed specimens and revealed a globular surface morphology of the adsorbed protein layer. The average diameter and height of the adsorbed salivary proteins were determined to be 15 +/- 3 nm and 2.0 +/- 0.5 nm, respectively. It was also found that the surface energy of the substrates affects the rate of pellicle formation, while the overall size of the adsorbed salivary proteins appears to be identical on all studied substrates.
Journal of Nanoscience and Nanotechnology 06/2004; 4(5):532-8. · 1.56 Impact Factor
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ABSTRACT: This study evaluated the microleakage and internal seal of fissure sealants placed by use of self-etching priming agents in comparison to phosphoric acid etching of enamel.
Seventy-two caries-free extracted human molars were divided into six groups with 12 teeth each. Occlusal surfaces were cleansed by either pumicing (Groups I, III, V) or by 15-s air-abrasion treatment with 25 microm aluminum oxide particles (Groups II, IV, VI). Fissures were sealed with the self-etching priming systems, Clearfil Liner Bond 2 (Groups I, II) or Resulcin AquaPrime (Groups III, IV). In Groups V and VI, sealants were placed after phosphoric acid etching. Half of the teeth in each group were thermocycled. After staining with 0.5% methylene blue, the teeth were sectioned for evaluation of microleakage. Internal adaptation of the fissure sealants was analyzed by SEM on replicas of cross sections.
Independent of the methods used for cleansing of the occlusal surfaces, fissure sealants in Groups I and II showed significantly more microleakage and less sufficient internal seal as compared to sealants placed in Groups III to VI. Sealants placed by Resulcin AquaPrime (Groups III, IV) leaked significantly more than sealants applied after phosphoric acid etching (Groups V, VI) of the enamel. However, statistical analysis (H-test) did not reveal significant differences concerning the internal adaptation of sealants placed in Groups III, IV, V and VI.
Concerning the microleakage data, use of the self-etching bonding systems, Clearfil Liner Bond 2 and Resulcin AquaPrime, cannot be recommended for fissure sealing, since the sealing ability is less effective as compared to the conventional acid-etching technique.
Journal of Dentistry 02/2004; 32(1):75-81. · 2.95 Impact Factor
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ABSTRACT: This study assessed the protective potential of salivary pellicles formed in situ over periods ranging from 2 to 24 h. Pellicles were produced on enamel slabs mounted on the palatal aspect of removable acrylic splints and exposed to the oral environment in three subjects for 2, 6, 12 and 24 h. Enamel specimens with and without pellicles were immersed in citric acid (1%) for 60 s, and the amount of dissolved calcium was measured by atomic absorption spectroscopy. In addition, specimens were processed for transmission electron microscopy (TEM). Mean values (standard deviations) for calcium release (mg/l related to the specimen's surface area of 5 x 5 mm(2)) were: 2-h pellicle 6.94 (1.55); 6-h pellicle 6.69 (2.05); 12-h pellicle 6.57 (2.31); 24-h pellicle 5.71 (2.46); enamel without pellicle 8.95 (1.66). There were no significant differences in calcium release that were dependent on pellicle formation time, but in comparison to enamel specimens without pellicle, significantly less (p <0.05) demineralization of the enamel was observed in pellicle-covered specimens. TEM showed that the pellicle was partly, but not completely dissolved following acid exposure. It is concluded that even a 2-h in-situ-formed pellicle layer protects the enamel surface to a certain extent against demineralization.
Clinical Oral Investigations 10/2003; 7(3):158-61. · 2.36 Impact Factor
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ABSTRACT: The aim of this in vitro study was to assess the marginal adaptation of prefabricated Class I ceramic inlay restorations placed with various luting materials.
Forty-two standardized occlusal cavities were prepared in extracted human molars with diamond burs exactly corresponding to the dimensions of prefabricated glass ceramic inlays. The prepared teeth were randomly assigned to seven groups of six teeth each and restored using (1). the composite resin Tetric Ceram in increment technique [Group I] or (2). ceramic inlays (Cerana) luted with: the composite based materials Dual Cement [Gr. II] and Panavia 21 [Gr. III], the compomer material Dyract Cem [Gr. IV], Dyract Cem with additional use of Prime & Bond 2.1 [Gr. V], the silicophosphate cement Trans-Lit [Gr. VI], or the ethylcyanoacrylate Cyano-Veneer [Gr. VII]. Marginal adaptation was evaluated by SEM-analyses before and after thermal cycling (2500 cycles; 5-55 degrees C) and mechanical loading (100N; 500000 cycles) using replica models. Kruskal-Wallis H-test and Mann-Whitney U-test were used for statistical analyses.
Group I (increment technique) as well as Groups II-V (inlay technique) revealed high percentages of perfect marginal adaptation in over 95% of the analyzed margins, both before and after thermo-mechanical loading. Statistical significant differences could not be detected within these groups. All inlays luted with silicophosphate cement (Group VI) and four of six inlays applied with Cyano-Veneer (Group VII) fractured under occlusal load.
A stable bonding to the enamel and to the ceramic inlay was achievable with the composite luting resins Dual Cement and Panavia 21 as well as with the compomer based luting material Dyract Cem but not with the use of the silicophosphate cement Trans-Lit or the ethylcyanoacrylate Cyano-Veneer.
Dental Materials 07/2003; 19(4):264-9. · 3.13 Impact Factor
