Influence of Calcium Phosphate and Apatite Containing Products on Enamel Erosion.

For the purpose of erosion prevention the present study aimed to compare the efficacy of two biomimetic products and a fluoride solution to optimize the protective properties of the pellicle. After 1 min of in situ pellicle formation on bovine enamel slabs, 8 subjects adopted CPP-ACP (GC Tooth Mousse), a mouthwash with hydroxyapatite microclusters (Biorepair), or a fluoride based mouthwash (elmex Kariesschutz) for 1 min each. Afterwards, samples were exposed in the oral cavity for 28 min. Native enamel slabs and slabs exposed to the oral cavity for 30 min without any rinse served as controls. After oral exposure, slabs were incubated in HCl (pH values 2, 2.3, and 3) for 120 s and kinetics of calcium and phosphate release were measured photometrically; representative samples were evaluated by SEM and TEM. The physiological pellicle reduced demineralization at all pH values; the protective effect was enhanced by fluoride. The biomimetic materials also reduced ion release but their effect was less pronounced. SEM indicated no layer formation after use of the different products. However, TEM confirmed the potential accumulation of mineral components at the pellicle surface. The tested products improve the protective properties of the in situ pellicle but not as effectively as fluorides.

[Web-based rehabilitation aftercare following inpatient psychosomatic treatment]. / Web-basierte Rehabilitationsnachsorge nach stationärer psychosomatischer Therapie (W-RENA).

BACKGROUND: High relapse rates following treatment for mental health disorders are a challenge for psychosomatic rehabilitation treatments. The goal of the present study is to evaluate the feasibility, acceptance and process-quality of a 12-week transdiagnostic Internet-based maintenance treatment (W-RENA) following psychosomatic rehabilitation treatment. Findings regarding effectiveness and moderators of treatment outcome that were already reported elsewhere are briefly summarized.In a preliminary study we first assessed whether rehab patients have the technical requirements and abilities to successfully participate in Internet-based treatments. Patients expressing interest for participation in W-RENA (N=400) were compared with non-participants (N=1789) with regard to sociodemographic and clinical characteristics. METHOD: In a 2-arm randomized controlled trial (N=400) we subsequently compared participants of W-RENA with participants of a treatment as usual group (TAU). Self-report measures were assessed at the beginning of inpatient treatment (t1), at discharge from inpatient treatment/start of W-RENA (t2), and at 3- (t3) and 12-months follow-ups (t4). RESULTS: The majority of assessed rehab-patients had the technical prerequisites (78.79%) and necessary skills (79.9%) to successfully participate in an Internet-based intervention. A third of the patients (32%) which were invited to take part in the intervention (and the study) expressed interest to participate. Study participants and non-participants differed only slightly. Most participants (80.6%) reported to have gained benefit from participating. Treatment achievements as well as quality of therapist alliance were rated high from both patients and therapists. Moreover, participants of the W-RENA group could stabilize their inpatient treatment outcomes up to 3- and 12-months follow-up better than controls could do (differences in symptom change from discharge to 3-months follow-up: d=0.38; to 12-months follow-up: d=0.55). Clinical significant symptom deterioration from discharge to 1-year follow-up could be reduced by 2/3 (29.45% vs. 11.45%). We could not identify any subgroup not profiting from study participation. Patients with low education benefited particularly. CONCLUSION: Internet-based aftercare interventions are a feasible, accepted and effective approach to successfully sustain treatment outcomes achieved in inpatient psychosomatic rehabilitation.

Comparison of different live/dead stainings for detection and quantification of adherent microorganisms in the initial oral biofilm.

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.

Effect of safflower oil on the protective properties of the in situ formed salivary pellicle.

AIM: 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. METHODS: 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). RESULTS: 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. CONCLUSION: 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.

The effect of acidic beverages on the ultrastructure of the acquired pellicle--an in situ study.

AIM: The aim of the present in situ study was to investigate ultrastructural alterations as well as protective properties of the pellicle layer during consumption of acidic beverages. METHODS: Bovine enamel slabs were fixed on buccal and palatal aspects of individual splints and exposed in the oral cavities of three subjects for 120 min. In the following, the subjects drank orange juice, coke light or sprite light. Half of the specimens were removed afterwards, the others were exposed to the oral fluids for another 120 min. Erosive alterations of the bovine enamel slabs were measured by determination of the Knoop-micro-hardness. In addition, the ultrastructure of the pellicle was evaluated by transmission electron microscopy (TEM). RESULTS: Determination of Knoop-micro-hardness yielded only little reduction of the relative Knoop-hardness in situ during consumption of sprite light (-0.053+/-0.019) and coke light (-0.075+/-0.04). With orange juice nearly no change of the hardness was recorded. TEM-pictures showed that the globular outer layers of the pellicle were removed to a different extent according to the localisation of the specimens in the oral cavity, whereas the basal pellicle was not affected by the acidic beverages. On the specimens carried for another 120 min after the erosive attack, lacunae filled with organic structures were observed underneath the basal side of the pellicle. CONCLUSION: During fast consumption of acidic beverages in situ, the erosive effects on pellicle coated bovine enamel are moderate and juices seem to be less harmful as compared with low pH soft drinks. Pellicle proteins in eroded lacunae may impact the remineralization process.

Electron microscopic detection and activity of glucosyltransferase B, C, and D in the in situ formed pellicle.

OBJECTIVE: 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. DESIGN: 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. RESULTS: 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. CONCLUSION: 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.

Influence of nanocomposite surface coating on biofilm formation in situ.

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.

Transmission electron microscopy comparison of methods for collecting in situ formed enamel pellicle.

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.

Influence of salivary pellicle formation time on enamel demineralization--an in situ pilot study.

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.