Proteomic analysis of extracellular vesicle cargoes mirror the cardioprotective effects of rivaroxaban in patients with venous thromboembolism.

BACKGROUND: Venous thromboembolism (VTE) remains a significant cause of morbidity and mortality worldwide. Rivaroxaban, a direct oral factor Xa inhibitor, mediates anti-inflammatory and cardiovascular-protective effects besides its well-established anticoagulant properties; yet, these remain poorly characterized. Extracellular vesicles (EVs) are considered proinflammatory messengers regulating a myriad of (patho)physiological processes and may be highly relevant to the pathophysiology of VTE. The effects of Rivaroxaban on circulating EVs in VTE patients remain unknown. We have established that differential EV biosignatures are found in patients with non-valvular atrial fibrillation anticoagulated with Rivaroxaban versus warfarin. Here, we investigated whether differential proteomic profiles of circulating EVs could also be found in patients with VTE. METHODS AND RESULTS: We performed comparative label-free quantitative proteomic profiling of enriched plasma EVs from VTE patients anticoagulated with either Rivaroxaban or warfarin using a tandem mass spectrometry approach. Of the 182 quantified proteins, six were found to be either exclusive to, or enriched in, Rivaroxaban-treated patients. Intriguingly, these proteins are involved in negative feedback regulation of inflammatory and coagulation pathways, suggesting that EV proteomic signatures may reflect both Rivaroxaban's anti-coagulatory and anti-inflammatory potential. CONCLUSIONS: These differences suggest Rivaroxaban may have pleiotropic effects, supporting the reports of its emerging anti-inflammatory and cardiovascular-protective characteristics relative to warfarin.

Shear Bond Strength of Adhesives Placed following Selective Removal of Red-Fluorescing Carious Dentine in vitro.

Red-fluorescing dentine indicates bacterial contamination [Caries Res 2002; 36: 315-319]. We investigated effect of removal of red fluorescent dentine caries on shear bond strength and fracture mode of 4 adhesive approaches. Sixty-five carious teeth and 50 noncarious controls were distributed into 4 groups: Clearfil™ self-etch (CSE), OptiBond™ FL total etch (OTE), Scotchbond™ Universal total etch (STE) and self-etch (SSE). Samples were excited at 405 nm and viewed through 530 nm filter. Carious samples were ground flat exposing strongly red-fluorescing (StrongRF) dentine, on which a composite cylinder was placed, using one of 4 adhesives. After 22 h in water, shear bond strength and fracture mode were analysed. StrongRF was removed; composite cylinders were placed on weakly red-fluorescing (WeakRF) dentine and tested as described above. Finally, red-fluorescing dentine was removed, and composite cylinders were placed on non-fluorescing (NonRF) dentine and tested. Composites were placed at 3 corresponding heights in controls. After 22 h in water, shear bond strength testing and fracture mode analysis were performed. Differences were tested using Mann-Whitney or Wilcoxon tests (p ≤0.05). Median (Q1, Q3) shear bond strength on StrongRF was SSE 14.4 (9.2, 18.2) MPa >CSE 10.2 (6.4, 17.3) MPa >STE 9.1 (6.9, 11.2) MPa >OTE 6.8 (4.0, 10.8) MPa. Shear bond strength increased statistically significantly for all adhesives on WeakRF: SSE 19.8 (13.6, 24.3) MPa >STE 19.5 (12.7, 23.1) MPa >CSE 17.5 (12.0, 22.5) MPa >OTE 15.8 (11.9, 20.9) MPa. Only STE 25.6 (22.4, 29.1) MPa and CSE 22.1 (17.6, 24.6) MPa were significantly different on NonRF compared to WeakRF. For controls tested at corresponding depths, superficial shear bond strength was OTE 18.7 (16.0, 22.1) MPa >STE 18.4 (12.0, 25.9) MPa >CSE 18.1 (12.7, 20.7) MPa >SSE 13.0 (9.6, 17.8) MPa. This was significantly higher compared to StrongRF except for SSE. Central shear bond strength was not significantly different to WeakRF, deep shear bond strength was significantly lower for SSE and CSE but higher for OTE compared to carious. Conclusion: StrongRF dentine should be removed for higher shear bond strength, but WeakRF dentine can often be preserved without compromising adhesive bond strength.

Fluorescence Spectroscopy Shows Porphyrins Produced by Cultured Oral Bacteria Differ Depending on Composition of Growth Media.

Red fluorophores synthesized by oral bacteria are important for fluorescence-based diagnosis and treatment because they are used as markers for bacterially infected tissue, mature plaque, or calculus. A range of porphyrins have been identified as the source of this fluorescence in carious tissue. It is not clear which of these porphyrins are produced by individual oral bacteria or whether this ability depends on other factors. This study examined and compared the fluorescence spectra produced by selected cultured oral bacteria when grown on agars containing different nutrients with spectra for protoporphyrin IX, Zn-protoporphyrin IX, haematoporphyrin, and haematin. Actinomyces israelii (Deutsche Sammlung von Mikroorganismen [DSM], 43320), Actinomyces naeslundii (DSM 43013), Fusobacterium nucleatum (DSM, 20482), Lactobacillus casei (DSM, 20011), Prevotella intermedia (DSM, 20706), Streptococcus mutans (DSM, 20523), Streptococcus oralis (DSM, 20627), Streptococcus salivarius (DSM, 20560) and Streptococcus sobrinus (DSM, 20742) were rehydrated and grown anaerobically on caso, caso blood (containing 5% sheep blood), and caso chlorophyll (containing 5% spinach extract) agar for 3 days at 37°C in the dark. Colonies were harvested, transferred to ethanol, and centrifuged. Fluorescence emission spectra were recorded from the supernatant at 405 nm excitation (Fluorolog 3-22, Jobin Yvon-Spex ISA, Edison, NJ, USA). All Streptococci, L. casei, and F. nucleatum produced red fluorescence when grown on caso and caso chlorophyll agar but not on caso blood agar. A. naeslundii and P. intermedia emitted intense red fluorescence when grown on caso or caso blood agar but not on caso chlorophyll agar. Fluorescence emission spectra of A. naeslundii and P. intermedia grown on caso blood agar correlated exactly with both fluorescence peaks for protoporphyrin-IX at 632 and 701 nm. Most peaks observed could be correlated with at least one of the emission peaks of protoporphyrin IX, Zn-protoporphyrin IX, or haematoporphyrin. Oral bacteria emitted red fluorescence matching known porphyrins, but this depended on nutrients available in the agar.

Case Report: Hypergranular Platelets in Vaccine-Induced Thrombotic Thrombocytopenia After ChAdOx1 nCov-19 Vaccination.

BACKGROUND: Vaccine-induced thrombotic thrombocytopenia (VITT) post SARS-CoV-2 vaccination is characterized by thrombocytopenia and severe thrombosis. Platelet function during patient recovery in the medium-/long-term has not been investigated fully. Here, we undertook a 3-month study, assessing the recovery of a VITT patient and assessing platelet morphology, granule content and dense-granule release at two distinct time points during recovery. CASE PRESENTATION: A 61 year-old female was admitted to hospital 15 days post ChAdOx1 nCov-19 vaccination. Hematological parameters and peripheral blood smears were monitored over 3 months. Platelet morphology and granule populations were assessed using transmission electron microscopy (TEM) at two distinct time points during recovery, as was agonist-induced platelet dense-granule release. Upon admission, the patient had reduced platelet counts, increased D-dimer and high anti-PF4 antibodies with multiple sites of cerebral venous sinus thrombosis (CVST). Peripheral blood smears revealed the presence of large, hypergranular platelets. Following treatment, hematological parameters returned to normal ranges over the study period. Anti-PF4 antibodies remained persistently high up to 90 days post-admission. Two days after admission, VITT platelets contained more granules per-platelet when compared to day 72 and healthy platelets. Additionally, maximal ATP release (marker of dense-granule release) was increased on day 2 compared to day 72 and healthy control platelets. CONCLUSION: This study highlights a previously unreported observation of platelet hypergranularity in VITT which may contribute to the thrombotic risk associated with VITT. Optimal approaches to monitoring recovery from VITT over time remains to be determined but our findings may help inform therapeutic decisions relating to anticoagulation treatment in this novel pathology.

Non-severe COVID-19 is associated with endothelial damage and hypercoagulability despite pharmacological thromboprophylaxis.

BACKGROUND: Hypercoagulability and endothelial dysfunction are hallmarks of coronavirus disease 2019 (COVID-19) and appear to predict disease severity. A high incidence of thrombosis despite thromboprophylaxis is reported in patients with moderate to severe COVID-19. Recent randomized clinical trials suggest that therapeutic-intensity heparin confers a survival benefit in moderate-severity COVID-19 compared to standard-intensity heparin, potentially by harnessing heparin-mediated endothelial-stabilizing and anti-inflammatory effects. OBJECTIVE: We hypothesized that patients with moderate-severity COVID-19 exhibit enhanced hypercoagulability despite standard-intensity thromboprophylaxis with low molecular weight heparin (LMWH) compared to non-COVID-19 hospitalized patients. METHODS: Patients with moderate COVID-19 and a control group (severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2]-negative hospitalized patients) receiving LMWH thromboprophylaxis were recruited. Markers of endothelial damage and plasma thrombin generation parameters were assessed. RESULTS: Tissue plasminogen activator levels were significantly increased in the COVID-19 group (8.3 ± 4.4 vs. 4.9 ± 2.4 ng/ml; P = .02) compared to non-COVID-19-hospitalized patients. Despite thromboprophylaxis, mean endogenous thrombin potential was significantly increased among COVID-19 patients (1929 ± 448 vs. 1528 ± 460.8 nM*min; P = .04) but lag time to thrombin generation was significantly prolonged (8.1 ± 1.8 vs. 6.2 ± 1.8 mins; P = .02). While tissue factor pathway inhibitor (TFPI) levels were similar in both groups, in the presence of an inhibitory anti-TFPI antibody, the difference in lag time between the groups was abrogated. CONCLUSIONS: Collectively, these data demonstrate that COVID-19 of moderate severity is associated with increased plasma thrombin generation and endothelial damage, and that hypercoagulability persists despite standard LMWH thromboprophylaxis. These findings may be of clinical interest given recent clinical trial data which suggest escalated heparin dosing in non-severe COVID-19 may be associated with improved clinical outcomes.

Routine Hematological Parameters May Be Predictors of COVID-19 Severity.

To date, coronavirus disease 2019 (COVID-19) has affected over 100 million people globally. COVID-19 can present with a variety of different symptoms leading to manifestation of disease ranging from mild cases to a life-threatening condition requiring critical care-level support. At present, a rapid prediction of disease severity and critical care requirement in COVID-19 patients, in early stages of disease, remains an unmet challenge. Therefore, we assessed whether parameters from a routine clinical hematology workup, at the time of hospital admission, can be valuable predictors of COVID-19 severity and the requirement for critical care. Hematological data from the day of hospital admission (day of positive COVID-19 test) for patients with severe COVID-19 disease (requiring critical care during illness) and patients with non-severe disease (not requiring critical care) were acquired. The data were amalgamated and cleaned and modeling was performed. Using a decision tree model, we demonstrated that routine clinical hematology parameters are important predictors of COVID-19 severity. This proof-of-concept study shows that a combination of activated partial thromboplastin time, white cell count-to-neutrophil ratio, and platelet count can predict subsequent severity of COVID-19 with high sensitivity and specificity (area under ROC 0.9956) at the time of the patient's hospital admission. These data, pending further validation, indicate that a decision tree model with hematological parameters could potentially form the basis for a rapid risk stratification tool that predicts COVID-19 severity in hospitalized patients.

Nonvalvular atrial fibrillation patients anticoagulated with rivaroxaban compared with warfarin exhibit reduced circulating extracellular vesicles with attenuated pro-inflammatory protein signatures.

BACKGROUND: Rivaroxaban, a direct oral factor Xa inhibitor, mediates anti-inflammatory and cardiovascular-protective effects besides its well-established anticoagulant properties; however, these remain poorly characterized. Extracellular vesicles (EVs) are important circulating messengers regulating a myriad of biological and pathological processes and may be highly relevant to the pathophysiology of atrial fibrillation as they reflect alterations in platelet and endothelial biology. However, the effects of rivaroxaban on circulating pro-inflammatory EVs remain unknown. OBJECTIVES: We hypothesized that rivaroxaban's anti-inflammatory properties are reflected upon differential molecular profiles of circulating EVs. METHODS: Differences in circulating EV profiles were assessed using a combination of single vesicle analysis by Nanoparticle Tracking Analysis and flow cytometry, and proteomics. RESULTS: We demonstrate, for the first time, that rivaroxaban-treated non-valvular atrial fibrillation (NVAF) patients (n=8) exhibit attenuated inflammation compared with matched warfarin controls (n=15). Circulating EV profiles were fundamentally altered. Moreover, quantitative proteomic analysis of enriched plasma EVs from six pooled biological donors per treatment group revealed a profound decrease in highly pro-inflammatory protein expression and complement factors, together with increased expression of negative regulators of inflammatory pathways. Crucially, a reduction in circulating levels of soluble P-selectin was observed in rivaroxaban-treated patients (compared with warfarin controls), which negatively correlated with the patient's time on treatment. CONCLUSION: Collectively, these data demonstrate that NVAF patients anticoagulated with rivaroxaban (compared with warfarin) exhibit both a reduced pro-inflammatory state and evidence of reduced endothelial activation. These findings are of translational relevance toward characterizing the anti-inflammatory and cardiovascular-protective mechanisms associated with rivaroxaban therapy.

Elevated plasma TFPI activity causes attenuated TF-dependent thrombin generation in early onset preeclampsia.

Early onset preeclampsia (EOP) is a pregnancy-specific proinflammatory disorder that is characterised by competing thrombotic and bleeding risks. It was the aim of this study to characterise thrombin generation, a major determinant of thrombotic and bleeding risk, in order to better understand the haemostatic balance in patients with EOP. Patients with EOP were recruited at the Rotunda Hospital, Dublin. Twenty-six cases of EOP were recruited over a 21-month period, out of 15,299 deliveries at the Rotunda. Blood samples were collected into sodium citrate plus corn trypsin inhibitor anticoagulated vacutainers, platelet-poor plasma was prepared, and calibrated automated thrombography was used to assess thrombin generation. Results were compared to age and sex-matched non-pregnant controls (n=13) and age- and gestation-matched pregnant controls (n=20). The rate and extent of thrombin generation triggered by low-dose tissue factor (TF) was significantly reduced in patients with EOP compared to pregnant controls, most significantly in cases of severe EOP. EOP patients displayed a trend towards an increased response to endogenous activated protein C and thrombomodulin relative to pregnant controls. Plasma tissue factor pathway inhibitor (TFPI) activity was increased in EOP patients. Inhibition of TFPI abolished the attenuation of thrombin generation stimulated by low-dose TF. In conclusion, patients with EOP are characterised by an attenuated coagulation response characterised by reduced thrombin generation stimulated by low-dose TF and elevated plasma TFPI activity. These changes in coagulation may modulate thrombotic risk and bleeding risk in patients with EOP.

Effect of platelet-derived ß-thromboglobulins on coagulation.

BACKGROUND: ß-thromboglobulins are derived from the cleavage of the CXC chemokine platelet basic protein and are released in high concentrations by activated platelets. Platelet-derived ß-thromboglobulins (ßTG) share 70% homology with platelet factor 4 (PF4), another CXC chemokine released by activated platelets. PF4 modulates coagulation by inhibiting heparin-antithrombin interactions, promoting protein C activation, and attenuating the activity of activated protein C. In contrast, the effect of ßTG on coagulation is unknown. AIM/METHODS: Clotting times, thrombin generation, chromogenic clotting factor assays, and surface plasmon resonance (SPR) were used to assess the effect of purified ßTG on coagulation. RESULTS: In normal pooled plasma, ßTG shortened the lagtime and time to peak thrombin generation of tissue factor (TF)-dependent and TF-independent thrombin generation. In factor VIII and factor IX-deficient plasmas, ßTG induced thrombin generation in the absence of a TF stimulus and in the presence of anti-TF and factor VIIa inhibitory antibodies. The procoagulant effect was not observed when thrombin generation was independent of factor X activation (supplementation of factor X-deficient plasma with factor Xa). Cleavage of a factor Xa-specific chromogenic substrate was observed when ßTG was incubated with factor X, suggesting a direct interaction between ßTG and factor X. Using SPR, ßTG were found to bind to immobilised factor X in a dose dependent manner. CONCLUSION: ßTG modulate coagulation in vitro via an interaction with factor X.

Endothelial barrier protective properties of low molecular weight heparin: A novel potential tool in the prevention of cancer metastasis?

BACKGROUND: One of the key events in the progression of cancer metastasis is the trans-endothelial migration of circulating tumor cells. Moreover, inhibition of tumor-induced vascular permeability has been shown to inhibit metastasis in vivo. Low molecular weight heparin (LMWH) appears to confer a survival benefit in cancer but the underlying mechanisms are poorly understood. OBJECTIVE: To characterise LMWH-mediated endothelial barrier protection and to explore strategies to limit the LMWH-associated haemorrhagic risk in this setting. METHODS: Endothelial barrier function was assessed using in vitro assays of endothelial permeability and tumor cell trans-endothelial migration. Thrombin-mediated activation of PAR-1 signalling was assessed by flow cytometry and western blotting. LMWH anticoagulant activity was assessed by calibrated automated thrombography and plasma anti-factor Xa activity assay. RESULTS: LMWH tinzaparin enhanced endothelial barrier function and reduced tumor cell trans-endothelial migration (73.9±5.7% of baseline; P<.05). Tinzaparin-mediated attenuation of thrombin-induced permeability was not mediated through an inhibition of thrombin proteolytic activity. In addition, fractions of LMWH with diminished anticoagulant activity retained endothelial barrier protective properties and a marked synergistic effect on barrier function was observed using combinations of sub-anticoagulant concentrations of tinzaparin with simvastatin (which exhibits endothelial barrier protective properties in vitro), with almost complete protection against agonist-induced endothelial barrier permeability achieved (7.9±0.2% of baseline; P<.05). CONCLUSION: Collectively, these results suggest that LMWH supports endothelial barrier function in a manner which does not appear to be dependent on its anticoagulant activity. If replicated in vivo, these findings could represent a novel therapeutic approach to the suppression of metastasis.

Splenectomy-related red cell lysis resistance causing analytical difficulty in a patient with a hematological malignancy.

A patient with a history of chronic lymphocytic leukaemia and a previous splenectomy underwent full blood count analysis in a general hospital. Her medical care had previously taken place in a different institution. A CELL- DYN Sapphire analyser measured her lymphocyte count at ten-fold higher than her known baseline. The sample was sent to her previous hospital, where the laboratory utilises an ADVIA-2120i analyser. The results of this analysis were in keeping with her baseline. The spurious result appears to be related to red cell lysis resistance following splenectomy; however, this resistance appeared to be specific to the analytical method used.

Fluorescence-aided caries excavation (FACE), caries detector, and conventional caries excavation in primary teeth.

PURPOSE: The purpose of this paper was to compare the ability of fluorescence-aided caries excavation (FACE) to remove infected dentin in primary teeth with that of conventional methods. METHODS: Sixty-six extracted carious primary teeth were divided according to lesion size into 3 groups of 22 teeth. Caries excavation was carried out with a slow-speed handpiece and round burs for all groups. In the first group, caries was excavated conventionally using visual tactile criteria. In the second group, a caries detector dye was used to detect carious dentin. In the FACE group, cavities were excited with violet light (370-420 nm) and observed through a 530 nm highpass filter. Orange-red fluorescing areas were removed. Undecalcified thin slices were prepared, stained with Giemsa, and examined for presence of infected dentin using light microscopy. Four samples were lost during processing. RESULTS: Histology showed infected dentin in significantly less FACE samples (3 of 22) compared to conventional excavation (9 of 20; P=.03), but not significantly less compared to caries detector (5 of 20; P=.35). CONCLUSIONS: Within the limitations of this in vitro study, it can be concluded that fluorescence-aided caries excavation is more effective than conventional excavation in removal of infected primary dentin.

Approximal caries development in surfaces in contact with fluoride-releasing and non-fluoride-releasing restorative materials: an in situ study.

This study investigated the effect of compomer on initial interproximal caries development. One-hundred and sixty cylindrical, and 40 semispherical, bovine enamel samples (control) were prepared, polished, and sterilized. Sixty semicircular samples were prepared from each of the compomer Dyract eXtra and the fluoride-free composite Spectrum TPH. Samples were stored in water and fluoridated twice daily for 28 d. A baseline quantitative light fluorescence (QLF) image was made of each cylindrical sample. Twenty volunteers received intra-oral appliances with eight sample chambers. Each wing contained 1 control sample and either 3 Dyract eXtra or 3 Spectrum TPH samples in contact with the enamel surface of a cylindrical enamel sample. Appliances were worn for 24 h a day for 28 d except during toothbrushing (twice daily) and placement in 10% sucrose solution (five times daily). A final QLF image was made after 28 d. Caries development was analyzed as the lesion area x mean fluorescence loss (DeltaQ % mm(2)) between these and the baseline images using QLF subtract software. The median DeltaQ was significantly lower in the Dyract eXtra group (-6.1% mm(2)) than in the Spectrum TPH (-13.9% mm(2), P

Quantity of remaining bacteria and cavity size after excavation with FACE, caries detector dye and conventional excavation in vitro.

In this in vitro study, quantitative confocal microscopy was used to show differences in the quantity of bacteria remaining in dentin after excavation with different methods. A further parameter was the cavity volume after excavation relative to the original lesion size. Teeth with dentin caries were divided into three groups of 20 each. The caries was removed by a single operator using a slow handpiece and a round bur. In the first group, Fluorescence Aided Caries Excavation (FACE) was carried out: violet light was used to illuminate the operating field and the operator observed the cavity through a high-pass filter and removed the orange-red fluorescing areas. The second group was excavated using Caries Detector, while the third group used conventional excavation. After excavation, cavity volume was measured; samples were stained for bacteria with ethidium bromide, and they were examined using confocal microscopy under standardized conditions. The bound stain was quantified in terms of fluorescence intensity on the confocal images. Total pixel intensity was significantly lower in the FACE Group than in the Caries Detector group (p = 0.046) and in the conventional excavation group (p = 0.021). Differences in cavity volume relative to original lesion size were not statistically significant (p = 0.86, 0.35 and 0.51). Within the limitations of this in vitro study, it can be concluded that FACE is more effective in removing infected dentin without significantly increasing cavity size when compared to conventional excavation and excavation with the aid of caries detector dye.

Subjectivity and examiner experience in diagnosis of residual caries--an in vitro study.

UNLABELLED: The aim was to evaluate subjectivity (using inter- and intraexaminer repeatability), the effect of examiner experience, and residual caries diagnostic accuracy with visual tactile (VT) criteria and using a caries disclosing agent (CD). Thirty teeth with occlusal caries were excavated by a single operator not involved in the diagnostic part of the study. A test area was marked in each cavity. Four dentists with more than five and five dentists with less than five years' experience rated the marked area twice (a week apart) using VT criteria. A week later, the samples were stained using Caries Detector. The same examiners rated the presence or absence of stain in the marked area twice (a week apart). Undecalcified thin slices were examined for bacteria using light microscopy. Overall kappa for inter-examiner repeatability was higher for CD (0.45) than VT (0.31). In the less experienced group the kappa value was higher for CD (0.41) than for VT (0.23). In the experienced group kappa was lower for CD (0.43) than for VT (0.46). Median kappa for intra-examiner repeatability was higher for caries detector (0.77, 0.53) compared to visual tactile (0.52, 0.34) for the more and less experienced examiners respectively. There was no significant difference between the experienced and the inexperienced group in combined sensitivity and specificity (mean) for VT (0.52, 0.53) or CD (0.60, 0.58). IN CONCLUSION: VT was more subjective than CD, except for experienced examiners who had a higher inter-examiner repeatability for VT than CD. Diagnostic accuracy for residual caries does not increase with experience.

[Enamel fluoride uptake following fluoride application and fluoride precipitation]. / Schmelz-fluoridaufnahme nach Fluoridierung und Fluoridfällung.

This study is on fluoride uptake into enamel following fluoride precipitation with calcium hydroxide. Five specimens each from 12 bovine incisors were polished, covered with a salivary pellicle, and distributed into five groups (n=12). A fluoride solution (43,500 ppm F from magnesiumfluorosilicate, copper-(II)-fluorosilicate and sodium-fluoride, pH 2; Tiefenfluorid Touchierlösung, Humanchemie) and Ca(OH)2-solution (Tiefenfluorid Nachtouchierlösung) were applied subsequently in group TN. "Touchierlosung" only was used in group T, sodium-fluoride (43,500 ppm F, pH 2) in group NaF, and aminefluoride (Elmex fluid, 10,000 ppm F, pH 4) in group EF. No fluoride was used in group NK (negative control). Following rinsing and 24 h storage in artificial saliva surface KOH-soluble fluoride content (KOHF), and structurally bound fluoride content (SBF) from three layers (0-33, 33-66 and 66-99 pm) was determined by fluoride electrode procedures. KOHF (median in microg/cm2) of NK was below the lower limit of quantification of the fluoride electrode. The other group values were significantly higher (Mann-Whitney test, p < or = 0.05). TN (1.6), T (1.4) and NaF (1.1) did not differ significantly. EF (0.6) was significantly smaller than TN and T but not smaller than NaF. SBF (0-33, 33-66, 66-99 pm; median in microg/cm3) of TN (445, 341, 275), T (644, 481, 360), NaF (804, 480, 307) and EF (449, 346, 280) did not differ significantly but, with the exception of TN, were significantly higher as compared to NK. A precipitation reaction with Ca(OH)2 following fluoridation did not increase enamel fluoride uptake.

Successful use of a single-retainer all-ceramic resin-bonded fixed partial denture for replacement of a maxillary canine: a clinical report.

This clinical report describes the prosthodontic treatment of a 60-year-old woman to close an edentulous space in the region of the maxillary canine. Single-retainer resin-bonded fixed partial dentures (FPD) have shown satisfactory results in different studies. Recent in vivo studies have shown excellent results for all-ceramic anterior FPDs after 5 years. In the present situation, a cantilevered all-ceramic FPD chosen to replace a missing maxillary canine showed success at the 2.5-year follow-up. Special attention was given to functional and minimal restorative considerations. The use of single-retainer all-ceramic FPDs is discussed. The present case does not represent a routine and well-documented approach for the replacement of a missing maxillary canine. Rather, it is a rarity that was successful because of space availability, present occlusal scheme, and patient cooperation. Implant-supported restorations always should be considered as the first treatment option in such a clinical situation.

Influence of bleaching agents and desensitizing varnishes on the water content of dentin.

This in vitro study investigated the possible dehydration of dentin caused by bleaching agents. Furthermore, it tested whether protective dentin varnishes can maintain the physiological moisture of dentin during bleaching treatment. Fifty-five standardized dentin cylinders were prepared from freshly extracted bovine incisors under constant water irrigation. Prior to bleaching, the treatment specimens were conditioned at room temperature in a hygrophor for 14 days. The samples were divided into 11 groups. The Group A specimens, which were completely dehydrated, and Group B, which was stored for 2 weeks in a hygrophor, served as controls (A, B n=5). The other samples (n=10 each group) were coated with Vivasens [VS] (C), Bilfuorid [BF] (D) and Seal&Protect [SP] (E). Five specimens from each group (C-E) were subsequently treated with an experimental bleaching gel (Exp BG) (20% carbamide peroxide [CP], glycerine-based gel): Cb, Db, Eb. The remaining specimens were bleached with Exp BG (F) only, Vivastyle (G: 16% CP, glycerine-based gel) or Vivastyle Paint On (H: 6% CP-varnish) for 7 days (n=5 each group) with bleaching time for gels: 2 hours/day, paint on: 20 minutes/day. After the respective treatments, the overall water content of each specimen was determined using the analytical method of Karl-Fischer-titration. The water content of bovine dentin (Group B, mean%+/-SD) obtained in this study amounted to 15.24+/-0.4. All bleaching products significantly reduced the water content compared to the controls (exp BG: 13.32+/-0.47, Vivastyle 13.2+/-0.27, paint on 13.72+/-0.54; p<0.05). Also, application of SP before bleaching resulted in reduced water content (14.06+/-0.12; p=0.0005). However, bleaching with exp BG following use of VS (14.99+/-0.42) or SP (13.85+/-0.26) did not result in a reduction of water content in dentin. Pretreatment with BF did not protect dentin from water loss during bleaching (12.44+/-0.38; bi p=0.0009). All glycerine-based bleaching products used in this study had a significant dehydrating effect on dentin. The application of protective varnishes prior to bleaching treatment may reduce or even prevent dentin dehydration.

Efficiency of 4 caries excavation methods compared.

UNLABELLED: This in vitro study compared the efficiency (time taken to excavate and successfully remove bacterially infected dentin) of Fluorescence Aided Caries Excavation (FACE), caries detector dye (CD), chemomechanical excavation (CS) and conventional excavation (CE). Teeth with dentin caries were assigned to 4 groups (n= 25). Caries excavation was carried out by one operator. In the FACE group, the operating field was illuminated with violet light. The operator observed the teeth through a high-pass filter and removed orange-red fluorescing areas with a slow speed bur. In the CS group, Carisolv was applied to the cavity using CS hand instruments and allowed to act for 30 seconds before caries was removed. In the CD group, caries was removed using the Caries Detector and, in the CE group, conventional excavation was carried out using visual-tactile criteria. The excavation time was recorded. Undecalcified thin slices (8 microm) were prepared, stained with giemsa and examined using light microscopy. The excavation time (median) was significantly shorter for FACE (3 minutes, 3 seconds) compared to CS (5 minutes, 8 seconds, p=0.015), CD (5 minutes, 26 seconds, p=0.003) and CE (4 minutes, 2 seconds, p=0.025). Histology showed remaining bacteria in significantly fewer (5/25) FACE samples compared to CS (15/25 p=0.004) CD (12/25 p=0.037) but not significantly fewer than CE (11/25 p=0.069). IN CONCLUSION: the excavation result with FACE is equal to CE and superior to CD and CS but requires a significantly shorter excavation time.

Comparative fluorescence spectroscopy of root caries lesions.

In this study, the light-emission properties of carious and sound root surfaces were investigated under a wide range of excitation wavelengths. Human molar teeth with exposed root surfaces containing light- and dark-discolored root caries (n = 3 of each) were selected. Emission spectra were recorded from carious and corresponding sound root surface areas from each tooth by using a fluorescence spectrophotometer at excitation wavelengths from 360 nm up to 580 nm, in steps of 20 nm. The spectra were corrected for fluctuations in detector sensitivity and excitation light intensity, and normalized to peak intensity. Excitation spectra were recorded for selected emission wavelengths that showed maximum intensity. Light- and dark-discolored root surface caries showed distinct fluorescence emission bands between 600 and 700 nm that were not present in sound root surface areas. These bands were strongest for excitation wavelengths between 390 and 420 nm. The excitation spectra of root caries revealed maximum excitation at around 405 nm, which is equivalent to the Soret band of porphyrin compounds. The emission spectra of both types of root caries lesions were shifted towards longer wavelengths (red shift at half maximum) when compared to the spectra of corresponding sound root surfaces. The red shift for dark-discolored root caries was higher than for light-discolored lesions at all excitation wavelengths.