Depth of cure and mechanical properties of nano-hybrid resin-based composites with novel and conventional matrix formulation

Objectives

This study’s purpose was to evaluate the depth of cure (DOC) and the variation of mechanical properties with depth of two nano-hybrid resin-based composites (RBCs) containing a novel monomer composition based on dimer-acid derivatives (h-Da) or rather tricyclodecane–urethane structure (TCD-urethane) compared to three conventionally formulated nano-hybrid RBCs based on hardness-profile measurements.

Materials and methods

Specimens were produced through different layering techniques (bulk, incremental) and curing times (10, 20, and 40?s). Mechanical properties (Vickers hardness (HV), modulus of elasticity (E)) were evaluated every 100?μm longitudinally throughout the bisected samples using an automatic micro-hardness indenter. DOC was determined as the depth at which the 80% hardness cutoff value in relation to the surface hardness was reached. Results were compared using one- and multiple-way ANOVA, Tukey HSD post-hoc test (α?=?0.05) and partial eta-squared statistic.

Results

Increasing curing time resulted in a significant increase in DOC. Generally, the novel-formulated materials showed higher DOC values. “Curing time” and “material” showed the strongest effect on DOC. Starting in 4?mm depth, significantly higher HV and E was reached for incremental compared to bulk-curing technique. Values in 0.1 and 2?mm depth (bulk, incremental) as well as in 4?mm depth (incremental) were independent from curing time, while in greater depths, values generally increased with curing time. “Filling technique” and “material” performed the strongest influence on mechanical properties.

Conclusions

Within the limits of this study, the novel-formulated RBCs showed better performance concerning DOC compared to conventional materials.

Clinical relevance

For cavities deeper than 3?mm, all tested materials should be placed incrementally to ensure adequate polymerization. In large cavities (≥6?mm), the lowest increment should be cured at least 40?s. The novel-formulated RBCs might be cured in comparatively bigger increments.     

Topographic Distribution and Progression of Soft Drusen Volume in Age-Related Macular Degeneration Implicate Neurobiology of Fovea

PurposeTo refine estimates of macular soft drusen abundance in eyes with age-related macular degeneration (AMD) and evaluate hypotheses about drusen biogenesis, we investigated topographic distribution and growth rates of drusen by optical coherence tomography (OCT). We compared results to retinal features with similar topographies (cone density and macular pigment) in healthy eyes.MethodsIn a prospective study, distribution and growth rates of soft drusen in eyes with AMD were identified by human observers in OCT volumes and analyzed with computer-assistance. Published histologic data for macular cone densities (n = 12 eyes) and in vivo macular pigment optical density (MPOD) measurements in older adults with unremarkable maculae (n = 31; 62 paired eyes, averaged) were revisited. All values were normalized to Early Treatment Diabetic Retinopathy Study (ETDRS) subfield areas.ResultsSixty-two eyes of 44 patients were imaged for periods up to 78 months. Soft drusen volume per unit volume at baseline is 24.6-fold and 2.3-fold higher in the central ETDRS subfield than in outer and inner rings, respectively, and grows most prominently there. Corresponding ratios (central versus inner and central versus outer) for cone density in donor eyes is 13.3-fold and 5.1-fold and for MPOD, 24.6 and 23.9-fold, and 3.6 and 3.6-fold.ConclusionsNormalized soft drusen volume in AMD eyes as assessed by OCT is ≥ 20-fold higher in central ETDRS subfields than in outer rings, paralleling MPOD distribution in healthy eyes. Data on drusen volume support this metric for AMD risk assessment and clinical trial outcome measure. Alignment of different data modalities support the ETDRS grid for standardizing retinal topography in mechanistic studies of drusen biogenesis.     

Lack of long‐term clinical benefit of thrombus aspiration during primary percutaneous coronary intervention with paclitaxel‐eluting stents or bare‐metal stents: Post‐hoc analysis of the PASSION‐trial

Background : Although current clinical guidelines recommend the use of thrombus aspiration (TA) during primary percutaneous coronary intervention (PPCI), previous studies evaluating TA demonstrated contradictory results. The aim of this study was to evaluate long‐term clinical outcome after TA in adjunct to PPCI for acute ST‐segment myocardial infarction (STEMI), as compared with conventional treatment, with the use of paclitaxel‐eluting stents or bare‐metal stents. Methods : We analyzed data of the PASSION trial, in which 619 patients with STEMI were randomly assigned to a paclitaxel‐eluting stent or a bare‐metal stent. TA was performed in 311 patients (50.2%). Clinical endpoints at 2 years were compared between patients who received TA during PPCI with patients who underwent conventional PPCI. The primary outcome of interest was a composite of cardiac death, recurrent myocardial infarction (MI), or target‐lesion revascularization (TLR). A propensity score model was made to account for baseline differences that could have affected the probability of performing TA. Results : Complete follow‐up was available for 598 patients (96.6%). The cumulative incidence of the combined outcome measure of cardiac death, recurrent MI, or TLR was 40 (13.0%) in the TA group and 41 (13.5%) in the conventional PPCI group (HR 0.96; 95% CI 0.62–1.47; P = 0.84). Also after adjusting for propensity score, no significant difference in event rate was observed between both treatment groups. Conclusions : In this post‐hoc analysis of the PASSION trial, TA in adjunct to PPCI did not affect rates of major adverse cardiac events at 2 years follow‐up, as compared with conventional PPCI. © 2011 Wiley Periodicals, Inc.     

Assessment of leptomeningeal collaterals using dynamic CT angiography in patients with acute ischemic stroke

Whole-brain dynamic time-resolved computed tomography angiography (CTA) is a technique developed on the new 320-detector row CT scanner capable of generating time-resolved cerebral angiograms from skull base to vertex. Unlike a conventional cerebral angiogram, this technique visualizes pial arterial filling in all vascular territories, thereby providing additional hemodynamic information. Ours was a retrospective study of consecutive patients with ischemic stroke and M1 middle cerebral artery +/−intracranial internal carotid artery occlusions presenting to our center from June 2010 and undergoing dynamic time-resolved CTA and perfusion CT within 6 hours of symptom onset. Leptomeningeal collateral status was assessed by determining relative prominence of pial arteries in the ischemic region, rate and extent of retrograde flow, and various topographical patterns of pial arterial filling. Twenty-five patients were included in the study. We demonstrate the existence of the following novel properties of leptomeningeal collaterals in humans: (a) posterior (posterior cerebral artery (PCA)–MCA) dominant collateralization, (b) intra-territorial ‘within MCA region'' leptomeningeal collaterals, and (c) significant variability in size, extent, and retrograde filling time in pial arteries. We also describe a simple and reliable collateral grading template that, for the first time on dynamic CTA, incorporates back-filling time as well as size and extent of collateral filling.     

Epithelial–mesenchymal transformation markers E-cadherin and survivin predict progression of stage pTa urothelial bladder carcinoma

Purpose

To determine whether the immunohistochemical markers survivin and E-cadherin can predict progress at initially diagnosed Ta bladder cancer.

Methods

We retrospectively searched for every initially diagnosed pTa urothelial bladder carcinoma having been treated at our single-center hospital in Germany from January 1992 up to December 2004. Follow-up was recorded up to June 2010, with recurrence or progress being the endpoints. Immunohistochemical staining and analysis of survivin and E-cadherin of the TURB specimens were performed. Outcome dependency of progression and no progression with immunohistochemical staining was analyzed using uni- and multivariate regression analysis, Kaplan–Meier analysis and uni- and multivariate Cox regression analysis.

Results

Overall, 233 patients were included. Forty-two percent of those were tumor free in their follow-up TURBs, 46 % had at least one pTa recurrence and 12 % even showed progress to at least pT1 bladder cancer. Aberrant staining of E-cadherin was found within 71 % of patients with progression in contrast to only 40 % in cases without progression (p = 0.004). Of all progressed patients, 92 % showed overexpression of survivin in their initial pTa specimen compared to 61 % without progression (p = 0.001). Kaplan–Meier analysis revealed aberrant E-cadherin staining to be associated with worse progression-free survival (PFS) (p = 0.005) as well as overexpression of survivin (p = 0.003). In multivariate Cox regression analysis, strong E-cadherin staining was an independent prognosticator for better PFS (p = 0.033) and multifocality (p = 0.046) and tumor size over 3 cm (p = 0.042) were prognosticators for worse PFS.

Conclusion

Adding the immunohistochemical markers survivin and E-cadherin could help to identify patients at risk of developing a progressive disease in initial stage pTa bladder cancer.

     

Cell cycle phase distribution analysis in chronic lymphocytic leukaemia: a significant number of cells reside in early G1-phase

BACKGROUND AND AIMS: Chronic lymphocytic leukaemia (CLL) is a frequent non-Hodgkin lymphoma characterised by a heterogeneous clinical course. Assessment of cell cycle phase kinetics might be important for prediction of clinical behaviour and prognosis. METHODS: Distribution of neoplastic cells in CLL within the cell cycle was evaluated by determining the labelling indices (LI, i.e. percentage of positive cells) of markers specific for late G1-phase (cyclin E), S-phase (cyclin A), and G2/M-phase (cyclin B1), and Mcm2, a novel marker of proliferative potential, in a large cohort of patients (n = 79) using tissue microarray (TMA) technology. Utilising a combination of these markers, an algorithm was developed--subtracting the combined LIs of cyclin E, cyclin A and cyclin B1 from the LI of Mcm2--to determine the percentage of tumour cells residing in early G1-phase, which is probably a critical state for the malignant potential of CLL. RESULTS: 27.11% of cells had acquired proliferative potential as indicated by expression of Mcm2. Only a small number of cells were found to be in late G1-phase (7.16%), S-phase (3.31%) or G2/M-phase (0.98%), while 15.66% of cells were considered to be in early G1-phase. CONCLUSION: Cell cycle phase distribution can easily be assessed by immunohistochemistry in routinely processed paraffin-embedded specimens. A large number of neoplastic cells in CLL have proliferative potential, with a significant sub-population residing in early G1-phase. Estimates of these cells may identify cases likely to exhibit a more aggressive biological behaviour and adverse clinical course.