P14.03 Shifting trends and entity-specific aspects in patients with brain metastasis: real-life analysis from 6031 individuals over an observation period of 30 years

BACKGROUND

We aimed to investigate the changing clinical characteristics of patients with brain metastases (BM) over the last three decades as the foundation for modern BM specific clinical trial planning.

MATERIAL AND METHODS

6031 patients with newly diagnosed BM from different solid tumors treated between 1986–2020 were identified from the Vienna Brain Metastasis Registry.

RESULTS

The fraction of BM originating from the most common BM causing primary tumors (lung cancer, breast cancer and melanoma) was stable over the observation period from 1986–2020. BM from renal cell carcinoma, colorectal cancer and cancer of unknown primary (CUP) decreased over time (p<0.001). Synchronous diagnosis of BM and primary tumor was more frequently observed in lung cancer and CUP patients compared to breast cancer patients (p<0.001). An increasing fraction of patients presented with asymptomatic BM (1986–1999: 20.2% vs. 2010–2020: 30.4%; p<0.001), specifically in lung cancer (p<0.001), melanoma (p<0.001) and renal cell cancer (p=0.004). A decrease of neurosurgical procedures (1986–1999: 39.3% vs. 2010–2020: 20.4%) and an increase of radiation treatments (1986–1999: 56.5% vs. 2010–2020: 73.0%) and systemic therapies (1986–1999: 0.6% vs. 2010–2020: 2.4%; p<0.001) was observed. Furthermore, median overall survival significantly increased across entities (1986–1999: 5 months vs. 2010–2020: 7 months; p=0.001). Intracranial progression as the cause of death increased across entities (p< 0.001). The prognostic DS-GPA (Hazard ratio [HR] 1.42; p< 0.001) and the Lung-molGPA (HR 1.67; p<0.001) could be validated.

CONCLUSION

We observed changes of BM presentation and clinical parameters during the observation period depending on primary tumor origins. Future BM studies should follow an entity-specific approach and address the characteristics of modern BM cohorts.

Fine-tuning of bioactive glass for root canal disinfection

An ideal preparation of 45S5 bioactive glass suspensions/slurries for root canal disinfection should combine high pH induction with capacity for continuing release of alkaline species. The hypothesis of this study was that more material per volume of bioactive glass slurry is obtained with a micrometric material (< 5 microm particle size) or a micrometric/ nanometric hybrid, rather than a solely nanometric counterpart. This should correlate with alkaline capacity and antimicrobial effectiveness. Slurries at the plastic limit were prepared with test and reference materials in physiological saline. Total mass and specific surface area of glass material per volume were determined. Continuous titration with hydrochloric acid was performed, and antimicrobial effectiveness was tested in extracted human premolars mono-infected with E. faecalis ATTC 29212 (N = 12 per material). While the nanometric slurry had a 12-fold higher specific surface area than the micrometric counterpart, the latter had a considerably higher alkaline capacity and disinfected significantly better (Fisher's exact test, P < 0.05). The hybrid slurry behaved similarly to the micrometric preparation.

Do bioactive glasses convey a disinfecting mechanism beyond a mere increase in pH?

AIM

To test whether bioactive glasses kill microbiota via mineralization or the release of ions other than sodium.

METHODOLOGY

Flame-spray synthesis was applied to produce nanometric glasses of different sodium content and constant Ca/P ratio: 28S5, 45S5 and 77S. Calcium hydroxide and nanometric tricalcium phosphate (TCP) were used as controls. Apatite induction was monitored by Raman spectroscopy. Bovine dentine disks with adherent Enterococcus faecalis cells were exposed to test and control suspensions or buffered solutions for 1 h, 1 day and 1 week. Colony-forming units were counted and disks were inspected using scanning electron microscopy. Suspension supernatants and solutions were analysed for their pH, osmolarity, calcium and silicon content.

RESULTS

Sodium containing glasses induced pH levels above 12, compared with less than pH 9 with sodium-free 77S. Calcium hydroxide, 45S5 and 28S5 killed all bacteria after 1 day and lysed them after 1 week. TCP caused the highest apatite induction and substantial calcification on bacteria adhering to dentine, but did not reduce viable counts. 77S achieved disinfection after 1 week without visible apatite formation, whilst the buffer solution at pH 9 caused only minimal reduction in counts.

CONCLUSION

Bioactive glasses have a directly and an indirectly pH-related antibacterial effect. The effect not directly linked to pH is because of ion release rather than mineralization.

Preparation of an ultra fast binding cement from calcium silicate-based mixed oxide nanoparticles

Building construction takes time, in part because the binding process of cement is based on the slow re-crystallization and precipitation of calcium silicate species. Since the material's reactivity is surface area limited, a reduction in particle size of Portland cements has been used to prepare faster binding formulations. The present work investigates a new and direct, one-step preparation of calcium silicate-based nanoparticles of a typical Portland cement composition by flame spray synthesis. Isothermal calorimetry revealed that the hardening of this new nano-cement corroborated a more than tenfold increase of initial reactivity with different reaction kinetics if compared to conventionally prepared cements. At present, the unfavourably high porosity of nano-cements, however, underlines the need for additional improvements of chemical composition and formulation to make these highly reactive materials applicable to modern construction work, where load-bearing strength is of importance.

Effect of sodium hypochlorite on human root dentine – mechanical, chemical and structural evaluation

AIM

To investigate the mechanical, chemical and structural alterations of human root dentine following exposure to ascending sodium hypochlorite concentrations.

METHODOLOGY

Three-point bending tests were carried out on standardized root dentine bars (n = 8 per group, sectioned from sound extracted human third molar teeth) to evaluate their flexural strength and modulus of elasticity after immersion in 5 mL of water (control), 1% NaOCl, 5% NaOCl or 9% NaOCl at 37 degrees C for 1 h. Additional dentine specimens were studied using microelemental analysis, light microscopy following bulk staining with basic fuchsin, and scanning electron microscopy (SEM). Numerical data were compared using one-way ANOVA. Bonferroni's correction was applied for multiple testing.

RESULTS

Immersion in 1% NaOCl did not cause a significant drop in elastic modulus or flexural strength values in comparison to water, whilst immersion in 5% and 9% hypochlorite reduced these values by half (P < 0.05). Both, carbon and nitrogen contents of the specimens were significantly (P < 0.05) reduced by 5% and 9% NaOCl, whilst 1% NaOCl had no such effect. Exposure to 5% NaOCl rendered the superficial 80-100 mum of the intertubular dentine permeable to basic fuchsin. Three-dimensional SEM reconstructions of partly demineralized specimens showed NaOCl concentration-dependent matrix deterioration. Backscattered electron micrographs revealed that hypochlorite at any of the tested concentrations left the inorganic dentine components intact.

CONCLUSIONS

The current data link the concentration-dependent hypochlorite effect on the mechanical dentine properties with the dissolution of organic dentine components.

Antimicrobial effect of nanometric bioactive glass 45S5

Most recent advances in nanomaterials fabrication have given access to complex materials such as SiO(2)-Na(2)O-CaO-P(2)O(5) bioactive glasses in the form of amorphous nanoparticles of 20- to 60-nm size. The clinically interesting antimicrobial properties of commercially available, micron-sized bioactive glass 45S5 have been attributed to the continuous liberation of alkaline species during application. Here, we tested the hypothesis that, based on its more than ten-fold higher specific surface area, nanometric bioactive glass releases more alkaline species, and consequently displays a stronger antimicrobial effect, than the currently applied micron-sized material. Ionic dissolution profiles were monitored in simulated body fluid. Antimicrobial efficacy was assessed against clinical isolates of enterococci from persisting root canal infections. The shift from micron- to nano-sized treatment materials afforded a ten-fold increase in silica release and solution pH elevation by more than three units. Furthermore, the killing efficacy was substantially higher with the new material against all tested strains.