Preparation, characterization, release kinetics, and <i>in vitro</i> cytotoxicity of calcium silicate cement as a risedronate delivery system
Bibliographic record
Abstract
Injectable bone cements have been well characterized and studied in non-load bearing bone fixation and bone screw augmentation applications. Current calcium phosphate cement or poly(methyl methacrylate) cement have drawbacks like low mechanical strength and in situ exothermic properties. This leads especially in patients with osteoporosis to worsening contact between implant and bone and can finally lead to implant failure. To improve these properties, a calcium silicate cement (CSC) was prepared, which additionally contained the bisphosphonate risedronate (RA) to promote osteoblast function. Cement setting rate and compressive strength were measured and found to be reduced by RA above 0.5 wt%. X-ray diffraction, Rietveld refinement analysis, scanning electron microscopy, and porosity measurements by gas sorption revealed that RA reduces calcium silicate hydrate gel formation and changes the cement's microstructure. Cumulative release profiles of RA from CSC up to 6 months into phosphate buffer solution were analyzed by high-performance liquid chromatography, and the results were compared with theoretical release curves obtained from the Higuchi equation. Fourier transform infrared spectra measurements and drug release studies indicate that calcium-RA formed within the cement, from which the drug can be slowly released over time. An investigation of the cytotoxicity of the RA-CSC systems upon osteoblast-like cells showed no toxic effects of concentrations up to 2%. The delivery of RA from within a CSC might thus be a valuable and biocompatible new approach to locally deliver RA and to reconstruct and/or repair osteoporosis-related bone fractures.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".