In vitroassessment of a gallium-doped glass polyalkenoate cement: chemotherapeutic potential, cytotoxicity and osteogenic effects

Metastatic bone lesions are often osteolytic, which causes advanced-stage cancer sufferers to experience severe pain and an increased risk of developing a pathological fracture. Gallium (Ga) ion possesses antineoplastic and anti-bone resorption properties, suggesting the potential for its local administration to impede the growth of metastatic bone lesions. This study investigated the chemotherapeutic potential, cytotoxicity, and osteogenic effects of a Ga-doped glass polyalkenoate cement (GPC) (C-TA2) compared to its non-gallium (C-TA0) counterpart. Ion release profiles revealed a biphasic pattern characterized by an initial burst followed by a gradually declining release of ions. C-TA2 continued to release Ga steadily throughout the experimentation period (7 d) and exhibited prolonged zinc (Zn) release compared to C-TA0. Interestingly, the Zn release from both GPCs appeared to cause a chemotherapeutic effect against H1092 lung cancer cellsin vitro, with the prolonged Zn release from C-TA2 extending this effect. Unfortunately, both GPCs enhanced the viability of HCC2218 breast cancer cells, suggesting that the chemotherapeutic effects of Zn could be tied to cellular differences in preferred Zn concentrations. The utilization of SAOS-2 and MC3T3 cell lines as bone cell models yielded conflicting results, with the substantial decline in MC3T3 viability closely associated with silicon (Si) release, indicating cellular variations in Si toxicity. Despite this ambiguity, both GPCs exhibited harmful effects on the osteogenesis of primary rat osteoblasts, raising concerns about excessive burst Zn release. While Ga/Zn-doped GPCs hold promise for treating metastatic bone lesions caused by lung cancers, further optimization is required to mitigate cytotoxicity on healthy bone.

Enhanced remineralisation ability and antibacterial properties of sol-gel glass ionomer cement modified by fluoride containing strontium-based bioactive glass or strontium-containing fluorapatite

OBJECTIVES

This study aimed to compare two types of bioactive additives which were strontium-containing fluorinated bioactive glass (SrBGF) or strontium-containing fluorapatite (SrFA) added to sol-gel derived glass ionomer cement (SGIC). The objective was to develop antibacterial and mineralisation properties, using bioactive additives, to minimize the occurrence of caries lesions in caries disease.

METHODS

Synthesized SrBGF and SrFA nanoparticles were added to SGIC at 1 wt% concentration to improve antibacterial properties against S. mutans, promote remineralisation, and hASCs and hDPSCs viability. Surface roughness and ion-releasing behavior were also evaluated to clarify the effect on the materials. Antibacterial activity was measured via agar disc diffusion and bacterial adhesion. Remineralisation ability was assessed by applying the material to demineralised teeth and subjecting them to a 14-day pH cycle, followed by microCT and SEM-EDS analysis.

RESULTS

The addition of SrFA into SGIC significantly improved its antibacterial property. SGIC modified with either SrBGF or SrFA additives could similarly induce apatite crystal precipitation onto demineralised dentin and increase dentin density, indicating its ability to remineralise dentin. Moreover, this study also showed that SGIC modified with SrBGF or SrFA additives had promising results on the in vitro cytotoxicity of hASC and hDPSC.

SIGNIFICANT

SrFA has superior antibacterial property as compared to SrBGF while demonstrating equal remineralisation ability. Furthermore, the modified SGIC showed promising results in reducing the cytotoxicity of hASCs and hDPSCs, indicating its potential for managing caries.

Development of hybrid bioactive nanofibers composed of star Poly(lactic acid) and gelatin by sol-gel crosslinking during the electrospinning process

The design of a biomimetic scaffold is a major challenge in tissue engineering to promote tissue reconstruction. The use of synthetic polymer nanofibers is widely described as they provide biocompatible matrices whose topography mimics natural extracellular matrix (ECM). To closely match the biochemical composition of the ECM, bioactive molecules such as gelatin are added to the nanofibers to enhance cell adhesion and proliferation. To overcome the rapid solubilization of gelatin in biological fluids and to allow a lasting biological effect, the covalent crosslinking of this macromolecule in the network is crucial. The sol-gel route offers the possibility of gentle crosslinking during shaping but is rarely combined with electrospinning. In this study, we present the creation of Poly(lactic acid)/Gelatin hybrid nanofibers by sol-gel route during electrospinning. To enable sol-gel crosslinking, we synthesized star-shaped PLA and functionalized it with silane groups; then we functionalized gelatin with the same groups for their subsequent reaction with the polymer and thus the creation of the hybrid nanonetwork. We evaluated the impact of the presence of gelatin in Poly(lactic acid)/Gelatin hybrid nanofibers at different percentages on the mechanical properties, nanonetwork crosslinking, degradation and biological properties of the hybrid nanofibers. The addition of gelatin modulated nanonetwork crosslinking that impacted the stiffness of the nanofibers, resulting in softer materials for the cells. Moreover, these hybrid nanofibers also showed a significant improvement in fibroblast proliferation and present a degradation rate suitable for tissue reconstruction. Finally, the bioactive hybrid nanofibers possess versatile properties, interesting for various potential applications in tissue reconstruction.

Effect of germanium oxide on the structural aspects and bioactivity of bioactive silicate glass

Ternary silicate glass (69SiO₂-27CaO-4P₂O₅) was synthesized with the sol-gel route, and different percentages of germanium oxide GeO₂ (6.25, 12.5, and 25%) and polyacrylic acid (PAA) were added. DFT calculations were performed at the B3LYP/LanL2DZ level of theory for molecular modelling. X-ray powder diffraction (XRPD) was used to study the effect of GeO₂/PAA on the structural properties. The samples were further characterized using DSC, ART-FTIR, and mechanical tests. Bioactivity and antibacterial tests were assessed to trace the influence of GeO₂ on biocompatibility with biological systems. Modelling results demonstrate that molecular electrostatic potential (MESP) indicated an enhancement of the electronegativity of the studied models. While both the total dipole moment and HOMO/LUMO energy reflect the increased reactivity of the P₄O₁₀ molecule. XRPD results confirmed the samples formation and revealed the correlation between the crystallinity and the properties, showing that crystalline hydroxyapatite (HA) is clearly formed in the highest percentages of GeO₂, proposing 25% as a strong candidate for medical applications, consistent with the results of mechanical properties and the rest of the characterization results. Simulated body fluid (SBF) in vitro experiments showed promising biocompatibility. The samples showed remarkable antimicrobial and bioactivity, with the strongest effect at 25%. The experimental findings of this study revealed that the incorporation of GeO2 into the glass in terms of structural characteristics, bioactivity, antimicrobial properties, and mechanical properties is advantageous for biomedical fields and especially for dental applications.

Effect of Biosilicate® Addition on Physical-Mechanical and Biological Properties of Dental Glass Ionomer Cements

This study investigated the influence of incorporating Biosilicate^® on the physico-mechanical and biological properties of glass ionomer cement (GIC). This bioactive glass ceramic (23.75% Na₂O, 23.75% CaO, 48.5% SiO₂, and 4% P₂O₅) was incorporated by weight (5%, 10%, or 15%) into commercially available GICs (Maxxion R and Fuji IX GP). Surface characterization was made by SEM (n = 3), EDS (n = 3), and FTIR (n = 1). The setting and working (S/W time) times (n = 3) and compressive strength (CS) were analyzed (n = 10) according to ISO 9917-1:2007. The ion release (n = 6) was determined and quantified by ICP OES and by UV-Vis for Ca, Na, Al, Si, P, and F. To verify cell cytotoxicity, stem cells from the apical papilla (SCAP) were exposed to eluates (n = 3, at a ratio of 1.8 cm²/mL) and analyzed 24 h post-exposure. Antimicrobial activity against Streptococcus mutans (ATCC 25175, NCTC 10449) was analyzed by direct contact for 2 h (n = 5). The data were submitted for normality and lognormality testing. One-way ANOVA and Tukey's test were applied for the working and setting time, compressive strength, and ion release data. Data from cytotoxicity and antimicrobial activity were submitted for Kruskal-Wallis' testing and Dunn's post hoc test (α = 0.05). Among all experimental groups, only those with 5% (wt) of Biosilicate^® showed better surface quality. Only M5% showed a comparable W/S time to the original material (p = 0.7254 and p = 0.5912). CS was maintained for all Maxxion R groups (p > 0.0001) and declined for Fuji IX experimental groups (p < 0.0001). The Na, Si, P, and F ions released were significantly increased for all Maxxion R and Fuji IX groups (p < 0.0001). Cytotoxicity was increased only for Maxxion R with 5% and 10% of Biosilicate^®. A higher inhibition of S. mutans growth was observed for Maxxion R with 5% of Biosilicate^® (less than 100 CFU/mL), followed by Maxxion R with 10% of Biosilicate^® (p = 0.0053) and Maxxion R without the glass ceramic (p = 0.0093). Maxxion R and Fuji IX presented different behaviors regarding Biosilicate^® incorporation. The impacts on physico-mechanical and biological properties were different depending on the GIC, but therapeutic ion release was increased for both materials.

In vitro immunomodulatory effects of novel strontium and zinc-containing GPCs

BACKGROUND

Glass polyalkenoate cements (GPCs) are bio-adhesives which consist of ionomeric glass particles embedded in a poly-salt matrix. These materials have been used in dentistry and orthodontics extensively but are presently being optimized as bone putties for orthopedic applications.

OBJECTIVE

This study utilized a patented ionomeric glass (mole fraction: SiO2:0.48, ZnO:0.36, CaO:0.12, SrO:0.04) to formulate two GPCs: GPC A (<45 μm particle size glass) and GPC B (45 μm-63 μm). These formulations were previously assessed for their effect on osteoblast viability and osteogenic function. However, the immunomodulatory effects of GPC A and B have not previously been investigated.

METHOD

Non-toxic concentrations of (a) GPC dissolution products and (b) fragmented GPC particles were tested for their ability to affect the secretion of cytokines (TNF-α, IL-1β, IL-6 and IL-10) by rat peripheral blood mononuclear cells (PBMCs), in the presence or absence of the stimulant liposaccharide (LPS). Additionally, the ionic concentrations of Sr, Zn, Ca, and Si were measured in GPC ionic extracts, and the size, shape and concentration of fragmented GPC particles in deionized water were characterized using an optical microscope-based particle analyzer.

RESULTS

The results showed that GPC A ionic products reduced the concentration of TNF-α secreted by stimulated cells compared with cells stimulated in the absence of GPC products. Interestingly, the particles released from GPC A significantly increased the secretion of both TNF-α and IL-6 from unstimulated cells, compared to control cells.

CONCLUSION

Neither GPC B ionic products nor released particles were found to be biologically active with respect to PBMC cytokine secretion.

Adhesion of bioactive glass-based adhesive to bone

Understanding the failure modes and the fracture resistance is critical in evaluating the performance of an adhesive for sternal fixation. In this paper, a fracture mechanics testing methodology was used to assess the adhesion of a bioactive glass-based adhesive to bovine bone in terms of a measured mode I critical strain energy release rate (G_IC). Reinforced double cantilever beam (DCB) samples were observed to produce repeatable values of G_IC. The measured G_IC was found to increase significantly from 5.41 to 12.60 J/m² with an increase in adhesive thickness from 390 to 990 μm because of the constraint from the two adherends regulating the plastic zone size ahead of the crack. The specimens failed cohesively in all cases demonstrating that there was good adhesion to bone, a condition necessary to restrict micromotion and thus provide rigid sternal fixation when used along with sternal wires. It was also found that when the bone was flooded with liquid during adhesive application a much lower G_IC of between 0.69 and 1.15 J/m² was measured. Overall, the results demonstrate that the fracture mechanics approach can be used to provide a quantitative measure of the adhesion of the bioactive glass-based adhesive to the bone and that the adhesive should only be applied to clean bone in a dry environment.

Comparative Evaluation of Two Glass Polyalkenoate Cements: An In Vivo Pilot Study Using a Sheep Model

Poly(methyl methacrylate) (PMMA) is used to manage bone loss in revision total knee arthroplasty (rTKA). However, the application of PMMA has been associated with complications such as volumetric shrinkage, necrosis, wear debris, and loosening. Glass polyalkenoate cements (GPCs) have potential bone cementation applications. Unlike PMMA, GPC does not undergo volumetric shrinkage, adheres chemically to bone, and does not undergo an exothermic setting reaction. In this study, two different compositions of GPCs (GPCA and GPCB), based on the patented glass system SiO₂-CaO-SrO-P₂O₅-Ta₂O₅, were investigated. Working and setting times, pH, ion release, compressive strength, and cytotoxicity of each composition were assessed, and based on the results of these tests, three sets of samples from GPCA were implanted into the distal femur and proximal tibia of three sheep (alongside PMMA as control). Clinical CT scans and micro-CT images obtained at 0, 6, and 12 weeks revealed the varied radiological responses of sheep bone to GPCA. One GPCA sample (implanted in the sheep for 12 weeks) was characterized with no bone resorption. Furthermore, a continuous bone-cement interface was observed in the CT images of this sample. The other implanted GPCA showed a thin radiolucent border at six weeks, indicating some bone resorption occurred. The third sample showed extensive bone resorption at both six and 12 weeks. Possible speculative factors that might be involved in the varied response can be: excessive Zn²⁺ ion release, low pH, mixing variability, and difficulty in inserting the samples into different parts of the sheep bone.

In vitro osteogenic performance of two novel strontium and zinc-containing glass polyalkenoate cements

Glass polyalkenoate cements (GPCs) are under investigation as potential bone adhesives, as they may provide an alternative to polymethylmethacrylate-based cements. GPCs containing strontium (Sr) and zinc (Zn) in place of aluminium (Al) are of particular interest because these ions are known stimulators of osteoprogenitor differentiation. GPCs have been manufactured from a novel bioactive glass (SiO2 :0.48, ZnO:0.36, CaO:0.12, SrO:0.04) in the past, but, while such materials have been assessed for their influence on viability, their influence on osteogenic function has not been investigated until now. For this study, two GPCs were formulated from the same glass precursor evaluated in previous studies. These GPCs were named GPC A and GPC B, and they differed in glass particle size, polyacrylic acid molecular weight, and their powder: liquid ratios. The effect of these two GPCs on osteogenic differentiation of primary rat osteoblasts were evaluated using three culture systems: culture with dissolution extracts, indirect contact with transwell-inserts and direct contact. Additionally, the degradation characteristics of GPCs were assessed, including their interfacial pH and surrounding pH. The experimental outcomes revealed that collagen deposition, alkaline phosphatase expression, and mineralization were largely dependent on GPC composition as well as the mode of interaction with cells. These markers were found to be significantly elevated in response to GPC A's dissolution products. However, osteogenic differentiation was inhibited when osteoblasts were cultured indirectly and directly with GPCs, with, overall, GPC B significantly outperforming GPC A. These results suggest that GPC degradation products effect osteogenic differentiation in a dose-dependent manner.

Shear Bond Strength and Film Thickness of a Naturally Antimicrobial Modified Dental Luting Cement

Although several natural plants and mixtures have been known and used over the centuries for their antibacterial activity, few have been thoroughly explored in the field of dentistry. Thus, the aim of this study was to enhance the antimicrobial activity of a conventional glass ionomer cement (GIC) with natural plant extracts. The effect of this alteration on the bond strength and film thickness of glass ionomer cement was evaluated and related to an 0.5% chlorohexidine modified GIC. Olive leaves (Olea europaea), Fig tree (Ficus carica), and the leaves and roots of Miswak (Salvadora persica) were used to prepare an alcoholic extract mixture. The prepared extract mixture after the evaporation of the solvent was used to modify a freeze-dried glass ionomer cement at three different extracts: water mass ratios 1:2, 1:1, and 2:1. An 0.5% chlorhexidine diacetate powder was added to a conventional GIC for the preparation of a positive control group (CHX-GIC) for comparison. The bond strength to dentine was assessed using a material-testing machine at a cross head speed of 0.5 mm/min. Failure mode was analyzed using a stereomicroscope at 12× magnification. The cement film thickness was evaluated in accordance with ISO standard 9917-1. The minimum number of samples in each group was n = 10. Statistical analysis was performed using a Kruskal–Wallis test followed by Dunn’s post hoc test for pairwise comparison. There was a statistically insignificant difference between the median shear bond strength (p = 0.046) of the control group (M = 3.4 MPa), and each of the CHX-GIC (M = 1.7 MPa), and the three plant modified groups of 1:2, 1:1, 2:1 (M = 5.1, 3.2, and 4.3 MPa, respectively). The CHX-GIC group showed statistically significant lower median values compared to the three plant-modified groups. Mixed and cohesive failure modes were predominant among all the tested groups. All the tested groups (p < 0.001) met the ISO standard of having less than 25 µm film thickness, with the 2:1 group (M = 24 µm) being statistically the highest among all the other groups. The plant extracts did not alter either the shear bond strength or the film thickness of the GIC and thus might represent a promising additive to GICs.

Bone cement as a local chemotherapeutic drug delivery carrier in orthopedic oncology: A review

Metastatic bone lesions are common among patients with advanced cancers. While chemotherapy and radiotherapy may be prescribed immediately after diagnosis, the majority of severe metastatic bone lesions are treated by reconstructive surgery, which, in some cases, is followed by postoperative radiotherapy or chemotherapy. However, despite recent advancements in orthopedic surgery, patients undergoing reconstruction still have the risk of developing severe complications such as tumor recurrence and reconstruction failure. This has led to the introduction and evaluation of poly (methyl methacrylate) and inorganic bone cements as local carriers for chemotherapeutic drugs (usually, antineoplastic drugs (ANPDs)). The present work is a critical review of the literature on the potential use of these cements in orthopedic oncology. While several studies have demonstrated the benefits of providing high local drug concentrations while minimizing systemic side effects, only six studies have been conducted to assess the local toxic effect of these drug-loaded cements and they all reported negative effects on healthy bone structure. These findings do not close the door on chemotherapeutic bone cements; rather, they should assist in materials selection when designing future materials for the treatment of metastatic bone disease.

Physical Properties of Glass Ionomer Cement Containing Pre-Reacted Spherical Glass Fillers

The aim of this study was to assess the effect of different commercial liquid phases (Ketac, Riva, and Fuji IX) and the use of spherical pre-reacted glass (SPG) fillers on cement maturation, fluoride release, compressive (CS) and biaxial flexural strength (BFS) of experimental glass ionomer cements (GICs). The experimental GICs (Ketac_M, Riva_M, FujiIX_M) were prepared by mixing SPG fillers with commercial liquid phases using the powder to liquid mass ratio of 2.5:1. FTIR-ATR was used to assess the maturation of GICs. Diffusion coefficient of fluoride (DF) and cumulative fluoride release (CF) in deionized water was determined using the fluoride ion specific electrode (n=3). CS and BFS at 24 h were also tested (n=6). Commercial GICs were used as comparisons. Riva and Riva_M exhibited rapid polyacrylate salt formation. The highest DF and CF were observed with Riva_M (1.65x10-9 cm2/s) and Riva (77 ppm) respectively. Using SPG fillers enhanced DF of GICs on average from ~2.5x10-9 cm2/s to ~3.0x10-9 cm2/s but reduced CF of the materials on average from ~51 ppm to ~42 ppm. The CS and BFS of Ketac_M (144 and 22 MPa) and Fuji IX_M (123 and 30 MPa) were comparable to commercial materials. Using SPG with Riva significantly reduced CS and BFS from 123 MPa to 55 MPa and 42 MPa to 28 MPa respectively. The use of SPG fillers enhanced DF but reduced CF of GICs. Using SPG with Ketac or Fuji IX liquids provided comparable strength to the commercial materials.

Calcium sulfate-containing glass polyalkenoate cement for revision total knee arthroplasty fixation

Poly(methyl methacrylate) (PMMA) bone cement is used as a minor void filler in revision total knee arthroplasty (rTKA). The application of PMMA is indicated only for peripheral bone defects with less than 5 mm depth and that cover less than 50% of the bone surface. Treating bone defects with PMMA results in complications as a result of volumetric shrinkage, bone necrosis, and aseptic loosening. These concerns have driven the development of alternative bone cements. We report here on novel modified glass polyalkenoate cements (mGPCs) containing 1, 5 and 15 wt% calcium sulfate (CaSO₄ ) and how the modified cements' properties compare to those of PMMA used in rTKA. CaSO₄ is incorporated into the mGPC to improve both osteoconductivity and bioresorbability. The results confirm that the incorporation of CaSO₄ into mGPCs decreases the setting time and increases release of therapeutic ions such as Ca²⁺ and Zn²⁺ over 30 days of maturation in deionized (DI) water. Moreover, the compressive strength for 5 and 15 wt% CaSO₄ addition increased to over 30 MPa after 30 day maturation. Although the overall initial compressive strength of the mGPC (~ 30 MPa) is less than PMMA (~ 95 MPa), the compressive strength of mGPC is closer to that of cancellous bone (~ 1.2-7.8 MPa). CaSO₄ addition did not affect biaxial flexural strength. Fourier transform infrared analysis indicated no cross-linking between CaSO₄ and the GPC after 30 days. in vivo tests are required to determine the effects the modified GPCs as alternative on PMMA in rTKA.

Synthesis of Colloidal Au Nanoparticles through Ultrasonic Spray Pyrolysis and Their Use in the Preparation of Polyacrylate-AuNPs' Composites

Colloidal gold nanoparticles (AuNPs) were prepared from two different liquid precursors (gold (III) acetate and gold (III) chloride), using the Ultrasonic Spray Pyrolysis (USP) process. The STEM characterisation showed that the AuNPs from gold chloride are spherical, with average diameters of 57.2 and 69.4 nm, while the AuNPs from gold acetate are ellipsoidal, with average diameters of 84.2 and 134.3 nm, according to Dynamic Light Scattering (DLS) measurements. UV/VIS spectroscopy revealed the maximum absorbance band of AuNPs between 532 and 560 nm, which indicates a stable state. Colloidal AuNPs were used as starting material and were mixed together with acrylic acid (AA) and acrylamide (Am) for the free radical polymerization of polyacrylate-AuNPs’ composites, with the purpose of using them for temporary cavity fillings in the dental industry. SEM characterisation of polyacrylate-AuNPs’ composites revealed a uniform distribution of AuNPs through the polymer matrix, revealing that the AuNPs remained stable during the polymerization process. The density measurements revealed that colloidal AuNPs increase the densities of the prepared polyacrylate-AuNPs’ composites; the densities were increased up to 40% in comparison with the densities of the control samples. A compressive test showed that polyacrylate-AuNPs’ composites exhibited lower compressive strength compared to the control samples, while their toughness increased. At 50% compression deformation some of the samples fracture, suggesting that incorporation of colloidal AuNPs do not improve their compressive strength, but increase their toughness significantly. This increased toughness is the measured property which makes prepared polyacrylate-AuNPs potentially useful in dentistry.

Novel adhesives for distal radius fixation: A biomechanical analysis

Wrist fractures can be difficult to treat due to advanced age of the patient, medical co-morbidities, and comminution of the bone. This study examines the effectiveness of two injectable glass polyalkenoate cements (GPCs), derived from two different glasses (A and B), as minimally invasive treatments for distal radius fractures. Twenty-seven fresh cadaveric radial pairs were tested either in compressive fatigue or to quasi-static compressive failure. The radii tested to failure had one pair fixated with a GPC while the other was left intact. The radii tested under fatigue had one pair fixated with a GPC and the other with a volar locking plate. A wedge osteotomy was used to simulate a severely comminuted fracture. When loaded to failure, the radii fixated with a GPC made from glass A or B were found to be, respectively, at least 57% and 62% as strong as their intact biological pair (95% Confidence Interval, Lower). Using a paired t-test, the radii fixated with either adhesive were found to be significantly stiffer than their biological pairs fixated with a volar locking plate for all cycles of fatigue loading. The adhesives under investigation demonstrate promise as treatment for distal radius fractures. In vivo investigations are warranted to determine the effect that the adhesives have on the bone remodelling process.

Incorporating Germanium Oxide into the Glass Phase of Novel Zinc/Magnesium-Based GPCs Designed for Bone Void Filling: Evaluating Their Physical and Mechanical Properties

The structural role of Germanium (Ge), when substituting for Zinc (Zn) up to 8 mol % in the 0.48SiO₂⁻0.12CaO⁻0.36ZnO⁻0.04MgO glass series, was investigated with respect to both the glass chemistry and also the properties of glass polyalkenoate cements (GPCs) manufactured from them. The Network connectivity (NC) of the glass was calculated to increase from 1.83 to 2.42 with the addition of GeO₂ (0⁻8 mol %). Differential thermal analysis (DTA) results confirmed an increase in the glass transition temperature (T_g) of the glass series with GeO₂ content. X-ray photoelectron spectroscopy (XPS) showed an increase in the ratio of bridging oxygens (BO) to non-bridging oxygens (NBO) with the addition of GeO₂, supporting the NC and DTA results. ²⁹Si magic angle spinning nuclear magnetic resonance spectroscopy (²⁹Si MAS-NMR) determined a chemical shift from -80.3 to -83.7 ppm as the GeO₂ concentration increased. These ionomeric glasses were subsequently used as the basic components in a series of GPCs by mixing them with aqueous polyacrylic acid (PAA). The handling properties of the GPCs resulting were evaluated with respect to the increasing concentration of GeO₂ in the glass phase. It was found that the working times of these GPCs increased from 3 to 15 min, while their setting times increased from 4 to 18 min, facilitating the injectability of the Zn/Mg-GPCs through a 16-gauge needle. These Ge-Zn/Mg-GPCs were found to be injectable up to 96% within 12 min. Zn/Mg-GPCs containing GeO₂ show promise as injectable cements for use in bone void filling.