Bone Cement Material Research Articles

Cerium as a crystalline phase stabilizer of α-TCP and its hydration and photothermal properties

Bone cement with photothermal properties can treat bone defects caused by bone tumors while killing residual tumor cells or preventing recurrence. In this study, trace amounts of cerium ions were introduced to enhance the crystal stability of α-TCP, thereby improving the hydration properties of α-TCP and obtaining excellent photothermal properties. The experimental results showed that the content of α-TCP in CON-TCP was 96.05 %, and the content of α-TCP in 1 % Ce-TCP was 99.77 %, with an increase of 3.87 %; the compressive strength of 0.5 % Ce-CPC hydrated for 5d increased from 16.6 MPa ± 2.18 MPa–32.16 MPa ± 2.77 MPa, with an increase of 93.73 %. The temperature of 0.5 % Ce-CPC can be raised to 50.9 °C in 2 min under the irradiation of 808 nm laser, which is an increase of 31.5 % compared with that of 38.7 °C in the blank group. Therefore, trace cerium-doped calcium phosphate bone cement has excellent physicochemical and photothermal properties, and it is a promising composite bone cement material, and the results of the present study are expected to be used to treat bone defects in bone tumors.

Mesoscopic model for the fracture of polymethyl methacrylate bone cement

Polymethyl methacrylate (PMMA) bone cement is widely used for biomedical applications. The fracture toughness (KIC) and tensile strength (ft) are two critical indicators directly influencing its safety and durability. However, different test methods are currently being used to determine the material parameters (KIC &ft) of PMMA bone cement. In order to address this issue, an innovative design method only employing the modified wedge split specimens is presented in this study to determine the PMMA bone cement material parameters (KIC &ft) simultaneously. Due to the discrete peak load Pmax, the resulting material parameters (KIC &ft) are discrete. Considering the discreteness of the material parameters (KIC &ft), their true values for PMMA bone cement were calculated through the standard statistical method. Further, a two-point simple method to determine the material parameters of PMMA bone cement has been proposed based on the equivalent area Ae. Finally, the numerical model of PMMA bone cement was developed from the mesoscopic level. The discrete mechanism of the peak load Pmax of PMMA bone cement due to the variation in particle contact strength was interpreted from the mesoscopic perspective.

Investigating the in vitro antibacterial efficacy of composite bone cement incorporating natural product-based monomers and gentamicin

ObjectiveThe objective of this study is to investigate the impact of four natural product extracts, namely, aloe-emodin, quercetin, curcumin, and tannic acid, on the in vitro bacteriostatic properties and biocompatibility of gentamicin-loaded bone cement and to establish an experimental groundwork supporting the clinical utility of antibiotic-loaded bone cements (ALBC).MethodsBased on the components, the bone cement samples were categorized as follows: the gentamicin combined with aloe-emodin group, the gentamicin combined with quercetin group, the gentamicin combined with curcumin group, the gentamicin combined with tannic acid group, the gentamicin group, the aloe-emodin group, the quercetin group, the curcumin group, and the tannic acid group. Using the disk diffusion test, we investigated the antibacterial properties of the bone cement material against Staphylococcus aureus (n = 4). We tested cell toxicity and proliferation using the cell counting kit-8 (CCK-8) and examined the biocompatibility of bone cement materials.ResultsThe combination of gentamicin with the four natural product extracts resulted in significantly larger diameters of inhibition zones compared to gentamicin alone, and the difference was statistically significant (P < 0.05). Except for the groups containing tannic acid, cells in all other groups showed good proliferation across varying time intervals without displaying significant cytotoxicity (P < 0.05).ConclusionIn this study, aloe-emodin, quercetin, curcumin, and tannic acid were capable of enhancing the in vitro antibacterial performance of gentamicin-loaded bone cement against S. aureus. While the groups containing tannic acid displayed moderate cytotoxicity in in vitro cell culture, all other groups showed no discernible cytotoxic effects.

Enhancing Bone Cement Efficacy with Hydrogel Beads Synthesized by Droplet Microfluidics

Effective filling materials, typically bone cements, are essential for providing mechanical support during bone fracture treatment. A current challenge with bone cement lies in achieving continuous drug release and forming porous structures that facilitate cell migration and enhance osteoconductivity. We report a droplet microfluidics-based method for synthesizing uniform-sized gelatin hydrogel beads. A high hydrogel concentration and increased crosslinking levels were found to enhance drug loading as well as release performance. Consequently, the droplet microfluidic device was optimized in its design and fabrication to enable the stable generation of uniform-sized droplets from high-viscosity gelatin solutions. The size of the generated beads can be selectively controlled from 50 to 300 μm, featuring a high antibiotic loading capacity of up to 43% dry weight. They achieve continuous drug release lasting more than 300 h, ensuring sustained microbial inhibition with minimal cytotoxicity. Furthermore, the hydrogel beads are well suited for integration with calcium phosphate cement, maintaining structural integrity to form porous matrices and improve continuous drug release performance. The uniform size distribution of the beads, achieved through droplet microfluidic synthesis, ensures predictable drug release dynamics and a measurable impact on the mechanical properties of bone cements, positioning this technology as a promising enhancement to bone cement materials.

Setting Properties along Bone Cement Preparation and its Effect on Material Properties

Bone cement is a material used in many orthopedic surgeries. Polymethyl Methacrylate (PMMA) is one of the acrylic-based bone cement materials. PMMA will be mixed with an activator (N, N-Dimethyl-p-toluidine (DMPT)), initiator (Benzoyl Peroxide (BPO)), radiopacifier / filler (BaSO4), and Methyl Methacrylate monomer. Once the materials were mixed, the activator react with the initiator to form radicals and activate the bulk polymerization reaction between the MMA monomer and PMMA molecules. The bulk polymerization reaction occurs exothermically and increases the bulk temperature. Barium sulfate (BaSO4) is an inorganic compound that can be acted as both radiopacifier and filler in bone cement. The specific objective of this study was to describe the effect of BaSO4 in bone cement composite formation. The solid material; PMMA, BPO, and BaSO4 were mixed firstly. The liquid portions; N, N-Dimethyl-p-toluidine (DMPT), and MMA were mixed and then poured into the solids one in a stainless-steel bowl. The bulk temperature was recorded after a one-minute mixing process. The samples were characterized by Gel Permeation Chromatography (GPC) and Differential Scanning Calorimetry (DSC). The highest setting temperature and setting time were 107.3°C and 10.6 min which was obtained in BaSO4 content variables of 7% and 11%, respectively. The average molecular weight of the samples was 561.5-1,332.0 kDa. From the DSC result, the glass temperature of the samples was 119.17-119.87°C.

Non-invasive method forassessing the densitometric tumor parameters and other structures using CT images

The purpose of the work was to study the capabilities of a clinically accessible software method for assessing the densitometric properties of a pathological lesion and other structures of the human body during adapted radio therapy (dynamic observation). To quantitatively assess the densitometric properties of human body structures during dynamic observation, a proprietary program was used, consisting of several subprograms. The versatility of the software method has been demonstrated both for assessing the density characteristics of a tumor during dynamic observation for any cases of visualization of tumor boundaries (including cases of unclear visualization of the tumor boundary) and other structures. Quantitative characteristics of tumor densitometric parameters are presented. The possibilities of using the same method are shown using the example of bone cement material used in oncology, which enters the irradiation field during radiotherapy. The quantitative information content of the method is shown.

Nonlinear viscoelastic model for time-dependent mechanical characterization of PMMA acrylic bone cements

Acrylic bone cement materials are widely used in prosthetic implants, orthopaedics and others trauma surgery. From the mechanical constitutive behaviour viewpoint, experimental analyses have provided ample evidence that such materials exhibit time-dependent properties. In this context, this work addresses the formulation of a nonlinear viscoelastic model for the behaviour of PMMA bone cements under compressive creep loading. Relying upon experimental data available for four PMMA bone cement types, a nonlinear Burgers-like rheological model is formulated and related parameters calibrated for the mechanical description of the time-dependent behaviour of these materials under isothermal conditions and one dimensional setting. The proposed model reveals relevant in reproducing both instantaneous and delayed properties of studied PMMA bone cements.

ROLE OF PERCUTANEOUS VERTEBROPLASTY IN VERTEBRAL COMPRESSION FRACTURES: EFFICACY AND SAFETY

Background: Percutaneous Vertebroplasty (PVP) is a minimally invasive interventional procedure performed by injecting bone cement or other therapeutic material into a painful osteoporotic or neoplastic compression fracture for pain or disability improvement. There is conflicting evidence regarding the use of vertebroplasty in osteoporotic vertebral compression fractures (VCFs) in the available literature. Objectives: To evaluate the efficacy and safety of Percutaneous Vertebroplasty in painful vertebral compression fractures in terms of pain alleviation and disability improvement, and thereby, study the profile of complications. Study design: Prospective observational study Study Participants: Patients with clinically symptomatic VCFs, who received various forms of treatment (interventional/conservative) were enrolled for the study. Patients who met the inclusion/exclusion criteria were finally selected. Methodology: Out of the selected patients, two groups were made, one who received the Intervention (PVP) and another group who received conservative management (Bed rest, medications, physiotherapy, etc.). Out of 31 patients selected, 11 were treated by PVP and 20 were treated by conservative management. These patients were followed up at 1-month, 3-month and 6-month intervals to record the Visual analog pain scores (VAS), Ronald Morris disability scores (RDQ) and any complication. Results: VAS scores in the vertebroplasty group decreased from (8.09±0.539) to (3.64 ± 0.674) at 1-month to (3.27±1.009) at 3-month to (3.09±0.831) at 6-month. VAS scores also decreased in the conservative group from (7.6±0.598) to (5.95±0.999) at 1-month to (5.1±1.294) at 3-month to (5.15±1.424) at 6-month. Vertebroplasty group showed the steep fall (-4.45) in VAS values as compared to a gradual decrease in VAS (-1.65) in the conservative group at 1 month follow up, concluding that conservative treatment has a slower effect on pain relief compared with the early response after PVP. Disability scores (RDQ) follow a similar trend with early and better improvement in the vertebroplasty group. RDQ scores: Vertebroplasty group (18.45±1.572 at baseline to 12.27±1.421 at 1-month to 11.82±1.079 at 3-month to 11.82±1.471 at 6-month), Conservative group (17.95±1.146 at baseline to 14.3±1.418 at 1-month to 12.9±1.518 at 3-month to 12.85±2.207 at 6-month). Subgroup analysis showed more benefit in malignant VCFs treated by PVP. The procedure was largely uneventful. An immediate complication was noted in one patient with cement extravasation into the venous channels, however, the patient showed pain and disability improvement without any adverse effects. Furthermore, no additional complication was noted during the follow-up period in any other patient. Conclusion: Percutaneous Vertebroplasty provides early and significant pain and disability improvement in vertebral compression fractures to comparison to conservative management. Implication: Minimal invasive technique for pain relief in osteoporotic and malignant vertebral compression fractures.

Bespoke Implants for Cranial Reconstructions: Preoperative to Postoperative Surgery Management System.

Traumatic brain injury is a leading cause of death and disability worldwide, with nearly 90% of the deaths coming from low- and middle-income countries. Severe cases of brain injury often require a craniectomy, succeeded by cranioplasty surgery to restore the integrity of the skull for both cerebral protection and cosmetic purposes. The current paper proposes a study on developing and implementing an integrative surgery management system for cranial reconstructions using bespoke implants as an accessible and cost-effective solution. Bespoke cranial implants were designed for three patients and subsequent cranioplasties were performed. Overall dimensional accuracy was evaluated on all three axes and surface roughness was measured with a minimum value of 2.209 μm for Ra on the convex and concave surfaces of the 3D-printed prototype implants. Improvements in patient compliance and quality of life were reported in postoperative evaluations of all patients involved in the study. No complications were registered from both short-term and long-term monitoring. Material and processing costs were lower compared to a metal 3D-printed implants through the usage of readily available tools and materials, such as standardized and regulated bone cement materials, for the manufacturing of the final bespoke cranial implants. Intraoperative times were reduced through the pre-planning management stages, leading to a better implant fit and overall patient satisfaction.

The study of self-regulating α-TCP based composite by micro/nano scaled silk fibroin and α-CSH on physicochemical and biological properties of bone cement.

A novel self-hardening α-tricalcium phosphate (α-TCP) bone cement complexed with different content of α-calcium sulfate hemihydrate (α-CSH) and micrometer hydroxyapatite mineralized silk fibroin (HA-SF) using micro/SF as curing liquid has been investigated in this work, which was capable of tunable setting time, degradation, mechanical property and ability to anti-washout. After addition 0 ∼ 25% α-CSH to the α-TCP cement with SFFs as curing liquid, it shortened the setting time of the modified composite to 10 ∼ 30min. Furthermore, the addition of SFFs improved the compressive strength of the composite from 5.41MPa to 9.44MPa. The composites with both Na2HPO4 and SFFs as curing liquid showed good anti-collapse performance. The weight loss ratio of bone cement was -0.18 ∼ 12.08% in 4weeks when the content of α-CSH in α-TCP/α-CSH was between 0 ∼ 25wt%. During the degradation of α-CSH, the amorphous α-TCP were deposited as hydroxyapatite to formed a plate-like products on the surface of composite. Compared to the composite with Na2HPO4 solution as the curing liquid, alkaline phosphatase (ALP) activity of the composites using SFFs as curing liquid were maintained at high levels on the 14th day especially when the Ca/P ratio was 1.7. This study provides a theoretical basis for the regeneration of bone defects guided by bone cement materials.

Insight into the fabrication, characterization, and in vitro cytotoxicity studies approaches of halloysite-based functional anhydride containing polymer nanocomposites

This study aims to design, synthesize, and characterization of maleic anhydride-vinyl acetate and its halloysite nanotubes and to evaluate the cytotoxic effects of nanostructures on human gingival fibroblasts. Poly(maleic anhydride-alt-vinyl acetate) [Poly(MA-alt-VA)] was synthesized via charge transfer complex-radical polymerization as potential dental fillings, adhesives, or bone cement materials. ATR-FTIR, XPS, and XRD spectroscopic methods were used to enlighten the structure–property of nanomaterials. Determining surface area and pore volume BET was used. Morphological characterization was viewed by HRTEM. Cytotoxic effects of nanocomposites on cell viability were evaluated by MTT assay for different incubation periods and concentrations for human gingival fibroblasts.

In vitro osteoconductivity of PMMA-Y2O3 composite resins

Polymethyl methacrylate (PMMA) bone cements are used as “glue” between orthopedic/orthodontic implants and bone, since they can be modeled and easily applied by the surgeon, while being chemically and biologically stable for many years after surgery. In this research, Y2O3 powder was added to commercial PMMA bone cement to produce a composite resin, which was then characterized and tested in vitro to evaluate the cell proliferation and the quality of osteoblastic bone formed in vitro on the composite. Biological assays showed an increase in cell proliferation on the Y2O3-PMMA composite as compared to the pristine sample. Alizarin Red staining (ARS) showed the amount of bone formed on a composite PMMA resin was about 30% higher than that on the pristine PMMA bone cement reference. The quality of bone tissue was evaluated using Raman spectroscopy, showing the bone tissue formed on the composite had a better degree of mineralization and a higher maturity as compared to the tissue grown on the control sample. These preliminary results suggest that Y2O3 plays a biologically active role in bone growth and Y2O3-composites are affordable, superior candidates as bone cement materials.

A Preliminary Review of Modified Polymethyl Methacrylate and Calcium-Based Bone Cement for Improving Properties in Osteoporotic Vertebral Compression Fractures

The incidence of osteoporotic vertebral compression fractures (OVCFs) increases gradually with age, resulting in different degrees of pain for patients, even possible neurological damage and deformity, which can seriously affect their quality of life. Vertebral augmentation plays an important role in the surgical treatment of OVCFs. As the most widely used bone cement material, polymethyl methacrylate (PMMA) offers inherent advantages, such as injectability, ease of handling, and cost-effectiveness. However, with its application in the clinic, some disadvantages have been found, including cytotoxicity, high polymerization temperature, high elastic modulus, and high compressive strength. To improve the mechanical properties and the biological performance of conventional PMMA bone cement, several studies have modified it by adding bioceramics, bioglass, polymer materials, nanomaterials, and other materials, which have exhibited some advantages. In addition, other alternative materials, such as calcium phosphate, calcium sulfate, and calcium silicate cements—including their modifications—have also been explored. In this review, we examined the existing research on the side-effects of conventional PMMA bone cement, modified PMMA bone cement, and other alternative materials designed to improve properties in OVCFs. An overview of various modified bone cements can help further scientific research and clinical applications.

Study of polymethylmethacrylate/tricalcium silicate composite cement for orthopedic application

BackgroundAmong orthopedic surgery materials, poly (methyl methacrylate) (PMMA) is most commonly used for its excellent mechanical properties and rapid self-setting time. However, PMMA bone cement has been reported to cause thermal necrosis and to have poor bioactivity, which must be improved. In contrast, tricalcium silicate (TCS), the most significant component of Portland Cement and the most effective bone cement material, might not always meet the needs of the cement due to its poor mechanical properties and elevated pH levels during hydration. We hypothesize that the benefits of both PMMA and TCS can be harnessed by mixing them together in different proportions. This would represent a better solution for the issues faced when using them alone. MethodsWe, therefore, prepared a novel organic-inorganic PMMA/TCS composite bone cement mixing PMMA and different amounts of TCS and tested its effect on the biophysical properties. ResultsThe addition of 30% TCS reduced the exothermic temperature and pH variation during cement setting and hydration processes. However, the mechanical and handling properties of the bioactive PMMA/TCS composite were not affected. The in vitro study also revealed that the composite materials had higher cell viability than pure PMMA and TCS. Also, the in vivo study on animals indicated that the composite materials were more capable of forming bone, which further reinforced the biocompatibility of the proposed PMMA/TCS bone cement. ConclusionBy combining the advantages of each component, it could be possible to construct a more effective composite bone cement material. This would meet the needs of implantation material for orthopedic surgeries or a possible bone filler.

Comparison of Outcomes of Surgical Repair of Spontaneous Temporal Bone CSF Leaks and Encephaloceles Using Bone Cement and Autologous Material.

To compare outcomes transmastoid repair of spontaneous middle fossa cerebrospinal fluid (CSF) leak using only bone cement (BC) versus only autologous material (AM) or combined materials (CM) with both bone cement and autologous material. Retrospective Chart Review. Tertiary Care Hospital. Forty-three adult patients undergoing transmastoid repair of spontaneous middle fossa CSF leak between 2014 and 2020 (BC:12, AM:15, CR:16). Cortical mastoidectomy, identification of defect, and repair with BC (Cranios® hydroxyapatite), AM (local bone, fascia, fat, and/or cartilage), or CM (Cranios® combined with autologous materials). Successful repair without recurrent CSF leak or encephalocele throughout follow up. Fifty-one percent of subjects were female. Mean age at repair was 58.6 years (SD 10.9). Mean BMI was 35.4 (SD 7.6; BC:36.3, AM:36.5, CM:33.6). Forty (93%) patients had successful repair without known recurrent CSF leak or encephalocele since surgery (BC:11, 91.6%; AM:14, 93.3%; CM:15, 93.8%; p = 0.49) over a mean length of follow up of 49.6 months (BC: 37.9, AM: 59.2, CR: 49.5). The difference in mean operative time amongst the groups was faster for patients using bone cement (BC: 100.2 min, AM: 182.8, CM: 133.2; p < 0.00001). BC, AM, and CM techniques each demonstrate effective and sustained means of repair for middle fossa CSF leak and encephalocele, even in the presence of multiple defects. Use of isolated BC offers a significant decrease in operative time with a noninferior outcome. Active CSF leak at the time of surgery is associated with increased risk of recurrence.

Fabrication of elastin additive on polymethyl methacrylate and hydroxyapatite-based bioactive bone cement

In this study, nanocrystalline-Hydroxyapatite (n-HA) was composed with Polymethyl Methacrylate (PMMA) bone cement-Elastin (ELN). After the addition of different weight percentages of ELN to produce four bone cement for orthopedic application such as vertebroplasty and bone filler. Evaluation of biological property using simulated body fluid (SBF) and phosphate-buffered saline (PBS) is performed to investigate adaptability, weight loss, and examined the pH change during a specific time. The morphology of the sample was investigated using Field Emission Scanning Electron Microscopy (FE-SEM) and Energy-dispersive X-ray Spectroscopy (EDX) to examine the morphology and microchemical analysis of bone cement materials. The mechanical properties of the samples such as tensile test and Charpy impact test are measured. The observation indicates that the pH is decreased after 24 h and ultimately the pH concentration changes remained constant about 6.2–6.7. The samples had highly low water absorption and porosity by the addition of elastin polymer. The tensile test and Charpy impact test show proper mechanical performance such as elastic modulus and impact strength about 2.31 GPa and 15.71 kJ. m−2 for the sample containing 10 wt% ELN. On the other hand, this cement can be hopeful for bone application such as rhinoplasty, tooth fillers, and orthopedics.

Bone Cement Formulation with Reduced Heating of Bone Cement Resin

Bone cement material is one of the key materials in bone surgery and orthopedic medicine. In this study, commercial polymethyl-methacrylate bone cement was mixed with boric acid and zinc borate to reduce the reaction temperature of the bone cement. The observation of temperature changes during the polymerization using laser thermometer and thermal camera showed that the use of boron compounds decreased the temperature of the bone cement at least 10 °C which is very critical for the biomaterial uses as it affects the biocompatibility of the material. Besides temperature monitoring, microbiological tests showed that the materials have certain antibacterial effect. Water contact angle studies also supported the biocompatibility studies. In the last part, mechanical tests showed that there was not significant change in the tensile strength and tensile modulus values. Antibacterial tests exhibited that zinc borate addition shows antimicrobial activity against S.epidermidis as well as boric acid addition over %5 concentration. According to the cell culture studies, boric acid can be interpreted as non-toxic up to 10%, while 10% and 20% zinc borate has toxic effect. This is the first study to use boron compounds in bone cement and it is proved that boric acid at low concentrations can be used for bone cement applications but zinc borate would not be suitable to use in medical applications due to toxic effects.

Application of New Bone Cement Biomaterials in Osteoporotic Compression Fractures

Silk fibroin (SF) is a kind of natural protein, which is widely used in biomedical materials because of its biodegradability, easy modification, biocompatibility and good mechanical properties. In this exploration, it was used as bone cement materials and compared with conventional bone cement materials to obtain the efficacy of different bone cement materials in the treatment of osteoporotic vertebral compression fractures. First, the effect of degumming time of silk in boiling on SF was analyzed. Then, hydroxyapatite silk fibroin (HA-SF) was added to calcium phosphate cement (Cap) by coprecipitation method. The properties of the composite bone cement were analyzed by morphology analysis and mechanical properties testing. Finally, 40 patients who underwent percutaneous kyphoplasty (PKP) from May 2019 to June 2020 were selected and divided into two groups. Among them, one group used the composite bone cement material proposed in this exploration, and the other group used the conventional bone cement material. Patients in different groups were evaluated for postoperative treatment. In the experiment, the sericin could be removed by boiling, and the SF short fiber could be peeled by boiling for a long time; the compressive strength of Cap material could be improved by adding HA-SF. At the same time, the introduction of SF could shorten the coagulation time under the premise of injectability, so as to improve the anti-collapse ability of Cap; the patients using different bone cement materials were compared, and the cobb angle, anterior height of vertebral body and VAS score of different groups were analyzed 3 days and 3 months after operation. The results show that the bone cement material proposed in this exploration can effectively treat osteoporotic vertebral compression fractures.

Prolonged Post-Polymerization Biocompatibility of Polymethylmethacrylate-Tri-n-Butylborane (PMMA-TBB) Bone Cement.

Polymethylmethacrylate (PMMA)-based acrylic bone cement is commonly used to fix bone and metallic implants in orthopedic procedures. The polymerization initiator tri-n-butylborane (TBB) has been reported to significantly reduce the cytotoxicity of PMMA-based bone cement compared to benzoyl peroxide (BPO). However, it is unknown whether this benefit is temporary or long-lasting, which is important to establish given that bone cement is expected to remain in situ permanently. Here, we compared the biocompatibility of PMMA-TBB and PMMA-BPO bone cements over several days. Rat femur-derived osteoblasts were seeded onto two commercially-available PMMA-BPO bone cements and experimental PMMA-TBB polymerized for one day, three days, or seven days. Significantly more cells attached to PMMA-TBB bone cement during the initial stages of culture than on both PMMA-BPO cements, regardless of the age of the materials. Proliferative activity and differentiation markers including alkaline phosphatase production, calcium deposition, and osteogenic gene expression were consistently and considerably higher in cells grown on PMMA-TBB than on PMMA-BPO, regardless of cement age. Although osteoblastic phenotypes were more favorable on older specimens for all three cement types, biocompatibility increased between three-day-old and seven-day-old PMMA-BPO specimens, and between one-day-old and three-day-old PMMA-TBB specimens. PMMA-BPO materials produced more free radicals than PMMA-TBB regardless of the age of the material. These data suggest that PMMA-TBB maintains superior biocompatibility over PMMA-BPO bone cements over prolonged periods of at least seven days post-polymerization. This superior biocompatibility can be ascribed to both low baseline cytotoxicity and a further rapid reduction in cytotoxicity, representing a new biological advantage of PMMA-TBB as a novel bone cement material.

Fracture Behavior of Two Biopolymers Containing Notches: Effects of Notch Tip Plasticity

This paper analyzes the notch effect on the fracture behavior of two biomaterials (a brittle bone cement and a ductile dental material) under mode I loading. U-notched Brazilian disk (UNBD) specimens of both materials were tested under remote compression, determining the corresponding fracture loads and load-displacement curves. Additionally, cracked rectangular and semicircular bend (SCB) specimens were tested under symmetric three-point bending in order to determine the fracture toughness of the two materials. Then, fracture loads were derived theoretically by applying the maximum tangential stress (MTS) and the mean stress (MS) criteria. Due to the brittle linear elastic behavior of the bone cement material, the MTS and MS criteria were directly applied to this material; however, given the significant nonlinear behavior of the dental material, the two fracture criteria were combined with the Equivalent Material Concept (EMC) for the fracture analyses of the dental material specimens. The results reveal a very good accuracy of both the MTS and the MS criteria for the fracture analysis of bone cement notched specimens. In the case of the dental material, very good results are also obtained when combining the MTS and the MS criteria with the EMC. The proposed approach can be useful for the fracture analysis of a wide range of biopolymers, from brittle to ductile behavior.