Mark Towler

Mark Towler
Ryerson University · Department of Mechanical Engineering

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213
Publications
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Publications

Publications (213)
Article
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This study evaluates compositions of tantalum-containing mesoporous bioactive glass (Ta-MBG) powders using a porcine fatal liver injury model. The powders based on (80-x)SiO2-15CaO-5P2O5-xTa2O5 compositions with x = 0 (0Ta/Ta-free), 1 (1Ta), and 5 (5Ta) mol% were made using a sol–gel process. A class IV hemorrhage condition was simulated on the ani...
Article
Full-text available
The most common complication of median sternotomy surgery is sternum re-separation after sternal fixation, which leads to high rates of morbidity and mortality. The adhered sternal fixation technique comprises the wiring fixation technique and the use of bio-adhesives. Adhered sternal fixation techniques have not been extensively studied using fini...
Article
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 gla...
Article
Full-text available
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 no...
Article
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The primary treatment for patients suffering from bone cancers is resection of the tumour followed by reconstruction of the damaged bone. Despite the administration of post-operative chemotherapy, tumour recurrence continues to present itself as a severe complication leading to re-operation. Attempts to incorporate chemotherapeutic drugs into bone...
Article
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Wire cerclage remains the standard method of care for sternal fixation, following median sternotomy, despite being beset with complications. An emerging treatment option has been to augment the wires with an adhesive. A patented ionomeric glass (mole fraction: SiO 2 :0.48, ZnO:0.36, CaO:0.12, SrO:0.04) has been used to formulate GPC+, a glass polya...
Article
Novel tantalum-containing meso-porous bioactive glass (Ta-MBG) powders, developed via the sol-gel process, have demonstrable hemostatic properties. However, powders can create dust in the operating environment and may be washed away if profuse bleeding occurs. Powders may not adequately compress wound tissue, and in certain circumstances, a thick c...
Article
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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 is followed in some cases by postoperative radiotherapy or chemotherapy. However, despite recent advan...
Article
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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 s...
Article
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...
Article
This study evaluates the hemostatic properties of tantalum-containing mesoporous bioactive glasses (Ta-MBGs) through a suite of in-vitro methods: hemolysis percentage, zeta potential, blood coagulation assays (Activated Partial Thromboplastin Time – APTT and Prothrombin Time - PT) and cytotoxicity tests. Five compositions of Ta-MBG, with x mol% Ta...
Article
Titanium‐containing borate bioactive glass scaffolds (0, 5, 15 and 20 mol%, identified as BRT0, BRT1, BRT3 and BRT4) with a microstructure similar to that of human trabecular bone, were prepared and evaluated in vitro for potential bone loss applications in revision total knee arthroplasty (rTKA). Methyl thiazolyl tetrazolium (MTT) cell viability a...
Article
Full-text available
Poly(methyl methacrylate) (PMMA) is widely used in joint arthroplasty to secure an implant to the host bone. Complications including fracture, bone loss and infection might cause failure of total knee arthroplasty (TKA), resulting in the need for revision total knee arthroplasty (rTKA). The goals of this paper are: (1) to identify the most common c...
Article
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Interest in strontium (Sr) has persisted over the last three decades due to its unique mechanism of action: it simultaneously promotes osteoblast function and inhibits osteoclast function. While this mechanism of action is strongly supported by in vitro studies and small animal trials, recent large-scale clinical trials have demonstrated that orall...
Article
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Synthesis and characterization of the first mesoporous bioactive glasses (MBGs) containing tantalum are reported here, along with their potential application as hemostats. Silica MBGs were synthesized using with the molar composition of (80‐x)% Si, 15% Ca, 5% P, and x% Ta. It was found that incorporation of >1 mol % Ta into the MBGs changes their p...
Article
A titanium-containing borate glass series based on the system (52-X) B2O3-12CaO-6P2O5-14Na2O-16ZnO-XTiO2 with X varying from 0, 5 and 15 mol% of TiO2 incorporated, identified as BRT0, BRT1 and BRT3, respectively, were used in this study. Scaffolds (pore sizes, 165-230 μm and porosity, 53.51-69.51%) were prepared using a polymer foam replication tec...
Article
Full-text available
Stainless steel wires are the standard method for sternal closure because of their strength and rigidity, the simplicity of the process, and the short healing time that results from their application. Despite this, problems still exist with sternal stability due to micromotion between the two halves of the dissected and wired sternum. Recently, a n...
Article
In 2014-2015, 61,421 total knee arthroplasties (TKAs) were performed in Canada; an increase of about 20% over 2000-2001. Revision total knee arthroplasties (rTKAs) accounted for 6.8% of TKAs performed between 2014 and 2015, and this is estimated to grow another 12% by 2025. rTKAs are typically more complicated than primary TKAs due to the significa...
Article
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Pharmacological therapy of osteoporosis reduces bone loss and risk of fracture in patients. Modulation of bone mineral density cannot explain all effects. Other aspects of bone quality affecting fragility and ways to monitor them need to be better understood. Keratinous tissue acts as surrogate marker for bone protein deterioration caused by oestro...
Article
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Mesoporous bioactive glasses (MBGs) are designed to have high specific surface area. They are formulated by a sol–gel process to formulate the glass followed by calcination. This study evaluates how calcination heating rate influences the porous architecture, and thereby the specific surface area, of MBGs. MBGs of molar ratio 80:15:5 for SiO2:CaO:P...
Article
Background: Cerclage wires remain the current standard of care following median sternotomy, despite significant complications including dehiscence and infection. This study uses a human cadaveric model to investigate the use of glass polyalkenoate cements formulated from two glasses, A (mole fraction: SiO2:0.48, ZnO:0.36, CaO:0.12, SrO:0.04) and B...
Article
Immediate controls of uncontrolled bleeding and infection are essential for saving lives in both combat and civilian arenas. Inorganic well-ordered mesoporous silica and bioactive glasses have recently shown great promise for accelerating hemostasis and infection control. However, to date, there is no comprehensive report assessing their specific m...
Article
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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 increa...
Article
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A novel bioactive glass series containing incremental amounts of silver oxide was synthesized, ground down, and subsequently incorporated into a dentifrice for the purpose of reducing the incidence of dental caries and lesion formation. Three glasses were synthesized using the melt quench route: Si-Control (70SiO2–12CaO–3P2O5–15Na2O, mol %), Si-02...
Article
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Mesoporous bioactive glass containing 1% Ga2O3 (1%Ga-MBG) is attractive for hemorrhage control because of its surface chemistry which can promote blood-clotting. The present study compares this proprietary inorganic coagulation accelerator with two commercial hemostats, CeloxTM (CX) and QuikClot Advanced Clotting Sponge PlusTM (ACS+). The results i...
Article
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Objective To develop a surgical technique for percutaneous upper extremity fracture fixation using a novel glass-based adhesive. Methods Three intact upper extremity cadaveric specimens with undisturbed soft tissues were obtained. Two were used to model a wrist fracture, and the third to model a proximal humerus fracture. Fractures were produced u...
Article
The suitability of glass polyalkenoate cements (GPCs) as injectable adhesives in orthopedics has been compromised by the presence of aluminum (Al), a component in the glass phase of all commercial GPCs. There has been considerable work on the development of Al-free GPCs which can be formulated based on calcium (Ca) zinc (Zn) silicate (Si) glasses....
Article
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Studies have shown that Raman spectroscopic analysis of fingernail clippings can help differentiate between post-menopausal women who have and who have not suffered a fracture. However, all studies to date have been retrospective in nature, comparing the proteins in nails sourced from women, post-fracture. The objective of this study was to investi...
Article
It has been reported that the adhesion of bioactive glass coatings to Ti6Al4V reduces after degradation, however, this effect has not been quantified. This paper uses bilayer double cantilever (DCB) specimens to determine GIC and GIIC, the critical mode I and mode II strain energy release rates, respectively, of bioactive coating/Ti6Al4V substrate...
Article
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Lidocaine hydrochloride is used as an anesthetic in many clinical applications. This short communication investigates the effect of complete substitution of lidocaine hydrochloride for deionized (DI) water on the physico-chemical properties of two novel glass polyalkenoate cements. Substituting DI water with lidocaine hydrochloride resulted in ceme...
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Osteoporosis is a common disease characterised by reduced bone mass and an increased risk of fragility fractures. Low bone mineral density is known to significantly increase the risk of osteoporotic fractures, however, the majority of non-traumatic fractures occur in individuals with a bone mineral density too high to be classified as osteoporotic....
Article
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In an attempt to combat the possibility of bacterial infection and insufficient bone growth around metallic, surgical implants, bioactive glasses may be employed as coatings. In this work, silica-based and borate-based glass series were synthesized for this purpose and subsequently characterized in terms of antibacterial behavior, solubility and cy...
Article
Chitosan-based hemostats are promising candidate for immediate hemorrhage control. However, they have some disadvantages and require further improvement to achieve the desired hemostatic efficiency. Here, a series of 1%Ga2O3-containing mesoporous bioactive glass-chitosan composite scaffolds (Ga-MBG/CHT) were constructed by lyophilization process an...
Article
Bioactive glasses have been used as coatings for biomedical implants because they can be formulated to promote osseointegration, antibacterial behavior, bone formation, and tissue healing through the incorporation and subsequent release of certain ions. However, shear loading on coated implants has been reported to cause the delamination and loosen...
Article
In this study, zinc borate-based glasses with increasing gallium content (0, 2.5, 5, 10, and 15 wt % Ga) were synthesized and their effect on the viability and proliferation of preosteoblasts and osteosarcoma cancer cells were investigated. Methyl thiazolyl tetrazolium (MTT) cell viability assays using glass degradation extracts revealed that the e...
Article
Bioglasses are employed for surgical augmentation in a range of hard tissue applications. Tantalum is a bioactive and biocompatible transition metal that has been used as an orthopedic medical device. It has a range of biological and physical properties that make its incorporation into ionic form into bioactive glass systems promising for various c...
Article
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Patients diagnosed with osteoporosis have reported loss of fingernail resilience as the disease progresses. Keratin is the predominant protein in human nail tissue, and its structure has been postulated to be different in fingernails clipped from subjects who have sustained fragility fractures and those who have not, which may offer a window into t...
Article
This work considered the effect of increasing Strontium ion (Sr²⁺) content on the structure of a series of glasses based on the B2O3-P2O5-CaCO3-Na2CO3-TiO2-SrCO3 series and their resultant fracture toughness when coated onto a surgical metal substrate. Six glasses with increasing Sr²⁺ content (0 to 25 mol%) were synthesized and subsequently charact...
Article
Zinc borate glasses with increasing gallium content (0, 2.5, 5, 10, and 15 Wt % Ga) were synthesized and their degradation, bioactivity in simulated body fluid (SBF), and antibacterial properties were investigated. ICP measurements showed that increased gallium content in the glass resulted in increased gallium ion release and decreased release of...
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Silica-based and borate-based glass series, with increasing amounts of TiO2 incorporated, are characterized in terms of their mechanical properties relevant to their use as metallic coating materials. It is observed that borate-based glasses exhibit CTE (Coefficient of Thermal Expansion) closer to the substrate’s (Ti6Al4V) CTE, translating into hig...
Article
The distal radius and the scaphoid are the most commonly injured carpal bones among both active adults and the osteoporotic elderly. The purpose of surgical treatment is to restore form and function to the wrist. Depending on the nature of the fracture, either topical procedures or invasive surgery can be applied. This article critiques the treatme...
Article
With over a million median sternotomy surgeries performed worldwide every year, sternal wound complications have posed a serious risk to the affected patients. A rigid therapeutic sternal fixation device has therefore become a necessity. In this work, the incorporation of up to 0.5 mol% of tantalum pentoxide (Ta2O5), in exchange for zinc oxide (ZnO...
Article
This work considered the effect of both increasing additions of Strontium (Sr(2+)) and incubation time on solubility and both antibacterial and osteo-stimulatory effects of a series of glasses based on the B2O3-P2O5-CaCO3-Na2CO3-TiO2-SrCO3 series. The amorphous nature of all the glasses was confirmed by X-ray diffraction. Discs of each glass were i...
Article
This study investigated the effect of composite scaffolds composed of poly (octanediol citrate) (POC) and a bioactive glass (composition, 48%SiO2-12%CaO-32%ZnO-8%Ga2O3) on the growth and osteogenic differentiation of human bone marrow-derived mesenchymal stem cells (hBMSCs). All the scaffolds, regardless of the amount of bioglass incorporation, wer...
Article
Full-text available
Raman spectroscopy was applied to nail clippings from 633 postmenopausal British and Irish women, from six clinical sites, of whom 42% had experienced a fragility fracture. The objective was to build a prediction algorithm for fracture using data from four sites (known as the calibration set) and test its performance using data from the other two s...
Data
Supplementary Table 1. The significance of different variable clinical risk factors for fracture and their correlation with the Raman based fracture score.
Article
Cranioplasty is the surgical repair of a deficiency or deformity of the skull. The purpose of cranioplasty is to provide protection for the brain following cranial surgery, and to offer relief to psychological disadvantages while increasing social performance. There are several materials that had been used for cranioplasty but an ideal product has...
Article
Full-text available
Glass polyalkenoate cements (GPCs) have potential for skeletal cementation. Unfortunately, commercial GPCs all contain, and subsequently release, aluminum ions, which have been implicated in degenerative brain disease. The purpose of this research was to create a series of aluminum-free GPCs constructed from silicate (SiO₂), calcium (CaO), zinc (Zn...
Article
This paper presents a new method for applying a uniform thickness bioactive glass coating to a Ti6Al4V substrate and postulates a fracture mechanics testing methodology to quantify the glass/metal adhesion in terms of a measured critical strain energy release rate (GIC). Bi-layer double cantilever beam (DCB) test specimens were developed for this p...
Article
BACKGROUND: The FRAX and QFracture risk calculators have previously been validated but their relative performance with respect to cost-effectiveness has yet to be evaluated. METHODS: The relative costs of implementing these two fracture risk calculators were assessed in two scenarios, firstly in a case-control group of 584 post-menopausal women usi...
Article
Haemorrhage remains the leading cause of potentially survivable death in both military and civilian populations. Although a large variety of hemostatic agents have been developed, many of them have an inadequate capacity to induce hemostasis and are not effective in killing bacteria. In recent years, mesoporous bioactive glasses (MBGs) were found t...
Article
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A bioactive glass (BG) in which Ga was substituted for Zn was formulated to investigate whether the ionic form of Ga can elicit effects similar to gallium nitrate. The ion release and pH of BG extracts were evaluated, as well as the in vitro cytocompatibility of extracts in contact with mouse fibroblasts and human osteoblasts. After incubation time...
Article
Gallium ion released from bioactive glasses can perform therapeutic functions depending on its concentration. In this study, zinc borate based glasses with increasing gallium content (0, 2.5, 5, 10, and 15 wt.% Ga) were synthesized and their structural properties and gallium ion release capabilities were investigated in order to understand how the...
Article
Full-text available
Bioactive glasses may function as antimicrobial delivery systems through the incorporation and subsequent release of therapeutic ions. The aim of this study was to evaluate the antimicrobial properties of a series of composite scaffolds composed of poly(octanediol citrate) with increased loads of a bioactive glass that releases zinc (Zn(2+)) and ga...
Article
Functional Layered “Diamond like Carbon (DLC)” coated interfaces for orthopedic load bearing applications were fabricated and assessed. They consisted of three layers, each designed for specific functions. The fabrication process was performed using magnetron sputtering at low temperatures on steel substrates. Structural investigations showed the l...
Article
Bioactive glasses have found applications in diverse fields, including orthopedics and dentistry, where they have been utilized for the fixation of bone and teeth and as scaffolds for drug delivery. The present work outlines the characterization of two novel titanium-containing glass series, one silica-based and one borate-based. For the silica-bas...