Glass Polyalkenoate Cements Designed for Cranioplasty Applications: An Evaluation of Their Physical and Mechanical Properties.

Basel Khader,Declan Curran,Mark Towler,Sean Peel

doi:10.3390/jfb7020008

Basel Khader, Declan Curran + Show 2 more

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https://doi.org/10.3390/jfb7020008

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Abstract

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 (ZnO) and sodium (Na2O)-containing glasses mixed with poly-acrylic acid (PAA) and to evaluate the potential of these cements for cranioplasty applications. Three glasses were formulated based on the SiO2-CaO-ZnO-Na2O parent glass (KBT01) with 0.03 mol % (KBT02) and 0.06 mol % (KBT03) germanium (GeO2) substituted for ZnO. Each glass was then mixed with 50 wt % of a patented SiO2-CaO-ZnO-strontium (SrO) glass composition and the resultant mixtures were subsequently reacted with aqueous PAA (50 wt % addition) to produce three GPCs. The incorporation of Ge in the glass phase was found to result in decreased working (142 s to 112 s) and setting (807 s to 448 s) times for the cements manufactured from them, likely due to the increase in crosslink formation between the Ge-containing glasses and the PAA. Compressive (σc) and biaxial flexural (σf) strengths of the cements were examined at 1, 7 and 30 days post mixing and were found to increase with both maturation and Ge content. The bonding strength of a titanium cylinder (Ti) attached to bone by the cements increased from 0.2 MPa, when placed, to 0.6 MPa, after 14 days maturation. The results of this research indicate that Germano-Silicate based GPCs have suitable handling and mechanical properties for cranioplasty fixation.

Highlights

Titanium miniplates and screws are used to repair defects in cranioplasty surgeries [1,2]
Zinc and silver ions have been added to the glass phase of Glass Polyalkenoate Cements (GPCs) because of their antimicrobial activity [25], and strontium ions (Sr2+) have been substituted for calcium ions (Ca2+) in order to increase radiopacity of the cement and stimulate bone formation around the implantation site [26,27,28]
Germanium based glasses have previously been investigated by Dickey et al [30,31,32] who reported that glass reactivity decreased with Ge incorporation, resulting in GPCs with extended working times of up to 10 min, setting times between 14 and 36 min, and compression strengths in surplus of 30 MPa after 30 days maturation [30]

Summary

Introduction

Titanium miniplates and screws are used to repair defects in cranioplasty surgeries [1,2]. PMMA has a high curing exotherm of up to 120 ̋C, which can result in necrosis of healthy bone tissue [6], leading to the loosening of the prosthesis [19]; a problem exacerbated by PMMA’s lack of chemical adhesion to bone [20]. They have not been used clinically in cranioplasty, Glass Polyalkenoate Cements (GPCs) have potential in this space as, unlike PMMA, they chemically bond with bone. We build upon the authors own previous work on zinc silicate-based GPCs by evaluating the effect on the physical and mechanical properties of these GPCs by incrementally replacing the Zn in the glass component with Ge [6,34]

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