Study of Polymethylmethacrylate / Tricalcium Silicate Paste Organic-inorganic Hybrid Bone Cement

• Main Authors: Yu-Chieh Su, 蘇育傑
• Other Authors: Ren-Jei Chung
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/3dje6y

碩士 === 國立臺北科技大學 === 化學工程與生物科技系生化與生醫工程碩士班 === 105 === Bone cement is used as a kind of orthopedic material for surgical filling and bone void filler because of its characteristics of self-hardening, good injectibility and moldability. Tricalcium silicate (TCS), the main component of Portland cement, is widely used in terms of biomedical materials. It has good biocompatibility and self-curing ability to serve as a bone cement. TCS bone cement can reach certain level of mechanical strength after setting, but this is unfortunately a brittle material. Polymethylmethacrylate (PMMA) cement has been used in orthopedics for more than seven decades because of its high compressive strength, viscosity, moldability and rapid setting ability. Nevertheless, the heat produced during polymerization could usually challenge its direct bonding to the surrounding bone tissue, which would eventually lead to aseptic loosening. In this study, bioceramics-TCS was chosen to bond directly to the surrounding bone tissue while PMMA could provide good rigidity. These two materials as a composite would complement each other and reduce the problems of loosening due to the high exothermic reaction of PMMA and brittleness of TCS. Therefore, PMMA was combined with TCS to form a composite bone cement. TCS was synthesized by sol-gel method. TCS was calcined in air at 1400°C for 4h and grinded into powder. TCS powder was then sieved through a 400 mesh size sieve to collect powders ≤ 38µm. TCS powder was mixed with citric acid solution at a powder/liquid ratio of 2:1, and then mixed with PMMA in paste form in different ratios to analyze the material properties and biocompatibility. The results showed that the addition of 0.5M citric acid could effectively reduce the setting time of TCS bone cement. The setting-time is in accordance with the regulation of ISO-5833 (Implants for surgery -- Acrylic resin cements) in the range of 5-15 min. For TCS/PMMA composite bone cement, higher TCS ratio would lead to lower temperature produced during polymerization. The curing temperature of the cement was successfully reduced with TCS addition with the highest temperature from 50.4°C of PMMA to the lowest of 39.1°C of TCS 30. In initial test of biocompatibility, specimens were soaked in artificial simulated body fluid (SBF). The pH of the SBF soaked with pure TCS was strongly alkaline while the addition of PMMA could successfully reduce the pH to the range of 7.0-8.5. In addition, there was bone like apatite precipitated on the material surface in 7 days as confirmed by XRD and SEM observations. In vitro studies were proceeded using human osteoblast cell line (MG-63) cultured directly on the materials or in the extracts. The results of cell viability measured using MTT and alkaline phosphatase (ALP) activity showed that the TCS/PMMA cement had great biocompatibility and osteoconductivity. In conclusion, this composite bone cement of PMMA combined with TCS has great potential in orthopedics to serve as bone restoration material.