Graded ceramic polymer composites for orthodontic applications
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1
University of Bristol, Oral and Dental Science, United Kingdom
Introduction: Ideal dental material is an essential to perform a successful treatment plan and guarantee patient satisfaction. Since traditional dental materials fail to emulate the anisotropic structure of enamel and dentin, they have many clinical drawbacks. Ice templating is a well-established processing route for approaching hierarchical assembly of complex structures with optimal control of the microstructure of component. In the present study, we aim to characterize a novel dental material, based on two networks of ceramic and polymer that fully interpenetrate with each other to emulate the structure of natural teeth and obtain superior characteristics compared with conventional dental materials.
Materials and Methods: Alumina powder (10 vol%) was mixed with (0.5 wt%) dispersant in distilled water. slurries were ball-milled for 18 hours to achieve better dispersion and reduce agglomeration. In order to improve the strength of the green bodies, gelatin powder was dissolved in water at 50 oC then added to the slurry and ball milled for 2 hours at very low speed to ensure an appropriate mixing. Different concentrations of gelatin solution (2.5, 5, 7.5 wt%) were added to characterize their effects on the final morphology of porous scaffold during the freeze casting process. Slurries were then frozen in a custom built system and then dried in a Freeze Dryer at (−55°C and 0.1 mbar) for 48 hours to make sure the ice was sublimated completely. The dried samples were ready to be sintered in a laboratory chamber furnace at 1600 ºC. Sintered blocks were silanated with pre-hydrolyzed 3-(trimethoxysilyl) propyl methacrylate and then heated at (140°C) for 6 hours. Samples were filled with polymer mixture composed of 1:1 urethane dimethacrylate and triethyleneglycol dimethacrylate with (1 wt%) benzoyl peroxide as heat initiator under vacuum followed by heating to (70°C) for 8 hours. Finally specimens were cut and polished for further characterizations.
Results and Discussion: All ceramic scaffolds exhibited around 86% open porosities measured by Archimedes method and image analysis. This means that water contained in the gel completely converted into ice crystals. A graded porosity was achieved by using different temperature gradient between the top and button in a gelation suspension. SEM micrographs of the fracture samples viewed in parallel to the freezing direction confirmed cells were distributed parallel to the freezing direction, suggesting that ice crystals were grown along temperature gradient of gel body and alumina particles were concurrently rejected from growing ice crystals (Figure 1). Optical micrographs of the polished surfaces viewed in perpendicular to freezing direction showed a typical hexagonal cellular structure with various sizes (Figure 2). Compression, flexural strengths and hardness of the composite material in addition to the bonding and wearing characteristics are aimed to be investigated in the progress of the study.
Conclusion: It is possible to engineer a material with a multi-level hierarchical gradient structure and thereby influence the ratio between ceramic and polymer content to resulting in a composite material with both ceramic and polymer rich layers providing the advantages of both materials.
Higher Committee of Education Development in Iraq; University of Bristol
Keywords:
composite,
polymer,
gel
Conference:
10th World Biomaterials Congress, Montréal, Canada, 17 May - 22 May, 2016.
Presentation Type:
Poster
Topic:
Biomaterials in dental applications
Citation:
Al-Jawoosh
S,
Bo
S and
Ireland
A
(2016). Graded ceramic polymer composites for orthodontic applications.
Front. Bioeng. Biotechnol.
Conference Abstract:
10th World Biomaterials Congress.
doi: 10.3389/conf.FBIOE.2016.01.02159
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Received:
27 Mar 2016;
Published Online:
30 Mar 2016.
*
Correspondence:
Dr. Su Bo, University of Bristol, Oral and Dental Science, Bristol, United Kingdom, B.Su@bristol.ac.uk