Fabrication and characterisation of ceramic-polymer composites for orthodontic brackets

• Main Authors: Cheong, Joo Ming, Su, B., Sandy, J. R, Ireland, A.J
• Format: Conference or Workshop Item
• Language: English; English; English
• Published: 2017
• Subjects: RK Dentistry
• Online Access: http://irep.iium.edu.my/70569/1/BOC%20poster%202017%20finalised.pdf; http://irep.iium.edu.my/70569/2/British%20Orthodontic%20Conference%20Programme.pdf; http://irep.iium.edu.my/70569/3/Poster%20presenter%20letter.pdf; http://irep.iium.edu.my/70569/

Objectives: To produce a ceramic-polymer composite for possible use as an aesthetic orthodontic bracket material. Design and Setting: A laboratory study undertaken at the Dental Biomaterials Laboratory, School of Oral and Dental Science, Bristol. Materials and methods: Freeze casting was used to fabricate 15.0%, 20.0%, 25.0%, 30.0% and 35.0% by volume porous ceramic frameworks and using 5 different temperature gradients from 0ºC down to: -10ºC, -20ºC, -30ºC, -40ºC and -50ºC. 5 frameworks were created for each of the ceramic loads/temperature gradients. Each framework was then infiltrated with UDMA-TEGDMA polymer, before being characterised using density, porosity, compressive strength and modulus of elasticity measurements. Results: A directional lamellar structure, with graduated nature of the ceramic framework was observed. The density of the ceramic frameworks increased with increasing ceramic % by volume from 15.0% to 35.0% (at temperature gradient 0ºC to -10ºC). An increase in porosity from the ceramic-rich layer to the polymer-rich layer was observed at 15.0% and 20.0% ceramic concentration. The compressive strength was significantly higher for frameworks made using 30.0% ceramic by volume loading and fabricated across a temperature gradient of 0ºC to -10ºC (p<0.001). The manipulation of the temperature gradient below 0ºC did not affect the density, porosity and compressive strength. The effect on the modulus of elasticity was small but statistically significant. Silane did not improve the mechanical properties of the composite materials. At some ceramic concentration, the polymer-rich layer had higher compressive strength values than the ceramic-rich layer. Conclusions: Ceramic-polymer composite materials produced using the technique of freeze casting show great promise as potential aesthetic orthodontic bracket materials.