Flexural Strength of Orthodontic Cement With Microcapsules

Objectives: The objective of this study was to determine the mechanical properties of orthodontic bracket and band cement formulated with microencapsulated remineralizing agents.
Methods: A heterogeneous polymerization technique was utilized to prepare microcapsules containing aqueous solutions of 0.8M NaF, 5M Ca(NO₃)₂ and 3M K₂HPO₄. These microcapsules were formulated into orthodontic cement that differed by the types of monomers used for the continuous phase, the glass loading level, and the fumed silica loading level. The monomers used in the formulations were bisGMA and TEGMA in different ratios. In these formulations, the microcapsules were loaded between 4-7w/w% (2-4w/w% of aqueous fluoride solution, 2w/w% of aqueous calcium solution and 1w/w% of aqueous phosphate solution). Flexural strength was assessed using specimens with a 2mm x 2mm x 20mm geometry in 3-point bend (n=12) after 7 days of water storage at 37⁰C.
Results: A table highlighting some of the results from the flexural strength measurements is shown below.
Conclusions: The flexural strength for orthodontic bracket and band cements formulated with microencapsulated remineralizing agents was measured. The flexural strength of these band and bracket cements can be optimized as a function of the glass loading, fumed silica loading and bisGMA:TEGMA ratio.