Adhesion of Orthodontic Cements Formulated with Microencapsulated Remineralizing Agents

Abstract

The objective of this study was to determine the adhesion to enamel and mechanism of failure of orthodontic bracket and band cements formulated with microencapsulated remineralizing agents. 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 5-10 w/w% (2-7 w/w% of aqueous fluoride solution, 2 w/w% of aqueous calcium solution and 1 w/w% of aqueous phosphate solution). Shear bond strength (SBS) to intact bovine enamel was determined by preparing bonded assemblies using an Ultradent fixture and loading to failure (1.0 mm/min) after 7 days of water storage at 37oC. Microscopy was used to determine the mechanism of failure. Shear bond strength and flexural modulus measurements were determined along with optical microscopy to study the effect of microcapsules on adhesion in an orthodontic cement.