Preparation and characterization of calcium-shellac spheres as a carrier of carbamide peroxide.

This paper describes a novel approach to prepare and characterize calcium-shellac spheres as a carrier of a tooth whitening agent carbamide peroxide. Calcium-shellac spheres were prepared using an extrusion technique based on dropping aqueous ammonium shellac solution into calcium chloride solution. The effects of formulation and processing conditions on the encapsulation efficiency of carbamide peroxide, physical and mechanical properties of the formed calcium-shellac spheres were investigated. The inner structure of the spheres was characterized using X-ray micro-computed tomography and their mechanical strength was determined using a Lloyds Material Testing Machine. Possible reactions between ammonium shellac and calcium chloride and carbamide peroxide, respectively, have been proposed based on experimental measurements using Fourier Transform Infrared Spectroscopy (FTIR).