Objectives: The objective of this study was to determine the effect of initial concentration of phosphate ion on the release from microcapsules with ion permeable membranes formulated in resin and rosin based varnish formulations. Methods: A heterogeneous polymerization technique was utilized to prepare microcapsules containing an aqueous solution of 0.8 M, 2.4 M, 4.0 M and 7.4 M potassium phosphate dibasic. Fifteen weight percent of microcapsules were formulated into both a resin and rosin based varnish formulation for a total of seven formulations. Ion release profiles were studied as a function of initial salt concentration and time for 12 weeks. Phosphate ion detection was performed by the molybdenum blue method and reported as ppm of phosphate ion released per gram of formulation. Results: Ion release profiles were studied as a function of initial salt concentration in the varnish formulations and are reported below:
Continuous Phase | Initial Conc in microcapsule (M) | Weight % of microcapsules | 1 day (ppm) | 1 week (ppm) | 6 weeks (ppm) | 12 weeks (ppm) |
Resin | 0.8 | 15 | 14 | 19 | 55 | 88 |
Resin | 2.4 | 15 | 46 | 70 | 227 | 367 |
Resin | 4.0 | 15 | 32 | 79 | 295 | 490 |
Rosin | 0.8 | 15 | 21 | 133 | 296 | 318 |
Rosin | 2.4 | 15 | 110 | 511 | 821 | 829 |
Rosin | 4.0 | 15 | 76 | 329 | 697 | 800 |
Rosin | 7.4 | 15 | 19 | 193 | 977 | 1128 |
Conclusions: Ion release profiles were generated for varnish formulations containing microencapsulated aqueous solutions that contained phosphate ions that may be useful in remineralization. The preparation of varnish formulations with controlled release profiles appears promising based on the variation of initial molarity of salt solution encapsulated in the microcapsule fillers. This work is funded in part by Premier Dental Products Incorporated, GL Materials Research LLC and an NSF University-Industry Partnership grant.