In the first stage of the experiment, an in vitro test using the direct contact test (DCT) will be performed. The nanoparticles will be incorporated to the cement in 3 concentrations: 0.5%, 1%, 2% , and the affect on S.mutans will be testes after 24 h, and after 14 days. The concentration will be compare to 0%. The purpose of the test is to make sure that the temporary cement with the nanoparticles supplement has an antibacterial affect against S.mutans, and that the cement without the supplement has no such activity. Furthermore, the dosages for use in vivo, will be decided based on this test.