“…Due to this incompatibility with the polymeric matrix, the contrast forms a segregated phase and makes mixing of reagents more difficult during the preparation. For this reason, some authors have suggested the use of alternative contrasts, such as iodine (Almén, 1995;Davy et al, 1997;Davenport et al, 1999;Ginebra et al, 2002;Nakamura et al, 2003;Artola et al, 2004;Kjellson et al, 2004;Van Hooy-Corstjensa et al, 2004) and/or bismuth (Rawls et al, 1996;Deb et al, 2002) based compounds. These compounds are chemically linked to specially designed monomers and are thus automatically incorporated into the BC formulation.…”