The decision to carry out this experimental study, that is explained in this book, came from both the desire and need to know how metal-free prosthetic structures, now widely used in restorative dental cosmetic treatments, react to the treatments of dental hygiene. The aim of this research was to find effective instrumental methodologies and procedures for scaling and deplaquing without compromising the structure of metal-free, monolithic lithium disilicate and layered zirconia prosthetics. At the present time there is little scientific literature that has examined how these newer products react to professional dental hygiene treatments. It is also important to have a good understanding of the different materials prosthetics are made of in order to better understand how the materials hold up when subjected to different treatments. In this book we gain insight into the difference between lithium disilicate monolithic and layered zirconia and a greater understanding of which instruments are better adapted in practical professional application.