We all have a general, familiar idea about ceramics. Like your tea mug or coffee cup. Ceramics are non-metallic solid materials, made of certain metal oxides and formed by a firing process. What is so special with ceramic materials? Ceramics as restorative materials in dentistry they are widely used because they are durable, aesthetic, and biocompatible. They are characterised by having a high melting temperature and very low electrical and thermal conductivity. Ceramics have high compressive strength, can resist chemical erosion but have very low tensile strength. This said, they are brittle materials. On the other hand, ceramic materials are inert and insoluble in water. Ceramic materials have three major indications in contemporary dentistry ceramic-metal crowns and fixed partial dentures, all-ceramic restorations consisting of short-span anterior bridges, crowns, onlays, inlays, and veneers, and ceramic denture teeth. A ceramic veneer, a laminate, is used to cover an unsightly area by bonding to the facial surface of the tooth. It is noteworthy that no contraindications have been reported for ceramics. How about ceramic materials in dentistry in details? Professor Leena Hupa will explain more about ceramics in general and then Dr Edmond Pow, Professor Timo Närhi, and Professor Niklaus Lang will continue the story. Zirconia, or zirconium dioxide, which is sometimes named as ceramic steel, possesses the ideal properties for dental use superior toughness, strength, and fatigue resistance. Zirconia has in addition, excellent wear properties, and is biologically inert no adverse reactions with tissues are reported. Zirconia is currently widely used as a dental biomaterial in frameworks and dental implant abutments and fixtures because of its high flexural strength, compared with alumina and cobalt chromium. Yttria, or yttrium trioxide, and minute amounts of some other oxides are added to stabilise the crystal structure transformation during firing at elevated temperature and improve the physical properties of zirconia. Many investigations on the biocompatibility of zirconia have reported no cytotoxic effects on cell culture tests and no adverse tissue reactions in animals, based on in vivo tests. However, bonding and adhesion, between zirconia and porcelain, and between resin cement and zirconia, is relatively weak due to the extremely inert, non-reactive character of zirconia. The adhesion strength between yttrium stabilised zirconia and cement is very weak, about 1.5 MPa without any pretreatment on the surface of zirconia. This said, zirconia needs surface treatment before cementation, such as gentle grit-blasting. As a biomaterial, zirconia is a material of choice because it has some pronounced advantages. On the other hand, zirconia is chemically inert leading to the fact that etching the surface of zirconia with mineral acids is cumbersome. It is noteworthy that zirconia remains stable even when implanted in the human body without any adverse reactions. There are no concerns about its radioactivity, either. What has aluminium trioxide or alumina got to do with dentistry? Alumina occurs in nature as the minerals bauxite, corundum, diaspora, and gibbsite. Native alumina is very hard, crystalline, and insoluble in water. Pure alumina is prepared by dehydrating one of its hydrous oxides. Alumina may be called the predecessor of full ceramic zirconia restorations in dentistry. Alumina was first introduced in dentistry as a reinforcing inclusion for porcelain in the mid-1960s. However, the inherently low tensile strength of porcelain, did not allow it to be used in areas subjected to high stresses. Today, alumina may still find its use as a framework material for the construction of crowns and small all-ceramic fixed restorations. As orthodontic brackets, alumina has also found an application in dentistry. It's also noteworthy that alumina in the powder form, is widely used as a grit-blasting material in dental technology.