Today's modern dentist must be a master of countless materials and techniques as the last 15 years has seen an explosion in restorative material options. Zirconia is one such material, and it has been applied extensively throughout dentistry.
Zirconium is a natural element found on the periodic table of elements (atomic weight 40 for you chemists out there). It's derivative zirconium oxide (aka zirconia) is one of the most studied ceramic materials on the planet and is used in countless industrial and commercial applications. Jet engines often contain zirconia as a thermal barrier coating due to its extremely low thermal conductivity. For the home, chef knives are being fabricated out of zirconia and being touted as "ceramic knives that never need sharpening." The most commonly known usage for zirconia is jewelry in the form of cubic zirconia synthetic diamonds.
Perhaps the most significant reason I enjoy using zirconia crowns is that they are excellent cosmetic alternative when a traditional full gold crown is indicated. Typical indications for usage of a full gold crown can include patients with heavy habitual grinding and when there isn't enough room to properly place a traditional porcelain/metal crown. Until zirconia, full gold crowns and porcelain/metal crowns were the only options available. Although very proven and predictable, full gold crowns are often cosmetically frowned upon by much of the population. I remember the first zirconia crown I ever completed was on a young woman in her mid 20s with insufficient space to properly place a traditional porcelain/metal crown . As I explained all the anatomical reasons and dental indications why I was recommending gold, I could read the growing disappointment in her face. Justifiably, her teeth were devoid of metal and contained only several white fillings. She was heartbroken that she would need the gold in her mouth. As an alternative, I suggested we try the zirconia crown as it could be made very thin and yet strong, in the same manner of the full gold crown. She agreed, we matched the color of the crown to her other teeth, and the case turned out beautifully.