In recent years, some discount labs and dentists in the US have oursourced the creation of crowns and bridges to labs in China with very mixed results.  The biggest concerns are related to the creation of dental structures which will not stand the test of time, but earlier this year, the National Association of Dental Laboratories reported on a case where a crown from China was tested and found to have an unsafe level of lead in the porcelain.  Just a few months earlier, toy manufacturers had to recall millions of toys due to use of lead paint, concerned about the risk that a young child might put the toy in their mouth.  Therefore, when the reports about lead content actually in the tooth first surfaced, it was met with an alarming response from the US public.

Any dentist or laboratory considering outsourcing should take pause.  When furniture companies or other manufacturers outsource to China, they do so for the cheap untrained labor and throw-away materials (particle board, etc).  With dental structures, we feel that quality workmanship and materials should be paramount, and above all, the medical creed is to "first and foremost, do no harm."

The actual letter issued from NADL regarding this matter is below (you may need to click on READ MORE to see it).

The video below shows the typical zirconia milling process using a disc.

Below is a video of the Ceron Milling Center process:

Below is a manual zirconia milling process:

Zirconia (Zirconium Oxide) is a white powdered metal used to create dental frameworks for crowns, bridges and other dental substructures.  It replaces gold or stainless steel used in the past, creates the appearance of a whiter more translucent tooth, and is transparent in xrays.  Zirconia has been in use in cosmetic dentistry for many years to acheive the most aesthetic result possible, but has more recently become widely accepted as the dental material of choice.

Several types of crowns and bridges that have been used in the past:

All Metal Crowns: In the past, some crowns in the anterior region were all-metal, either gold or stainless steel.  However, as porcelain has become stronger in recent years, all-metal crowns are generally not used.

Metal-Plastic Crowns: Metal-Plastic crowns are the least expensive crowns used today, although they are rarely used in the United States because the plastic coating tends to change color over time.

Metal-Porcelain Crowns: These are the least expensive crowns and most popular crowns created over the past 10 years.  The disadvantage is that the metal must be covered with an opaque porcelain to try to hide the dark metal color, so the tooth does not look real.  While metal crowns are not preferred by most US dentists, gold substructures are often used when the crown needs to be thin, which might be too brittle for an all-porcelain crown.

All Porcelain Crowns: All porcelain crowns are increasingly popular, particularly in cosmetic dentistry and especially since new porcelain materials are harder than past materials which had a tendency to break or chip.  All porcelain crowns are the most expensive type, sometimes costing twice as much as a metal-porcelain crown.  They are a much better choice than metal for front teeth, but because they are more fragile than metal or zirconia substrates, all-porcelain is not a good material for anterior teeth or large bridges which might be subject to more pressure.

Zirconia Crowns: Zirconia is the best material available for bridges and for creating a strong translucent tooth that rivals all-porcelain crowns.  Zirconia crowns are significantly less expensive than all-porcelain crowns, and about the same price as gold-based metal-porcelain crowns (slightly higher than stainless steel).  Also, because zirconia substrates can be milled with a laser milling machine, the substrates tend to fit better and are less labor-intensive than either a metal-procelain or all-porcelain solution, providing a superior product with a quicker turn-around at a lower cost.