Comprehensive testing and analyses by the ADA found that NO detectable amount of lead was released from the porcelain- metal dental crowns evaluated under extreme laboratory testing conditions. The ADA's Paffenbarger Research Center in Maryland conducted the tests in response to the concerns over safety of foreign-made dental work. One hundred two porcelain- to-metal crowns were tested from different manufacturers. Feldspathic porcelain has a trace amount of lead naturally in it. Forty-four porcelain powders were tested, which resulted in hardly any lead to 113 ppm, with an average of 46 ppm in the 102 tested crowns.

Also tested was the release of lead in finished crowns with results that no lead was detected at all even under more extreme conditions than in the mouth, even with acidic conditions under high temperatures.

In response to a television report last February, the ADA developed their own research method to measure lead concentration. They have shared their results with the CDC and the FDA.