Seems like China is having a problem keeping things from where they're not supposed to be. The pet food scandal with melamine contamination, lead in children's crayons and toys, and now lead contamination showing up in porcelain & metal crowns/caps that are placed in people's mouths. Air transport shipping has made it economically feasible to ship dental lab cases off-shore to China where for a myriad of reasons it costs less than if fabrication took place in the United States. Workmanship can be quite good and comparable quality in the best of scenarios. At the worst, you may end up getting what you pay for: cheap materials with compromised quality.
Apparently in China there few regulatory agencies that have much authority to act on behalf of the consumer. It's definitely "let the buyer beware". Some dentists may be unaware that their US based laboratory has shipped their patients lab case overseas. Please be assured that the dental labs I use are very local: 2 are within 2o miles of my dental office, one other is located in Southern California and is adamant about their "made in USA" status.