In the wake of a Midwestern woman being sickened by lead-tainted dental work that was outsourced to China, consumers are being asked to inquire about the origins of their crowns, veneers, bridges and dentures.

Millions of dental prostheses are being prescribed by dentists in the United States but are made in labs in China, India, the Philippines, Mexico, Eastern Europe, Costa Rica and elsewhere. Many experts are concerned about the outsourcing because raw materials used abroad may not meet U.S. standards.

Foreign labs produce a substantial proportion of Americans' restorative appliances, and are supposed to follow rules, said Bennett Napier, co-executive director of the National Association of Dental Laboratories in Tallahassee. "The FDA regulates the raw materials used ... [and] these labs have to register with the FDA and they are supposed to use FDA-approved materials. But the FDA is inspecting less than 1 percent of the restorations that are coming in from foreign dental laboratories," he said.

The new scare rekindles memories of lead-contaminated products from China last year.

Long Island dental lab owners Leslie and Terry Cloper say consumers should be concerned because "patients do not know where their lab work is being done. When you buy food or clothing there is a label requirement," she said. "But when you have something inserted in your mouth there isn't," Leslie Cloper said.

The couple, who own Lema Dental Lab in East Setauket, receive constant inquiries from foreign laboratories seeking work. Although the Clopers say they've resisted the pressure, other area labs and dentists find overseas pricing attractive. With the aid of global overnight shipping, dental appliances are ready in about the same amount of time they would have taken locally.

Toxic levels of lead were found in the dental work of a 73-year-old Ohio woman whose crown was made in China. The case was reported last week by an Ohio television station.

Afterward, officials at the American Dental Association notified federal regulatory agencies, calling on the government to investigate the case and to determine whether it's isolated or indicative of a wider trend. In a statement last week, the dental association said it has begun its own investigation.

"We will communicate our findings to the public and the dental profession, as well as to the appropriate government agencies," association officials said in a statement. Dental officials added: "The ADA is taking this report very seriously. However, we do want to keep it in perspective. There simply isn't enough information available to presume that the presence of lead in dental crowns or other prostheses is widespread."

The National Association of Dental Laboratories estimates between 15 and 20 percent of all restoration work is outsourced - and patients are unaware.

Dentists, often affected by what insurers are willing to pay, find the low-cost foreign work attractive, the Clopers said. Their lab, for example, charges dentists $128 for a single crown fused to a metal base, but labs in China do it for $29.