Ceradyne Alleges Unfair Practices by Foreign Firms : Trade: The Costa Mesa company and 3M try to bar Japanese and German companies from U.S. sales of translucent ceramic brackets used by orthodontists.

Ceradyne Corp., a manufacturer of ceramic and metal products, has filed an unfair trade practice complaint against Japanese and German competitors involving ceramic brackets used in orthodontic braces.

The complaint filed with the U.S. International Trade Commission by Ceradyne, Minnesota Mining and Manufacturing Corp. and a 3M subsidiary seeks to bar Tomy Corp. of Tokyo and Dentaurum J.P. Winklestroeter KG of Ispringen, Germany, from selling in the United States translucent ceramic brackets used by orthodontists. The suit also names Dentaurum’s U.S. subsidiary and a Tomy distributor in the United States.

The ITC--the federal agency that investigates unfair trade practices and violations of U.S. trade regulations--has until Dec. 18, 1992, to decide on the merits of the complaint. A finding in Ceradyne and 3M’s favor carries no enforcement authority but could help the companies seek financial restitution in court.

Ceradyne jointly developed the translucent brackets with 3M’s Monrovia, Calif., subsidiary, 3M Unitek Corp. The products are marketed under the name Transcend. Tomy’s product is called Allure, while Dentaurum’s product is sold under the name of Fascination.

Ceradyne’s translucent brace--made from ceramic and other materials--picks up the color of a patient’s underlying teeth and effectively disguises the brackets. Transparent brackets disguise the braces but have a tendency to break easily. Opaque brackets are more durable but often don’t match a patient’s teeth and are more visible.

“There are settlement discussions under way for all parties involved,” said Terry K. Qualey, 3M’s assistant chief intellectual property counsel.

If the parties decide to settle out of court, the ITC would have to approve the accord.