By Adria Calatayud

The European Union antitrust body said it opened an investigation into U.S. medical-device maker Align Technology, to assess whether the company's sales strategy for teeth aligner Invisalign and dental scanners broke competition rules.

The European Commission, the EU's executive arm and antitrust enforcer, said Tuesday that it is concerned Align might have unfairly leveraged the market-leading position of Invisalign to force dentists to purchase the company's second key product, an intra-oral scanner sold under the iTero brand.

Align Technology didn't immediately respond to a request for comment.

The probe, which followed a complaint by a competitor, will assess whether Align's strategy breached EU competition rules by tying sales of Invisalign to those of iTero, the European Commission said.

This marks the European Commission's first formal antitrust investigation in the medical-devices sector, it said.

Write to Adria Calatayud at adria.calatayud@wsj.com