FORT COLLINS, Colo. (AP) _ Teledyne Industries Inc., sued in February by Optiva Corp. in a patent infringement dispute, said Monday it had filed a countersuit against Optiva.

Optiva had sued Teledyne over the SenSonic Plaque Removal Instrument made by Teledyne's subsidiary, Teledyne Water Pik, based in Fort Collins. Optiva claimed patent infringement on its Sonicare toothbrush and misappropriation of trade secrets.

Teledyne's countersuit, filed in U.S. District Court in Seattle, disputes Optiva's claims, arguing two of Optiva's patents are invalid, and alleges defamation and unfair competition practices by Optiva, based in Bellevue, Wash.

``We have filed this lawsuit to protect our brand. We want to reassure our customers, retail accounts, dental professionals, and employees of the integrity and quality of our product,'' said Mel Cruger, president of Teledyne Water Pik.

Efforts to telephone Optiva late Monday for comment met with a recorded message saying the offices were closed for the day.