Target used to sell its own brand of teeth whitener for $15 less than Crest 3D White Whitestrips, the market leader, which cost about $40 a box. Then came a phone call from Procter & Gamble (P&G). A lawyer for the company informed Target that P&G was suing Clio USA, the manufacturer of the private-label product, and two distributors for infringing patents on the strip of material used to apply whitener to teeth, says P&G General Counsel David Weirich. P&G, the world's largest consumer-products company, spends about $2 billion a year on research and development and has never been shy about defending its more than 40,000 patents.