SOUTHFIELD, Mich., May 21 -- American Dental Technologies Inc. has received clearance to market a laser device that removes the dark tissue evident during the early stages of tooth decay while keeping healthy enamel intact. The company said it received marketing approval from the US Food and Drug Administration for its PulseMaster Nd:YAG lasers to remove only decayed tissue from teeth; other types of dental laser devices are used for decay that has progressed and penetrated tooth enamel.The PulseMaster laser procedure usually can be performed without the need for anesthesia. We regard this hard tissue clearance as a milestone in laser dentistry because it is the first clearance for this specific indication for use, said Ben Gallant, president and chief executive of American Dental Technologies.