A study has begun of inlayed teeth of Meso-American Indian skulls using scanning electron microscopy and modelling techniques. Round cavity preparations 2-3 mm in diameter and 1-2 mm deep had been cut through the enamel and just into the underlying dentin of the teeth.The vertical walls of the preparation met the floor in either a square, rounded or undercut form. Towards its center, the floor was occasionally elevated, sometimes depressed and commonly rounded. Closer examination showed abrasion anomalies as concentric, shallow grooves cut into the tooth tissue. A modification of the Semenovian principle was employed to determine the tool: 1) from the marks registered in the cavity and 2) the outline form of the preparation itself. Preparing cavities experimentally in teeth using wood and stone drills and sand as an abrasive produced certain characteristics consistent with those in the MesoAmerican teeth in which wooden drills created a variety of cutting patterns which included flat, elevated and depressed floors in the preparations. We have tentatively concluded that suggestions for the use of a tubular drill does not adequately explain the variety of forms encountered and that the cutting patterns were more consistent with the use of a wooden drill and sand. -- AATA