Abstract: The invention achieves its purposes with a grommet thimble incorporating a bore sleeve which may be fitted with retainer means for a sanitary dam. When this thimble is fitted into the specially-prepared entrance portion of a root canal, the retainer means extends from the tooth for holding a dam of rubber or the like without injury to surrounding gingiva during placement of a clamp for the rubber dam. The root canal can be prepared with the sleeve and dam in place, the sleeve and dam serving to facilitate the establishment and maintenance of a sterile field of operation without creation of unnecessary lacerations on the surrounding gingiva. After completion of the desired preparation procedure, or of partial completion, a temporary plug can be removably fitted into the sleeve protection of the work done or in process. For completion of a restoration several options are available. The retainer means can be left in place and used to anchor a core with or without a post. Alternatively a post can be fastened (e.

Abstract: A dental hand-piece of the type known as "contra-angle" uses a pair of helical gears on shafts that rotate on respective axes which pass by each other but do not intersect. The gears, one set of which is on a tool driver and the other set of which may be formed in the shaft of a dental tool, engage in respective pitch circles, the diameters of which are smaller than their respective outer diameters.

Abstract: A dental contra-angle which supports a tool socket for combined motion consisting of two oscillatory movements simultaneously, one motion being a linear reciprocating motion parallel to the axis of rotation, and the other motion being an oscillatory motion around the axis of rotation. A tool receiving aperture opens through one end of the socket and extends along the axis toward the other end. A tool for treating a root canal, when installed in the socket, will be given a combined motion consisting simultaneously of a linear reciprocating motion in the axis of the root canal, and an angular oscillatory motion around the axis of the root canal. The resulting motion of such a tool is one of dipping with simultaneous partial rotation.

Abstract: Novel tool operating apparatus is exemplified in a dental treatment device capable of driving alternatively at least a first tool and a second tool, each tool being intended to execute a different form of motion, with a single tool driving means to which each of several different tools can be removably coupled. The driving means includes a rotatable drive shaft fitted with tool engagement means in the form of a disc affixed to the shaft and lying in a plane that makes an acute angle with the rotational axis of the shaft. One tool can be fitted over the shaft to engage the disc so as to rotate the tool with the shaft. A second tool can be fitted over the shaft so that the shaft can rotate within the tool, but the tool will not rotate with the shaft. The second tool has means for cooperating with the shaft so as to execute an oscillatory motion relative to the shaft axis.