Contra-angle head for dentistry

Claim 1

A contra-angle head for a dental handpiece comprising a rigid tubular housing member elongated on its axis to provide an alley open at a first end for receiving a drive shaft and having at the second end a chamber with an access opening though a side of said housing member for receiving in said chamber a dental tool for rotation on a tool axis that is transverse to said housing member axis, said chamber having a tool shaft opening through a diametrically-opposite side of said housing member from said access opening for passing a dental tool shaft, means in said tool shaft opening to support said dental tool shaft, when present, for rotation around said tool axis, a latch member in the form of a thin-walled tubular shell slidingly enclosing a portion of said housing member including said second end and being movable relative to said housing member, said latch member having a first latch aperture which is large enough to allow a tool to pass through said first access opening from outside said shell and a second elongated latch aperture the width of which is approximately the same as the diameter of said tool shaft opening, said latch apertures being located diametrically opposite each other in said shell, means for locating said latch member on said housing member and operative to put said latch member alternatively in a first location on said housing member in which said first latch aperture is in register with said access opening and in a second location on said housing member in which a cover portion of said shell overlies said access opening, said second latch aperture being long enough and so oriented as to leave said tool shaft opening uncovered when said latch member is in each of said locations and at all positions between them.