Abstract: An autoclaving collar having a distal end and a proximate end is presented for fastening to the proximate end of a conventional dental handpiece to protect the impeller of the handpiece from the corrosive environment of autoclaving or sterilization. The collar has an opening at its distal end and an axially extending cavity that communicates with the opening and an annular shoulder which is concentric with the longitudinal axis of the collar for captively holding an O-ring member which seals the proximate threaded end of the conventional dental handpiece when the collar having internal mating thread is sufficiently threaded onto the proximate end of the dental handpiece.