preferably comprises an elongated body having a first end portion 24 that interacts with the socket 14 and the chuck 21 and a second end portion 26 that allows a dental tip or needle 28 to be attached to the extension member 22 as will be discussed in more detail with respect to fig8 the extension member 22 is arranged so that a disposable dental tip 28 may be removably attached to the second end portion 26 of the extension member 22 fig2 shows an exploded view of the adaptor assembly 20 the adaptor assembly 20 comprises the chuck 21 and an annular collet 30 the chuck 21 includes a plurality of circumferentially spaced externally tapered jaws 34 which will allow the extension member 22 to be clamped within the chuck 21 the collet 30 and the jaws 34 are preferably designed of a resilient plastic so that they will grasp the extension member 22 securely and with enough resistance to firmly retain the extension member 22 within the chuck 21 without damaging the extension member 22 a first o ring 36 sits between the chuck 21 and an externally threaded coupling member 38 to provide a fluid sealing connection between the chuck 21 and the threaded section 38 any suitable sealing means may be used in place of the first o ring 36 that allows a.