Conversion assemblies enable an air/water dental syringe adapted for connection to an existing tip such as an autoclavable tip to instead receive disposable tip. A conversion kit includes a cap subassembly with a cap body having a distal opening into which the disposable tip is inserted, and an adapter subassembly having a proximal end configured for connection to the syringe body and a distal end configured for coupling to the cap subassembly. The adapter subassembly includes one or more components with cut-outs, grooves or channels to direct air and water from the syringe body to the air-carrying channels and water-carrying tube of the disposable tip through the cap subassembly. To accommodate a wide variety of syringe styles, the adapter subassembly may include a proximal receptacle to receive a stem on the syringe a proximal stem insertable into the syringe one or more proximal air- or water-carrying tubes insertable into the syringe or a threaded connection to the syringe body.
