Adapter units enabling a disposable tip to connect to an existing dental syringe configured to receive a different type of tip such as an autoclavable tip. In addition, adapter units constructed in accordance with this invention provide built-in light sources and/or video camera units, thereby providing the syringe bodies to which the adapters attach capabilities that they could not have without the adapters. A self-contained module, removably coupled to the retainer body, includes a light-emitting diode (LED), a battery powering the LED, and a switch to turn the LED ON and OFF, the LED generating light generally proximally toward the distal end of the disposable tip. In the preferred embodiments, the retainer body includes a cavity into which the self-contained module is removably received. The conversion kit may further include a lens to direct light from the LED toward the distal end of the disposable tip.
