A dental syringe is a syringe

Syringe

A syringe is a simple pump consisting of a plunger that fits tightly in a tube. The plunger can be pulled and pushed along inside a cylindrical tube , allowing the syringe to take in and expel a liquid or gas through an orifice at the open end of the tube...

 used by dentist

Dentist

A dentist, also known as a 'dental surgeon', is a doctor that specializes in the diagnosis, prevention, and treatment of diseases and conditions of the oral cavity. The dentist's supporting team aides in providing oral health services...

s for the injection of an anesthetic

Dental anesthesia

Forms of dental anesthesia are similar to general medical anesthesia except for the use of nitrous oxide, relatively uncommon outside of the dental field in the United States.-Local anesthetics:...

. It consists of a breech-loading syringe fitted with a sealed cartridge containing anesthetic solution.

The ancillary tool (generally part of a dental engine

Dental engine

A dental engine is a large chair-side appliance found in a dentist's office. At minimum, a dental engine serves as a source of mechanical or pneumatic power for one or more handpieces; typically, it will also include a small faucet and a spit-sink, which the patient can use for rinsing, as well as...

) used to supply either water or air to the oral cavity for the purpose of cleaning debris away from the area the dentist is working on, is also referred to as a dental syringe.
A 3-way syringe has separate internal channels supplying air, water or a mist of air and water, created by combining the pressurized air with the waterflow. The syringe tip can be separated from the main body and replaced when necessary.