Abstract: The droplet spray teeth cleaning system includes in one aspect a window of temperature and volumetric flow ratio between air and gas for safe and comfortable yet effective operation, the volumetric flow ratio ranging between approximately 24 and 875 and the temperature from approximately 27° C. to a maximum of 60° C. The temperature is maintained by a flow-through heater (74) arranged around a liquid line portion (51) of the droplet spray system, preferably in a handle portion (52) of the system. Also included is a thermocouple heat sensor arrangement (78) which determines the temperature of the liquid prior to the nozzle portion and a control (76, 53) for maintaining the temperature within the temperature/flow ratio window. A filter (126) is provided, preferably in the head portion of the system, for filtering out particles from the liquid, while at the same time permitting adequate flow therethrough at least during the expected lifetime of the replaceable head portion of the system.