Treating teeth or associated tooth structure by the use of an abrasive-laden fluid stream which provides fluid at high pressure to a manifold with selectively operable valves, delivers fluid at a selected pressure to a mixer for fluid and abrasive and delivers the mix to a handpiece for application of abrasive-laden air to a tooth or tooth structure. Low pressure priming air pressurizes the air abrasive device. A path for pure air bypasses the air/abrasive device. A control allows for delivery of air or air and abrasive as desired. Fluid pressure is controlled by a manually-operable servo system. Following treatment with the air/abrasive, a purge line purges the system downstream from the abrasive device of excess abrasive particles. A vacuum removes abrasive particles and debris from the patient's mouth. The abrasive delivery device may include a hand-held nozzle having fluid ports operable by the fingers of the operator to control system functions. The vacuum includes a ridge, disposable collection chamber for sterile disposal of abrasive and debris and may include a common filter for the purge circuit and the system for removal of abrasive particles and debris. Connection to the existing suction system in the dental office or use of a water powered venturi to provide suction is disclosed. Pressure regulating and relief means insure instantaneous change of pressure levels.