Abstract: A dental appliance for evacuating debris and liquid from the mouth during dental operations having a collector member and a flexible collector membrane. The collector member has a semi-rigid bite block portion adapted to be gripped by the molars of the patient. The collector member also has a combination tongue guard and collector membrane holder formed integrally therewith and it has a first groove located with its open surface facing laterally to one side and a second groove located with its open surface facing laterally to the opposite side for detachably securing predetermined lateral edge surfaces of the collector membrane. The collector membrane is made of a flat sheet of polyethylene foam having a predetermined peripheral contour and it has a first groove engaging surface, a second groove engaging surface and a pair of tab members formed adjacent the opposite ends of the collector membrane.