A device for preventing suck back of oral secretions into air-driven dental handpiece when the air-driven dental handpiece is stopped. The device includes a high-pressure valve to close a high-pressure inlet port and a low-pressure valve to close a low-pressure inlet port or an exhaust air outlet. The device further includes an actuating member that closes the high-pressure valve. High pressure air of the air-driven dental handpiece can push back the high-pressure valve to open state. The low-pressure valve is coupled to the high-pressure and moves with it. A compression member interrupts the low-pressure valve and the high-pressure valve, wherein the compression member causes the low-pressure valve to close first while allowing the high-pressure valve to keep moving further to close the first path with a time delay.

A zero-suckback device for a disposable high-speed turbine dental drill handpiece includes two units respectively installed at two ends of the head of the handpiece. On one side of the handpiece head where a drill pin is installed, one unit consists of an elastic shaft sealing casing which is centrally embedded with a central framework made of hard substances and a non-elastic shaft sealing casing, and a lip portion of the elastic shaft sealing casing fits a wind wheel shaft with a tapered end. On the cover side of the handpiece head and between a button housing and a head housing, an O-shaped sealing ring is installed, and a one-way ball valve is installed at the center of the button housing. Suckback prevention measures are adopted at both sides of the handpiece head, so matters sucked back can be controlled to be a very low level, nearly zero.

A method of preventing suckback of a dental handpiece and a dental handpiece system having a bypass injection structure are capable of effectively blocking a suckback phenomenon that occurs at the moment a rotating impeller stops. The method of preventing suckback includes bypassing air pumped from an air pump in a state where a flow path of an air supply pipe is blocked at the moment the impeller stops rotating and halts inside a head casing and injecting the air into the head casing through an air discharge pipe to block the suckback phenomenon.

Centrifugal deflection device intended to be fitted to a surgical or dental handpiece to prevent the penetration of foreign matter that results from an operation, the centrifugal deflection device including a ring coupled in rotation either directly or via a tool shank to a drive shaft of the handpiece. This device is characterized in that the ring is covered by a sleeve secured to the front end of the body of the handpiece and which, with the ring, delimits an ejection chamber. The ejection chamber includes an inlet that communicates with a rear area of the handpiece and an outlet that communicates with the external environment, the ring having a first diameter at the outlet of the ejection chamber and a second diameter at the inlet of the ejection chamber, the first diameter of the ring being larger than the second diameter of the ring.

A dental turbine driven by pressurized air comprises a head housing (1) with a turbine chamber (2) and a rotor shaft (3) mounted using an anti-friction bearing (8a) with a non-rotatably mounted turbine wheel (13). The outer race (10a) of the anti-friction bearing (8a) extends into the turbine chamber (2) in axial direction. The turbine wheel (13) comprises an annular web (16a) that is arranged concentrically to the outer race (10a) of the anti-friction bearing (8a) and, together with the outer race (10a), forms a gap seal (17a). This gap seal (17a) extends in axial direction between outer race (10a) and annular web (16a) and prevents the sucking-in of liquids and dirt particles into the turbine chamber (2) during inertial rotation of the turbine wheel (13).

A dental handpiece includes a barrel, an air turbine, a central shaft, a bearing and a seal. The barrel includes an axial open end. The air turbine is rotatably provided in the barrel. The central shaft is secured to the air turbine to rotate with the air turbine. The bearing is mounted in the barrel and supports the central shaft for rotation. The seal is trumpet-shaped and arranged between the open end of the barrel and the bearing. The seal includes a sealing portion sleeved over an outer cylindrical surface of the central shaft. The sealing portion is deformable to separate from the outer cylindrical surface of the central shaft or closely contact the outer cylindrical surface of the central shaft depending on a pressure difference between interior and exterior of the barrel.

A zero-suckback device for a disposable high-speed turbine dental drill handpiece includes two units respectively installed at two ends of the head of the handpiece. On one side of the handpiece head where a drill pin is installed, one unit consists of an elastic shaft sealing casing which is centrally embedded with a central framework made of hard substances and a non-elastic shaft sealing casing, and a lip portion of the elastic shaft sealing casing fits a wind wheel shaft with a tapered end. On the cover side of the handpiece head and between a button housing and a head housing, an O-shaped sealing ring is installed, and a one-way ball valve is installed at the center of the button housing. Suckback prevention measures are adopted at both sides of the handpiece head, so matters sucked back can be controlled to be a very low level, nearly zero.

A dental drill head, constituted of a head housing, a wind wheel, and bearings, the head housing being constituted of a head housing cover and a head housing cavity, and the wind wheel being constituted of a wind wheel shaft and wind wheel blades. An anti-suck-back device is configured between the head housing cover and a wind wheel shaft end part to which the wind wheel shaft corresponds. The present invention, which adopts the aforementioned technical scheme, firstly makes it possible to reduce the intake in of contaminants when suck-back is taking place as the impeller is braked; and secondly, while there is still a positive pressure inside the head, the rubber head covering uses elastic force to brake the impeller and completely prevents the intake of contaminants. Moreover, the structure is simple and costs are low. Since the pressing area is reduced and the cavity is arranged between the rubber layers and the head covering, the teeth are less susceptible to touching the pressing portion. Even when the teeth do happen to touch the pressing portion, the cavity is so arranged that the teeth still will not touch the brake disc, thus avoiding any effect on the rotational speed; arranging the rubber ring inside the annular slot both prevents suck-back and automatically adjusts the dynamic balance, which is a double advantage and also lowers costs.

An air turbine handpiece having: a head portion with built-in free turbine blade, a neck portion installed consecutively with the head portion and grasped by an operator, a grip portion installed consecutively with the neck portion, an air supply duct for driving the turbine blade, and an exhaust duct for exhausting the air. The exhaust duct is provided with a reflux duct, open at one end to the exhaust duct, and open at the other end to the turbine room as the exhaust exit, a value in which an aperture at the reflux exit of the reflux duct is divided by an aperture in the air supply port of the air supply duct, becomes one or less, and the reflux exit of the reflux duct is opened to the turbine room near the air supply port between the air supply port and the exhaust exit.

A dental preparation instrument having a pneumatic turbine (1) with a rotor (5) for driving a tool (1.1), wherein the rotor (5), which is mounted in a turbine chamber (18) for rotation about an axis of rotation (4), is impinged by compressed air from a compressed-air nozzle (22). A first radial partition (23) has an opening (17) via which an annular space (8) is in flow connection with an outlet duct (19).