A dental instrument comprising: (a) a body, the body including an enclosed container having a removable portion for holding abrasive particles, the body having a conduit extending inside the container and in fluid communication with the interior of the container, - the conduit including a passageway extending across the boundary of the container to its exterior at a first location to provide a flow path from the exterior of the container into the passageway, - the conduit including a channel extending across the boundary of the container to its exterior at a second location to provide a flow path from the channel to the exterior of the container, - the conduit generally extending within the container from the first location of the container toward the second location of the container, - the conduit including at least one opening to provide fluid communication from the interior of the container into the conduit, at least one aperture disposed between the at least one opening and the second location of the container in fluid communication with the interior of the container; (b) a restriction formed in the conduit between the at least one opening and the passageway; (c) a source of pressurized fluid being connected to the passageway to provide pressurized fluid to the conduit; wherein pressurized fluid flowing through the conduit into the container passing the restriction, creating a reduced pressure adjacent the at least one opening to draw abrasive particles from the interior of the container into the conduit, abrasive particles being entrained in the pressurized fluid flowing in the conduit toward the at least one apertures, an amount of the particle-laden pressurized fluid flowing through the at least one apertures to the interior of the container, the remaining portion of the particle-laden pressurized fluid flowing past the at least one apertures of the conduit and then the channel to exit the container, characterised in that the size of the restriction is variable. (a) a body, the body including an enclosed container having a removable portion for holding abrasive particles, the body having a conduit extending inside the container and in fluid communication with the interior of the container, - the conduit including a passageway extending across the boundary of the container to its exterior at a first location to provide a flow path from the exterior of the container into the passageway, - the conduit including a channel extending across the boundary of the container to its exterior at a second location to provide a flow path from the channel to the exterior of the container, - the conduit generally extending within the container from the first location of the container toward the second location of the container, - the conduit including at least one opening to provide fluid communication from the interior of the container into the conduit, at least one aperture disposed between the at least one opening and the second location of the container in fluid communication with the interior of the container; the body including an enclosed container having a removable portion for holding abrasive particles, the body having a conduit extending inside the container and in fluid communication with the interior of the container, - the conduit including a passageway extending across the boundary of the container to its exterior at a first location to provide a flow path from the exterior of the container into the passageway, - the conduit including a channel extending across the boundary of the container to its exterior at a second location to provide a flow path from the channel to the exterior of the container, - the conduit generally extending within the container from the first location of the container toward the second location of the container, - the conduit including at least one opening to provide fluid communication from the interior of the container into the conduit, at least one aperture disposed between the at least one opening and the second location of the container in fluid communication with the interior of the container; - the conduit including a passageway extending across the boundary of the container to its exterior at a first location to provide a flow path from the exterior of the container into the passageway, - the conduit including a channel extending across the boundary of the container to its exterior at a second location to provide a flow path from the channel to the exterior of the container, - the conduit generally extending within the container from the first location of the container toward the second location of the container, - the conduit including at least one opening to provide fluid communication from the interior of the container into the conduit, at least one aperture disposed between the at least one opening and the second location of the container in fluid communication with the interior of the container; (b) a restriction formed in the conduit between the at least one opening and the passageway; (c) a source of pressurized fluid being connected to the passageway to provide pressurized fluid to the conduit;