Hand held dental instrument for carrying a working tool and driving it in relative movement, including: - a body with a proximal end of the body with an internal connecting bore and a distal end of the body, adapted to be connected at its proximal end to driving means and to fluids feed means, - a head connected to the distal end of the body, able to carry the working tool, and including means for spraying fluids in the direction of the working area of the tool, - at least first fluids conveying means, for conveying the fluids through the body from the proximal end of the body and transmitting them to the fluids spraying means of the head, including an upstream fluids conveying channel, a downstream fluids conveying channel, and a fluids collecting chamber in the body, between the upstream fluids conveying channel and the downstream fluids conveying channel, characterized in that: - the fluids collecting chamber is radial, including a circular section radial blind bore, produced in the body and opening onto the exterior surface of the body, with a back wall terminating in the near vicinity of the internal connecting bore of the body, - the upstream fluids conveying channel extends radially from the internal connecting bore of the body towards the back wall of the radial fluids collecting chamber, - a filtration piece, having an exterior shape substantially complementary to the interior shape of the radial fluids collecting chamber, is mounted in the radial fluids collecting chamber with a clearance to allow the passage of and to filter fluids between the upstream fluids conveying channel and the downstream fluids conveying channel. - a body with a proximal end of the body with an internal connecting bore and a distal end of the body, adapted to be connected at its proximal end to driving means and to fluids feed means, - a head connected to the distal end of the body, able to carry the working tool, and including means for spraying fluids in the direction of the working area of the tool, - at least first fluids conveying means, for conveying the fluids through the body from the proximal end of the body and transmitting them to the fluids spraying means of the head, including an upstream fluids conveying channel, a downstream fluids conveying channel, and a fluids collecting chamber in the body, between the upstream fluids conveying channel and the downstream fluids conveying channel, characterized in that: - the fluids collecting chamber is radial, including a circular section radial blind bore, produced in the body and opening onto the exterior surface of the body, with a back wall terminating in the near vicinity of the internal connecting bore of the body, - the upstream fluids conveying channel extends radially from the internal connecting bore of the body towards the back wall of the radial fluids collecting chamber, - a filtration piece, having an exterior shape substantially complementary to the interior shape of the radial fluids collecting chamber, is mounted in the radial fluids collecting chamber with a clearance to allow the passage of and to filter fluids between the upstream fluids conveying channel and the downstream fluids conveying channel. - the fluids collecting chamber is radial, including a circular section radial blind bore, produced in the body and opening onto the exterior surface of the body, with a back wall terminating in the near vicinity of the internal connecting bore of the body, - the upstream fluids conveying channel extends radially from the internal connecting bore of the body towards the back wall of the radial fluids collecting chamber, - a filtration piece, having an exterior shape substantially complementary to the interior shape of the radial fluids collecting chamber, is mounted in the radial fluids collecting chamber with a clearance to allow the passage of and to filter fluids between the upstream fluids conveying channel and the downstream fluids conveying channel.