| 摘要 |
<p>The apparatus contains first valves (4a, 5a) which may be opened by high pressure air that then passes through apertures (23, 33) to be used to drive the air-turbine of the hand-piece of a dental drill. Upon completion of the dental treatment, the high pressure air supply is turned off and the first valves (4a, 5a) therefore close. Furthermore, a low pressure air supply (50) is now able to open second valves (4b, 5b) and low pressure air passes along the apertures (23, 33) to provide a small positive pressure in the hand-piece so as to prevent contaminated saliva and the like from leaking into the hand-piece.</p> |
