Rob Wallace
One thing that you need to consider is the careful regulation of air pressure - these handpieces are designed to run at pressures between 30 and 40 p.s.i. and not much higher. If you exceed the design pressure, there is a very good chance you will destroy or otherwise permanently damage the turbine, which can be quite costly to replace. My next door neighbor is a dentist, and that was his first advice to me - be absolutely sure you have excellent air pressure regulation! Your system should also provide some form of filtration - any particles entering the handpiece can result in catastrophic failure!

Having no experience with your 'water-in, water out' question regarding cooling (or even the need for cooling), I can only say that there are many, many people who simply use air pressure alone to drive their handpieces. A different issue which may be of more immediate concern is whether or not the handpiece/turbine must be lubricated or not. I would research this requirement for whatever handpiece you might be considering to purchase. The compatibility of connector configurations is also important; be absolutely sure you check on the supply connector's hole pattern and its compatibility with the handpiece, since there are several different types, which are often related to the different brands of handpieces - there is no one universal system!

Good luck!

Rob