I happen to go through the below article about about forms of damage which have not been taken in sufficient consideration up tonow, or those that might have been noticed, but have been deliberately ignored.
How do turbines cause damage?
1. In the effects of grinding and drilling burs on the tooth enamel. The turbine does not grind down in the manner of slower machines, but rather breaks up the enamel prisims by impact, not only on the edes of cavities and preparations but also far down into the enamel supposed to remain intact: this has been proved by samples recorded through electron microscope. The cracks thus caused not only allow bacterial toxins but also the bacteria themselves and macromolecules to pass and penetrate in the dentine. This encourages caries.
2. But the major damage is caused in and on the dentine itself. Many colleagues are of the opinion that the pulp receives too much heat due to friction when turbines are used in treatment. Additional abundant cooling would avoid such a burden. As, due to the high rotation speed, both a congestion and negative pressure occurs on the dentine, a dry (or water-less) zone is formed at the very point of drilling or grinding/milling.
3. In an edition of a German-language journal (the ZWR), SCHOLER, a Swiss colleague described trials with air and water-cooler turbines: to culminate, he discovered that already after 5-20 seconds of milling or grinding with turbines, an increase in pulp temperature by 12 degrees C
As a result of the high rotation speed, turbulence are produced around the burs which produces a very high negative pressure over the dentinal tubules . This negative pressure does not increase in linear, but in exponential fashion: as a result of this state, the peritubular dentine linings, and the cylindrical odontoblastic processes are damaged or sometimes torn out, even odontoblast cores may be partially sucked into the tubules
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