The FDA specifically mentions “poorly maintained” handpieces as being a contributor to overheating. The nature of electric handpieces is such that burns can occur during use if the components are worn. Electric handpieces will use as much power as required to maintain torque and speed regardless of the condition of the handpiece. Note that handpieces will wear out over time, inadequate maintenance will only expedite this process, so even if you follow proper maintenance, be sure to be mindful of your handpiece performance.
With pneumatic handpieces, once wear starts the handpiece will often bog down, perform sluggishly, or even fail to run, so it’s rare for a practitioner to fail to notice wear. With electric handpieces, none of these symptoms are likely to be exhibited so you may not be aware of deterioration of the components. The main thing to watch for is concentricity of the bur. With wear, the bur will often lose concentricity, so watch your bur carefully for wobble or other signs of erratic rotation. It’s also a good idea to carefully touch your handpiece at the end of a procedure to check for signs of overheating. If it is painful to touch for more than a few seconds, it’s overheating. Deterioration is generally a gradual thing and overheating should be noticed before a catastrophic failure occurs.