More Capabilities, Less Noise

Todd Snyder, DDS (TS): I started using electric handpieces more than 20 years ago when I opened my office. The benefits include durability, substantially lower noise levels, and better torque. Electric handpieces not only allow dentists to cut through objects but also to control the speed. It is possible to turn an electric handpiece down to a very slow speed, such as 2,000 rpm or 4,000 rpm, to make it operate like a slow-speed handpiece and cut tooth structure. It is not recommended to perform an entire preparation this way, but for tiny refinements, despite the slow speed, it has such high torque that it will remove what is needed. This allows dentists to prepare teeth very precisely and to see what they are looking at without the water.

ID: You mentioned the noise levels. We are hearing a lot-no pun intended-about hearing loss and the impact of handpieces on practitioners. What safeguards are available for that?

TS: Although I have not experienced any hearing loss-likely because I use an electric handpiece-I have seen research indicating that it is definitely an issue. A dentist who rents a space three operatories down from mine uses traditional air turbines, and when you are in my operatory, the sound of those is actually louder than my own handpiece is. I have sampled several hearing protection devices, ranging from simple ones that you roll up and stuff in your ear to the larger earmuff-style devices typically associated with construction work or concerts. Some of the devices tie around the neck, and some are specifically calibrated to only cut out noise that is at damaging levels.

ID: Similarly, what advances have been made in the ergonomics of handpieces to reduce the occurrence of repetitive stress injuries and operator fatigue?

TS: Today, handpiece motors are only about half of the size that they once were, and the handpieces have become significantly lighter as a result. Also, the older motors had brushes inside of them, and it was necessary to replace the brushes periodically. The durability was good, but it is far better with the smaller, lighter, brushless motors. Regarding balance, older handpieces would pull back on your hand and almost float there. The ergonomics are much better now.

ID: Do you have any recommendations or tips for preparation design with modern materials? What impact does the choice of handpiece have?

TS: As I mentioned, reducing the speed of the handpiece to 4,000 rpm or less allows the dentist to finesse the final preparation and margin design for a really smooth, perfect margin. A diamond bur can be used at that speed.

If you cut through modern materials such as lithium disilicates, lithium silicates, and zirconia when replacing a crown, veneer, or a complex case, you will create a significant amount of fatigue on your hand as well as the burs because these materials are so durable. An electric handpiece's ability to provide the necessary torque to cut through modern materials is an advantage. Traditional feldspathic porcelain-fused-to-metal restorations were easy to remove quickly, but in the next 2 to 5 years, the harder, modern materials will likely become the norm in terms of what we regularly need to cut through.

ID: What other considerations should dentists be aware of when choosing and optimizing handpieces?

TS: Many dentists do not recognize the importance of the manufacturer-recommended speeds for the various polishers we use, including some of the newer, spiral polishing wheels. The manufacturers provide windows, such as 8,000 to 12,000 rpm, and the polishers all work so much better when used within the specified parameters. Of course, with an air-driven handpiece, the dentist can only estimate the speed; you just put your foot down on the pedal and it goes.

Tangential to that, presets have been one of the best advances. My handpiece has eight presets, so I can just press a button, and it goes to that exact speed and remains constant. Different handpieces have specific settings for endodontics, surgical procedures, and more. At least one new handpiece that I've seen has very advanced controls for safety, and another has two motors and two cables coming out so that the dentist is able to swap back and forth between high and low speeds faster.

In addition, concentricity is important. This is defined as the ability of the handpiece to produce a cutline consistent with the diameter of the bur. When placed in the newer electric handpieces, burs do not wobble or shake as much as they did in air-driven handpieces. They remain parallel and stay within their zone so the dentist can achieve a better cut. This also leads to greater durability.

Todd Snyder, DDS
Private Practice
Laguna Niguel, California