Ask Dr. Christensen: Electric handpieces

June 1, 2005
Some of my colleagues have been changing to electric high- and low-speed handpieces.


Some of my colleagues have been changing to electric high- and low-speed handpieces. I am very satisfied with my air-driven handpieces. What advantages do you see for electric handpieces?

Answer from Dr. Christensen

Electric handpieces have been in dentistry for many years, and they have been used for years in various parts of the world with success. Until recently, they have not been popular in the U.S. To answer your question, I will discuss the electric handpiece question in two parts - low-speed and high-speed electric handpieces.

A few years ago, I converted some of our operatories to electric handpieces. Immediately, it became evident that the low-speed electric handpieces outperformed the low-speed air handpieces because of obvious advantages. The low-speed electric handpieces had torque and higher rotating speed that allowed fast, effective cutting of dentures, occlusal splints, provisional restorations, stone casts, and other relatively hard substances. The dental assistants became possessive of the operatories with the low-speed electric handpieces in them, and the low-speed air handpieces with their low torque and high noise production fell into disuse.

Other significant advantages of the low-speed electric handpieces were the extremely low noise level and precision cutting. Even with the high-velocity suction turned on, it was difficult to hear the electric handpieces when activated. Precision cutting of hard objects with either the straight cone or the contra-angle was evident and desirable.

The high torque, low noise, precision cutting, and ease of use of the low-speed electric handpieces soon won over the staff. Currently, I cannot recommend low-speed air handpieces when they are compared with low-speed electric handpieces. The electric handpieces are clearly superior to air-driven handpieces.

High-speed electric handpieces are desirable in several ways, but - in my opinion - their superiority over high-speed air rotors is not as clear as with low-speed handpieces.

The high torque of electric high-speed handpieces running at up to 200,000 rpm is impressive. When cutting single teeth for crown preparations, they perform very well from start to finish. High torque, obvious precision cutting, and low noise are the major desirable features. However, the relatively large heads, greater weight, and frequent need to manually change the rpm settings are disadvantages of most electric high-speed handpieces.

When cutting several teeth for crown preparations, I prefer to use an air rotor to remove the majority of the necessary tooth structure and previous restorations. After the gross tooth preparation, I prefer switching to an electric high-speed handpiece, which allows easy and precise refinement of the tooth preparations.

Would I suggest changing to electric handpieces? My answer is yes, with the limitations I have suggested.

An area in which the precision of electric handpieces is desirable is when accomplishing definitive occlusal equilibration. Practical Clinical Courses has just released V3105, “Uncomplicated Occlusal Equilibration;” and V3104, “Occlusal Splints - Predictable, Frequent Use.” For more information, contact Practical Clinical Courses at (800) 223-6569, or visit our Web site at


I am confused about the current recommendations for pulp-capping. What are the best materials and techniques for pulp-capping?

Answer from Dr. Christensen

The best type of pulp cap is none at all, but decisions about these uncertain situations occur at times in every practice. Research supports the relative success of pulp-capping. But some pulp caps fail after a period of time, and patients should be warned about this possibility. For years, calcium hydroxide was the most used material for pulp-capping. But about 10 years ago, it fell into disrepute. In recent years, research has been performed and published that again supports the use of calcium hydroxide for pulp-capping. In the meantime, other methods have come into common usage.

One of the most important considerations in any pulp-capping procedure is correct diagnosis of the health status of the tooth and pulp to be capped. The tooth should not be symptomatic before starting the procedure. The pulp exposure should be small, not much larger than 0.5 mm in diameter. The exposure should bleed freely, but not profusely. Dental caries surrounding the exposure should have been removed before the exposure. If these conditions are present, the chance of success using one of several techniques listed is very good.

The following materials for pulp-capping are being used with success:

Resin-modified glass ionomer (RMGI) is my choice. Materials such as 3M ESPE Vitrebond or GC Lining Cement LC can be placed directly on a small exposure, light-cured, and - followed by the bonding agent and restorative material of your choice - be placed over the resin-modified glass ionomer. When considering the characteristics of the materials suggested, it becomes evident that RMGI is actually a “filled” self-etching primer, which seals the dentinal tubules, bonds to the tooth, and provides potential fluoride release.

Bonding agents have been suggested by numerous clinicians. When using liquid bonding agents as the pulp-capping material, they are placed directly on the pulp exposure after hemostasis has been achieved. After the placement of the liquid bonding agent - and before the final restoration - a suitable hard, pressure-resistant material, such as a resin-modified glass ionomer, must be placed before the restoration.

Calcium hydroxide may be used as a pulp cap with success, despite the negative comments some speakers have made about it in recent years. When placed on the exposure, a suitable hard, pressure-resistant material should be placed over the calcium hydroxide before seating the final restoration.

I suggest that proper diagnosis of the health of the tooth being considered for pulp-capping is probably more important for the success of the procedure than the pulp-capping material used.

Select a technique that appeals to you, carefully and properly diagnose the teeth to be capped, and expect clinical success most of the time.

Occasionally, a pulp exposure is present when performing a Class 2 resin-based composite. PCC video C501B, “Predictable, Long-Lasting Class 2 Resin Restorations” will help ensure you do not further injure the pulp-capped tooth when placing the restoration. For more information, contact Practical Clinical Courses at (800) 223-6569, or visit our Web site at

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