Sterilizing handpieces

by Noel Kelsch, RDHAP
n.kelsch@sbcglobal.net

To me, integrity is doing the right thing even when no one is looking. Ethics are the rules for deciding correct conduct based on the available information. There are times in our lives when we have to take a stand. Sometimes those are in the strangest places during the most trying times. Other times the everyday little things make an impact on someone’s life. Using integrity and ethics in our decision making in infection control is how each of us can decrease the infection risks in dental care.

For many years we have known that reusing a dental handpiece without autoclaving it can put patients at risk. The studies surrounding this issue have repeatedly shown that both high speed and low speed hand pieces that are not autoclaved can be a source of cross contamination.1,2 In one study using a low-speed air-driven handpiece used with prophy angles, the investigators assessed contamination inside the nosecone, motor, and prophy angles.

Using two handpiece types in 160 tests where the prophy angle end was contaminated in vitro with Geobacillus stearothermophilus, it was determined that the motor became contaminated in 20% of the cases. On the other hand, when the internal motor was contaminated, the microbes were transmitted to the prophy angle in 47% of 160 other samples. In another in vivo study of 20 subjects, 75% of the 420 samples obtained from low-speed handpiece/prophy angle systems were contaminated with oral flora.2

The part that is really important for all dental health-care professionals (DHCP) to remember is that these studies show that even with the use of a simple prophy angle, the internal unit of the handpiece became contaminated, and cross contamination became a strong possibility.

In 2008, the Centers for Disease Control (CDC), in its Guideline for Disinfection and Sterilization in Healthcare Facilities, reminded us that “Handpieces can be contaminated internally with patient material and should be heat sterilized after each patient. Handpieces that cannot be heat sterilized should not be used.” No handpiece should be used on more than one patient without being autoclaved between patients. Barrier protection and wiping down with a disinfectant does not assure no cross contamination. The internal part of the angle is as important as the external.

The acceptable methods of sterilization include chemical vapor sterilizers, dry heat, and autoclaves. Ethylene oxide gas is not recommended for dental handpieces.3

What to look for in a handpiece from a sterilization aspect

Some things to consider when purchasing a handpiece:

  1. Is it designed to be autoclavable
  2. Does it have sleek, smooth designs that will not hold debris
  3. Is the finish able to withstand the sterilization process over a long period of time? Titanium withstands chemicals and the sterilization process better than chrome plate.
  4. Does it have smooth surfaces that do not trap debris and bacteria, and a seamless finish with no gap between outer casings

But sterilization could destroy the handpiece, and they cost so much

Yes, the life expectancy of a handpiece can be decreased from the sterilization process. But that is not the only factor that plays into handpiece longevity. While it is difficult to determine just what factors shorten the life expectancy of a handpiece, there have been studies of handpieces that are being actively used and sterilized. One study from the United States Air Force Dental Investigation Services is a reminder how important maintenance is for these tools. This study concluded that with a properly sterilized handpiece, you can expect about 500 sterilization cycles without significant reduction in performance if the handpiece is properly maintained.4 That translates to about one year of use per handpiece. Purchasing and maintaining handpieces is the price DHCP need to pay in order to comply with the CDC recommendations and many state laws.

How do we care for the handpiece?

There are many resources to help you with the longevity and maintenance of these units. As DHCPs, we need to all read and follow the directions that come with our equipment. If we do not understand the care and maintenance recommendations, we need to call the manufacturer and ask for more details.

The mission of the National Dental Handpiece Association is to improve clients’ ability to deliver patient care by maintaining their powered instruments with exceptional service and integrity. The following guidelines represent a general approach to handpiece maintenance. Always follow the suggested maintenance procedures supplied with the handpiece. It is important to follow these instructions to the letter to avoid disputed warranty claims, especially during the warranty period.

Surface clean the handpiece. CDC guidelines call for flushing water through the handpiece in the operatory for 30 seconds to remove potential contaminants from the internal water line. In the sterilization area, clean off any bioburden using a brush under running water. A mild detergent is acceptable. Bioburden left on dental instruments may act as a protective shield for microorganisms in the sterilizer. Alcohol should never be used as a cleaning agent as it can dehydrate spores and increase resistance to sterilization. Do not use any chemical solutions for cleaning. Foreign substances may have a detrimental effect on the sterilizer or the handpiece, through a harmful reaction during the sterilization cycle.

Dry off the handpiece. This step is very important if the office is using a chemiclave sterilizer. Excess water will allow oxidation to occur in the chamber, leading to corrosion.

Lubricate the handpiece. Use the proper lubricating tip to spray oil into the drive airline. Spray until oil comes out of the handpiece head. This ensures that lubricant has penetrated to the bearings. Even if the lubricant is delivered incorrectly, oil coming from the head indicates it has reached the bearings. Note: Using spray oil has become less popular because of perceived mess and waste. Many offices are moving to dropper-style applicators to oil the handpiece. Use of a dropper makes the next step — running out the excess oil — critical because the droplets will not be delivered to the bearings without being propelled by pressurized air. If you prefer a dropper, apply two to three good size drops to the drive air hole and immediately run the handpiece.

Run the handpiece to expel excess oil. After lubrication, it is important to run the handpiece to evenly distribute the oil through the bearings, and to expel excess oil to prevent coagulation during autoclaving. Install a bur in the chuck and run the handpiece for 20 seconds. Do not use bur blanks, as they are not made to ISO specifications and do not run concentrically, which could possibly damage the turbine. (Note: some manufacturers specifically state NOT to install a bur prior to operation. Air flush stations located in the sterilization area are an excellent investment. A flush station eliminates a trip back to the operatory to run the handpiece. These stations are readily available from many sources and only require a connection to an airline. Most stations have a handpiece adapter that operates the handpiece when pressed. Using an air station also prevents oil from being exhausted back into the handpiece tubing, which can lead to discoloration and stiffening. After operating, remove the bur. Lever style handpieces must remain in the closed position during sterilization.)

Clean fiber-optic surfaces. Alcohol and a Q-Tip may be used to remove excess oil and debris from all fiber-optic surfaces.

Bag the handpiece. CDC guidelines recommend bagging instruments and handpieces to maintain sterility. A paper/plastic combination bag is preferred, which allows steam to dissipate through the paper side while contents remain readily identifiable.

Sterilize. Autoclave the handpiece following manufacturer guidelines. Allow the sterilizer to completely process through the dry cycle.

Dry the handpiece. After the cycle, place the bag containing the handpiece paper side up on top of the sterilizer to thoroughly dry. This is a warm area. As the heat from the sterilizer rises, the handpiece will dry more thoroughly. New sterilizer models feature dry/storage compartments outside the chamber. Paper side up allows the moisture from the condensing steam to evaporate easily. Leaving the plastic side up traps condensation in the bag, creating a corrosive atmosphere for the handpiece.

Many manufacturers offer a fully automatic clean and lube station to take staff time and guesswork out of the maintenance process. Most units have one-touch operation, applying a cleaner and lubricant before running the handpiece. Although costly, these maintenance centers reduce staff time associated with handpiece maintenance. Some manufacturers extend handpiece warranties if their automatic station is used.

Low speed motors and attachments

This is an area were everyone needs to take a stand. Dentistry is not static and studies have indicated it is vital autoclave the entire unit including the motor.

This is where a lot of confusion comes into play. One study in particular showed low-speed motors were shown to be contaminated internally during use with prophy angles and the internal contaminants released from the handpiece. Data from this investigation demonstrate that, unless low-speed handpieces (inclusive of motors and angles) are sterilized properly between patients, they may become cross-contaminated.1 The 2008 update from the CDC revealed that internal parts of the angle is as important as the external in regards to cross-contamination. The need for all handpieces and motors to be autoclaved was confirmed.

CDC made a very strong statement in 2008, “handpieces that cannot be heat sterilized should NOT be used.”7

Motors, especially vane rotors, do not require much oil. Dental motors and attachments require higher viscosity oil than a high-speed spray. One or two drops of oil in the drive airline are all that is necessary. Run the motor to distribute the oil. Also apply some oil as a preventive measure to forward/reverse valves, shift rings, and sheath attachment points. Wipe away excess oil with a paper towel.

Most straight sheaths do not require lubrication. An external cleaning is recommended with a brush under running water prior to bagging the nose cone for sterilization.

It is very important to take latch angles apart for proper lubrication. At least once a day, unscrew the head from the sheath and remove the transmission gear for cleaning and oiling. I suggest this step first thing in the morning as part of the opening routine. A Star latch angle requires the knuckle in the middle to be unscrewed in order to remove the transmission gear. Apply a drop of oil under each gear on the transmission gear as well as into the center hole. Apply several drops of oil to the exposed cartridge while the transmission gear is removed.5,6

Each DHCP must make decisions in infection control that involve integrity and ethics. In doing so, each of us can decrease the risks involved in dental care.

Noel Brandon Kelsch, RDHAP, is a syndicated columnist, writer, speaker, and cartoonist. She serves on the editorial review committee for the Organization for Safety, Asepsis and Prevention newsletter and has received many national awards. Kelsch owns her dental hygiene practice that focuses on access to care for all and helps facilitate the Simi Valley Free Dental Clinic. She has devoted much of her 35 years in dentistry to educating people about the devastating effects of methamphetamines and drug use. She is a past president of the California Dental Hygienists’ Association.

References

1. Chin JR, Miller CH, Palenik, CJ, Internal contamination of air-driven low-speed handpieces and attached prophy angles. J Am Dent Assoc. 2006 Sep;137(9):1275-80
2. Herd S, Chin J, Palenik CJ, Ofner S, The in vivo contamination of air-driven low-speed handpieces with prophylaxis angles. J Am Dent Assoc. 2007
3. Centers for Disease Control and Prevention. Recommended infection-control practices for dentistry. MMWR Morb Mortal Wkly Rep 1993;42(RR-8):1-12.

4. Leonard DL, Charlton DG. Performance of High-Speed Dental Handpieces Subjected to Simulated Clinical Useand Sterilization. J am Dent Assoc. 1999;130(9):1301-11.

5. Interview with handpiecetrdingpost.com
6. www.handpieceinfo.com accessed 8/11/2011.
7. Centers for Disease Control and Prevention (CDC). Guideline for Disinfection and Sterilizationin Healthcare Facilities, 2008.

 


 

Things to watch out for

Using a chemical wipedown on a handpiece before sterilizing — Not only is this redundant, but it may multiply harmful reactions when subjected to heat.

Using an ultrasonic cleaner or solution — Never immerse a handpiece in any fluids other than a cleaning solution offered by the handpiece manufacturer.

Lubricating in the wrong hole — The drive airline leads directly to the turbine. Other orifices such as exhaust, water, etc., do not. If you are using a liquid oil applicator on a swivel-type handpiece, it is critical that you deliver oil to the correct internal opening.

Incorrect lube applicator — Make sure the spray tip fits the handpiece quick disconnect correctly. Some models depend on a pressurized fit to flush debris out of the handpiece.

Not applying enough lubricant — Staff is sometimes admonished not to overspray oil into the handpiece to reduce excess residue, however, you must ensure that oil is getting to the bearings by seeing oil in the head.

Not running the handpiece prior to autoclaving — Failure to operate the handpiece following lubrication will result in gumming up the turbine, as excess oil gets baked into the bearings. An undesirable clinical effect is expelling oil into the operating field after not properly running out excess.

Not cleaning the fiber-optic bundles — Failure to keep the fiber-optic bundle surfaces clean will lead to a buildup of oil and debris, affecting the ability to transmit light.

Leaving the bur in the chuck during autoclaving — While a bur is held in an autochuck, the spring is compressed. Subjecting any spring to heat and corrosion under tension will weaken it and shorten its life. Leaving a bur in a manual chuck can lead to debris building up on the chuck, leading to increased operating difficulty.

Leaving levers open during autoclaving — When a lever autochuck is activated, about eight pounds of force are exerted through the front O-ring of the turbine. During normal operation, this force is momentary as the bur is changed. Leaving the chuck open during the autoclave cycle means compressing the O-ring while subjecting it to heat for 30 minutes, dramatically accelerating failure.

Failure to maintain autoclaves — If your autoclave is not properly cleaned, buildup that contaminates the entire system, including your handpieces, can occur.

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