Practice Tips #95: Glossary of Equipment Terms

Our goal at American Dental has always been to empower you and your staff. We do this by sharing tips and tricks for easy equipment repair. The reality is that knowing just a little bit about your equipment and its components can help you reduce downtime and costs in your practice. This month, we’ve put together a handy glossary of some common dental equipment terms to help you cut through the “equipment speak.” We hope to help you identifying parts or translate what your dental technician is telling you.


anti-retraction glossary termThis valve only allows flow in one direction— usually applies to water, but vacuum lines often have anti-retraction valves. Also referred to as a “check valve.”


Equipment surfaces for easily cleaning. It contains a minimum number of grooves or surface irregularities that trap bacteria-laden debris.


A serrated fitting used to keep tubing in place. Tubing slips over the barb, followed by a plastic sleeve over the tubing to keep it in place. Most barbs in dental units come in one of two sizes: small (1/16" o.d.) or large (1/8" o.d.) for use with air and water supply lines. Barbs also for use on large vacuum lines. Vacuum barbs are not for use with sleeve clamps.

For more information on barbed fittings, check out Practice Tips #5 and #32.


A hollow cylinder that holds a bur in a handpiece. Manual chucks on high-speed handpieces are easily replaceable and available from American Dental Accessories.

Chuck Design

For more information on chucks and handpiece components, check out Practice Tips #22, #63, #66, and #90.

Compression Fitting:

Another type of fitting to hold tubing in place. A compression fitting includes a connector to which the tubing attaches, a plastic sleeve that compresses (squeezes) the tubing, and a nut that forces the sleeve to compress. As the nut is tightened on the fitting, the sleeve is compressed onto the tubing securing it in place. Compression fittings are most often used for larger tubing, 1/4" o.d. or 3/8" o.d.

For more information on compression fittings check out Practice Tips #5 and #32.

D.I.S.S. (Diameter Indexed Safety System):

This is a standardized system to keep nitrous and oxygen lines separate. The oxygen and nitrous lines have standardized sizes to keep from mixing them up. This is a VERY important safety feature, so you provide proper oxygen amounts to the patient when necessary.


A polymer component designed to seal between two (usually rigid) surfaces. A gasket can have any shape or cross-section. Note that o-rings can be used as gaskets, but they conform to a specific shape and cross-section. Meaning an o-ring could be referred to as a gasket, but a gasket is not necessarily an o-ring.

Read more on installing sterilizer door gaskets in Practice Tips #93.


Abbreviation for a dental handpiece, a precision dental rotary instrument/drill. HP also stands for horse power. In dentistry, this would only be in the context of a compressor or vacuum motor.


An abbreviation term for a dental high volume evacuator, also known as high speed suction or large diameter aspirator. Standard HVE's (in the US) fit on 1/2" i.d. tubing and have a 7/16" i.d. opening to accept tips.

ID or OD (id/od):

Abbreviation for inside or outside diameter measurements. These are the distances from one side of a circular object (e.g. tubing) to the other side; measured through the center. For some common diameter sizes for convenient comparison, see our online diagram.

Junction Box:

Used to refer to the main (master) valves and regulators that control the air and water flow to the dental unit. Also known as the box used to cover the aforementioned valves and regulators. Junction boxes are sometimes referred to as “utility centers.”

For more information on junction boxes, check out Practice Tips #3, #23, and #73.

"Midwest" or "Borden" Style:

"Midwest" style handpieces or connectors are the most common type of tubing connection used in the United States. Midwest-style handpieces connect to 4 or 5-hole handpiece tubing. Even though they attach to 4-hole tubing, many Midwest-style handpieces will have only 2 holes, any extra holes are simply not used & should be deactivated at the unit. "Borden" style tubing and connectors have only 3 holes. Borden-style handpieces may have 1, 2, or 3 holes, but will connect to all 3-hole tubing. This type of connector is most commonly used outside of the United States.

For more explanation on these connectors and other handpiece connectors, check out Practice Tips #36.

Momentary Valve:

A spring-loaded toggle valve that returns to the "off" position when released.

For more on toggles, check out Practice Tips #19.

MPT or FPT: 

Abbreviation for male or female pipe thread. Threads placed onto a pipe with an inside diameter (i.d.) as listed. Note that the size listed refers to the pipe, not the threads. Thus a 1/2" FPT is a female thread placed on a 1/2" i.d. pipe. As the pipe diameter needs to be consistent, this makes the diameter of the thread much larger, approximately 3/4" in this case.

For more on pipe threads, see Practice Tips #5 and our online size diagram.


A term the original equipment manufacturer. It used as a reference to their part number.


A circular object with a circular cross-section made of a flexible material (usually some sort of synthetic rubber). O-rings seal between two surfaces or hold different rigid components together. Sometimes they can serve both purposes at the same time.

If you need a replacement o-ring, American Dental offers an online size diagram for the most commonly used sizes. Print it off and compare your o-ring to the diagram to choose the correct one. Read more about o-rings in Practice Tips #7.


Abbreviation for pounds per square inch. It is a unit of pressure measuring force. In the dental unit, there are gauges to indicate the handpiece drive air pressure in P.S.I. (pounds per square inch). You’ll also find valves that regulate the air pressure going to your dental unit in your junction box or utility center. Dental units and handpieces require specific air and water pressure to function properly, typically a 2:1 ratio of air and water.

For more information on the correct P.S.I. for your dental unit check out Practice Tips #3.

Practice Tips:

American Dental technical assistance posts with easy to follow tips and tricks for reducing practice overhead and equipment downtime. The glossary of equipment terms help with translating these Practice Tips into useful information during repair.

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Relieving Valve:

When referring to a relieving toggle, “relieving” means that the toggle valve allows the air to be exhausted from around the toggle when switched to the "off" position. Also referred to as "3 way" valve. This is required when the switch provides air to another valve (e.g. master) to allow it to turn on. NOTE: This type of valve only haS air flowing through it, even though it may turn water off and on.

For more assistance with toggles, read Practice Tips #19


Abbreviation for a saliva ejector valve, also known as slow speed suction or low volume suction. It is a small diameter aspirator.

The glossary of equipment terms go on and on, but this will get you started. If you have any questions about your equipment, feel free to give us a call for expert, FREE technical assistance at 1-800-331-7993. You can also reach out to us on our embedded chat system on main web page or email us your technical questions to:


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