Practice Tips #7: O-rings


O-rings are used extensively in dental equipment - everything from your handpiece to your sterilizer uses them. They can be made from a variety of materials and come in a vast array of sizes. Many people will also refer to them as gaskets, although o-rings are not truly gaskets.

An o-ring will always be circular and have a circular cross-section. The cross-section can be thought of as the shape of the material that forms the “o”. If you were to cut an o’ring and look at the end, the shape you see is the cross-section.


O-rings come in a variety of sizes and can have many different applications. In our catalog, the o’rings are shown at actual size on our measurements

To determine the correct size, you can simply lay an old o’ring on the page for identification. O-ring manufacturers also use a special numbering system for standard o’rings. Standard o-rings will have a 3 digit number to correspond to the size, the larger the number, the larger the o-ring. Many equipment manufacturers incorporate these numbers into their part numbers which can simplify cross-referencing. For example, A-dec part #030.002.02 corresponds to o-ring number 002 and American Dental Accessories part #18-OR-002. NOTE: while the sizes are standardized, the applications are not. A “002” size o-ring could be used on many different things in many different brands of equipment. When choosing an o-ring, always look for the correct size, rather than describing your particular application.


Most o-rings are made in a variety of materials depending on the application. In a typical dental unit, most of the o’rings will be made out of some type of synthetic rubber which will dry out over time.

O-rings should be regularly lubricated with a silicone-based lubricant to maintain elasticity and prolong their life. Petroleum-based lubricants (such as Vaseline) can actually accelerate the drying out of o-rings and should not be used. While it isn't practical to completely disassemble your dental unit to lubricate all the o-rings, certain components can be more prone to wear and are more readily accessible. The o-rings on vacuum valves, for example can be simply accessed without using tools and should be lubricated at least once a week. For other items, if something is sticking, (like a syringe button, or your foot control) try dismantling to expose the o-rings and generously lubricate with silicone-based lubricant. Many times, this will restore your equipment to normal function quickly and easily.

American Dental Accessories, Inc.

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