Can’t see the video? You can also view this video on our blog or Youtube.

As it turns out, the problem was simply a worn, bad, or improperly installed cassette seal. Our techs were unable to make a definitive determination but replacing the seal did correct the problem. The simplest things are often a great starting point if using process of elimination to diagnose (sometimes, all one can do).

This demonstration shows the proper method of replacing a Statim cassette seal as well as the importance of lubricating the seal when installing. It may have simply been lack of lubrication that lead to the failure of the original seal (our techs were never able to make a definitive conclusion- but this is something to keep in mind).

Lubricating the cassette seal or door gasket of your sterilizer (as applicable) should be part of your routine maintenance. See previous issues of Tech Tips for more information on trouble shooting and repairing the Statim or other sterilizers.

Can’t see the video? You can also view this video on our blog or Youtube.

American Dental supports this initiative and reminds you of the importance of routine maintenance to keep your units working well (and free from leaks).

A common cause of water leaks is a worn water relay valve. In issue #35 of Tech Tips we showed you how to replace this valve.

Air/water syringes are another common source of leaks. Several issues of Tech Tips have been dedicated to repairing and maintaining syringes.

Stop leaks in your dental unit with Tech Tips!

Biofilm in the water lines can create an environment in which Legionella bacteria can exist and proliferate, so it’s vital to ensure your unit’s water supply is consistently clean.  To ensure that you’re up-to-date on best practices, please visit the ADA and review their Statement on Dental Unit Waterlines.  The main recommendations for improving water quality at this time are the following:

We recommend BluTab Waterline Maintenance Tablets and our independent water reservoirs.

Air mixing with water (or water mixing with air).

If either button is sticking, that could cause the air or water to continue running and lead to this problem. See “sticking buttons” below. If the buttons are not sticking, the problem is likely inside the syringe head.

There is a small o’ring inside the syringe which keeps the air and water separate (the “small adaptor nut” o’ring part #01-06). This o’ring could be worn or missing and should be replaced.

It is also possible that there is condensation in the air line from the compressor. In this case, you would only have trouble with water mixed in when hitting the “air” button, and not air mixed in when hitting the “water” button. An easy way to determine if you have water in your air line from outside the syringe, is to detach the air line from the bottom of the syringe, and let the air from the line blow into a paper towel or onto your hand. You’ll know pretty quickly if there’s moisture in the line.

Water can also get into the air line from other valves in the unit. See some of our previous issues for more information on trouble shooting water in the air line from other sources.

No Air

No air comes out when hitting the air button. This is almost always due to an obstruction somewhere. Start by trying without a tip installed on the syringe. If you now get air, the obstruction was in the tip. Putting it in an ultrasonic cleaner for a minute or two may clear it up. Otherwise, discard it as the tip is worn out.

If you get no air without a tip either, the clog is further upstream. Remove the holding mechanism from the syringe and check for debris on the inside of the head. Usually the holding mechanism is unscrewed using a 5/32” allen (hex) wrench. Remove the button and valve core (if your syringe uses valve cores) and check for debris here as well.

Detach the tubing from the base of the syringe and verify you have air pressure in the line. If you do not have air pressure in the tubing, the clog is at a valve or junction before the syringe. Call our techs to trouble-shoot further (or see our previous issues on leaking, junction boxes, & pneumatics).

No water

Follow the same procedure as above for no air. Additionally, if you use plastic barriers over your syringe, it is very common to get debris on the inside as staff will often poke the syringe tip through the barrier when changing tips. If the tip is poked through the barrier, every time the tip is poked through, a small piece of plastic is shoved into the syringe with it. We frequently see syringes with a huge wad of plastic built-up inside the small adaptor nut o’ring (#01-06, see above). Check carefully as this is typically clear plastic and hard to see. You should be able to remove it with a scaler or explorer. You might also want to show your staff to make certain they cease using this technique.

If there is no debris evident inside the head, continue as above (under “no air”).

Sticking Buttons

This is more frequently experienced with the water button than the air button. Mineral deposits from hard water, debris in the water line, or corrosion can all wear the water button and the o’rings on it. If it is sticking, remove the button and lubricate with a silicone-based lubricant. In fact, it’s a good idea to regularly lubricate your buttons as part of  routine maintenance to keep them moving smoothly. We recommend once a month, but you may want to adjust the frequency depending on your conditions and experience (e.g. if you have particularly hard water, a greater frequency may be warranted).

Lubrication may be enough to restore proper function. If not, you will need to replace the button (or valve core, if your syringe uses valve cores). As a temporary fix, you can swap the air and water buttons of your syringe. This will cause the air button to stick, but this is often less problematic than having the water constantly leak.

See our previous issues on  syringe repair for step-by-step instructions on removing and changing buttons.

Spinning Tips

Most syringes are designed for quick changing of the tips so the tips are just held in with o’rings. This allows the tip to be easily pulled out or pushed in- no loosening or tightening of components. Older designs used a brass or plastic syringe cone to help retain the tip, but these required use of a wrench to unscrew or tighten the holding mechanism to change tips. The cones, however, often had a slit that ran the length of the cone which would restrict lateral movement of the tip.

Newer designs that just use round o’rings do not provide the same lateral tension. You’ve got a round peg in a round hole. Tightening the holding mechanism can compress the o’rings further limiting rotation of the tip, but it’s difficult to tighten enough without preventing easy tip changes.

Most current designs use two o’rings to hold the tip; the first o’ring (closest to the tip) can be replaced with a cone to limit rotation. Not all assemblies have room for a cone here, but most should.

The DCI collar-type syringe uses ball-bearings to hold the tip in place. DCI makes a tip with extra notches on the end of the tip. These notches will fit in-between the ball bearings of their collar mechanism making it harder to spin the tip. The DCI collar has 6 ball bearings in the mechanism, some of the other brands of collar syringe use fewer ball bearings so the notches won’t limit rotation as effectively in these syringes.

Last of all, you can rely on simple physics. Rather than pushing on the side of the tip for retraction, use the hook-like end of the tip to pull. Syringe tips are designed to stay in place when pulled on with only modest force, tips are not designed to resist rotational forces.

Leaking- air or water not shutting off

Most syringes currently on the market have a spool-type button that serves as the valve. The button itself turns the air or water on. If the water or air is staying on, typically the button has failed. If the button has failed, simply replace it. A sticking button will also lead to failure of air and water to shut-off. See above under “sticking buttons” for possible remedies.

Some (mostly older) syringes will use a valve core under the button. This is what actually turns the air and water off and on, the button simply activates the valve core. If your syringe uses valve cores, typically the valve core will need to be replaced using a valve core wrench.

Leaking- air or water coming out somewhere other than the tip

“Leaking” can also mean air or water coming out from somewhere other than where it is supposed to. Most components of the syringe are sealed with o’rings. Leakage around any of these components will usually be remedied by replacing the corresponding o’ring.

For leakage around the holding nut, replace the large skinny o’ring (#01-05) that seals it. If you have leakage out around the buttons, replace the buttons (unfortunately, o’rings are not available for most buttons, so the entire assembly should be replaced).

A note on disposable tips:

Many disposable tips on the market require a special adaptor to properly fit your syringe. If not using this adaptor, many problems can be observed such as water mixing in with the air (see above), poor spray pattern, or even tip ejection (which can cause harm to patients). If your disposable tip does not have the same shape and design as a standard tip (a skinny water line protruding out the back and a groove toward the back to line up with the o’rings) it will require a special adaptor. Regardless of brand or style, it’s always a good idea to give the tip a little tug after inserting to make certain that it’s properly and securely seated.

However, if the tip is identical to an autoclavable tip (just made of plastic in whole or in part – such as our Smart Tips), then you probably don’t need to use an adaptor. Of course, if you use autoclavable tips you’ll avoid this issue altogether (to say nothing of reducing waste and saving money).

For step-by-step guidelines are performing the various repairs mentioned above, check out previous issues of Tech Tips:
How to Repair a Leaky Syringe- Part 1
How to Repair a Leaky Syringe- Part 2
How to Rebuild Your Air/Water Syringe- Video

Can’t see the video? You can also view this video on our blog or Youtube.

For more information on syringe repairs and troubleshooting leaking syringes please visit the following issues of Tech Tips:

How to Repair a Leaky Syringe- Part 1

How to Repair a Leaky Syringe- Part 2

Can’t see the video? You can also view this video on our blog or Youtube.

This is the last issue of Tech Tips for 2011, and we would like to thank all of our readers for your support and suggestions. We look forward to publishing a lot more helpful time & money saving articles.

Happy Holidays from American Dental Accessories!

First of all, the construction of the dental handpiece can influence its performance. (Check out Tech Tips issue #22 on Highspeed Handpiece Design for the fundamentals of how dental handpieces are constructed.) The basic construction of a turbine is illustrated below. The turbine depicted is that for a Midwest Quiet Air™ standard chuck highspeed handpiece, but most turbines are similar in design and will use the same types of components.

The impeller catches the drive air causing the turbine to spin. Naturally, the more air the impeller can catch, the more energy from the drive air is transferred into torque. As they can catch more air, usually larger impellers = more torque. Of course, engineers spend countless hours designing the impellers of dental handpieces to capture as much air as possible while keeping size to a minimum. So size is far from the only consideration (and is not an absolute either- size doesn’t overrule all other considerations by any means). The number of vanes, the shape of the impeller, using twin impellers or a number of other engineering tweaks and tricks can all result in more efficient impeller designs without increasing size.

Next, we have the bearings. The bearings reduce friction and allow the turbine to spin. Without bearings, most turbines would not spin at all (or not without the application of tremendous force). Given their role, the bearings used can also have a tremendous influence on torque. Cage types, materials, shielding, (just to mention a few factors) will all have an effect on bearing performance and thus, torque. Larger bearings often go hand-in-hand with large impellers, but again, don’t put too much confidence in size. This is only one method of potentially increasing torque.

The key for most practitioners is to keep your bearings in good shape so they can do their job.  Most practitioners will notice a degradation of performance as bearings wear. Worn bearings increase friction requiring more energy to spin the turbine. With extreme wear, concentricity can also be affected further reducing torque as energy can be diffused by lateral movement (i.e. bur wobble) in addition to further increased friction. So, to get maximum torque, it’s important to keep your bearings in good shape through good routine maintenance (as discussed in Tech Tips #9).

Bearings simplify rotation of the turbine as the impeller catches the drive air, but the drive air itself is providing the motive force, so of course, drive air will have a tremendous impact on torque.

You need clean dry air to run your handpieces.  Debris in the air can clog the lines impeding air flow and reducing pressure. Debris can also wreak havoc on the delicate components of your dental handpieces (particularly the bearings). While having a lesser impact, the same can be said of water in the air lines. Make certain your air is properly filtered and the filters are well maintained. Make sure to check your compressor regularly (see issue #34 On Routine Office Maintenance) and be attentive to the quality of air coming out of your unit. Small problems can turn into big ones if ignored for too long; just as a small cavity can lead to a root canal if ignored for too long.

Air pressure will also influence torque, but more is not necessarily better. Once again, dental handpieces are precision-engineered instruments designed to operate under very specific conditions. While turning up your air pressure may give you more torque, this may also stress the components giving you shorter turbine life. In addition, under extreme pressure turbines can stall out (analogous to flooding the engine of your car). Just as many cars are designed to get their best mileage at a certain speed, many dental handpieces are designed to yield the best performance at a certain air pressure. Check with the manufacturer of your dental handpiece for their recommendations.

Drive air pressure (& thus, torque) can also be affected by exhaust. If your dental handpiece isn’t properly exhausting, this can cause back-pressure reducing the net pressure on the impeller (or even counter pressure) having a significant effect on torque. Most dental units (“bracket tables”) and dental handpieces in the United States use a standard ISO-B (or ISO-C) coupler (see Issue Tech Tips #36 “ABC’s of ISO” for more information on couplers) which will allow the exhaust to flow back into the unit. Make certain that this line is kept clear and open and is free of kinks or obstructions. Air which is properly exhausted will flow over the impeller better, also yielding more torque.

While the impeller and bearings can have an impact on torque, the other components of the turbine should not have much impact. The spindle (central shaft) of the turbine simply provides a location to mount the bearings and impeller and holds the chuck which in turn holds the bur. A worn spindle could affect the balance of the turbine which would result in a loss of torque (and wear to the bearings), but a spindle in good condition should have almost no impact. As the chuck resides in the center of the spindle, it has just as much effect on torque as the spindle. The main impact on performance from the chuck would be poor bur retention. While this wouldn’t directly affect torque generated, this would impact the transference of torque to the bur (as the bur slips) so you would have a net reduction of applied torque.

Test for good bur retention every time you use your handpiece (just tug on the bur a little). You should also clean the chuck (if a push button or lever handpiece) as part of routine maintenance. If using a chuck with a wrench (aka standard chuck), you can unscrew the chuck from the back of the turbine to inspect it. A properly functioning chuck should have no jagged or irregular edges and should be split evenly at the end. With wear, the chuck will often lose a piece at the end (which will affect bur retention).

As you can see, a number of factors can impact the torque of your dental handpiece. Keep an eye on your air, make certain to perform routine maintenance, and always test for good bur retention and you should get great performance from your dental handpieces.

Their comprehensive courses will cover everything from simple to complex. Learn techniques for removing teeth with minimal trauma and how to handle complications if and when they arise.

Techniques in delivering anesthesia, suturing, as well as using the physics of various instruments to make your job easier will all be discussed.

There will be 16 hours of lecture discussing everything you need to know to up your extraction game and handle any possible complications.

In addition, over the four day course there will be 24 hours  of hands-on work with patients in need of care, so you’ll receive a total of 40 hours of PACE credit. These are poor people in remote areas who are otherwise unable to receive care. Receive a great learning experience while delivering humanitarian aid to these unfortunate souls.

E-mail info@amerdental.com for more information and to get on the sign-up list now!