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The first step in this process is to establish what will be called our control film. To do this we will take a pan/ceph cassette load it with film and place it on the floor with the side that normally faces the pan or ceph head facing up in a room where we can aim an intra-oral head down at it. We will place our aluminum stepwedge on top of this cassette in one corner. Using something convenient like a yardstick, position the tube head 30 to 36 inches away from the cassette but directly over it facing down. The only reason for the distance is to make sure we have enough radiation spread to expose the whole cassette. Set the timer on the X-ray to a low setting somewhere around 8 pulses or .13 seconds @ 70kVp & 7mA. Make an exposure and process the film. When the film is out of the processor, there will be steps of increasing density on the processed film and one step will have a clear dot as a marker. What we want to see is that the bar with the dot on it is at about 1.0 Optical Density (O.D.) To determine the density we will use the medium of newspaper print. Taking the newspaper, lay it on top of a counter and place the processed film on top of the newspaper. One Optical Density is determined to be the density where you can just barely read the newspaper print through. If the bar with the marker is lighter than one O.D. then you will have to increase the X-ray timer and try this again. If the bar with the marker is darker than one O.D. then you will have to decrease the X-ray timer and try again. When you finally have a film that matches one O.D. at marked bar then you need to record all of the settings that it took to make that film; (Timer setting, which X-ray unit, which cassette, at what distance.) You will need to save this control film for daily comparison.

Now, daily you will take the same X-ray unit, the same cassette and make an exposure at the timer setting you used to get 1 O.D. at the bar with the marker on it. Process that film and lay it and the control side by side. They should be identical. If not, the test is telling you that you have a problem with your processing. It could be bad chemistry, over or under heated chemistry, bad process timing, light leakage, or replenishment problems. You should keep these films for at least three months. Now in addition to keeping the films you should set up a sheet for daily record keeping. I recommend a graph that has 1-31 on the X-axis representing the days of the month, and numbers from -5 lighter to 0 to +5 darker on the Y-axis. Each day when you take a stepwedge test film and compare it to the control. If they are equal you record a zero. If the test film is one step darker you would record a +1 and so on. Your safety zone is about -1 to +1. If you show further deviation than that you had better check your processor to ensure that it is working properly.

An Aluminum Stepwedge (Part# 608111) is available direct from Cone Instruments @ 800-321-6964 and costs under $60. (They will request a credit card payment.)

Crabtree Quality Control

This test is required on all Peri-Pro or manual processors and is required if the office does not have a pan or ceph cassette available for quality control testing. The front of the device looks like this:

The directions on this testing device are very good. The basic process involves inserting an un-exposed intra-oral film beneath the copper square. You bring an intra-oral X-ray head down on the device so that the cone covers the copper square. You then expose the film using normal settings and time for a posterior bitewing. After processing the film, it has a density on it. Take the Crabtree device and flip it over. The back looks like this:

The exposed film gets inserted on the top and a slider with different comparative densities that are numbered gets moved back and forth until they match the exposed film?s density. You record the number. If processing is working and your technique is normal the device should match the test film on a 3, 4, or 5. This test is a simple fast, cost effective way to check your processor for proper operation.

The Crabtree Device is available directly from Xray QC @ 970-470-0859 or you can visit their website at http://www.xrayqc.com/

Handpiece Repair

Handpiece Repair

R-Tech Dental is
Handpiece Experts Certified!

We service KaVo, Lares, Midwest, Star, W&H, and many other electric handpieces, highspeeds, slowspeeds, and scalars using manufacturer specific parts with factory warranties.

We offer VERY FAST and COST-EFFECTIVE handpiece repair!

We want to make the repair process for your handpieces as easy as possible. Below are some simple steps you can follow to ensure your handpiece(s) get to us properly, they get repaired the way you want, and that we get them back to you as quickly as possible.

Step 1 Fill out the order form.	Either download the Handpiece Repair Form. If you do not have Adobe Acrobat, you may download it from directly from Adobe Systems.	Or you can complete the Handpiece Repair Form to the right, from within the R-Tech Dental website.
Step 2 Prepare a Mailing Label	Print the Mailing Label.	Affix label to your mailing box and send it to us via USPS.
Step 3	Complete a Postal Service For 3811 if you would like a Return Receipt.

Call 800-880-4957 with questions, or to place your order.

R-Tech Dental Handpiece Services
16 Taylor Street
Chippewa Falls, WI 54729
800-880-4957

Check Valve Retraction

Today, Penny, from Dr. Tim Flor's office in Waseca, told me that she attended a seminar where they suggested that all units be checked to make sure that the handpiece hoses have check valves installed to prevent retraction of liquids from the patients mouth.

Check valves do serve a purpose when they work. Check valves are designed to only permit the flow of air or water in one direction. There is normally a small arrow stamped on their exterior that indicates which way flow will be permitted. They are installed on each water bearing handpiece line within a delivery unit. Check valves are usually constructed of either a small piece of rubber tubing that is pinched flat on one end (A duckbill valve) or they are constructed using a small ball bearing, a spring, and an o-ring.

Penny wanted to know if I felt that it was necessary to have them inspected and to have new check valves installed. My thoughts on check valves are as follows:

PROS:

Check valves do prevent backflow from the patient when they are working properly. This helps prevent additional bacteria contamination of the unit.
They are necessary in some applications such as flush toggles on delivery units, or cavitron dual select devices that allow for selection of different medicaments.

CONS:

The check valves tend to get a contamination within them that causes them to leak thus defeating their originally intended purpose.
Check valves tend to clog preventing all flow of water to the handpiece.
As they are "anti-retraction" devices, they tend to not allow the water to drawback upon termination of a foot pedal depress. This means that a small amount of water dribbles from the end of the handpiece everytime you stop.
They really need to be checked every 6 months to see if they are retracting and should be replaced if they are.

Here is a picture from a microscope showing a check valve that has failed due to buildup of bacteria on the surfaces of the duck bill valve:

If you would like, we can check your delivery system handpiece hoses for retraction and offer suggestions. Check valves do work, but they do go bad and must be replaced regularly if you intend to reap the benefits that they provide. A strict regiment of waterline disinfectant use (such as Mint-A-Kleen) will help extend the life of your check valves.

Crabtree Quality Control

Handpiece Repair

Check Valve Retraction

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