Who should hold the film in a patients mouth if the patient is unable to do so

I am a dentist working in a dental clinic in India. I take nearly 5 to 10 dental x rays every day and hold the film in the patient's mouth while I'm taking the x ray. I am hoping to conceive in the near future. How safe for my child is my professional exposure to x rays? Can I continue with the job after conceiving?

The usual procedure for taking dental x rays is to have the operator stand behind a barrier wall or at least stand six to eight feet from the patient when actuating the x-ray machine. A bitewing x-ray film is used. The technician or dentist places the dental x-ray film in front of the tooth or teeth to be x rayed. The patient clamps down on the bitewing and the operator steps out of the room or steps back six to eight feet and clicks the shutter of the x-ray machine. In this manner, the operator is exposed to a minimum amount of scatter radiation and the embryo, for practical purposes, will not be exposed at all. When you are pregnant, or planning to become pregnant, you could wear a lead apron, but it really would not be necessary. In modern dental practice, I do not believe that anyone should be routinely holding the film in a patient's mouth several times a day.

Robert Brent MD, PhD

Answer posted on 12 January 2010. The information posted on this web page is intended as general reference information only. Specific facts and circumstances may affect the applicability of concepts, materials, and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice. To the best of our knowledge, answers are correct at the time they are posted. Be advised that over time, requirements could change, new data could be made available, and Internet links could change, affecting the correctness of the answers. Answers are the professional opinions of the expert responding to each question; they do not necessarily represent the position of the Health Physics Society.

Dr. Fraser Hale, a Board-certified veterinary dental specialist in Guelph, Ontario, has been providing referral dental services for the past 26 years. He is active as an invited speaker at national and international conferences and has several publications in journals and textbook chapters.

Copyright and/or publishing rights held by the Canadian Veterinary Medical Association

It is axiomatic to a veterinary dentist and to an ever-growing number of general practitioners that whole-mouth intra-oral dental radiographs are an absolutely essential part of the minimum database for all dental patients as are intraoperative and postoperative images. There are several excellent textbook, journal, and online resources on the subject but there are a few lesser-known tips and tricks that will be the focus of this column.

Patient positioning

I suppose there is no right or wrong answer here, just personal preferences. That said, I have a very strong personal preference for doing all of my dental work with the patient in passive, lateral recumbency. I think it is physically and physiologically easier on the patient and it works very well for me. I tend to start with the patient lying with their right side up. I radiograph and examine the right side, then turn the patient over (turning belly-under) to radiograph and examine the left side. This requires no positioning troughs or sand bags or tie-downs and does not restrict respiratory movements.

Contamination barriers

Oral and dental surgeries are “dirty” work in that the oral cavity is always heavily contaminated. While achieving or maintaining sterility in the operative field and work area is not possible, it is very important to do all we can to avoid cross contamination between patients. Therefore, all dental equipment and materials ought to be autoclaved between cases, used once and discarded, or covered by a disposable contamination barrier. Many items such as instrument trays, air-water syringes, and X-ray tube heads cannot be autoclaved or discarded so they need to be covered with a disposable plastic contamination barrier. These items are available in various shapes and sizes from any number of human dental supply companies. Figure 1a shows our X-ray tube head covered by a clear plastic contamination barrier bag. As I position the tube head during surgery, I only contaminate the disposable barrier, which is changed between cases to avoid cross contamination. Figure 1b shows a self-adhesive sheet of plastic that can be placed over the control panel and activator switch for the same purpose — to keep the machine clean and to avoid cross contamination between patients.

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Figure 1a

Disposable contamination barrier sleeve over X-ray tube head.

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Figure 1b

Disposable contamination barrier sheet over control panel on X-ray generator.

When using a digital intraoral dental radiographic sensor, it needs to be protected from contamination. The long, narrow contamination barriers intended for use on the air-water syringe of your dental cart work well for this. Just put the wired sensor in one of these long clear plastic sleeves for protection from contamination. We take it one step further. The digital radiography (DR) sensors are almost all black. It is dark in the mouth, so seeing the sensor in the mouth (to aim the tube head at it accurately) can be tricky. To make it easier to see the sensor, we cover it with a latex finger cot. This adds another layer of protection against contamination as well (Figure 1c, ​,dd).

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Figure 1c

Top, a box of air/water syringe covers. Bottom right, a box of latex finger cots. Bottom left, the digital dental X-ray sensor in its natural state.

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Figure 1d

The digital dental X-ray sensor all dressed and ready for action.

When using phosphor sensor plates (PSPs, computed radiography), the image (blue) side of the sensor plate needs to be kept free of contamination not only to avoid spread of pathogens between patients but also so the scanner can read the latent image from the plate. If there is blood or other foreign material on the blue side of the plate, this will show up as a white artifact on the image. Therefore, PSPs must be placed in sealed, disposable contamination barriers. It seems odd that I would have to instruct you to seal these little envelopes, but I have received images from clinics that were attempting to economize by not sealing and then reusing the envelopes. Blood and other oral fluids would leak in, contaminate the image surface, resulting in so much artifact on the images that they were barely readable (Figure 1e).

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Figure 1e

A radiograph of the left caudal maxilla of a dog with a great deal of contamination on the sensor plate, resulting in a non-diagnostic image (waste of time, money, and radiation exposure).

No matter how careful you are, your Phosphor Sensor Plates (PSPs) may occasionally pick up some contamination. This can usually be removed by wiping with 99% rubbing alcohol and a gauze square.

Sensor positioning aides

Whether using analog film, wired sensors or PSPs, you need to hold these items in the mouth in their proper position during exposure. There are various acceptable ways of holding dental films/sensors in position in the mouth and none of them involve anyone’s hands being anywhere near the patient during exposure. For me, the best thing to use to hold the film/sensor in place is a piece of paper towel. It is inexpensive, readily available, clean, disposable, and infinitely adaptable to any shape/size of mouth.

The occlusal view

Most references teach 2 basic intraoral techniques. The parallel technique is used to image the mandibular molars and some of the premolars. The bisecting angle technique is used for the rest of the teeth. Another very useful technique is the occlusal view. This is mostly used for images of the maxilla and to look for/localize retained root remnants or as a post-operative view to confirm complete extraction of the teeth in question. To obtain an occlusal view, the film/sensor is placed in the mouth parallel to the hard palate and the X-ray beam is directed perpendicular to this in a simple dorso-ventral projection. In Figure 2a, of a dry-bone skull, I have removed the right upper 4th premolar, then placed a radiodense probe in one of the sockets, but which one? Is that “root” in the buccal or palatal socket? In Figure 2b of an occlusal view of the area, we can see that the “root” is clearly in the palatal socket and so now we know where to go to get it out. Figure 2c is an occlusal view of the right caudal maxilla of a Pekingese dog, taken after I had thought my extractions in this area were complete. As you can see there are remnants of the mesial and distal roots of the 1st molar still in place (the 2nd molar was absent from this mouth upon presentation). Having identified that the extraction of the 1st molar was incomplete, I went back, found and removed the root remnants and re-radiographed to confirm and document their complete removal before closing the wound (Figure 2d).

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Figure 2a

A bisecting angle view of the right maxilla in a dog skull after removal of the 4th premolar tooth and placement of a radiodense object in either the mesiobuccal or palatal sockets. How can we determine where this errant “root” is located?

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Figure 2b

That same area as viewed using the occlusal view. Now it is very apparent that the “root” is hiding in the palatal socket. Identifying where the root tip is is the first step in removing it.

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Figure 2c

Occlusal view of the right maxilla of a Pekinese dog following extraction of the remaining teeth. But wait, there are remains of the mesial and distal roots of the 1st molar tooth still clearly present in their sockets.

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Figure 2d

Occlusal view of the same dog after retrieval of the retained root remnants. Now that their complete removal has been confirmed and documented, the wound can be closed.

While mainly used for maxillary structures, the occlusal view can also be useful for localizing mandibular structures in the third dimension.

Separating the roots of the upper fourth premolar teeth

The upper fourth premolar teeth in dogs and cats have 3 roots known as the distal, mesiobuccal, and palatal roots (Figure 3a). Depending on the precise alignment of the palatal root relative to the mesiobuccal root, the 2 may be superimposed one over the other in a standard lateral bisecting angle intra-oral projection. To separate the roots on a radiograph, we employ parallax shift.

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Figure 3a

Plastic model of the right upper 4th premolar tooth in a dog identifying the three roots.

To visualize parallax shift, imagine standing at the side of a very straight road, with a telephone pole 3 m in front of you. As you look at the first pole, you cannot see the next pole because it is hiding behind the first one. If you take a few steps to your right, you will be able to see the next pole in the line and it will appear to have moved to the right with you as the nearest pole will appear to have moved to the left, relatively. The SLOB rule stands for, “Same Lingual, Opposite Buccal” and means that if you move the X-ray tube head toward the nose to do a rostral-to-caudal oblique view, the root that seems to have moved toward the nose as well (the root that moved in the same direction) would be the lingual (or palatal) root and the root that moved in the opposite direction (towards the tail) would be the buccal (mesiobuccal) root.

All of that is well and good, but here is another way of figuring out which root you are looking at. Your right hand can act as an analog for the right upper 4th premolar. Hold your right hand up with your thumb to the left and the first 2 fingers to the right and fold your 3rd and 4th fingers in (Figure 3bi). Your thumb represents the distal root, your first finger represents the mesiobuccal root and your second finger represents the palatal root. If you look at your hand straight on with only 1 eye, you can see the distal and mesiobuccal roots but cannot see the palatal root (hiding behind the mesiobuccal). Move your head (analog for the X-ray tube head) to the left to mimic a distal to rostral oblique projection. Now you can see the palatal root in between the other two. Next, move your head to the right, mimicking a rostral to distal oblique projection and it is the mesiobuccal root that appears between the other two. Use your left hand when imaging the left upper 4th premolar tooth.

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Figure 3bi

My right hand acting as an analog for a right maxillary 4th premolar tooth. My thumb represents the distal root, my index finger represents the mesiobuccal root, and my second finger (which cannot be seen because it is hidden behind my index finger), represents the palatal root.

The almost parallel technique

The domestic cat has a very prominent zygomatic arch. When using the standard bisecting angle technique for imaging maxillary premolars and molars in a cat, the arch is superimposed over many of the teeth, making it difficult to make an accurate diagnosis. One option to try to mitigate this concern is to employ the “almost parallel technique.” To do this, the sensor is placed in the mouth against the palatal aspect of the down-side teeth and basically parallel to the crowns/roots of the up-side teeth (Figure 4a) and the tube head is directed as seen in Figure 4b.

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Figure 4a

A dry bone cat skull with a PSP sensor plate (left out of its contamination barrier sleeve for visual clarity) placed against the palatal side of the down-side (left teeth) and parallel to the crowns of the up-side (right teeth). The X-ray tube head is angled “almost parallel” to both with the objective being for the beams to sneak under the arch to give a relatively clear view of the teeth.

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Figure 4b

A view of the right maxilla in a cat using the “almost parallel” technique. The zygomatic are is visible but so are all roots of these teeth.

Finding the 3rd molar

In small dogs, brachycephalic dogs, and especially small brachycephalic dogs, it can be a challenge to get the sensor distal enough to get an image of the mandibular third molar (or to prove that it is absent) using the usual parallel technique. When faced with this I will place the sensor as deep in the mouth as I can (sometimes partially down the throat) and then angle the X-ray beam from caudal to rostral. I am not trying to get a pretty image of the third molar, I am just trying to determine if it is present or not (Figure 5).

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Figure 5a

This parallel technique view of the left mandible in a mature pug does not really make it clear if the third molar is present or not.

Labels

When using digital radiography (DR) or computed radiography (CR) systems, the software allows you to place text information right on the images. This is useful but can also be a liability depending on how you use it.

Within the software, there will be an area that allows you to dictate what information will appear on the label on each image. I like to go minimalist here. I do not need my clinic name on the images, so I leave that off. I prefer not to use patient or owner names on the labels either. Instead I use the patient number. That way, I can share the image on VIN (Veterinary Information Network) or social media without violating client confidentiality. Also, a patient number takes up less space on the image. I will include time and date of the image as well as a notation regarding the anatomic region shown in the image. I place the label in a corner of the image where it will not be covering any diagnostically valuable information and select a font size and colour that allows it to show up well (Figure 6).

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Figure 6

An image of the left mandibular premolars with the label positioned away from any diagnostically useful information. The use of the patient ID number lets me know who this is but I can still share it without violating client confidentiality.

Orientation

Interpreting intraoral dental radiographs (any radiographs for that matter) is easiest when the images are oriented in a consistent and logical fashion. Position the images as if you are standing in front of your patient, looking them in the face. The right teeth are on your left, the left teeth on your right. The crowns of the upper teeth point down and the crowns of the lower teeth point up. It will make your life easier if you always rotate the images into this orientation before trying to interpret them (Figure 7).

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Figure 7

A partial study (on analog film) of a 5-year-old toy poodle with massive periodontal disease. The images have been oriented and arranged in the proper fashion with the dog’s right teeth to our left, left teeth to our right, upper teeth pointing down and lower teeth pointing up.

How to get to Carnegie Hall

I am referencing an old joke here about a tourist stopping someone (who just happened to be a musician) in the street in New York City to ask, “How do you get to Carnegie Hall?” and the answer offered was “Practice, practice, practice!” So it is with getting diagnostic intraoral dental radiographs in an efficient manner. It is a learned skill that can only be learned by doing it over and over, day after day, not periodically on the occasional case. This is just one of the many reasons for doing whole-mouth studies in all of your dental patients, not just the ones with obvious deep pathology. It will not only help you improve your speed and accuracy in getting the images, it will also help you with your interpretation because reading dental radiographs is also a learned skill best honed through constant practice.

One way to speed the process of getting your whole-mouth study completed is to have one staff member doing the radiographs while another is getting the anesthetic monitors connected to the patient. When using our Computed Radiography (CR) system (that is the one using the PSPs), we use a 3-person team (P1, P2, P3) like this. As soon as the patient is intubated and in lateral recumbency, P1 starts to attach the various anesthetic monitors, P2 places the sensor plate and aims the tube head for the first image, we all leave the room to expose the image. We go back in, P1 resumes setting up the monitors, P2 hands the first plate to P3 and sets up for the second shot while P3 feeds the first plate into the scanner, we all leave the room and expose the second plate. We go back in, P1 resumes getting the patient monitors set up, P2 passes the second plate to P3 who puts that in the scanner, while P2 sets up the third plate for the third image. And so it goes until all images for the right side are done. Then we flip the patient and repeat.

It only takes 2 people to use the DR system (the wired sensor). P1 sets up the monitors while P2 sets up each image and both leave the room as each image is exposed.

Another key is to not stress too obsessively about getting the angle perfect every time. It is common for neophytes to spend an inordinate amount of time trying to line everything up just right before exposing the shot and often the adjustments they are making are so small they would have no significant effect on the diagnostic quality of the image. Sometimes the best move is to just shoot the image and see what you get. If it is no good, you can always try again.

It is an excellent idea to obtain a cadaver specimen or dry bone skull and set aside a good chunk of time to just practice when there are no concerns about anesthesia, cost, radiation exposure, or any of the other distractions of working on a live patient.

A reasonable goal to aim for would be to be able to complete a whole-mouth series in a cat in under 10 minutes and in a large dog within 20 minutes.

Conclusion

In conclusion, intraoral dental radiography is very quickly becoming standard of care and so if you have not already embraced it voluntarily, you will likely be compelled to in the near future. Once you fully incorporate intraoral dental radiography into the management of your dental patients, you will wonder how you ever got along without them.

“The winds of change are blowing. You can tie yourself to a tree or build yourself a kite.”

​

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Figure 3bii

A radiograph of a right maxillary 4th premolar tooth with a clear view of the distal root to the left and mesiobuccal and palatal roots superimposed one over the other to the right. In this view, neither of those roots can be seen clearly.

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Figure 3ci

I have moved my head (camera) to the left, mimicking a caudal to rostral oblique projection. As my head moved left, it appears that my second finger (the palatal root) also moved to the left and we can now see it between the other two “roots.”

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Figure 3cii

A radiograph of the right maxillary fourth premolar tooth in a dog shot in a caudal to rostral oblique direction. From left to right we see the distal root, the palatal root and the mesiobuccal root.

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Figure 3di

Here I have moved my head (camera) to the right, mimicking a rostral to caudal oblique projection and my second finger (palatal root) is now visible to the right of my index finger (mesiobuccal root).

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Figure 3dii

A radiograph of the right maxillary fourth premolar tooth shot in a rostral to caudal projection. From left to right we see the distal root (partially hidden behind the first molar tooth), the mesiobuccal root and the palatal root.

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Figure 5b

This caudal to rostral oblique view in the same dog demonstrated that the third molar was present, mal-oriented and unerupted. Such a tooth is at risk for the development of a dentigerous cyst and should be removed.

Footnotes

Use of this article is limited to a single copy for personal study. Anyone interested in obtaining reprints should contact the CVMA office (gro.vmca-amvc@nothguorbh) for additional copies or permission to use this material elsewhere.

How should exposed patient films be handled?

Which film holder can aid in positioning the film during an endodontic procedure?

When a film holder device is not being used what is the recommended position for the sagittal plane of the patient?

When you are placing the film packet in your patient's mouth which side of the film packet would you place toward the patient's teeth?