A hint for taking xrays

Thee places that patients have the most difficulty with handling intraoral films are any lower films due to lack of space and proximity to the sensitive tissue of the floor of mouth and upper posteriors due to gagging.

I believe I've already made a post about managing gagging with impressions and intraoral films so this will focus of xrays of the lower teeth.

The most common film including the lower teeth is the bitewing. This is an excellent tool to screen for interproximal caries, subgingival calculus and bone loss. Compared to a lower PA radiograph it is fairly well tolerated. Situations where it is not tolerated are gaggers, obese (who have significant increase in tongue size), and nervous patients who have increased muscle tone during procedures and are less likely to follow your instructions.

There are 2 options of films each with their own pros and cons:
-Thin PSP or analogue films: These tend to have sharper edges and have more issues in the feeling of cutting the floor of mouth and as they are flexible, if the patient bites on the film or has increased muscle volume or tone, this film can distort or bend and be ruined. They are less likely to bite down fully as it can cause pain to do so with the film impinging against the soft tissues
-Thicker Xray sensors: This has increased bulk and patients are more likely to gag on these and feel as though they can't fit it in their mouth. They are less likely to bite down fully as they feel like their mouth is too full

Patients must bite down fully for bitewings for adequate diagnostic information. Most of the time if patients do not bite down fully, the maxilla is properly exposed (in patients without a shallow palate) and the mandible is the side that suffers loss of diagnostic information. You will usually capture the coronal portion of the teeth above the interproximal area which is of poor diagnostic value (See below)

Patient isn't biting down fully on film. You can see the space between the upper and lower teeth a well as the lost diagnostic value on the lower teeth

PA Films will be similarly affected with a higher risk of cone cut (as you are aiming at the place the film should be as well as a loss of diagnostic value at the apex of the lower teeth

Alternatives to these films would be to order an OPG which removes the risk of gagging and film intolerance as well as the the need to bite down on potentially sore posterior teeth in a toothache appointment. This will capture a wealth of diagnostic information with the tradeoff of poorer detail.

For managing gaggers, the strategy is the same as for posterior film gaggers. Sit the patient up and have them hold their breath before biting down and while exposing the film. Another trick recently mentioned is to keep their eyes open. Apparently it is impossible to gag while your eyes are open.

For managing cutting the floor of mouth: This is a tricky area to navigate as there is a small space between the tongue and the floor of mouth that will be tolerable to the patient. Films (especially Thin ones) will cut into the floor of the mouth or be bent if placed too close to the teeth.One reason is that the hard palate is at its shallowest at that point and the film will be forced into the most moveable end (downwards) and as well as the floor  of mouth attachment is highest at this point. One way around this is to use a rigid xray film holder to avoid distortions when the patient bites down on the film unfavourably. The Rinn brand of holders for example also enclose the film's edges and take away the sharpness issue with the trade off of making the film noticeably more bulky. Films should be placed into the lingual sulcus as far inferiorly as possible then the patient asked to close down on this position. This is a more controllable way of placing the film as you can gauge the patient's discomfort with their mouth open rather than when it is closed and you cannot see whether the film is far down enough. This will also mean that the action of closing the mouth won't increase the discomfort of the patient as the film is already as far down as it will go. Patients closing to push the film down will lead to pseudo closing where only the lips are closed and not the teeth.Thicker sensors or thin sensors in relaxed patients can be placed even further on top of the tongue. This is more resilient tissue and won't be as painful to close down onto. Thinner sensors will tend to bend if this is done. When the patient bites down in this manner, the tongue will be depressed and the film exposed. This is especially desirable in shallow palate patients where the midline is the highest point that the xray can go. Due to the reduced space on top of the tongue and the increased musculature forcing the film upwards, you may find the tradeoff that some of the diagnostic value is cut off from the lower teeth however the xray is usually diagnostic and almost always better than the one shown above.

Film on the left is too close to the teeth and will cut into the attachment of the floor of mouth. Film in the centre is placed over the tongue and will depress the tongue in patients without strong muscle tone (usually only possible with sturdier xray sensors or thin sensors in certain holders). Film on the right is a thin sensor that is placed more lingually away from the attachment of the floor of mouth.

For managing the feeling of bulk in their mouth: This is more a behavioural management strategy. On one hand you can sit them up (lowers the tongue and stops the tongue dropping back to allow more room in the mouth) and support the back of their head for comfort but they will still have to put up with something foreign in their mouth. I make sure to tell every patient that it is a quick procedure and it will be in and out of their mouth very quickly. It is important to instruct them that they have to close down when I tell them till their teeth touch together. It is very easy for them to think they are closing all the way when really they are straining their lip muscles closed with the teeth apart. Very annoying for us as it means we can't retract the lip to check the teeth are fully together. A tip is for those patients (mainly female I have noticed) who when closing are in obvious discomfort, scrunching their eyes and straining their lip muscles together: Their teeth are not together. Don't expose the film but get them to open, give them a breather and try again. 

Lower PAs are similar in that the film should be placed as far down lingually as possible before the patient closes. You will be able to tell at this point if the patient cannot tolerate the film and will be forced to try alternative methods. There is more control in this method as you can pick the position where the floor of the mouth is loosest and place the film there. Alternative methods include OPG and angling the beam more steeply to compensate for poor film placement (see below). This is a compromise however and will lead to significant distortion. You can also consider the application of local anaesthetic before film placement especially if this is required anyway for the procedure

A patient who isn't biting down sufficiently will miss diagnostic information a the tooth apex with the paralleling method. To compromise, a patient who isn't biting down sufficiently for a lower pa, an extremely steep tube angle can be taken to ensure the whole tooth is captured however there will be extreme foreshortening. For critical procedures e.g surgery opg should be considered or for endodontic procedures, topical or local anaesthetic should be applied to the lingual sulcus.