There are three things to get right in positioning you for an X-ray:
They are: the X-ray beam, the object in question and the film.
The dentist will set these up to get the most accurate image possible. This is often aided by using an X-ray holder, which is specially designed to line everything up. This allows detailed comparisons to see how, for example decay has progressed in your tooth
over the period of say a year.
, a soft paper tab can be used to bite on but the special holders remain the most accurate and best way to take X-rays. Sometimes the dentist will ask you to hold the film with a finger instead- for example, it may be difficult for you to tolerate the holder or it's a tricky angle and not a lot of space in your mouth.
This is known as the ‘bisecting angle technique’- a fancy name for the way they manually position the X-ray and film to obtain a good image of the tooth. The dentist must judge the different angles correctly in order to capture an accurate image of your tooth. If the angles are not correctly calculated, the image of the tooth can be stretched or shorted.
Small X-ray films are placed into a holder that is put in the correct position in your mouth and you are asked to gently bite down to hold it in place. It's not particularly comfortable, but it's only for a second or two. Different holders are used for bitewings and Peri-Apicals.
As a general rule we have two sizes of X-ray film; a standard size and a small sizeused mainly for kids and for patients who cannot tolerate the larger one because of a gagging problem.
The dentist sets the exposure depending on your age and jaw structure, aligns it with the holder, steps out of the room and presses the button. You need to hold really still after the X-ray machine is positioned, which is only for a couple of seconds, during which you will hear a beep. The beep lets you know the X-ray is being taken.
Before taking the X-ray if you have a cobalt chrome partial denture
you will need to remove it otherwise the metal will prevent the dentist from being able to see the teeth.
For an OPG
, the dentist or radiologist will position you in the machine and get you to pop your chin on the chin rest, tilt your head forward to the head rest and bite gently on a tab. It is important to remove all earrings and metal objects like dentures or piercings (fillings are ok haha), or these will show up big and bright and can make the X-ray more difficult to read.
The machine will rotate around you for about 15 seconds during which time you need to stay nice and still or the image can turn out blurry.