In part two of her article, Dr Paroo Mistry looks at two other X-Rays that may be taken when planning orthodontic treatment.
Part one can be viewed here
Upper Standard Occlusal
This X-ray is taken with the same X-ray machine used to take bitewings and periapicals, which you may have experienced at your dentist. This time the patient is asked to bite onto an X-ray film and the X-ray tube is then positioned pointing down through the bridge of the nose and onto the X-ray film. This is much more comfortable than a bitewing or periapical as the film fits comfortably between the top and bottom teeth. This X-ray is a detailed view of the roots of the top front teeth. I take this view in a lot of my cases. This allows me to check if there is any pre-existing root shortening of the front teeth. If the ends of the root are ‘blunt’ or a ‘pipette shape’ then there is some evidence to show that they may be more susceptible to root shortening during brace treatment. If I suspect that the patient may be slightly higher risk, then I would repeat this X-ray during treatment to monitor the roots. I would always take this X-ray if the patient reported a history of trauma to the upper front teeth any time in the past.
This X-ray is taken on a large X-ray machine, similar to the OPG machine. This time the patient is asked to stand up straight and small rods are placed in the patient’s ears to help support them in the correct position. It is important to bite your teeth together when the X-ray is being taken (unless you are specifically asked to bite in a different position). This X-ray is a side view of the skull. It allows me to assess the position of the lower jaw relative to the upper jaw. In orthodontics, we can only move the teeth within the bone; if the bone is in the wrong position then it becomes much harder to correct the bite.
Whenever I take this X-ray, I identify specific landmarks on the picture and I use these points to record certain measurements. I then compare these measurements to average values that have been published in the literature so I can see how the patient compares to ‘average’. The key features I look at on this X-ray are:
- The position of the top jaw compared to the lower jaw. The ideal is when the lower jaw sits just behind the top jaw. However some people may have a prominent chin and a reverse bite where the lower front teeth bite in front of the upper front teeth. I can use this X-ray to see how much of this reverse bite is due to the position of the jaws. If the measurements are far off average, then I may not be able to correct the bite with braces alone. These patients are best treated with a combination of brace treatment and surgery to reposition the jaws.
- The angle the top teeth are relative to the upper jaw bone, and the angle the lower teeth sit relative to the lower jaw bone. Again we compare these angles to the ‘average’ values. If the angle I measure on the X-ray is significantly higher than average, then it tells me that the teeth are at maximum capacity within the bone so if there is crowding then I may need to extract teeth to provide space to straighten them. Conversely, if the angles measure up much less than average, then I may be able to avoid extractions and simply put the braces on and let the teeth come forward as they straighten.
So to conclude, the X-rays I choose to take when I am planning treatment depends on the patient and the findings in my initial clinical examination. However, given the information I could be missing without X-rays, I would not want to start treatment without viewing any X-rays at all. In some cases, after seeing the X-rays, I may decide that treatment would not be suitable for the patient as the risks outweigh the benefits. In other cases, I may have to manage the treatment differently or have different treatment goals. Either way the patient is fully informed and there are no surprises along the way.
I’m very grateful to Dr Paroo Mistry for writing these articles for my blog and I’m sure you will see more articles from her appearing in the future.
Dr. Paroo Mistry is the Specialist Orthodontist at Oakwood Orthodontics as well as a Consultant Orthodontist at Chase Farm Hospital in North London.