How does the Dentist Read Bitewing X-rays?
The most common screening view as we have mentioned is the bitewing X-ray. I always explain to my patients exactly what it is that I’m looking for and I point out anything to note or that may be of interest.
When we assess your bitewings we are looking at the following:
We are looking for any new signs of dental decay and if some was noted last time and we decided to monitor it, then we are looking for any sign of progression. Often it helps to have the previous X-rays available for comparison- for detection and monitoring purposes.
In-between the teeth, decay presents as a small dark triangle in the outer layer of the tooth (enamel) just under where the teeth contact. It has its base at the outside and points in towards the middle of the tooth.
Decay on the tops of teeth will only be visible if the decay has progressed quite far since superimposition of enamel will mask any minor changes. It is only once it has progressed quite deep into the dentine that sufficient tooth tissue will have been lost to actually show up on the X-ray.
When the decay is only present in enamel (which has no nerve endings) (i.e. it doesn’t extend into the dentine), we have a chance to turn things around and avoid a filling– if we take the right preventative action straight away. To improve our oral hygiene, we need to introduce regular flossing, get sufficient fluoride to the area and watch the sugars we are eating.
If however the decay extends through enamel into the dentine by spreading out along the border, a filling will be required. The closer the shadow (dark area) gets to the nerve in the tooth, the deeper the filling will be and the more likely further problems will occur.
It is important to note that decay has always progressed a little further than it shows on the X-ray. This is because it takes a certain amount of demineralization, (tooth breakdown) before changes will actually become visible on an X-ray.
We can grade the level of decay as reaching:
1- Just the outer enamel
2- Up to but not through the enamel/dentine border
3- Into the outer part of the dentine layer
4- Deep into the dentine
5- All the way through into the dental pulp or nerve.
Remember, the enamel is the slightly whiter cap on the top of the tooth, the dentine is the darker layer underneath and the nerve, or pulp is the thin dark line, or lines in the centre of the tooth.
We look at all the restorations you have in your mouth; this includes any white fillings, silver fillings, crowns, bridges or implants. We are checking that the margins are ok, that there is no new decay (secondary caries) around them, or anything else which could potentially be a problem and require treatment.
- Periodontal status (checking for gum disease)
We need to check the amount of bone support you have for your teeth and see if there are any signs of gum disease. In addition we are looking for any plaque retentive factors that could be contributing to the worsening of the disease, such as calculus, poorly shaped existing fillings or crowns and decay.