Why do I need to have X-rays taken?

Dental X-rays are needed to help the dentist complete the picture of your mouth. They show the dentist the areas which they cannot otherwise see. Most commonly this is the roots of your teeth, the bone that supports them and directly in-between your back teeth.

Dental X-rays can help the dentist find and treat problems early on, before they have chance to develop into something more serious, saving you time, money, inconvenience and pain. They provide extra pieces of the puzzle to which the dentist adds information from the examination, to determine an accurate picture of what is actually going on.

They may be taken for the following reasons:

• Screening. Routine screening views (taken according to your caries risk) can pick up early signs of tooth decay or gum disease.

• Diagnosis. To help provide the dentist with extra information to diagnose your problem.

• Treatment. As part of treatment for:

(i) Root canals
(ii) Implants
(iii) Wisdom teeth
(iv) Fillings
(v) Gum disease
(vi) Crowns
(vii) Trauma
(viii) Extractions
(ix) Orthodontic treatment

When do I need to have X-rays taken?

Your dentist will review your history, examine your mouth and decide whether or not X-rays are necessary for any of the reasons above.

It is ultimately your decision as to whether you decide to have X-rays, but without them the dentist may not be able to diagnose or treat your problem effectively.

We don’t need to take X-rays of the front teeth to check for decay (un-like with the back teeth) because they are thin enough that when we shine the dental light off our mirror, we can detect if anything is going on. We call this process called ‘trans-illumination’.

What about Screening X-rays? How often do I need them?

How often X-rays should be taken as part of routine checkups depends on your risk of having problems and the likelihood of the dentist finding something that needs treatment.

The Australian Practical Guidelines for assessing dental caries (decay) in-between the back teeth suggest the following intervals:

• For children 12-24 months
• For adolescents 18-36 months
• For adults 24-36 months

The FDA in America has similar guidelines for the low risk group, but ‘recall patients with clinical caries (that is visible decay in the mouth) or increased risk of developing caries’ are as follows:

• For children 6-12 months
• For adults 6-18 months

With regards to periodontal (gum) disease, the decision is left up to the dentist to decide if and when X-rays are necessary, but radiation exposure should be kept to a minimum.

These routine X-rays are assuming that you don’t have any signs or symptoms of dental disease or anything that looks suspicious and needs further investigation. In such circumstances, or if you are undergoing treatment that requires it, X-rays will be need to be taken.

If you are high risk, then the likelihood of finding new problems is high and bitewing X-rays may be needed as often as every 6 months. If you carry on like this, it is a slippery and expensive slope of fillings, root canals, crowns and down the track- extractions and dentures. It is important that you actively take steps to lower your risk and try to prevent this from happening; we will discuss this in the next section.

If you are low risk, and see the dentist regularly, then they may only be needed every couple of years (this is the case for most of my patients).

If you are a new patient, the dentist may recommend you have X-rays at your first visit to provide a more comprehensive initial examination and to act as a baseline for changes that may occur over time.

Generally, if I have a new patient who has had X-rays taken only 6 months ago at another practice, I will either request the X-rays be sent across to us or, assuming everything was fine, I would simply talk to them about the importance of why we need them and recommend retaking them in 12-18 months time. If I find something suspicious during the examination, they may. of course, need to be taken.

I have heard of dentists pressurising patients into having X-rays by commenting, “How am I supposed to do a proper examination if I don’t take them every time?”

In general, caries (decay) and the bony changes seen in gum disease progress slowly and so X-rays are not necessary at every 6-month check-up. They are definitely not needed twice a year- if every-time you have them- the dentist says, “Yep! They are fine!”

If you are unsure why the dentist wants to take X-rays…. Ask!

What influences your Screening X-ray Interval?

The biggest factors that influence your risk, therefore how often your screening X-rays should be taken, are:

• Your Diet.

High sugar diets that include frequent sugary snacks and drinks place you at high risk.

• Your Hygiene.

If you are not able to effectively remove plaque and bacteria from around your teeth and gums for whatever reason- be it laziness or because you are medically compromised, then you are more likely to develop problems. Adding anything to your mouth such as a partial denture or braces, even something as simple as a dental bridge will tip the balance towards higher risk, so it’s really important to take extra care with your hygiene.

Other factors that affect your risk include:

• Susceptibility (your genes). Some of you are simply more resistant to developing problems, be it decay, gum disease or both. This may be due to less virulent bacteria in your mouth, stronger immune responses to infection, or more resistant enamel. There are few publications stating this- it is just what I have observed over the years.

• Health.Your general state of health is obviously a contributing factor.

• Medical conditions. If you suffer from certain medical conditions that affect your ability to keep your teeth clean, you are at risk. Examples would be any kind of physical handicap, debilitating arthritic conditions, stroke patients or carpel tunnel syndrome- which may make grasping and manoeuvring a toothbrush difficult. Mental problems that prevent understanding the importance of cleaning, or that cause you to forget to clean, such as dementia and Alzheimer’s would also put you in the high-risk category. If family or friends are diagnosed with any similar conditions, it can suddenly make keeping their teeth clean very difficult- please be aware and take the necessary steps to ensure they are cared for. Watch out for ‘sugar based’ medicines and swap them for ‘sugar free alternatives’, particularly if taking them for the long term.

• Immune response. If you suffer from a condition such as HIV, neutropenia, uncontrolled diabetes, or take immuno-suppresssants of any sort, your body’s ability to defend itself is reduced. This can affect your saliva, your resistance to decay and leave you more prone to gum disease.

• Poorly formed teeth. If your teeth don’t form properly- either the enamel layer (amelogeneis imperfecta) or the dentine layer (dentinogenis imperfecta)- then the teeth are more at risk of getting problems.

• Dry mouth. (Xerostomia). Saliva is our natural protection against acid and helps clear and breakdown food debris. A lack of it gives you what is known as dry mouth, which leaves you more prone to dental caries. You will often be aware if you have dry mouth- it can be a significant problem. The quality and quantity of saliva you produce can be affected by medication, (some antidepressants, anti-anxiety drugs and antihistamines), radiation to the head and neck, Sjögren’s Syndrome, or damaged salivary glands.

• Age. Children and seniors tend to have more erratic routines and diets higher in sugar. During development, children may need X-rays more frequently to assess their teeth and jaws. Teeth are most vulnerable to decay when they first erupt, because the outer enamel is very immature. Diet and brushing is also more difficult to control with children, which leads to more frequent problems.

• Current disease. If you have active decay or gum disease in your mouth, this signifies high risk.

• Past disease. If you have had a lot of dental work such as fillings, root canals, extractions, crowns etc. it tells a story that you were once high risk. Now circumstances may have changed for the better- cleaning routines and diet may have improved, but the chance of getting a problem with a treated tooth is still more likely than a healthy natural tooth- be it ‘new decay’ or ‘failure of the filling’. Insurance companies understand this and some decide on the premium you pay based on the amount of work you have already had done on your teeth. This is generally a good indication of your future risk.

It is important to understand that just because you have a high sugar diet or lots of plaque around that you won’t necessarily get dental caries, but the chances are much greater- hence the phrase is ‘high risk’ and not ‘caries pending’. It is a combination of all factors and believe me, you want to do all you can to stack the odds in your favour.