Dental X-rays and OPG imaging

A visual examination shows your practitioner roughly two-thirds of each tooth. The surfaces between teeth, the roots, the bone supporting them and anything still under the gum are only visible on a radiograph.

That is why imaging is part of a thorough examination — not to find more work, but because decay between teeth and bone loss around roots are invisible until they are advanced enough to cause symptoms, by which point the treatment is bigger.

What we use

Digital intra-oral X-rays. We use phosphor plate technology rather than traditional film. It requires a lower radiation dose than the film systems it replaced, the image appears within seconds, and there are no developing chemicals to dispose of.

On-site OPG (orthopantomogram). A single image that captures both jaws, all the teeth, the sinuses and both jaw joints in one pass. Because the machine is here, we can take it during your appointment rather than sending you to a radiography centre and delaying your treatment by days.

Intra-oral camera and Diagnocam. High-resolution images of individual teeth, so you can see on the screen what your practitioner is describing. Being shown the problem is more useful than being told about it.

What a radiograph reveals

• Decay starting between teeth, where a mirror and probe cannot reach
• The bone level around each tooth — the definitive record of gum disease
• The condition of existing fillings, crowns, bridges and root canals
• Infection at the root tip
• Developmental issues — extra teeth, missing teeth, teeth forming out of position
• Trauma to teeth and surrounding bone
• The position of wisdom teeth, and their relationship to the nerve in the lower jaw

What a radiograph does not reveal

Just as important, and less often said:

• Early decay on a biting surface often does not show until it is well established — which is part of why fissure sealants exist
• A cracked tooth frequently does not appear at all, because a crack running along the line of the beam is invisible to it
• How a tooth feels — pulp health is assessed by testing and symptoms, not by the image
• Soft-tissue conditions of the cheeks, tongue and palate, which are examined visually
• Whether a tooth hurts. An alarming-looking image on a comfortable tooth and a normal image on a painful one are both common

A radiograph is one piece of evidence, read alongside what your practitioner sees and what you report. Anyone treating it as the whole answer is over-reading it.

The different types, and why we choose one

Bitewings show the crowns of the upper and lower back teeth together, and are the standard image for detecting decay between teeth.

Periapicals show a single tooth in full, from crown to root tip and the bone around it — used when investigating a specific painful tooth, or before and after root canal treatment.

OPG gives the wide view: all teeth, wisdom teeth, both jaw joints. Used for treatment planning, wisdom tooth assessment and where a broad overview is needed.

Your practitioner selects the smallest image that answers the clinical question.

What it is like to have them taken

Intra-oral images involve a small plate placed inside the mouth and held in position for a few seconds while the exposure is made. It is over quickly. The plate can feel awkward against the palate or the floor of the mouth, particularly at the back.

If you gag easily, say so before we start. There is a good deal we can do — a different plate position, breathing through the nose, a topical spray, taking the image in stages, or using the OPG instead, which requires nothing in the mouth at all.

An OPG takes about twenty seconds. You stand at the machine, bite gently on a small guide, and the arm rotates slowly around your head. You stay still and breathe normally. Jewellery, glasses and any removable denture come off first, because metal casts a shadow on the image. Nothing touches you and nothing goes in your mouth.

Children manage both well when they know what is coming. Explaining that it is a camera that takes a picture of the teeth, and that it does not touch or hurt, is usually enough.

Is it safe?

Dental radiographs use a very small radiation dose — small compared with the natural background radiation everyone is exposed to simply from living in Australia, and reduced further by digital sensors. Modern equipment collimates the beam tightly so exposure is confined to the area being imaged.

Small is not the same as zero, and we treat it accordingly. We take radiographs only where there is a clinical reason to, not automatically at every visit. Your practitioner weighs your age, your history of decay and gum disease, your current symptoms and when your last images were taken.

Two principles govern this, and they are worth knowing by name because every practice should be able to explain how it applies them:

• Justification — an image is only taken where the information it gives will change what happens next. If the answer would be the same either way, there is no reason to take it.
• Optimisation — where an image is justified, it is taken with the lowest dose that still produces a diagnostic result: digital sensors, a tightly collimated beam, the smallest view that answers the question.

If you are pregnant or think you may be, tell us. Dental radiography with appropriate shielding is generally regarded as safe during pregnancy, but routine imaging that can reasonably wait is usually deferred, and we will discuss it with you rather than proceeding by default. Where there is pain or infection, the risk of leaving it untreated usually outweighs the imaging — that is a conversation, not an assumption.

How often?

There is no fixed schedule. A patient with no decay history and healthy gums needs images far less often than someone with active disease. Intervals are set individually and reviewed — typically bitewings every one to two years for low-risk adults, more frequently where there is active decay or periodontal disease, and less frequently again once things are stable.

Children are assessed on the same basis, adjusted for the fact that decay can progress faster through the thinner enamel of a baby tooth.

If we recommend images, ask why. You should get a clear answer.

Comparing images over time

A single radiograph is a snapshot. Its real value shows when it sits beside the one taken two years earlier, because the comparison answers a question a single image cannot: is this changing, and how fast?

A small shadow between two teeth that is identical to the one recorded two years ago is behaving very differently from one that has visibly advanced. The first is usually monitored and managed preventively; the second is usually restored. This is a large part of why we ask for previous images and why we keep yours.

Already have recent X-rays elsewhere?

We can arrange the transfer. If you have had radiographs taken at another practice within a useful period, we can request them with your permission rather than repeating the exposure and the cost. Our reception team handles the request on your behalf — call (03) 9088 5808, or use our transfer of records form.

This is worth doing before your first appointment where possible.

Your images are part of your clinical record and are retained accordingly. You are entitled to request a copy, and we can send them to another practice or a specialist on your instruction.

Cost and claiming

Radiographs have their own item numbers and are itemised separately from your examination. Your practitioner will tell you what is recommended and what it costs before taking anything.

We claim on the spot through HICAPS — bring your card and pay only the gap. Eligible children aged 0–17 may have imaging covered under the Child Dental Benefits Schedule.

Questions we are asked

Can I refuse X-rays? Yes. You can decline any procedure. What we will do is explain what cannot be assessed without them, so the decision is an informed one — principally decay between teeth and bone levels, neither of which can be judged by looking.

Do I need a lead apron? Contemporary guidance has moved away from routine thyroid collars and aprons for most dental imaging, because tightly collimated digital equipment delivers so little scatter that the shielding adds very little and can obscure the image. Ask and we will explain what we do in your case.

Can I see my own X-rays? Yes, and we would rather you did. They go up on the screen and your practitioner talks you through what is being pointed at.

Why does a new dentist want new X-rays when I had some last year? Often they do not, if the previous ones can be obtained — which is exactly what the transfer of records form is for. Ask before assuming they need repeating.

Is an OPG enough on its own? Not for detecting early decay between teeth. An OPG is a wide, lower-detail view; bitewings show the fine detail in the contact areas. They answer different questions.

Book an appointment

Victorian Dental Group — 291 Wattletree Road, Malvern East VIC 3145

Phone (03) 9088 5808 · Monday to Friday, 8:00am–5:00pm · closed weekends and public holidays

Book online at any hour.

This page is general information and does not replace advice from a registered dental practitioner about your own circumstances. Please see our Disclaimer.