Reducing the exposure of people to radiation is a prime principle governing all medical professionals when we use X-rays for treament or diagnosis. There is a risk and benefit to all treatments. The amount of radiation from a standard set of dental X-rays is about equivalent with the exposure someone recieves in a plane trip from Brisbane to Sydney (or about 500 times less than in one mammogram). We would recommend that general diagnostic dental X-rays for most people every 2 years will significantly reduce the risk of undetected decay causing irreparable damage (see photos). We would consider the possibility of flying to Sydney every 2 years a low risk for harm from radiation.
White areas are fillings
Dark area is new decay bottom left Red line shows decay extent, Pink area is the tooth nerve outline
Why do we need X-rays in dentistry at all? Decay usually occurs in areas hard to clean such as the flossing surfaces of the teeth. The decay in the above photos occured in les than 18 months and could not be detected in the mouth due to its position under the gumline. If the decay reached the nerve of the tooth there are two options for treatment. One involves complicated and expensive root canal treatment (which needs several X-rays to complete) or removal of the tooth (which needs an X-ray to assess the risk of permanent nerve damage, breaking the root, damaging the sinuses etc). If one took the approach of simply removing painful teeth and avoided any X-rays, then apart from the risk of permanent nerve damage or complications, the end result will be a poor ability to eat good healthy food. The outcome of this is an increased risk of poor health and bowel cancer from poor nutrition.
This is why we try to balance the risks and benefits of treatment. If you have 6 monthly dental checks, brush twice per day, floss every night, and eat a healthy diet with low processed carbohydrates, then dental X-rays can be taken less often.