Sir, a recent article in the BDJ relating to wrong site surgery1 correctly highlighted some of the risks. However, it was surprising that little reference was made to the risk from incorrect orientation of digital intra oral radiographs in the surgery when indirect X-ray sensors are employed.

Processing errors which can occur when converting conventional film radiographs, as part of a referral process, into digital copies using a scanner have been highlighted previously.2 Things have moved on and a large number of practices are now employing digital systems to create electronic images, especially for intra oral radiographs.

Although there is a capacity within the software for basic manipulation – to rotate, invert, correct a mirror image by the diagnostician and indeed a requirement for every dentist to report on the radiograph, we feel that errors in orientation can occur when there are no visual clues – decayed, missing or filled teeth.

There does not appear to be consistent agreement among dental schools or practitioners as to where the marker should be placed when taking periapical or bitewing radiographs. Unlike conventional radiographs, an image is produced even if the film is placed back to front in relation to the X-ray tube. In processing, in many of the readers the film can only be inserted vertically, requiring reorientation of the image, often by the operator before it is saved on the screen.

There is a potential for errors to occur, especially in multi-surgery practices, when the prescribing dentist is not the operator and does not process the radiograph. As was highlighted in the article errors can occur when the clinician performing the treatment is not the one who constructed the treatment plan and where, in a busy practice, there is a delay between the taking and viewing of the radiograph.

To illustrate the point, the writer has seen an example where records refer to the intention to remove an upper right eight and where the image on the screen is of an upper left eight. If the patient's symptoms have subsided, how easy it would be for a locum dentist to remove the wrong tooth. On another occasion, a radiograph was taken on a nine-year-old following trauma and it was very difficult to ascertain whether the radiograph of the two central incisors was correctly orientated. It is envisaged that many other clinicians may have had similar confusions in orienting digital radiographs.

If guidelines were in place so that there was a consistent approach by all IRMER practitioners to the placement of the identifier on the film when taking, processing and reading the radiograph, the margins of error would be considerably reduced.