Over recent years, the range of diagnostic aids available to the dental clinician has been revolutionised by dramatic advances in technology.
In spite of technological advances, it is appreciated that not all dentists have direct access, either personally or by local referral, to all of the techniques described in this overview of the risk management issues relevant to radiotherapy.
However, most of the general principles will still be relevant and worthy of consideration.
It is worth emphasising at the outset that conventional x-ray films, digital images created from intra-oral sensors, magnetic resonance imaging (MRI) and computerised axial tomography (CAT scans) - to name but a few - may have little in common in a technological sense, but they all share the common purpose of assisting a clinician in the diagnostic process. Radiography can of course assist with the provision of various treatments, often as an aid to measuring structures that cannot be seen with the naked eye, and radiotherapy is of course a treatment modality in itself. But in dentistry most x-rays are taken to provide information which, coupled with information gleaned from a proper history, examination, and other investigations, will assist the clinician to reach a proper diagnosis.
Each technique carries risks (and costs) and these must be balanced against the anticipated benefits.
Good radiation practice dictates that radiographs should only be taken if clinically necessary; the minimum number of films should be used consistent with adequate diagnosis, and the fastest films available should be used, consistent with good quality. It follows, therefore, that if a patient is to be exposed to x-rays, the ideal result should be the maximum amount of information derived from the minimum dose of radiation.
Equipment and training
Radiographs should only be taken by individuals who have been appropriately trained for the purpose, and whose current knowledge of the equipment and techniques would allow them to achieve the desired objective - the maximum diagnostic yield from the lowest possible level of exposure of the patient to radiation.
Problems have arisen in the past because a dentist's knowledge of the subject, perhaps gained many years earlier as an undergraduate student, has not been updated to reflect the many changes that have impacted upon this area of dental practice during the intervening period.
Legal responsibilities
Dentists may also own premises housing x-ray equipment, as well as employing staff who may be involved in the taking and management of x-rays. If so, they will have separate legal obligations to ensure that the equipment:
- satisfies contemporary standards
- is properly installed and safe to use
- is well maintained and regularly serviced
- is checked, and that it presents no hazard to patients, to those operating the equipment, or to any third party
This applies equally, whether the voltage, exposure and other variables are set manually, pre-set electronically or microprocessor-controlled.
In most countries there are specific legal standards with which the dentist and all users need to be familiar as well as complying with them.
Any person who has any role at all in operating the equipment, or in processing x-rays, must be properly trained and their knowledge regularly updated. Those who convert to digital x-rays do need to ensure that everyone involved in creating and handling the images is properly trained in the use of the chosen system.
Necessity
Many dental conditions cannot properly be diagnosed without the assistance of radiographic evidence, and failure to obtain this when it is appropriate, coupled with consequential damage to a patient, invites the allegation of a failure to exercise reasonable skill and care.
As a general rule, good clinical practice dictates that preoperative x-rays should be taken before certain procedures. It is commonly accepted, for example, that x-rays are a prerequisite when planning orthodontics, or implant treatment, or dento-alveolar surgery.
Similarly, x-rays are generally indicated before providing crowns or bridges, commencing endodontic treatment, or extracting buried teeth or roots. Further x-rays should be taken after root canal treatment and are usually of help in establishing working lengths during endodontic procedures. Even where an apex locator is being used, a diagnostic x-ray can still help to identity/ confirm canal morphology and potential problems.
Image quality
Any film that has been under or over-exposed, incorrectly angled or badly positioned may prove to be of poor diagnostic value and, if knowingly operating at a disadvantage because of the resulting lack of information, a dentist can be left vulnerable to allegations of negligence.
Failure to take a radiograph when indicated, or treatment based upon insufficient or inadequate radiographs, can leave a dentist open not only to criticism, but also to complaints and claims which might then prove difficult to refute.
A common pitfall of intraoral radiographs in the third molar region is a failure to cover the full depth of the mandible to indicate the relationship of the apices of any third molar teeth to the neuro-vascular bundle and the lower border of the mandible. In the absence of such information, the opportunity to warn the patient in advance of the possibility of inferior dental nerve damage or even fracture of the mandible is lost. If either of the foregoing events subsequently occurs, any allegation of negligence can become difficult to resist.
Processing
Exposing a patient to radiation, to produce an image of no diagnostic value, cannot be justified.
As a result, the quality of diagnosis, treatment planning and monitoring of patients is often dependent upon film processing techniques just as much as radiography skills. Radiographs form a very important part of clinical records and given the right of access that patients now have to their records in many countries, a radiograph with little or no diagnostic value acutely hinders the successful management of any complaint or claim and does nothing to further a dentist's professional image and reputation.
Labelling
A surprising number of cases result each year from errors in the mounting and labelling of x-rays, leading to treatment being provided on the wrong side of the patient's mouth. The underlying administrative error is often compounded by a failure to stop and check that the clinical situation is consistent with the x-ray appearance. Such problems can be avoided by having a consistent system of orientating the film when taking, mounting or labelling any x-rays.
Interpretation
When a given radiographic appearance is entirely consistent with the history, the clinical findings and the reported symptoms, then no clinician can be blamed for interpreting the x-ray accordingly.
In many cases, however, the radiographic evidence is at best equivocal and at worst, downright unconvincing. On these occasions it is unwise to make a diagnosis on the evidence of the x-rays alone. Radiographs are just one of many diagnostic tools, which the clinician uses when forming a diagnosis.
In some parts of the world, it is not unusual to refer a patient to a specialist radiology clinic for both imaging and a diagnostic report. Generally, however, it is still the role of the dental surgeon to carry out both procedures within the practice itself.
Even an excellent radiograph, being only two-dimensional, can have its shortcomings and it will sometimes be necessary to take additional films from various angles to obtain information that is sufficiently reliable for the clinician to reach a diagnosis with certainty. This is particularly important when the ensuing treatment is likely to be irreversible or extensive.
Great care needs to be taken to avoid misinterpreting radiographic artefacts.
Many cases have resulted from the provision of treatment unnecessarily, based upon a failure to recognise the anatomical significance of a certain radiographic appearance.
The superimposition of adjacent structures (for example, the mental or incisive foramen over root apices, leading to a diagnosis of a periapical area) is a familiar example.
Digital Images and computerised X-rays
From a diagnostic perspective, one of the advantages of images held in digital form, is the ability to manipulate and enhance the images by serial magnification, or by adjusting the greyscale, contrast or brightness of the image. Positive reversal of the dark/light pixels can even convert the normal 'negative' image of a conventional x-ray into a 'positive' image. The drawback is that clinicians may take a little time to adjust and develop their diagnostic skills to these less familiar images.
From a diagnostic perspective, one of the advantages of images held in digital form, is the ability to manipulate and enhance the images by serial magnification, or by adjusting the greyscale, contrast or brightness of the image. Positive reversal of the dark/light pixels can even convert the normal 'negative' image of a conventional x-ray into a 'positive' image. The drawback is that clinicians may take a little time to adjust and develop their diagnostic skills to these less familiar images.
When conventional x-rays are scanned (perhaps for administrative convenience) and saved as digital images, this fact must be clear in the clinical records. If the records are also held in electronic form, there must again be a robust audit trail sufficient to demonstrate the contemporaneous nature of each entry in the clinical records and to allay any worries that the image could have been tampered with.
Summary
Radiographs, in their various forms, are a very important part of modern dentistry, and in a dento-legal sense they can determine the entire course of a complaint or claim. Practitioners who are taking advantage of the considerable advances arising from information technology, should be aware of the many risk management and dentolegal issues that these techniques now have the potential to create, particularly if patient data is sent between countries for interpretation.