The provision of crowns and bridges, in particular, and to a lesser extent that of other fixed restorations such as inlays and veneers, are responsible for a substantial number of negligence claims against dentists.
They also account for a significant proportion of all the damages and legal costs paid out. Although this text focuses on crowns and bridges, many of the principles discussed are equally applicable to other kinds of fixed restoration.
Paradoxically, part of the problem is that crown and bridgework occupies such a central position in the restorative armamentarium, that there is an ever-present danger that familiarity will breed contempt. Modern instrumentation has made tooth preparation quicker and easier, and modern materials have greatly simplified impression taking and temporisation in particular. Furthermore, patients are keeping their teeth later in life, and practitioners and patients alike are increasingly looking for restorative solutions that can make this possible. Teeth that might have been extracted in the past are now being retained and restored.
If the technical procedures themselves are being made easier and more predictable, this invites the question of why crown and bridgework continues to feature so prominently in negligence claims against dentists.
The clue to the answer may be found in the fact that what tends to go wrong most often, is the basics - the fundamental principles that every dental student learns at university, but which can so easily fall by the wayside some years later. An awareness of, and adherence to, these basic principles will go a long way towards minimising dento-legal problems associated with the provision of crowns and bridges.
Case assessment
Every successful treatment plan is based upon an informed and thorough case assessment. This must begin with a comprehensive medical and dental history. Of particular relevance in cases where crowns and bridges are being considered, are clues from the dental history such as a high caries rate, a history of periodontal problems, TM J/muscle or other head and neck pain, headaches or parafunction (including bruxism). Sometimes, careful questioning of the patient's past dental history reveals a history of fractured teeth or restorations. A vague history of a recurrent need for much dental care over many years should signal the need for further investigation.
Baseline charting
The patient's presenting symptoms (if any) and/or the reason for attendance should be recorded, together with a note of the time interval since the patient's last dental treatment. A detailed charting, ideally showing the precise extent of existing restorations, is the best foundation for everything that follows.
Note also any cracks, areas of discolouration, the nature, position and extent of any tooth wear, and any signs of early decalcification, as well as areas of caries and defective restorations (Fig. 1). Clinical photographs and intra-oral camera images can be an invaluable addition to the quality of the baseline records in these situations.
All of the above can be of great assistance if a dentist is subsequently challenged as to why he/she recommended or provided crowns for a given tooth at all. It also helps in defending the familiar allegation that the dentist 'crowned a perfectly good tooth' without justification.
Periodontal assessment
Teeth, which are to be used as crown or bridge retainers, should always have been subjected to a periodontal assessment.
It is prudent to measure and record probing depths around such teeth, and to record the presence or absence of any inflammation, mobility, tenderness to percussion, pain/sensitivity etc. It is worth stressing that it is just as important to record negative findings as positive ones. Up-to-date pre-operative periapical radiographs of any teeth to be crowned or used as bridge retainers along with proposed pontic sites are a sensible precaution in order to confirm the presence of adequate supporting bone and the absence of any retained root or other pathology in the areas in question.
Pulpal and periapical assessment
Periapical radiographs can be invaluable in screening for evidence of periapical change, and to assess existing root fillings, although such x-rays are of course only aids to diagnosis in this respect, to supplement clinical findings. Here again, the clinical records should also show that vitality tests were undertaken of any teeth, which were being considered to support crowns or bridges. Even where teeth give a normal response to such testing, the very fact that the test was done and recorded (including the type of vitality test) all serves to demonstrate that a proper level of skill and care was taken during the preoperative investigations.
Where existing root fillings are present in a tooth, the patient should be asked when these were provided, and their answer recorded. An apparently 'short' or defective root filling placed six months ago is obviously more significant than the same radiographic appearance would be in a tooth where the root filling was placed six years ago, and where there have been no signs of apical change, and no reported symptoms.
There is ample research evidence to confirm that many crowned teeth are likely to lose their vitality over time, many cases involve pulpal and apical problems that arise shortly after crowns and bridges have been fitted. The earlier steps described - all of them simple ones - would considerably strengthen a dentist's position when defending allegations that the subsequent endodontic problems could have been avoided.
Sometimes a large and deep pinned amalgam core is provided, and the crown is immediately prepared and fitted shortly afterwards. When the tooth in question develops an irreversible pulpitis almost immediately, it can reasonably be asked why a suitable period of monitoring and evaluation was not allowed, to enable the symptoms to be reviewed before proceeding with the final restoration.
Occlusal assessment
Many authorities advocate that any case involving the provision of more than 2-3 units of crown and/or bridgework should involve a detailed pre-operative assessment of the existing occlusal relationships. This ideally includes the taking and mounting of study models on a semiadjustable articulator using a facebow and occlusal records that transfer accurately the existing static and dynamic occlusal relationships.
Needless to say the working casts should be mounted in a similar fashion. Many dento-legal problems occur when new restorations prematurely fail by chipping, fracturing or debonding as a result of undetected occlusal errors.
Alternatively, the newly provided restorations inadvertently alter the existing occlusal scheme to such an extent that it exceeds the patient's adaptive capability and the patient goes on to develop often debilitating TM J or muscular problems. The damages and legal costs awarded in such cases can be alarmingly high.
A stable oral environment
Clearly it makes no sense to provide crown and bridge restorations in an oral environment where caries and periodontal disease are not controlled; this is a recipe for premature failure.
Investigation of tooth wear may also be necessary to explore possible dental erosion, or toothbrush abrasion.
Dietary investigation may be indicated and oral hygiene instruction, and dietary counseling might be a sensible first step followed by a period of monitoring and review, before considering whether or not fixed restorations are desirable, necessary or even appropriate.
Aesthetics
The 'consent' considerations in the elective provision of crowns and bridges involving teeth which are essentially healthy and unfilled, should be approached with great caution because of the enormous potential for dento-legal problems, especially where the treatment was suggested by the dentist, rather than requested by the patient.
Two points tend to arise consistently with aesthetic concerns involving fixed restoration:
1) The patient does not feel they have been sufficiently involved in shade selection, or in agreeing the appearance of the teeth, and who argues subsequently, when problems arise, that the process was rushed and/or the dentist made decisions without sufficient consultation, or even against their wishes.
2) Areas of visible metal, often on the occlusal surfaces of teeth, but sometimes even the metal 'collars' that are commonly seen on the lingual/palatal surfaces of fixed restorations. It is sensible to discuss with the patient in advance the possible need for any exposed metal so that any particular concerns that a patient might have in this respect can be identified and addressed.
Temporisation
Many practitioners underestimate the importance of the temporisation stage. Evidence suggests that much of the pulpal damage that can occur does so during the preparation and immediate post-operative period.
The routine application of sealants or desensitizing agents immediately following the preparation of vital teeth is to be encouraged. Practitioners should also be confident that all temporary restorations are well-fitting to minimise the risk of bacterial contamination of the dentinal tubules and the concommittant development of pulpal problems.
Temporary restorations also provide an excellent opportunity to trial proposed changes to the appearance of the teeth. Any shortcomings can be readily identified and remedied at this stage rather than be carried through to the final restorations where adjustments can be costly and demoralising.
Problems on fitting
The two most common problems encountered with fixed restorations are with the marginal fit and with the occlusion.
No amount of adjustment will resolve the problem of a crown or bridge with a defective marginal fit and a problem of this nature will still be easy to identify months or years later. The marginal fit of all fixed restorations needs to be carefully evaluated, around the entire margin, before taking the decision to fit the restoration.
The need for extensive occlusal adjustment at the time of fitting can also create other problems, which are self-evident to the patient. The creation of perforations in allmetal restorations or the exposure of underlying metal in porcelain bonded restorations, continues to create a steady flow of complaints. Patients also tend to be reluctant to accept the need to adjust opposing teeth (especially natural teeth) in order to accommodate a crown or bridge that presents occlusal problems at the time of fitting.
Complex cases
No practitioner should undertake treatment that is beyond his/her training, experience, skills and expertise. There are a number of postgraduate courses that support the development of the additional skills required to provide this type of treatment and the prudent practitioner may consider a period of further study to be appropriate. The possibility of a referral of complex restorative cases to a consultant or a more experienced colleague should always be kept in mind, either to assist with case assessment or treatment planning, or to assume responsibility for the treatment itself.
Prevention
An integral part of the provision of any fixed restoration should include appropriate advice and instruction to ensure that the patient can maintain the continuing health of the supporting and surrounding tissues.
Any special preventive techniques, such as cleaning under bridge pontics, should be explained to the patient whenever indicated and the fact that this advice has been given, duly recorded in the patient's notes.
Contractual considerations
Because of the level of costs involved in the provision of crowns and bridges, it is always a sensible precaution to confirm the fees in advance and in writing.
It should be made clear whether the fees quoted are an estimate and/ or illustration, or a firm indication of the treatment that is to be provided and the cost involved. This is particularly important when specifying the materials to be used and/or the teeth that are involved, as any variation from this subsequently might otherwise be held to be a breach of contract.
In the same way, the question of consent must be properly addressed and seen to be so. The patient's decision to proceed with crown and bridgework must be based upon a balanced explanation of the nature and purpose of the treatment, what it involves, and what risks/limitations the proposed treatment presents. This is important, for example, when retainers have a slightly questionable prognosis for any reason, or where there are any special difficulties involved in the case. The patient must be made aware of any alternatives to the proposed treatment, and how they compare. If a patient's consent is based upon misleading and incomplete information, then it may well be held to be invalid. This can lead to litigation either under contract law or in negligence (alleging that the dentist failed in the duty of care to obtain an appropriate consent).
Summary
The range of issues covered in the text serves to illustrate that there is no such thing as 'simple' crown and bridge restoration. Every case needs to be approached with care and caution. The cost to the dentist of failed crown and bridgework is often very high indeed, reflecting not only a return of any fees paid, but also the cost of subsequent remedial work, and its successive replacement over the lifetime of the patient.
Module 11 in this series, 'Margins of error' discusses the importance of monitoring the condition of previously placed crowns and bridges.