SOME MEDICO-LEGAL IMPLICATIONS OF IMPLANT PROSTHODONTICS

Copyright ROGER GOULDEN (2000)


When you think about it, implants should be pretty easy. The average implant fixture is about 3.5 mm in diameter, thus requiring the drilling of a hole in the bone of about 3.5 mm. Since all general practitioners, however gifted, earn their living by drilling teeth on a daily basis to tolerances of the order of several microns whilst cutting cavities, and of the order of several minutes of parallelism when preparing crowns, we are all clearly capable of preparing implant sites.

When crowns are provided in general practice it is commonplace for these to be executed with an accuracy of fit at the margins of something of the order of 30 microns. This is a very close tolerance, but since the fit of many of the components used in implant prosthodontics is achieved in the machining of those components to far finer tolerances in the factory, this consideration does not even apply. If one then considers the achievement of an acceptable aesthetic result, I think most practitioners would agree that the attainment of a first class appearance of individual teeth is somewhat easier with dentures than with fixed crown and bridgework. Since much of the laboratory procedures in implant prosthodontics is often more akin to denture technology than crown and bridge, then the aesthetic outcome of such treatment should be highly predictable.

So why is it that there is a huge, and growing, industry in medico-legal activity involving implants?

There are two categories of such cases: one where the treatment was properly executed and the other where it was not. In the first category the hapless dentist will simply be falling foul of our contemporary (and most lamentable) culture of compensation seeking. There can be no doubt that in implant litigation many of these cases will predominantly be triggered by the high level of expense where patients who perceive, for whatever reasons, that they have been badly treated, will seek retribution - which may not have been the case had their financial outlay been of the order of tens of pounds rather than hundreds or even thousands of pounds. When confronted by such aggressive moves by patients, the dentist is forced to defend himself, and the best defence is to have ensured that the treatment was performed to the highest standards possible, with each and every stage carried out ‘by the book'. You will be able to show that the patient will have been fully informed of the benefits, risks, costs and all the other factors necessary to convince the lawyers that proper informed consent had been obtained and that the treatment that was provided was fully in accordance with contemporary teaching and practice.

Provided this route has been followed, these cases will eventually go away, although it must be said probably not without many months of worry, stress and expense. The second category is possibly simpler to avoid, provided three things are constantly kept in mind. These are treatment planning, treatment planning and treatment planning. You will plan your assessment of the patient. For example, do they smoke? Do they have existing periodontal disease? Do not be tempted to undertake implants on such patients as there is a good chance that they will fail, and the research literature tends to confirm this view [see notes (1) and (2) below]. And that will not help you when the treatment does fail and the patient decides to sue.

The degree of proof required in civil matters is less that than needed in criminal matters [see note 3]. In civil proceedings it is only necessary to establish a fact ‘on the balance of probabilities', and it would not take much to convince the judge that the failure of the implants shown in figure 1 was probably caused by cross infection from organisms present in the extensive periodontal pocketing at the adjacent natural teeth.

Figure 1

You will plan your surgical phase from study casts, CT scans and other radiographs, or possibly with one of the CAD programs currently available. Are you sure you are going to get your fixtures at the right angles? The case shown at figure 2 did not happen by chance, whereas nobody could possibly have planned that shown at figure 3. And that outcome will not help you either when your patient has to be told that, because of the poor relative angulation, it is technically impossible to construct the crowns, which was the whole object of the exercise in the first place. Your patient will also be less than pleased when you have achieved the optimum fixture angulation to allow your technician to readily construct the ideal superstructure, but at the expense of permanent damage to the inferior dental nerve.

Figure 2	Figure 3

And do not think, if it is your practice to refer for the surgical phase, whilst doing the prosthodontics yourself, that such considerations are not your problem, as it is firmly your responsibility to ensure that the overall treatment is properly planned. It will not help you if the fixtures were placed by the most highly regarded oral surgeon if these turn out to be incorrectly positioned, so that the overall treatment fails, as you should have planned the operation with him. In addition to joint treatment planning with your surgeon, you might care to consider going into the operating theatre with him so that you can observe the proceedings, possibly to suggest modification of the drill angulation if you are unhappy. You will treatment plan the case with your technician. Is he capable of creating castings and components of sufficient accuracy that you can guarantee a passive fit with all elements fully seated?

The result shown at figure 4 is not the outcome you want - and when a case such as this fails (as it probably will) and the patient sues (as they surely will), remember that it is no excuse to say that it was the fault of the laboratory that the sub-frame would not seat as accurately as you would have liked. It was your responsibility to ensure that they were up to the job just as much as it was your responsibility to reject the casting and request a remake regardless of any inconvenience, expense and general loss of face that this would generate.

Figure 4

You will also have treatment planned the aesthetics with all involved parties, which includes the technician who will have to make the appliance and the patient who has to wear it. It will be no good trying to convince the patient that they will ‘get used to it' when the final appearance such as that shown at figure 5 is unacceptable. Never ever make the mistake of thinking that the patient is simple, or worse, stupid. But then, that will not happen, because your first step in your implant treatment planning is critically to evaluate your own strengths and weaknesses. At the end of that exercise you will be able to decide whether you are competent to undertake the case or whether it might be helpful to go on some courses first, perhaps as part of the CPD that we will all have to do. 

Figure 5

Alternatively, you might consider that you would be better advised to refer the patient to a more suitably qualified colleague. Never forget that there is no finer way for any practitioner, of whatever level, to demonstrate his expertise than by recognising what he cannot do. Any patient is only going to appreciate such referral, as this action can only show that their best interests are your greatest concern.

Remember, the superior practitioner demonstrates his superior skills by recognising when to avoid getting into a position where those superior skills might be tested to the full, or worse, exceeded.


References

(1) Bain CA, Moy PK. The Association Between the Failure of Dental Implants and Cigarette Smoking. Int J Oral Maxillofac Implants 1993; 8: 609-615.

(2) Gouvossis J, Sindhusahe D, Yeung S. Cross Infection from Periodontally Involved Sites to Failing Implant Sites in the Same Mouth. Int Oral Maxillofac Implants 1997; 12: 666-673. 3) Stevens Commentaries on the Laws of England. London: Butterworth, 1950.