Restorative Dentistry

Suffer Little Children

This month’s tips follows on from last month’s ‘Mind the gap’ and considers how we might improve the effectiveness and efficiency of the treatment we offer for children/teenagers who have lost a central incisor tooth.

Standard NHS practice says provide an acrylic denture. If the denture provided is of a spoon design, then retention is poor to non-existant and relies on the tongue holding it in place. If the design fits to the gingivae then there is a serious risk of inducing gingivitis particularly if the denture is worn both day and night or oral hygiene is poor – a common problem with teenagers. Retention can be improved by making a ‘T’ shaped denture base with Adams cribs on the first molars, providing that the occlusion allows, but this is not always possible.

We need to consider the natural history and follow up for those unfortunate children over a period of several years and document what happens:

Dentures break and are sent for repair
Dentures are lost, sometimes on more than one occasion.
The denture is not worn for even a very short period, for example during repair, when the space closes up very rapidly.
Space loss precludes the creation of a mirror image central incisor later in life and makes strategic aesthetic planning more difficult.
Denture aesthetics can be very poor
Children forced to wear a denture can be ridiculed and bullied.
Denture hygiene can be poor
Few if any NHS dentures are fibre reinforced.
Wire so-called strengtheners function as wire weakeners of acrylic denture bases.

In other words, it is cheap and nasty, but is it cheap?

Before moving on to my tips for improving clinical outcomes I should like to apply the concept of RCCS to these cases. This is a management concept I learned about when I set up the Dental Practice Unit in Sheffield, and stands for the Revenue Consequences of Capital Schemes. In this case the Capital scheme is the cost of the first provision of an acrylic P/-. The consequences are the ongoing costs of maintaining what we have just provided. So what can they be, replacements, sometimes more than one, repairs and the costs of further clinical time and surgery overheads. The latter costs are often omitted from consideration by budget holders who only see the cost of the first provision in their bottom line, and have not had the business training to understand the concept of on-costs in relation to the whole care provision programme. In these days of budgetary restraints in the Public Service there is not an endless fund of taxpayer’s monies to pay for your failure to think outside the box. Would Department of Health officials please take note and find ways of encouraging better use of Public Funds for this group of children.

There are several options to consider:

Orthodontics to move the lateral incisor into the central position so it can be crowned to look like a central. You can’t! The emergence profile is wrong, the resulting crown never looks good, and it is another waste of professional and patient’s time. Secondarily the maxillary canine is moved mesially. This is another mistake. It disrupts the normal canine protected occlusion and posterior occlusion as that also move mesially and is very likely to give rise to temporomandibular joint dysfunction symptoms later in life. (as an aside, the worst case I was ever asked to restore was a 20 year old who had lost both central incisors in an accident at age 10 years, both laterals had been moved mesially over the course a three years, , she had severe occlusal disruption, and it was impossible to achieve any result until the laterals were extracted , Fig 1).
Transplanting a premolar into the central incisor space. This requires special surgical skills, and there is no guarantee that the transplanted tooth will ‘take’ in the either the short or long term. Failure will result in a large bony defect that will require bone grafting. Similar considerations in relation to emergence profile as mentioned in 1 above are relevant. In some cases the transplanted tooth will require elective devitalisation before crowning.
An adhesive bridge. This is the preferred option, but not just any adhesive bridge. Conventionally, the bridge would be bonded to the palatal surface of the other central incisor providing that there is sufficient occlusal clearance. Grinding the palatal surface to provide clearance is contra-indicated, whilst fitting the bridge and hoping for Dahl effect to depress other teeth may well result in a debond first. The question to ask is what is my success rate with palatal bonding? If the bridge debonds then the palatal surface of the tooth needs careful cleaning to remove all composite cement tags, and the fit surface of the bridge similarly cleaned. The best way for the latter, unless you have air abrasion available, is to ask your technician to burn off the composite in a porcelain furnace. But, this takes time, during which the adjacent teeth will have moved so the bridge won’t fit back easily.

Cleaning the tooth surface is easier if you have air abrasion, but it can be very difficult to see if tags of composite remain on the tooth surface. Tip – when you have removed what you think, rub over the palatal surface with an old steel ball ended burnisher. A little steel will be picked up by the residual composite as a grey area, thus showing where further attention is required.

If too much tooth is removed, then future retention will be impaired. If the bridge is ‘recemented’ without first cleaning the surfaces it is likely to debond again in short order.

A better adhesive bridge. This is my method and virtually guarantees fail-safe bonding. I make a fibre (Stick) reinforced bridge bonded to the labial aspect of the remaining central incisor (Fig 2). This provides a superb, very large bonding surface that will, when the time eventually comes to remove the bridge, not be as easy as it would at first seem.

15a

15b

I make the labial surface about 1mm thick and cantilever the pontic. If you plan to use this technique then you must have parental consent that the remaining central will be slightly bulkier labially. It does not seem to be a problem with toleration of the changed labial contour. Take a simple set of impressions for your technician and a shade, and ask for a normal shape of pontic. This ensures that lower incisors will not over-erupt and interfere with protrusive jaw movements.

Advantages:

No tooth preparation
A mirror image of the existing central incisor can be created in the laboratory
Excellent bonding and little or no risk of a debond
If orthodontics is also required the optimum teeth can be extracted.
If fixed appliance orthodontics is required then a bracket can be bonded onto the labial surface of the retainer tooth
Space is maintained
Future costs are minimised
It is possible to achieve excellent aesthetics
Patient confidence is boosted.
The occlusion is not changed and risks of developing TMJ dysfunction symptoms later in life significantly reduced.
Later bone grafting or implant placement is not compromised.
Later smile designs are not compromised.

Disadvantages:

Slightly bulkier central incisors labially
Higher initial laboratory cost
Composite may discolour with time

When the time comes to place an implant, the preferred long term restorative solution, it is not necessary to remove the bridge; it can still function as a ‘temporary’ whilst the implant integrates. Simply thin the pontic by drilling away the palatal aspect to leave an intact labial facing. Access to the bone can be achieved. Even if some of the incisal edge needs to be removed to gain the correct axial inclination for the implant, this can simply be repaired with composite in order to maintain aesthetics.

In this case orthodontics has made matters worse. Moving lateral incisors to be crowned as centrals never really works and canine guidance is always lost as this tooth also moves mesially.

In summary, I have proposed a more cost effective and socially acceptable solution to the problem presented by central incisor loss in childhood than current NHS practice.