Treatment planning

Abstract

Restorative dental care is planned in a series of stages. Casts mounted in an articulator are used as an essential part of this process.

Main

An effective treatment plan is dependent on gathering information from the history, examination and special tests, such as radiographs and vitality testing, and analysing it to make a diagnosis. In restorative dentistry diagnoses are frequently multiple: successful treatment planning depends on accurate diagnoses and appropriate decision-making. The series has emphasised the importance of effective prevention, it has also recognised that restoration may be needed to protect the remaining tooth structure.

The treatment plan

The treatment plan should take the patient and dentist to the point where disease is controlled and the dentition functional and stable. Absolute stability is not achievable: all restorative work deteriorates to the point where failure becomes inevitable. Restorative work cannot be guaranteed for a patient's lifetime and no outrageous claims for longevity should be made.

The dentist must be aware of the patient's wishes. Frequently they ask the dentist to select the treatment. Rather they should be encouraged to make decisions for themselves while the dentist's role is to provide the information. Very often the patient's expectations of treatment are different from our own.^1,2

In the worn dentition, it may be difficult to determine the major aetiological factor. Commonly, more than one type of wear is present. It is rare to find a patient with tooth surface loss without at least some element being caused by acid erosion.³ Management of the patient whose teeth are worn poses the following questions:

• 1 Does the patient perceive that there is a problem?

• 2 Is the wear currently active: if so, is it rapid or slow?

• 3 Will the patient cooperate in a preventive approach to the management. If so, how easy will it be to monitor its success?

• 4 Is the wear so severe that restoration is required?

• 5 If restoration is required, is there sufficient crown height and do occlusal relationships allow reasonable form and stability to be achieved?

• 6 Are other teeth likely to require restoration in the short to middle term?

The answers determine the strategy for management. They all require decisions and patient involvement, particularly with regard to their possible long-term consequences as was discussed in Part 7 on failures.

The first stage in developing a treatment plan is to decide which teeth have a hopelessly poor prognosis, which are sound with a good prognosis and finally which teeth require treatment and why. This may not always be evident immediately as some teeth may require investigation to make or confirm a diagnosis, while decisions regarding periodontally compromised teeth may be influenced by the patient's efforts in plaque control.

Treatment plan -v- sequence of treatment

Once the treatment plan, the ultimate goal, is known, the dentist must establish a course that will reach it, the sequence of treatment.

Treatment plans should be written down for both dentists' and patients' benefit and the dentist should commit the sequence of treatment to paper. This may show illogicalities: if these are not identified treatment may become unduly complicated or impossible to deliver. For example, it is wise to complete placement of any necessary amalgam restorations before providing the patient with an occlusal splint because re-fitting an existing splint over a newly placed restoration is a complication that is better avoided.

Sequence of treatment

The treatment can be broken down into a sequence of stages. These are:

The need for re-assessment

During treatment the effects of what has been done should be periodically reviewed. This allows either the dentist or patient to retire honourably from active treatment if that seems appropriate. For example, the patient's plaque control may not reach an appropriate standard. This is clearly important in its own right but is also a useful barometer of a patient's level of interest and commitment. Efficacy of plaque control should be measured by bleeding scores not by plaque scores. Plaque scores inform only about performance on the day while bleeding scores give a longer term view.

Sometimes it becomes apparent that the patient may not wish to continue with treatment or the need for the planned work has diminished. Organisation of treatment into stages allows convenient points to be reached when the dentition is relatively stable. If the dentist or patient agree, the patient can enter a maintenance programme and be reviewed periodically. The other phases of treatment are organised to allow a logical progression toward completion of the treatment plan.

Stabilisation phase

The aims are the resolution of any acute problems and the stabilisation or elimination of active disease. Included are:

• Relieving pain and discomfort.

• Instituting effective plaque control procedures: this may include some initial non- surgical periodontal treatment.

• Eliminating active carious lesions.

• Extracting teeth that have a hopeless prognosis.

• Any necessary gross occlusal adjustment, for example a grossly over-erupted tooth.

• Replacement of missing teeth. This may be needed because of appearance or because few posterior teeth are in occlusion preventing there being a sufficiently stable position of closure. If teeth are replaced early in treatment, the prosthesis should generally be provisional with the definitive one being provided during the final restorative phase.

It is prudent to avoid being fully committed to extensive treatment of a patient too soon. Generally existing crown and bridgework should not be removed early in treatment. Dentists often do this on grounds of its being ill-fitting and wishing to provide better temporary restorations: most temporary coverage does not achieve this aim. Once existing work has been removed there is a commitment to complete treatment which a lack of patient compliance can make difficult.

Re-assessment 1

This is a review of whether the patient's condition has stabilised. Is the patient comfortable, are they are able to accept treatment, what improvement has been made in their standard of plaque control? Does the patient appear to be interested in treatment? It may be that a lack of response or difficulties in accepting treatment require revision of the long-term goals.

Preliminary restorative phase

Treatment is directed toward:

• Investigating individual teeth, providing cores and new plastic restorations as necessary.

• Any definitive endodontic treatment.

• Non-surgical periodontal therapy.

• A full analysis of the occlusion.

The clinical examination of the occlusion is supplemented by an extra-oral analysis using accurate study casts made from alginate impressions and a facebow transfer so that the maxillary cast can be mounted in an articulator. An inter-occlusal record taken in the retruded axis position (RAP) is needed to relate the mandibular cast to the maxillary and thereby to the hinge axis of the articulator. The casts are used to assess in more detail the extent of the tooth surface loss and to determine which teeth might benefit from further restoration. Consideration then must be given to determining exactly what difficulties may complicate the proposed restorations.

Re-assessment 2

A further review of progress is made and any concerns that the dentist or patient has over the final phase of treatment can be discussed.

There are a number of aspects to re-assess:

• Disease control

• The aims of the definitive restorative phase

• The position of the teeth

• The crown height available

• The position of mandibular closure and the jaw relationships.

Periodontal condition and disease control

There should be no active disease. Homecare should be commensurate with supporting the final restorative phase of treatment. If there are specific sites of periodontal concern remaining despite good plaque control, there may be indications for periodontal surgery. However, the traditional goal of pocket elimination by surgical means is becoming increasingly hard to substantiate.

The definitive restorative phase

The aims of the final restorative stage should be well defined. Decisions about whether to provide indirect restorations for patients with worn teeth are based on:

• Aesthetics

• Occlusal stability

• Protection of the remaining tooth structure.

Two sets of study casts should be available that are mounted accurately in the articulator. One acts as a baseline record. The second is available for rehearsing treatment, for example crown lengthening surgery, occlusal adjustment or diagnostic waxing.

The position of the teeth

Assessment of the casts or a diagnostic wax-up may show that one or more teeth are malpositioned and sometimes orthodontics can be helpful. Orthodontics in the pre-restorative management of the worn dentition is discussed in Part 10 of the series. It needs to be planned jointly by the restorative dentist and the orthodontist. It must be established whether permanent retention will be necessary post-treatment: it is frequently required after teeth have been moved in adult patients.

Crown height

The study casts and the wax-up provide a very good idea of clinical crown height. If the teeth are too short, aesthetics, retention and resistance form and occlusal stability are all likely to be compromised. A surgical crown lengthening procedure should be considered to increase the height available. This aspect of treatment will be described in Part 11. Where teeth have large cores, it is important that the margins of the final crowns are placed apical to the margins of the cores on sound dentine — 2 mm is considered sufficient.⁴ Frequently this is impossible without prior crown lengthening.

Creating space for restoring worn teeth by control of the jaw relationship

There are a number of other ways of creating space to allow restoration of short teeth. These are by:

• Altering the position of mandibular closure while maintaining the existing vertical dimension of occlusion

• Increasing the vertical dimension of occlusion

• Reversing the changes that have taken place in the position of the teeth as a result of the wear through relative axial tooth movement.

Sometimes a combination of more than one of these approaches is necessary. In all instances, it is important to determine a stable RAP before planning the definitive restorations. This requires a period of wear of an occlusal splint. The details of this appliance can be found in Part 3 of this series.

Alteration of the position of mandibular closure

This is considered when there is need to restore teeth in the anterior part of the mouth and the rest of the dentition is generally sound. The change in the position of mandibular closure is effected by occlusal adjustment. The aim is to create a new intercuspal position (ICP) some way distal to but at the same vertical dimension as the existing one. The feasibility of doing this depends on the nature of the discrepancy between RAP and ICP: there must be significant mandibular translation between the two positions for it to be a possibility.

The magnitude of this type of movement is hard to determine from intra-oral examination. It is seen best on mounted study casts by determining the change in the position of the articulator 'condyles' relative to their condylar housings when the casts are slid into the intercuspal position from the retruded axis position. The only reliable way of determining whether elimination of the anterior slide would create space anteriorly is by rehearsing it on the second set of mounted casts.

Figures 1, 2, 3, 4, 5, 6, 7, 8 show a 30-year-old female who had begun to wear the incisal edges of her maxillary central incisors primarily through dietary erosion such that the incisal edges had begun to chip. Figure 1 shows the edge-to-edge incisal relationship in ICP. The mandibular incisors occluded against the worn incisal edges. There was no space available to allow the restoration and protection of these maxillary teeth. The patient was found to have a significant horizontal component to the slide from retruded into intercuspal (figs 3, 4, 6, 7). Adjustment of the posterior teeth to eliminate the discrepancy produced a new intercuspal position with the mandible positioned further distally increasing the overjet sufficiently to allow conservative restoration of the incisal edges of the maxillary incisors with composite resin (fig. 8).

Figure 1

Labial view of anterior teeth showing chipping of incisal edges of maxillary incisors

Figure 2

Incisal edges of maxillary anterior teeth demonstrating acid erosion

Figure 3

Mounted casts showing initial contact in the retruded axis position

Figure 4

The 'condyle' has moved away from the rear wall of the condylar housing by 'translation' as the casts have slid into ICP

Figure 5

Trial adjustment of the casts to eliminate the slide between retruded and intercuspal

Figure 6

Intercuspal position prior to occlusal adjustment

Figure 7

Intercuspal position following elimination of the slide from retruded to intercuspal showing a small increase in overjet

Figure 8

Incisal edges of the maxillary incisors restored with adhesive composite restorations

Increasing the vertical dimension of occlusion

This is the traditional way of creating space for the restoration of worn teeth. The decision to increase the vertical dimension of occlusion brings with it the obligation to restore a large number of teeth to ensure that the teeth in both arches have antagonists on mandibular closure. Treatment is demanding for both operator and patient with many hours being spent by the patient in the dental chair: it is only undertaken when simpler alternatives are inappropriate.

Increasing the vertical dimension not only provides space for restorations but also gives scope for levelling a disordered occlusal plane. Figures 9 to 15 show a middle-aged man in whom increasing the vertical dimension of occlusion created space for restorations while at the same time producing a level occlusal plane.

Figure 9: Patient with worn and restored anterior teeth, missing teeth and an uneven occlusal plane.

The teeth are in their intercuspal position

Figure 15

A middle-aged patient with a dentition affected by tooth surface loss

Total face height measured in the rest position has traditionally been thought of as relatively constant. However, this is not the case. If mandibular rest position were thought of as being consistent with minimal jaw muscle activity, electromyographic studies carried out in the early 1960s by Ramfjord indicated that low levels of muscle activity were found over a range of about a centimetre in most people.⁵ Clinical experience has indicated that moderate increases in the vertical dimension of occlusion are well tolerated by patients as long as they are accompanied by a stable position of mandibular closure together with anterior guidance that provides separation of the posterior teeth on mandibular movement.⁶ This view is supported by what little research is available.⁷

Aesthetic limitations on lengthening the teeth incisally often make an adjunctive surgical crown lengthening procedure necessary if the appearance is to be reasonable (fig. 15). The potential aesthetic disadvantages are that in moving the gingival margin apically, it comes to rest on a narrower portion of the root. This makes the embrasure spaces larger which may be difficult to disguise using the final restorations and so-called 'black-hole' disease may result (fig. 16).

Figure 16: The same patient following surgical crown lengthening and placement of metal-ceramic crowns.

The wide embrasures are evident

Deliberate axial tooth movement

The method was originally described by Dahl.⁸ He used removable bite-planes to intrude worn anterior teeth that he wished to crown without having to restore the posterior dentition. His original description was of treating individuals in their sixties. However in the past 20 years, it has been applied to patients of all ages affected by tooth wear. Developments, particularly the use of tooth-borne appliances luted to the teeth using glass ionomer cement, has led to increased predictability and patient compliance. Such an appliance is shown in the treatment of someone whose retained deciduous maxillary canines had become very worn and the opposing canines over-erupted (figs 18 to 23).

Figure 18

Buccal view of patient with worn deciduous canine

Figure 23

Tooth surface loss having affected the occlusal surface of a mandibular molar in a 17 year-old

Casts mounted in an articulator prior to treatment are used to assess where the teeth will be after axial movement. It is important that there are stable occlusal contacts after treatment otherwise the teeth will re-erupt.

The technique is often used to simplify the full reconstruction of the worn dentition. An appliance cemented to the maxillary anterior teeth creates space posteriorly allowing easy access for the placement of any necessary cores. Once the axial tooth movement is complete and the posterior teeth have re-established contact, sufficient space will have been created anteriorly to allow these teeth to be restored. This is followed by the placement of the necessary posterior crowns. This approach will be described more fully in Part 12 of the series.

Relative axial tooth movement, reversing the changes that accompany wear, allows simpler restorative procedures. Figures 24 and 25 show the occlusal surface of a lower first molar tooth in a late teenager. The tooth had been eroded by carbonated drink and there was no clearance on closure between it and its antagonist. The tooth was restored with an adhesive nickel-chrome occlusal casting. This was around 1.5 mm thick and after cementation was initially the only site of occlusal contact. Two weeks later, axial tooth movement had taken place and all the teeth had intercuspal contacts.

Figure 24

Mandibular first molar restored with adhesive metal casting cemented at an increased vertical dimension of occlusion

Figure 25

Diagnostic wax-up made at the beginning of the definitive restorative stage

The final restorations

The aims are to provide optimal aesthetics, reasonable function and ensure that any restorations placed are compatible with the patient maintaining themselves in a disease-free state. The previous investigative stages will, in conjunction with the patient's wishes, have determined which teeth would benefit from restoration. Diagnostic waxing forms an essential part of the planning.

Diagnostic waxing

Restorative treatment is much more predictable when the outcome can be envisaged (fig. 25). It is also gives the patient an idea of the final result and encourages realistic expectations. Specifically diagnostic waxing will:

• Allow dentist and patient to see a mock-up of the final restorations.

• Indicate if there is sufficient crown height to give adequate retention and resistance form in the preparations, reasonable aesthetics and adequate occlusal form.

• Show where occlusal plane discrepancies (for example, slightly over-erupted antagonist teeth) need correction if a desirable occlusal scheme is to be achieved and optimal aesthetics produced.

The wax-up provides a number of additional advantages. It can guide tooth preparation using it to make matrices that are either used to evaluate the preparations or as templates for the temporary coverage. The temporaries have ostensibly the same form as the final restorations so they can be used to check the appropriateness of the tooth reduction by measuring their thickness. The temporary crowns can also be used to rehearse the final result. It is an interesting thought that dentists are trained as undergraduates to make a wax 'try-in' for a removable prosthesis. However it seems this is rarely advised for a fixed prosthesis or a number of crowns. The temporary restorations fulfil that role and the final crowns should present few surprises either to the dentist or the patient.

Re-assessment 3

This final review is an evaluation of whether the original aims of treatment have been met and whether further active restorative care is required. If all is satisfactory, the patient enters the maintenance phase. The details of which were described in Part 6 of the series.

This article has described the importance of determining, in conjunction with the patient their restorative needs and has outlined an approach to the delivery of care. The way in which teeth wear, together with their inherent eruptive potential, can combine to create particular difficulties in restoration. They often present broad, flat functional surfaces where their relationships with antagonists make it difficult to create adequate space for effective restoration. Various strategies that can be used to create space for restorative purposes have been outlined. The benefits of deliberate axial tooth movement as a conservative method for management have been described. Orthodontics and surgical crown lengthening can also be valuable adjuncts to restorative care. The next two articles in the series will discuss in more detail their use and limitations in the restorative management of worn teeth.

Figure 10

Buccal view of the teeth in occlusion

Figure 11

The mandibular relation in the retruded contact position

Figure 12

A diagnostic wax-up and set-up in RAP at an increased occlusal vertical dimension

Figure 13

A labial view of the maxillary provisional prosthesis made from a matrix of the diagnostic wax-up

Figure 14

An anterior view of the final anterior restorations

Figure 17

Buccal view of patient with worn deciduous canine

Figure 19

Palatal view of cemented 'Dahl' appliance on c321/12c

Figure 20

Buccal view of patient occluding on anterior appliance

Figure 21

Following axial tooth movement, posterior occlusion re-established

Figure 22

Following removal of the appliance showing the space available to allow restoration