Treatment of localized anterior toothwear with composite restorations at an increased occlusal vertical dimension

Localized anterior toothwear is a problem increasingly being encountered by both patient and practitioner.¹ It is usually caused by a combination of erosion, attrition and abrasion, and may be generalized or confined to the anterior teeth. Rapid toothwear increases the interocclusal space and causes loss in vertical face height but in a large number of patients the rate of toothwear is slow, allowing compensatory eruption of the opposing teeth. This maintains intercuspal tooth contacts and occlusal face height, thus reducing the interocclusal space available for restoration. This is a common problem in patients with localized toothwear and restoration of these teeth becomes a challenge.

The interocclusal space required for restoring the teeth may be created in a number of ways:²

• Reduction of the opposing teeth (periodontal crown lengthening surgery can increase the clinical crown height, thereby allowing further tooth reduction);
• Occlusal adjustment if there is significant discrepancy between the retruded contact position and the intercuspal position;
• Increasing the occlusal vertical dimension by restoring the posterior teeth in at least one jaw
• Elective endodontic treatment and restoration with posts and cores;
• Orthodontic treatment.

It is important to identify the cause of toothwear and commence preventive care before undertaking restorative treatment.³ Restorative treatment may involve use of fixed and/or removable prostheses,^4,5 although the use of crowns can be destructive in an already compromised dentition. Adhesive cast restorations^6,7 have been used to overcome these problems. However, the aesthetics of these restorations remain problematic.

Composite resin has been used for the restoration of anterior teeth since the 1980s. The newer materials have overcome many of the earlier problems of staining and provide excellent aesthetics. They are simple to use and provided that moisture control is optimized during placement, are successful.

Technique

A detailed history of the presenting complaint, patient's diet and social activity must be taken. This should be followed by clinical examination (Figure 1a,b), and radiographic assessment of the teeth if necessary. Articulated study casts are used to assess the degree of toothwear and interocclusal space and to discuss the available treatment options with the patient – they are also useful for monitoring the toothwear. The patient must be warned that at the end of treatment the back teeth will not meet.

The shade of composite to be used is selected using a guide and the teeth to be restored are then isolated (preferably with rubber dam) to obtain optimal moisture control. The composite resin is then placed freehand incrementally to build the tooth to the original full contour:

• Minimal tooth preparation is carried out to round any sharp edges of the teeth to be treated and the teeth are cleaned using a slurry of pumice and water.
• The enamel surfaces are acid etched for between 30 and 60 seconds (according to manufacturer's instructions), washed with copious amounts of water and air dried.
• The exposed dentine surfaces are treated with light-cured dentine bonding agent.
• The composite is then applied freehand. It is important that the composite is placed in small increments to allow adequate curing and to reduce the polymerization shrinkage. The best surface result is obtained if a thin homogenous layer of composite finishes the build-up.

Each tooth must be treated individually and the embrasure spaces protected by a clear matrix strip. The authors prefer to restore alternate teeth, for ease of application of the composite. At the end of each application the gross excess of composite is removed to facilitate placement of the next one.

Once all the composites have been placed, the rubber dam is removed and gross finishing and polishing of the composites carried out (Figure 2). The occlusion is then checked using articulating paper and care is taken to ensure that in the retruded contact position there is even contact between all the teeth restored (usually the upper anterior teeth; Figure 3). As there is normally little or no interocclusal clearance prior to restoration, the finished restorations increase the vertical dimension of occlusion and thereby create posterior disclusion (Figure 4). The lateral excursions are canine-guided if possible.

The patient is reviewed a week later and the restorations finished using Soflex discs (3M Healthcare, Loughborough, UK) and/or polishing points (Enhance, Dentsply, Weybridge, UK). The occlusion is also rechecked.

Composite resins used

The composite resin used in this report was a microfill composite (Durafill, Kulzer; Panadent, London, UK) with Scotchbond multipurpose bonding system, (3M Healthcare). Other composites (e.g. Herculite XRV, Kerr, UK) are likely to have a similar performance.

The method presented here used a direct build-up of the composite resin freehand at the chairside. The use of clear preformed crown forms or vacuum-formed matrices obtained from a diagnostic wax-up of the teeth may provide similar results. Indirect composite restorations made in the laboratory will reduce chairside time and may perform equally well, but the practitioner will incur a laboratory fee.

Follow-up

The patient must be warned that it will take some weeks for them to adapt to the new restorations but that the occlusion should be established within 3 to 6 months. They must also be warned that they may experience some postoperative discomfort and difficulty in eating some types of food such as lettuce and ham. Problems with food collection on the occlusal surfaces of the teeth are occasionally encountered.

Further review and close monitoring of occlusion is carried out at 1, 3, 6, 9 and 12 months (Figures 5 and 6).

Discussion

The principles of the technique described were based on those of Dahl and Krogstad 1975,⁸ who placed a removable cobalt chromium anterior bite plane in an 18-year-old patient with localized anterior toothwear. The appliance was worn continuously and was removed only for cleaning. These authors then followed 20 patients treated in a similar manner and found an overall increase in occlusal vertical dimension which could have been due to a combination of intrusion of the anterior teeth and eruption of the posterior teeth.⁹ Their appliance produced poor aesthetics and, although fixed alternatives using the same principle have been documented,¹⁰ this disadvantage has not been overcome.

In the case described, composite resin was used to overcome this problem and found that the restorations lasted over 2 years. This would suggest that in some patients these restorations could become a practical short to medium-term solution for localized anterior toothwear.

Differential wear of teeth against various restorative materials has been recognized; ideally it is preferable for the restoration to wear rather than the opposing tooth. In this context success should be viewed as minimal or no wear of the opposing teeth and study casts taken preoperatively would aid in monitoring the extent of wear. Some wear of the restorations is expected and a reasonable period of service would be between 3 and 5 years.

Of 16 patients of the authors who have completed treatment using this technique, none have complained of discomfort and posterior tooth contacts were re established on average within 6 months.¹¹ Maintenance of these restorations has been minimal; in some cases incisal chipping was noted but this was easily repaired. These patients are currently under longer-term follow-up and will be reported in due course. Despite this apparent success we recommend regular follow-up, particularly during the phase of active tooth movement. Our experience with Dahl appliances is that rarely no apparent tooth movement occurs – in these cases the treatment plan must be re-evaluated. The long-term follow-up of these restorations will be continued but we are confident that they a place in general practice.

Disadvantages

The main disadvantage of this method is the time required to place the restorations. Although indirect composite restorations would overcome this problem, the technique is nevertheless clinically demanding and not always suitable if crown height and volume have been lost. Additionally, placing the restorations at an increased occlusal vertical dimension with posterior disclusion goes against most traditional principles of occlusion. It was noted that the posterior teeth came into occlusion within a short period of time and although the creation of unstable posterior occlusion was not observed, the possibility of uncontrolled and untoward tooth movement remains a concern. Tooth eruption is a biological phenomenon with a multifactorial origin.¹² Slagsvold and Karlsen¹³ have shown in monkeys that teeth taken out of occlusion have eruption potential and that the antagonism of teeth inhibits eruption.

Advantages

This technique offers a simple, cost-effective and easily maintained means of restoring worn teeth. It involves less clinical time than conventional crown and bridgework and provides patients with a dramatic improvement in appearance. Additionally, the crown height and contour can be altered relatively easily and maximum amount of tooth substance can be preserved.

When these restorations need to be repaired or replaced, it is important to create a new etchable surface by removing the surface layer of infiltrated enamel and dentine before fresh composite resin is added. This is a limiting factor in the number of repairs that may be carried out.

Use in worn dentition

Although we have reported the use of composite resin solely in the treatment of localized anterior toothwear, its use has been reported in the reconstruction of the worn dentition.¹⁴ However, caution should be exercised when faced with a patient with generalized or extensive toothwear, as no long-term follow-up data are available.