Information for patients undergoing treatment for toothwear with resin composite restorations placed at an increased occlusal vertical dimension

Epidemiology of toothwear

The cause of TW may be considered to be multifactorial, being mainly due to erosion, attrition and abrasion, with abfraction also being a source of TW. However, the problem becomes increasingly significant when two or more factors present together. TW has been termed pathological when extensive areas of dentine are exposed,4 and may be measured by indices such as those proposed by Smith and Knight in 19844 or, more recently, by the relatively easy-to-use index proposed by Bartlett and colleagues.5^,6

The incidence of TW in England, Wales and Northern Ireland has recently been examined in the 2009 Adult Dental Health Survey,1 with the results indicating that:

Results from other papers have indicated TW in adults ranging from 3% with severe TW at age 20 years, to 17% at age 70 years,7 while a study of 1010 students in London, aged 18 to 30 years, showed that enamel wear was common to all subjects and that 76.9% had one or more surfaces with dentine exposed, and males had significantly more wear than females.6 Again in London, Smith and Robb examined 1007 patients, finding that patients under 26 had the worst TW, that only 9 of those examined had no TW and that there was extensive TW in 10% of those examined.8 Again males had more TW than females.8

Most recently, a major study has reported on the incidence of TW in 3187 patients in seven countries in Europe.9 The results indicated large differences between different countries, with the highest levels of TW being observed in the UK, with risk factors including heartburn, acid reflux and repeated vomiting. A moderate increase in TW with increasing age was also noted, and TW was associated with all acidic intakes studied, but especially with fresh fruit and isotonic/energy drinks. The prevalence of significant TW was 26% of the study population, with severe TW being found in 3% of the participants.

In summary, the results of this brief review suggest that TW is a substantial and increasing problem. Of greatest worry is the incidence in younger patients, since their worn teeth will require treatment throughout their lifetime.

Achieving space for the restoration of worn anterior teeth

Work by Declan Anderson in 1962 examined the effect of placing a supra-occluding restoration on a posterior tooth, with the results indicating that the patient's occlusion was regained after a period of up to 41 days.10 In addition, in 1981, Slagsvold and Karlsen demonstrated, in monkeys, that teeth taken out of occlusion had the potential to erupt and that the antagonism of teeth could inhibit eruption.11 However, the work of Anderson went largely unnoticed until a concept for achieving the necessary space for restoration of anterior teeth affected by TW was put forward in a series of papers by Dahl, commencing in 1975.12^,13^,14 He initially used a removable appliance, approximately 2 mm thick, on the palatal aspects of maxillary anterior teeth affected by TW (the so-called Dahl Appliance), causing the posterior teeth to be discluded. Later versions were cemented cobalt chromium appliances. Dahl and Krogstad13^,14 reported that the posterior teeth later subsequently regained their occlusal contacts, with the effect being attributed to be a combination of intrusion of the anterior teeth and eruption of the posterior teeth. However, it could also be considered that mandibular condylar repositioning to a more superior and retruded position could account for some of these changes.3 One statement from Dahl's work is worthy of quotation verbatim, this relating to the ‘jeopardising consequences’ of crowning teeth:12

‘In an effort to avoid capping a great number of teeth, with its many jeopardising consequences, a technique has been developed by which the necessary space for the crown material has been obtained by orthodontic measures’.

The purpose of Dahl's appliance was to obtain space to restore teeth affected by TW: he then used the space which had been created to restore the teeth with restorations, such as gold pinlays and crowns. Patient acceptance of the procedure was reported as being good, with the main problem reported to be lisping.13 The ‘Dahl concept’ has been further developed in the past 15 years by using resin composite restorations bonded to worn surfaces,15 with Dental Update being among the first journals, in 1997, to publish the description, by Darbar and Hemmings, of the use of resin composite in the treatment of TW at an increased occlusal vertical dimension.16 These clinicians described freehand build-up of the resin composite, but considered that a clear preformed vacuum-formed matrix (obtained from a diagnostic wax-up) could also provide similar results. They warned patients that it could take ‘some weeks’ for them to adapt to the new restorations but that the occlusion should be re-established within 3 to 6 months.

Bonding to dentine: which type is best?

Given that the majority of patients with TW will have exposed dentine, the achievement of a reliable bond to dentine is therefore central to successful treatment with resin composite restorations. While bonding to enamel was first described in 195517 and remains the most reliable bonding substrate in dentistry, the achievement of a reliable bond to dentine has been more elusive, principally because dentine contains circa 10% water and 20% organic material. Often, in severe TW cases, there may remain a small rim of peripheral enamel near the gingival crevice where it may be considered that it has been protected by the crevicular fluid from acid attack: this has been termed ‘the enamel ring of confidence’.3

Currently, bonding agents may be classified into ‘Etch and Rinse’ (alternatively termed ‘Etch and Bond’ or ‘Total Etch’) or ‘Self-Etch’, with the latter being sub-classified into strong etching potential and mild self-etching potential.18^,19^,20 The self-etch bonding agents are of sufficiently low pH to etch the dentine surface and initiate bonding. These systems are attractive because of their ease of use, but their clinical effectiveness, as measured by retention of restorations in non-retentive cavities, such as Class V, has been considered to be less than ideal in a systematic review published in 2005.21

It is therefore suggested that the etch and rinse systems should be used in cases where retention of the restoration is principally achieved by the bond to dentine, such as in Class V cavities, and in the treatment of cases of severe toothwear where little enamel remains for bonding. However, there is recent evidence from Peumans and colleagues,22 in an 8-year evaluation of a self-etch adhesive, that the performance of self-etch adhesives may be improving. However, it is the view of the present author that one paper is not sufficient to make him change his clinical practice so, until additional papers also demonstrate the clinical effectiveness of self-etch dentine bonding systems, the author suggests that reliance on an etch and rinse bonding agent is prudent in clinical situations where the restoration is retained wholly by the action of the bonding agent.

Most recently, the concept of selective enamel etching has been put forward.22^,23 In this, the enamel cavity margins are etched with 35% phosphoric acid and the dentine surface is not etched. This technique has been demonstrated to produce margins to enamel which are less prone to staining and has been considered to give protection to the dentine bond by the creation of a protective enamel/composite interface.22 However, it may be postulated that self-etch systems may be used satisfactorily in clinical situations where there is adequate resistance and retention form, although that statement is by no means without controversy.

Case report

The patient, a 35-year-old male, was referred, complaining of sensitivity and rough incisal edges affecting his maxillary incisor teeth. He admitted to daily consumption of large volumes of carbonated drinks. Clinical examination (Figures 1 and 2) showed the typical signs of severe erosive toothwear (thin, chipped incisal edges and large areas of dentine exposed on the palatal aspect) affecting principally the maxillary anterior teeth, with the pulp being visible through a thin film of dentine in UL1 and UR1. Study casts were made, principally for the instruction of the patient. He was advised that treatment to cover the exposed dentine surfaces was essential and that this should be carried out at the earliest possible convenient appointment so that the pulps which were visible did not become exposed.

Following full clinical and radiological examination, a diagnosis of erosive TW was made. By way of informed consent, the patient was provided with a Patient Information Leaflet (Table 1) advising:

Regarding the longevity of the resin composite restorations, the patient was advised:

Following discussion of these points, consent was given and the treatment commenced. The teeth were cleaned using pumice and water and the bonding agent Scotchbond 1 (3M ESPE, St Paul, MN, USA) was used, following etching with 35% phosphoric acid. The restorations were formed, freehand, in Filtek Supreme XT (3M ESPE, St Paul, MN, USA: A2 body and enamel), with metal strips being placed between the teeth during these procedures. Retraction of the lips and cheeks was achieved using Optragate small (Ivoclar Vivadent, Leichtenstein). Initial occlusal adjustment, finishing and polishing of the restorations was carried out at the first treatment visit (Figure 3), although the patient experienced difficulty in achieving a reproducible intercuspal position. On the visit on which the anterior restorations were placed, the patient was asked to check the restorations with his tongue to ensure that there were no rough edges and was advised that the final occlusal adjustment and polishing with various grades of discs and points and diamond polishing paste would be done at a second visit one week later. On that occasion, the patient was found to be closing in a reproducible new intercuspal position allowing the restorations to be checked and adjusted in intercuspal position and in protrusive and lateral excursions (Figure 4). The patient expressed pleasure at the appearance of his teeth and stated that the sensitivity had disappeared.

Discussion

The treatment described is not without risk of discomfort to the patient although, being minimally invasive, can generally be carried out without anaesthesia. However, patients must be informed of the potential disadvantages of treatment (vide supra). The Patient Information Sheet used by the author is presented in Table 1. This is also available at the end of this article on the Dental Update website and can be printed off and used by readers in their practice. The Information Sheet also contains information for patients who have fixed or removable prostheses in their posterior sextants, as such patients should be advised that it is unlikely that these fixed prostheses will erupt into occlusion and may therefore require replacement, with the cost of this necessarily being borne by the patient. Similarly, removable prostheses have no innate eruptive potential and will therefore require either a remake or the addition of resin to the occlusal surfaces of the posterior teeth to bring them back into occlusion, again with the attendant costs.

The success of the treatment described has been reported by a number of authors (Table 224^,25^,26^,27^,28^,29^,30), with the data presented in the table indicating a good degree of patient satisfaction, with the posterior occlusion being re-achieved in all but a small proportion of cases, and no detrimental effect on TMJ, periodontal or pulpal health. The general conclusion that may be made from these papers may be considered to be that resin composite restorations placed at an increased occlusal vertical dimension may be a viable and minimally interventive treatment option for the treatment of localized anterior TW, although the restorations require maintenance. In this regard, most recently, Gulamali and colleagues have reported the 10-year findings of the patients treated with resin composite restorations placed in their worn anterior teeth at an increased occlusal vertical dimension.30 They concluded that the use of composite was a viable medium-term option, but that 90% of restorations had major or minor failures and required maintenance. However, they also reported that biological complications of treatment were rare and that there was least good survival in Class II div 2 occlusion patients. They further concluded, with regard to the success of the restorations, that the amount of parafunction seems more important than the occlusal relationship. It may, however, be considered that improvements in bonding systems and, indeed, in resin composite materials, should today facilitate an improved performance when compared with the restorations in the study by Gulamali et al.30 In the author's experience, chipping or partial debonding appears to occur most frequently in teeth with no, or minimal, enamel at the margins of the worn surfaces (which is to be expected), but the majority of problems are reparable. Additionally, an audit of the performance of restorations placed for the author's patients indicates less good performance of restorations placed in worn mandibular (as opposed to maxillary) teeth. In this regard, it is therefore fortunate that mandibular anterior teeth are often protected by the tongue to some degree and therefore do not present as needing treatment as frequently as maxillary teeth. The author generally offers patients a review at three months post-treatment, at which time their satisfaction with their dental appearance is discussed, with crown lengthening surgery and all-ceramic crowns being offered if the patient is not satisfied with the pragmatic aesthetic result which has been offered.

With regard to the treatment of severely worn posterior teeth, Bartlett and Sundaram have reported on the use of direct and indirect resin composite restorations, with their results indicating suboptimal results, with over 50% of restorations being lost at periods of up to 3 years.27 However, the composite used in some cases was an experimental one. It could be surmised, however, that the restoration of severely worn posterior teeth is a substantial clinical challenge.

Finally, resin composite does not possess greater resistance to wear than enamel and, accordingly, the treatment may have to be repeated at some time in the future. Figure 5 illustrates a patient at presentation, and Figures 6, 7 and 8 that same patient following oral hygiene advice and bonding of resin composite to the palatal aspect of UL3 to UR3, and the incisal edges of LL3 to LR3, causing disclusion of the posterior teeth and removing the traumatic complete overbite. Eight years following this initial treatment, the restorations are all still in situ but have worn, with a complete overbite only 1 mm (or 6 months) away. The patient has therefore been advised that the treatment may have to be repeated in the near future.

Toothwear has been considered to have a measurable impact on patients' satisfaction with their dental appearance, on their oral comfort and on their eating and chewing capacity.31 The treatment described has the potential to correct these problems while, at the same time, maintaining the biologic principles of maintaining pulp vitality and periodontal health, with a good fallback position should a restoration subsequently fail (in contrast to methods used to treat TW in the past before adhesive technology was sufficiently developed and when crown lengthening and crowning were the standard32). This is the basis of the Daughter Test,33 namely, ‘would you carry out this treatment on a loved one, colleague or friend’? The results may not always be of the highest aesthetic standards, such as may be achieved by veneers or crowns, but the patient's teeth, which are already worn, are not further mutilated by tooth preparation. This is the concept of pragmatic aesthetics.3

Conclusion

Resin composite restorations, bonded using an etch and rinse dentine bonding agent, may provide reliable restorations for worn teeth. However, patients should be fully informed of the disadvantages and advantages of treatment by way of a Patient Information Sheet.