From Volume 42, Issue 6, July 2015 | Pages 525-532
The incidence of toothwear in the population is increasing, as is the number of referrals regarding this problem to secondary care dental hospital consultants and specialists. This paper outlines current theories in aetiology, diagnosis and management of localized and generalized toothwear, as well as describing clinical tips for assessing such patients.
It is accepted that a degree of toothwear occurs naturally with age. Excessive toothwear, however, can be exceedingly damaging; causing painful symptoms, poor aesthetics or problems with eating and speech. Anecdotal evidence suggests that patients are increasingly presenting with problems of toothwear both in primary and secondary care settings. This article describes the aetiology, diagnosis and treatment options for toothwear and aims to help clinicians manage patients with this condition.
Toothwear can be defined as ‘the loss of tooth substance by means other than caries or dental trauma’. Tooth surface loss (TSL) is an alternative term used which can confuse dentists and patients, and can understate the severity of the problem by implying that only the surface of the tooth is lost.1 The term toothwear is easy for patients to understand, which is very important, as successful management of the condition depends on the patient's understanding of the wear process and its aetiological factors. There are different types of toothwear which can occur in isolation but which more commonly occur in combination:
Physiological toothwear is that which is expected for the patient's age, commensurate with normal day-to-day function.2 If the rate of toothwear is in excess of that expected for the patient's age, or if the remaining tooth structure or pulpal health is compromised, then the toothwear is regarded as pathological.2 Toothwear commonly occurs so slowly that the pulp recedes, meaning that patients are often asymptomatic despite having lost a substantial amount of tooth tissue.
Attrition is wear caused by tooth-to-tooth contact. It produces well defined facets on the teeth, often with matching facets on the opposing teeth. Tooth clenching/grinding habits are linked to attrition and patients may or may not be aware of these habits. Their presenting complaint may be of temporomandibular disorder (TMD) symptoms rather than the toothwear itself.
Abrasion is wear of the tooth caused by something other than another tooth. This can be due to foreign objects rubbing against the teeth. Inappropriate toothbrushing habits (including interdental brushes) can produce V-shaped notches at the cervical margins of the teeth where the dentine and cementum are less wear-resistant than the enamel (Figures 1a, b). Holding foreign objects in the teeth, such as pens, pipes, hairgrips and nails/tacks can all lead to abrasion. Obtaining information such as the patient's occupation as part of the history is therefore essential in gaining vital clues as to the aetiology of toothwear. The pattern of toothwear can be irregular as it is dependent on the patient's habit. In providing porcelain restorations, dentists place a foreign substance which preferentially wears away opposing natural teeth.
Abfraction describes non carious cervical toothwear thought to be caused by microfractures of the cervical enamel rods due to repeated compression and flexure of the teeth under occlusal loading. Like abrasion, wear of this type can also present as V-shaped notches at cervical margins of teeth.
Erosion can be due to extrinsic or intrinsic acid. Medical problems can lead to gastric acid entering the mouth and damaging the teeth (Table 1). Extrinsic acids from the diet or the environment can also cause toothwear. Some occupations pre-dispose people to erosive toothwear, for example if they are involved in industrial work and exposed to acidic vapours or dust; or if they are a professional wine-taster. The critical pH for tooth substance dissolution is 5.5. Stomach contents, vomitus3 and fruit juices4,5 have pH values much lower than this.
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Erosion is characterized by shallow flat smooth concavities with round limits and smooth matte surfaces, which are often plaque and stain free.6 It is common for restorations to stand proud of tooth tissue where the acid has eroded the enamel and dentine around the restoration (Figure 2). The pattern of wear caused by extrinsic acids differs depending on how, and for how long, the acidic substances are held in the mouth and the frequency with which and time of day that they are consumed. Extrinsic acid wear can be less severe than toothwear caused by intrinsic acid and can affect the labial and incisal surfaces. Erosion due to gastro-oesophageal reflux disease (GORD) or vomiting often affects the palatal surfaces of the upper teeth, as the acid makes immediate contact with this area when regurgitated and the tongue covers and protects the lower teeth. Worn surfaces which are stained suggest historic toothwear, whereas glassy smooth unstained surfaces suggest wear may be ongoing.
Saliva confers a major protective function against toothwear due to its role in pellicle formation, buffering, acid clearance, and hard tissue remineralization.7 Therefore patients suffering from xerostomia are more likely to experience problems with toothwear.
The Adult Dental Health Survey of 2009 findings show that there is an increasing prevalence of toothwear amongst the UK population:8
Although the highest levels of toothwear were seen in UK adults, wear is common in other countries and a significant percentage (29%) of European adults also exhibited toothwear.9 Toothwear seems to be increasingly common amongst younger age groups and, as these people will retain their teeth into old age, it is imperative that wear is identified quickly and managed appropriately.
Toothwear indices have been developed primarily to calculate the prevalence of toothwear in communities, but they have also been used to diagnose, grade and monitor wear of different aetiologies.10,11 The best known index is the Smith and Knight classification10 where each surface of each tooth is given a score from 0–4 depending on its appearance. Some indices – like the Smith and Knight index – record toothwear irrespective of aetiology,10 whereas some are aetiology specific, eg erosion indices.12 The Basic Erosive Wear Examination (BEWE) calculates a summary score, where the sum of the highest score from each sextant is calculated12 (Tables 2a, b). None of the indices has universal acceptance, which is likely to be due to their vague definitions of criteria and lack of standardized terminology, and the fact that their use is subjective, meaning severity scores are not clear-cut.11,13 It is important to be aware of these indices, or at least to have an understanding of how toothwear can be graded. What is perhaps more important for a General Dental Practitioner (GDP) is being able to recognize toothwear, counsel a patient on how to prevent it from getting worse, and knowing how to restore teeth affected by wear.
| Score | Clinical Appearance |
|---|---|
| 0 | No erosive toothwear |
| 1 | Initial loss of surface texture |
| 2 | Distinct defect, hard tissue loss <50% of surface area |
| 3 | Hard tissue loss ≥50% of surface area |
| Highest score Sextant 17–14 | Highest score Sextant 13–23 | Highest score Sextant 24–27 | Score Sum |
| Highest score Sextant 37–34 | Highest score Sextant 33–43 | Highest score Sextant 44–47 |
It is only through a careful and thorough history that aetiological factors of toothwear can be identified and a process of management instigated commencing with prevention of the wear. Gaining sensitive information on the patient's medical history can be difficult, particularly if the patient is suffering from an eating disorder.14 Referral to a GMP (after obtaining the patient's consent) may be appropriate if it is suspected that the patient may be suffering from an eating disorder, or from GORD.
The evidence base for the clinical effectiveness of fluoride therapy in the prevention of toothwear is limited. High fluoride varnish or gel applications have been shown to be more beneficial than fluoride toothpaste in the laboratory setting.15 Whitening toothpastes should be avoided owing to their abrasiveness as this could increase the toothwear. Fluoride toothpaste will of course be beneficial in caries prevention even if its benefit in preventing toothwear is unclear.
Patients suffering from xerostomia should be encouraged to drink tap water or chew sugar-free gum to help keep their mouth moist. Prescription of a saliva substitute may also be beneficial, but care must be taken to avoid prescribing one with acidic components which could contribute to the wear.
If the toothwear is mild, the patient is asymptomatic and unconcerned by aesthetics, then a combination of prevention and monitoring of the toothwear may be best.16 Taking accurate impressions to obtain good quality models and taking photographs, and careful storage of these for reference at future appointments, are suitable ways of monitoring the wear.16
In order to decide the most appropriate way of restoring worn teeth, a careful assessment of the occlusion must be undertaken clinically. The worn teeth and the inter-occlusal space need to be examined in the inter-cuspal position (ICP) and the retruded contact position (RCP). The wear may be localized or generalized; and can be worse on certain teeth. All of this must be accurately recorded to aid with planning treatment. Taking alginate impressions, an RCP registration and a facebow record, to enable models to be articulated on a semi-adjustable articulator, and then prescription of a diagnostic wax-up can be invaluable to aid treatment planning decisions (Figures 3a, b).
If space exists in ICP between the worn teeth, then restorations can be easily provided. One common difficulty in restoring worn teeth, however, is the fact that often space has been lost due to the gradual loss of tooth tissue, and compensatory tooth eruption and alveolar bone growth maintaining the occlusal vertical dimension.17 In order to protect the worn teeth and improve function and aesthetics, space must be created using one (or a combination of) the following methods:
Although clinical experience shows this to be quite rare, where there has been generalized toothwear of one arch, and there has not been any dento-alveolar compensation, there will be overclosure and the OVD will be decreased. Patients generally tolerate well the worn teeth being restored around the original OVD. When dento-alveloar compensation has occurred in combination with generalized toothwear of one arch, a hard occlusal splint can be provided at an increased OVD prior to restoration to check that the patient can tolerate the new OVD. The new restorations are then provided by re-organizing the occlusion around the RCP. In some situations providing a splint may be misleading as it becomes more of a test of the patient's ability to tolerate a removable appliance than the effect of increased vertical dimension. Generally, most patients will adapt to a small increase in vertical dimension within the hinge axis of opening.
The Dahl effect is particularly useful where there is localized toothwear, for example, affecting the palatal surfaces of the maxillary anteriors. The original Dahl appliance was devised as a removable partial coverage bite plane made of cobalt chrome, used to create space for restoration of worn palatal upper anterior teeth through dento-alveolar extrusion of the posterior teeth and intrusion of the anteriors18 (Figure 4). Modern management of localized wear involves building up the worn teeth with composite restorative material, resulting in the teeth which are not built up being out of occlusion for a few weeks or months. Over time in the majority of cases the teeth out of occlusion re-establish contact. This is a biologically sound approach which can be completed quickly and studies have shown such composites to have good survival rates.19,20
Adjusting teeth in one or both arches can create a small amount of space, and this approach can be particularly useful where a single tooth requires restoration. Occlusal reduction of an already worn tooth should be avoided as this can cause loss of vitality, sensitivity, and a loss of height axially which will negatively affect the resistance and retention form of the definitive restoration.
This technique is useful when the patient has a large horizontal slide between RCP and ICP. Eliminating a premature contact found on the retruded hinge axis allows the mandible to be distalized and restorations provided in this new position. This enables worn anterior teeth to be restored without increasing the OVD.
Surgical crown lengthening can be used where the wear is severe and there is inadequate crown height for definitive restorations. This technique is invasive and often requires bone removal. In addition, margin preparations are then provided on a narrower root surface increasing the likelihood of loss of vitality.
Fixed appliance orthodontics is a conservative, although time consuming, way of creating space for restoration of worn teeth.21 It is especially useful in improving the alignment of the anterior dentition by increasing the overjet or reducing the overbite to create space, or where there is an existing malocclusion. Disadvantages of orthodontics include the inability to intrude teeth reliably and the risk of root resorption. In addition, patient compliance can compromise success of the treatment.
Where there is insufficient crown height to place a conventional crown, root canal treatment could be electively performed and a post-crown placed. This technique is outdated and significantly destructive, and resultant axial forces on the tooth have the potential to cause root fracture and early tooth failure. With the advances in adhesive dentistry and availability of surgical crown lengthening techniques, this option can be avoided and is not recommended.
In deciding how to restore worn teeth, it is important that removal of additional tooth tissue is kept to a minimum to prevent loss of vitality as the wear process will have already compromised the teeth. Table 3 shows the advantages and disadvantages of various materials.
| Composite | Cast Metal/Gold | Dentine-bonded Crowns | Porcelain-bonded Crowns | |
|---|---|---|---|---|
| Advantages |
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| Disadvantages |
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Composite is readily available to practitioners, cost-effective, provides an acceptable aesthetic result, and offers almost unrivalled clinical flexibility along with capacity to preserve natural tooth tissue. A technique which can protect the teeth, restore aesthetics and function with no attendant harm to the worn teeth, seems hard to argue against ethically, practically and biologically. Composite does have its limitations, however, and may be less effective in bruxists.
If a substantial amount of tooth tissue has been lost and porcelain crowns are to be used to restore the teeth, making the palatal occluding surface of the crowns in metal reduces the risk of iatrogenic damage to opposing natural teeth.
Whichever material is chosen for definitive restorations, it is worthwhile providing a soft splint at treatment completion for night-time wear, particularly if the patient is a bruxist or if there is an attritive element to their wear, to protect the new restorations and prevent further wear.
Where significant wear exists with little supra-gingival tooth tissue then an overdenture may be the only realistic option to replace the teeth.
With the exception of severe toothwear cases, where a full mouth re-organization of the occlusion or where crown lengthening is required, the majority of this treatment can be completed in the primary care setting. Certainly, even in such complex cases, a GDP should be competent in obtaining a good history and giving preventive advice and treatment. In addition, the role of the GDP in longer term follow-up and maintenance is an important one.
Toothwear in the UK population is increasing. Various factors can lead to toothwear and these factors must be identified and controlled before treatment commences. There are numerous different techniques and materials which can be used to restore worn teeth, and much of the management of toothwear patients can be successfully completed within the primary care setting.
