From Volume 46, Issue 8, September 2019 | Pages 708-720
The aim of this article is to provide the reader with the necessary information to manage localized anterior tooth wear cases successfully using minimally invasive and conservative methods in a general dental practice setting. This article will focus on the use of direct resin composite restorations. It will provide an update on the different techniques available to restore anterior tooth wear using direct resin composite and its method of application.
Tooth wear is loss of hard dental tissue, from causes other than bacterial involvement such as caries, trauma or developmental disorders.1,2 Continuing pathological tooth wear poses a risk to both the remaining tooth structure and pulpal health.
The definitions and causes of tooth wear are briefly summarized in Table 1. Patients tend to present with evidence of multiple tooth wear types due to the multifactorial aetiological nature of tooth wear.3,4 Erosion is regarded as the most significant cause.5,6 These causes present with a specific clinical presentation (Table 2). An example of multifactorial tooth wear is seen in Figure 1 a–c.
| Types of Tooth Wear | Definition |
|---|---|
| Erosion | Erosion is the irreversible loss of tooth structure due to chemical dissolution by acids not of bacterial origin. The source of the acid can be intrinsic (from the gastrointestinal tract) or extrinsic (from the patient's diet).3 |
| Abrasion | Abrasion is the irreversible loss of tooth structure due to physical wear of the teeth by a foreign object. |
| Attrition | Attrition is the irreversible loss of tooth structure as a result of excessive tooth-to-tooth contact as in mastication, with possible abrasive substance. This is commonly seen in bruxists.3 |
| Abfraction | Abfraction is the irreversible loss of tooth structure most commonly at the cervical region of the tooth. This is thought to be as a result of concentrated occlusal forces at the cervical margins of teeth.3,9 |
| Types of Tooth Wear | Clinical Features |
|---|---|
| Erosion | |
| Abrasion |
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| Attrition |
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| Abfraction |
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Epidemiological studies in developed nations assessing the extent and severity of tooth wear have shown it to be a common condition which is increasing in both extent and severity,7 and is increasingly presenting in younger patients.8,9 With the population retaining teeth for a longer period, significant numbers of patients are presenting to general dental practitioners and specialists requesting treatment.10
A thorough history and examination, including appropriate investigations, should be carried out before considering treatment. Emphasis should be on identifying the aetiological factors involved in the tooth wear and controlling or minimizing their effect on the patient's dentition. This is an acceptable treatment plan in patients presenting with minor tooth wear which has not yet resulted in clinical symptoms, aesthetic or functional problems. Where tooth wear has resulted in clinical signs and symptoms related to function and/or aesthetics, active restorative intervention may become required. This intervention should be minimally invasive, conservative of tooth tissue to help prevent biological complications and provide durable aesthetic restorations with high levels of patient satisfaction.11Table 3 summarizes the range of treatment options available to treat tooth wear.
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The ‘Dahl’ concept was introduced to create space to restore worn anterior teeth where interocclusal space was lacking.12 The concept involved placing a localized fixed or removable appliance or restoration in supra-occlusion at an increased occlusal vertical dimension (OVD), leaving the rest of the dentition out of occlusion and, over a period of time, the occlusion re-establishes contact at an increased OVD.13
The mechanism of how this worked was further studied by ‘Dahl’14 and demonstrated that the creation of interocclusal space involved alveolar compensation and condylar repositioning. The objectives of the ‘Dahl’ concept have been reported to be achieved in approximately 94%–100% of cases,15 with re-establishment of posterior occlusion ranging from just under 2 months to 18 months, with a mean of 7 months.6 This space can then be utilized for restorative treatment whilst minimizing/preventing the need to remove tooth tissue to provide interocclusal space for restorations.16
A thorough history, clinical examination and any relevant investigations should be carried out on every patient. The treatment of tooth wear should only be considered once primary disease, such as caries and periodontal disease, is stable and the patient has optimal oral hygiene in order to ensure a predictable outcome.
Patients must be aware of the occlusal changes planned and the limitations of the treatment proposed. Adaptation to the restorations can be difficult, given that patients' posterior teeth may not be in contact for an average period of 7 months16 following restorative intervention. As a result, transient tenderness of their front teeth, changes to speech and masticatory habits can be expected.16 A patient information leaflet can be found in the literature to help clinicians gain informed consent from patients.17
A thorough occlusal assessment is needed, particularly when re-organization is proposed. The occlusion and planned re-organization can be assessed and trialled outside of the mouth with the use of articulated study casts. A diagnostic wax-up of the planned re-organization, with the desired occlusal scheme and aesthetics as prescribed by the clinician, can then be produced (Figure 2). A stone model of the wax-up should be duplicated to avoid damage to the original casts (Figure 3).
The wax-up should be assessed to ensure that:
The wax-up can be used to create a pull-down stent which, in conjunction with a temporary restoration material, such as Luxatemp® Automix Plus (DMG, Hamburg, Germany), can be inserted into the patient's mouth and be used as an intra-oral mock-up so that the patient can visualize the finished result. The clinican should ensure that there is no undercut that the material can engage. Undercuts will need to be blocked out with wax and a layer of petroleum jelly applied on the affected teeth to ensure that the stents can be easily removed.
The proposed shade of the composite should be taken at the planning stages of treatment. This should be carried out on well-hydrated teeth to ensure that the correct shade is chosen. Different composite shades can be directly applied onto the teeth (without etch, prime and bond) in order to help in attaining the appropriate aesthetics.
The use of adhesive resin composite to treat cases of tooth wear was first described by Bevenius et al in 1994.20 Since then the use of direct composite in the management of localized anterior tooth wear has been well regarded as an appropriate and conservative treatment option. This is mainly due to advances in both resin bonding and resin composite based materials providing a more predictable and longer lasting restoration.14
Direct composite use in the management of tooth wear has its advantages and disadvantages (Table 4).21
| Advantages | Disadvantages |
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The success/survival of direct composite in the management of tooth wear has been reported by several authors (Table 5). Overall, the literature indicates that direct composite resin use is an acceptable, medium-term, definitive restoration in the management of tooth wear.3 It has also been shown to provide a good level of patient satisfaction, with no detrimental effect on the temporomandibular joints (TMJs), periodontal or pulpal health when carried out appropriately.22 Lack of posterior support was a main factor associated with failure.23 It is recommended that missing posterior teeth are replaced to reduce anterior loading on composite restorations. These studies have also shown that, where the direct composite is placed on anterior teeth in supra-occlusion at an increased OVD, the posterior occlusion re-establishes contact in most cases, with very few reported issues with this change.
| Author & Year | Duration of study | Patient number & Restoration number | Results & Conclusions |
|---|---|---|---|
| Poyser et al, 200738 | 2.5 years | 18 patients, 168 direct restorations |
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| Bartlett & Sundaram, 200622 | 3 year period | 29 patients, 58 pairs of restorations |
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| Hemmings et al, 200014 | 2.5 years | 16 patients, 104 restorations |
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| Gulamali et al, 201111 | 10 years | 26 patients 283 restorations |
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| Milosevic & Burnside, 201623 | 8 years | 164 patients 1010 restorations |
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However, there are a few reported issues with the use of direct composites for this purpose. These include minor fracture of the material, which is relatively straightforward to manage, and bulk fracture, which will require the preferred total replacement of the restoration. The restorations and their margins can also pick up staining over time and require polishing on a frequent basis, this being dependent on the patient's oral hygiene and diet.
The teeth that are to be restored should have existing restorations removed and the underlying tooth tissue cleaned/prepared with use of an ultrasonic scaler, pumice slurry or an air abrasion device to remove any staining/debris.
Some clinicians ‘freshen up’ the surface of the teeth prior to composite application by removal of a minimal layer of tooth tissue with either a high speed diamond or an air abrasion unit to improve bonding. The use of air abrasion has been shown to increase bond strength without sacrificing tooth structure.24 A high speed diamond can also be used to create a long bevel margin in enamel in order to improve the transition between tooth and composite restoration.
Isolation of the teeth and control of moisture is vital to ensure optimal bonding and ultimately the success of treatment.25,26 This can be achieved with use of cotton wool rolls, (dry) rubber dam and suction.
As used in Figure 4, the authors recommend that teeth should be total etched with 32% phosphoric acid (3M Scotchbond™ Universal Etchant, MN, USA) for 20 seconds. The etchant should be washed off and dried, taking care to avoid overdesiccation. Optibond™ Solo (Kerr Corp, Ca, USA) should then be applied using a microbrush, dried to allow for solvent evaporation and then cured for 30 seconds.
Direct composite can be placed using a variety of techniques which include:17
This technique involves the placement of the composite restoration without the use of dental impressions or a matrix/stent for guidance. Although this reduces laboratory costs in the preparatory stage, it can lead to greater operator time on the day of treatment. This technique requires a high degree of operator skill and a good knowledge of the average widths and relative proportions of teeth to achieve both an aesthetic and occlusally acceptable outcome. G-aenial composite (GC Corp, Tokyo, Japan) has been used by the authors in free hand build-up cases. This material does not slump during placement; it flows when moved around with an instrument and it does not stick to the instrument. Determining occlusal morphology can be difficult to do free hand without an aid or template. To assist in this, the composite resin can be added initially to the cingular areas of the maxillary canines and the mandible manipulated into its retruded arc of closure (before curing). The patient can be guided to close into the uncured resin until the desired space is achieved to place material to restore the remaining anterior teeth. The remaining teeth can then be ‘built-up’ by incremental application of resin composite using occlusal stops ascertained initially as a reference guide.27,28
This method is highlighted in Figure 5. A customized polyvinylsiloxane (PVS) matrix (Protesil labor™ (Vannini Dental Industry, Grassina, Italy)) was derived from the approved diagnostic wax-up. This technique provides the clinician with a template to duplicate the occlusal form already established using the palatal/lingual aspect of the stone duplicate model of the diagnostic wax-up. The stent should extend beyond the buccal aspect of the proposed position of the incisal tip/occlusal surface. It should extend lateral to the teeth to be restored to provide a stable base and positive location for the stent to be seated. The stent should be rigid but thin, so it is comfortable for the patient and allows good access to place and manipulate the composite clinically.
The clinical process involves placing the resin composite in layers from the palatal aspect in the desired morphological shape and position, as guided by the matrix.22 Composite is placed on palato-incisal aspects which then act as a scaffold for the free hand placement of the composite in the labio-incisal aspects.18 In the labio-incisal aspects, composite can be layered to the desired morphology and colour using a variety of resin shade available.
The management of the interproximal region can be difficult and the clinician must ensure that an appropriate contact point is produced. This can be achieved by creating a barrier using either metal matrices, such as Flutrec (Pulpodent, MA, USA), matrix strips or PTFE tape. The material of choice for this is operator dependent. Metal matrices and matrix strips should be positioned inter-proximally within the stent, extending 4–5 mm beyond the contact area. Some clinicians advocate the use of restoring alternate teeth to prevent bonding of adjacent teeth.18 Drawbacks of this method are putty stent flexion, the management of interproximal areas, difficulty in the lingual areas with tongue movement and also moisture control.
A stone duplicate model of the diagnostic wax-up is used to form a vacuum-formed transparent matrix. This can be made from a material such as Memosil® (Heraeus Kulzer, Newbury, Bucks, UK) or Duran™ (Scheu-Dental GmbH, Iserlohan, Germany) as highlighted in Figure 6. Figure 7 shows the resultant imprint of the pressure moulded thermoplastic tray lined with transparent addition silicone Registrado Clear™ (VOCO GmbH, Cuxhaven, Germany).
The vacuum-formed stent is designed to cover all the teeth to be restored, extending beyond the teeth that are being restored to provide a positive location and stability of the stent. It should be made in a transparent material to allow the resin to be cured through the stent. The stent should be rigid enough to hold its shape when loaded with composite.7 This can be achieved by extending the matrix 3 mm beyond the proposed restorative margin.22 The stent can be sectioned interdentally at the anterior teeth, 3–4 mm below the contact area, which is used for the passive placement of the metal matrices/matrix strips to manage interproximal excess.
Loading holes are created on the stent. These can be located on the desired incisal edge (Figure 8) or located midway between the existing tooth surface and the desired incisal edge, on the buccal surface of the teeth to be restored. This can be done using a round bur OS1023 (Brasseler, GA, USA). The template is seated in place, with matrices inserted interdentally between the template sectioning. Resin composite should be injected through the loading holes, in increments, using a back-flow technique to avoid air entrapment.
The viscosity of the resin composite can be used by using pre-heated resin composite.18 An alternate method is to insert resin composite material into the matrix with pre-placed interproximal matrices, which is then seated and light cured in situ.25,29 Small holes can be placed in the stent to allow excess resin composite material to flow out.
If interproximal excess is not managed appropriately, the patient will find it difficult to clean interproximally, which can compromise periodontal health. The inability to place the material incrementally can lead to high polymerization exotherm and contraction.28,30 There is also a higher risk of voids and air entrapment within the composite material which may or may not be visualized clinically. This can weaken the restoration making it more liable to fracture.31 To control the interproximal region, the matrix can also be sectioned interdentally in the desired inter-proximal area to allow the passive placement of inter-proximal metal matrices or wedge-shaped cellulose acetate strips to help control the interproximal region, as described with the putty stent.
Should tooth surface loss extend to the palatal gingival margins, the use of a PVS putty stent or a vacuum-formed transparent matrix may make the placement of composite more difficult in these regions. In these cases of palatal tooth surface loss, particularly at the level of the palatal gingival margin, free hand composite resin placement or indirect composite resin restorations may provide a better prognostic value as they offer more controlled composite placement for some clinicians.
Finishing and polishing should be carried out once all teeth to be restored in one clinical session have been treated. This will help prevent interproximal bleeding, which will affect resin composite bond strengths to the remaining teeth to be restored.18
The occlusion should be refined to the proposed occlusal scheme and ensure even and shared contact with appropriate anterior and lateral guidance, which is smooth without interferences, deviations or displacement. The posterior teeth will be out of occlusion until the objectives of the ‘Dahl’ concept are achieved and the patient should be monitored over subsequent months until this contact is re-established.
Initially, the composite restorations can be adjusted, and gross excess removed using a fine diamond bur, followed by fine carbide burs (Brasseler USA®, GA, USA) or a scalpel to remove overhangs (Figure 9). Final polishing can be carried out using a sequence of Sof-Lex™ discs (3M St Paul, USA) (Figure 10). This can be followed by a final lustre with Astrobrush® (Ivoclar Vivadent AG, Schaan, Lichtenstein) to achieve a successful post-operative outcome (Figures 11 a–d). Interproximal finishing is carried out with abrasive interproximal strips, such as Sof-Lex™ strips in the correct sequence (3M ESPE, Ontario, Canada) and should ensure that there is an appropriate contact point and embrasure space that is smooth and the patient is able to carry out interproximal cleaning at these sites.
The provision of a bilaminar occlusal guard will help prevent further tooth wear and protect the composite restorations, particularly for patients who suffer from sleep bruxism or daytime clenching. The guard should only be worn during the period of bruxism or clenching.32
Patients should be advised that their ‘new bite’ will feel strange for a few days, but should be reassured that they will become accustomed to this within a few weeks.
Regular follow-up is needed to ensure that patients are maintaining good oral hygiene, to monitor and ensure that the aetiological factors of their tooth wear are still under control and to monitor the progression of the posterior occlusion re-establishing contact.
Patients may also attend with staining, chipping or bulk fractures on an infrequent basis, which will require polishing, the addition of composite, or the preferred option of total replacement of the restoration. It is therefore useful to have the articulated models/stents available to help where required.
To ensure optimal outcomes in the management of tooth wear, an appropriate diagnosis and treatment plan is required with emphasis on prevention and control of aetiological factors before proceeding with prosthodontic intervention. Direct resin composite restorations are a conservative and minimally invasive treatment option that can be readily carried out in general practice. Patients should be advised that this treatment often involves regular maintenance, with repairs and rebuilds which may have an impact on the decision for patients.
