From Volume 46, Issue 9, October 2019 | Pages 812-816
This article will focus on the active management of localized anterior tooth wear using indirect resin composite restorations. Emphasis will be placed on minimally invasive methods of tooth preparation in order to preserve biological tooth tissue in an already compromised tooth structure. Active management commits the patient to considerable long-term maintenance and it is important, as with any treatment, that the advantages and disadvantages are fully explained to the patient.
Indirect composite resin restorations have been described since the mid-1970s, but it is only recently that they have been introduced into the marketplace with the desired mechanical and aesthetic values to provide an alternative to the use of dental ceramics.1 Their application has its advantages and disadvantages, as summarized in Table 1.2 The key advantages offered over their direct counterparts are a reduced level of polymerization shrinkage, as this takes place extra-orally, and reduced clinical chairside time, as any prescribed occlusal and aesthetic requirements will be carried out extra-orally by the dental technician.
| Advantages | Disadvantages |
|---|---|
| Improved control over occlusal contour and vertical dimension when compared to direct restorations | May require the removal of hard tissue undercuts. |
| Can be added to and repaired relatively simply intra-orally when compared to cast metal restorations | Restorations may be bulky |
| Aesthetically superior to cast metal restorations | Laboratory costs |
| Less abrasive than indirect ceramic restorations | Require at least two appointments in comparison to direct resin composites |
| Superior strength and wear resistance when compared to direct materials | Inferior marginal fit with visible cementation lines which may require masking with direct resin composite.15 |
| Reduced level of polymerization shrinkage as this takes place extra-orally. This lessens the undesirable effects of polymerization contraction, such as post-operative sensitivity and marginal leakage, with associated secondary caries and marginal staining. |
The success and survival of indirect composite restorations in the management of tooth wear has been reported by several authors (Table 2). Overall, favourable outcomes were reported; the restorations were well tolerated, with high levels of patient satisfaction in the placement of indirect palatal composite veneers. There was a high incidence of minor wear and repair, which was treated by monitoring, repair or refinishing. Major failure requiring replacement was uncommon.3 On the other hand, Bartlett and Sundaram reported on the use of direct and indirect restorations in the management and treatment of severely worn posterior teeth and suggested that the use of direct and indirect resin composites for restoring worn posterior teeth is contra-indicated.4,5 However, these authors used a microfilled composite which are known to perform suboptimally under occlusal loading.
| Author and Date | Duration of Study | Patient Number and Restoration Number | Results |
|---|---|---|---|
| Gow and Hemmings, 200216 | 2 years | 12 patients |
96% success rate |
| Redman, Hemmings and Good, 20033 | 3 years | 31 patients |
A very favourable outcome was reported |
| Bartlett and Sundaram, 20065 | 3 year period | 29 patients, 58 pairs of restorations | Indirect cusp coverage with micro-filled composite resin restorations were used to treat cases of posterior tooth wear 22% of restorations fractured and 28% completely lost in tooth wear group |
Given that the tooth structure in most tooth wear cases is already compromised, emphasis should be placed on minimally invasive preparations to optimize the mechanical, biologic and aesthetic success of the indirect composite restorations. Where the vertical dimension is to be increased, little or no axial tooth reduction would be required. However, if the clinical crown height of anterior teeth and premolars is less than the recommended clinical crown height of 3 mm,6 crown lengthening may be an invaluable means of enhancing retention and resistance form.7
The finish line of the preparation should be placed supra-gingival and onto sound tooth tissue.8 If there is a need to place the margin subgingivally to achieve adequate occlusal cervical dimension, it should extend by no more than half the depth of the gingival sulcus.9 The finish line should be detectable on the die in order to aid the technician, and have no unsupported lips of tooth structure at the edges which can chip away on the die or the tooth, resulting in a marginal gap and a poorly fitting restoration.
The key to an excellent impression which contains sufficient detail and accuracy is a careful interplay of several factors. These include the careful preparation of the dental structures, gingival displacement, tray selection, the appropriate choice of impression material, moisture control and impression technique. Clinicians should appreciate how these factors can influence their results. Whilst it is outside the scope of this article to discuss impression taking techniques in more detail, more information can be found in the literature.10
The cementation of relatively conservative restorations is made possible by the retention and strength received from bonding systems. Bonding facilitates the retention of indirect restorations, such as indirect resin composite palatal veneers, which may otherwise lack traditional preparation features.
Bonding with multi-step resin composite cements is supported by long-term data.11 However, the ease of use and potential advantages of newer self-etch adhesives and self-adhesive resin composite lutes is promising. There is a variety of bonding systems available; for example three-step bonding systems Rely X™ Arc (3M ESPE) and Nexus 3 (Kerr), two-step bonding systems Calibra (Dentsply) and one-step bonding Panavia™ (Kuraray) and Clearfil Esthetic Cement (Kuraray). These present with different levels of technique sensitivity and long-term bond strengths which can lead to variable clinical outcomes. Therefore, it is important to understand the physical and aesthetic properties of the systems available and ensure that they are used according to manufacturer's guidelines. Deviation from these guidelines may adversely affect bond strengths.12,13
Indirect composite restorations are manufactured extra-orally and this allows the dental technician to establish the desired occlusal and aesthetic prescription with more ease for the clinician and patient. The restorations should provide occlusion as prescribed, which should ideally be mutually protective, with appropriate anterior and lateral guidance 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 until this contact is re-established.
Clinical case 1 (Figure 1) presents a 63-year-old female with severe anterior maxillary tooth surface loss of erosive aetiology. Her main concern was increasing sensitivity to the anterior dentition with concerns about their longevity of her teeth. A comprehensive history and examination revealed a history of gastric reflux and current high acidic fruit diet. Study casts were taken and mounted in the retruded contact position on a semi-adjustable articulator. There was insufficient interocclusal clearance available in the intercuspal position and retruded contact position, and tooth preparation to accommodate a palatal restoration would have inevitably caused pulpal tissue exposure. The Dahl approach was therefore taken, and consent was gained using a patient information leaflet found in the literature.4 Indirect composite resin palatal veneers in supraocclusion were used to avoid unnecessary pulpal exposure and stabilize wear. Tooth preparation was confined to a fine supragingival chamfer margin on the palatal aspect of UL3–UR3 to aid the technician in locating the planned finish line of the restorations. Unsupported enamel was removed with a brown silicone rubber point (Shofu). Provisional restorations were not required because the tooth preparation carried out was so minimal that it did not affect occlusal function or positional stability of the teeth and the restorations would be cemented in supraocclusion. The occluso-aesthetic prescription to fabricate the veneers included contouring the indirect resin composite palatal veneers to provide even and shared anterior guidance, canine-guided lateral excursions, protrusive mandibular movements with posterior tooth separation and a prominent cingulum to provide a definitive occlusal stop to the opposing teeth and reduce the likelihood of unwanted labial tooth movement. The indirect composite veneers Gradia® (GC Corporation) were made at a suitable minimum thickness of 1.5 mm.14 The veneers were cemented using Panavia™ 2.0F (Kuraray) in one visit. To ensure that the veneers are cemented in the correct sequence, the veneers were seated on the study cast next to the dental unit and one veneer was cemented at a time in a logical order.
Due to mild incisal edge wear on UL1–UL3, direct composite resin Gradia Direct (GC) was applied. The wear on the maxillary premolar dentition and mandibular anterior dentition was also stabilized with direct resin composite restorations. Posterior occlusal contacts were re-established after a period of three months post cementation. The patient adapted well to the new occlusal prescription and reported a significant reduction in sensitivity on follow-up.
This case is an example of restorative strategies being combined to produce a satisfactory restorative result. Whilst there is no prescription in the literature indicating when direct or indirect composite resin restorations should be used, there are multiple factors associated with every case to consider when planning the restoration of localized anterior wear cases. In this case, for example, it would have been difficult to achieve the desired occlusal prescription chairside using direct composite resin on multiple teeth, and therefore the indirect approach was taken in this case.
A significant proportion of tooth wear cases presenting in a general practice setting can be successfully managed with appropriate preventive measures. Of those that require active restorative intervention, reversible additive techniques should be applied to restore the worn dentition, where possible. Indirect resin composite restorations are a more minimally invasive treatment option in comparison to conventional dental ceramics and have more superior aesthetics than metal (Nickel Chromium) palatal veneers. Like any other dental treatment, it is vital that patients are appropriately consented and that they understand their responsibility in the care and maintenance of their dentition with regular routine recall.
