Principles

Tooth wear (TW) may be subclassified in a variety of different ways: localised, generalised, anterior, posterior mandibular or maxillary. Although a significant proportion of pathological TW cases may be effectively managed using a passive-preventative approach, as described in Chapter 9.1, for certain patients active restorative intervention will be indicated, for instance where there may be:

• Aesthetic concerns
• Symptoms of pain and discomfort
• Functional difficulties
• The presence of an unstable occlusion
• A rate of tooth surface loss that is of extreme concern to either the dental operator or the patient, which furthermore if neglected may culminate in exposure of the dental pulp.¹

The protocol for active restorative intervention may vary considerably, depending on various aesthetic and functional-mechanical considerations, as well as the quantity and quality of residual tooth tissue.

Maxillary anterior teeth are more likely to be affected by pathological TW, especially where erosive agents are causative (perhaps due to the lack of direct buffering from saliva, which mandibular anterior teeth may benefit from, coupled with the action of the tongue to hold acidic substrates in close proximity to these teeth). This chapter will largely focus on the management of maxillary anterior TW using simple restorative techniques. However, the principles for restoration apply equally to the lower anterior dentition.

In deciding how to optimally restore maxillary anterior teeth affected by the process of wear, there are six key aspects to consider:

• 1) Pattern of anterior, maxillary tooth surface loss
• 2) Interocclusal space availability
• 3) Space requirements for the dental restorations being proposed
• 4) Quantity and quality of available dental hard tissue and enamel respectively
• 5) Aesthetic demands of the patient
• 6) Speech.¹

For cases of anterior maxillary wear involving visible facial surfaces, restorative techniques will invariably require the prescription of tooth-coloured aesthetic materials, hence dental ceramics and/or resin composite.

Where possible, restorative techniques should be minimally invasive (as the affected dentition will have sustained injury and volumetric loss already) but also offer the potential for adjustment should the planned changes be poorly accepted or tolerated. Contingency planning should be given due consideration. For these purposes, the use of resin composite applied directly offers a suitable option.

Direct composite resin when used in the management of cases of TW offers the advantages of providing:

• Acceptable aesthetic outcome
• Non-invasive procedure
• Diagnostic tool
• Acceptable level of tolerance by pulpal tissues
• Minimal abrasion to antagonistic surfaces
• Ease of repair and adjustment
• Cost-effective material
• Restorations may be applied within a single visit.²

The disadvantages of direct resin composite restorations for this purpose include:

• Polymerisation shrinkage, which may culminate in marginal leakage and staining
• Accelerated wear rate (when compared to metals/ceramics) and possible inadequate wear resistance for posterior use
• Bulk fracture(s)
• Discoloration
• Need for optimal moisture control
• Need for good quality/quantity of dental enamel
• Complexity of application, particularly for palatal veneers, and limited control over occlusal and interproximal contours.²

It is generally accepted that resin composite restorations when applied to areas of high loading should be placed in the thickness range of 1.5–2.0 mm. Thus, in order to place this quantity of material, there is a need to provide the desired level of interocclusal clearance.¹ This may occasionally be present in the intercuspal position, where an open bite may exist, or the patient presents with a rate of wear that exceeds the rate of dento-alveolar compensation (which serves to maintain the function of the masticatory system). In some cases, the required interocclusal clearance may also be present where there is a discrepancy between intercuspal position and retruded contact position (see Chapter 3.1).

Where interocclusal clearance is not present, the operator may choose to follow traditional prosthodontic protocols and create space to accommodate restorations/restorative materials through the process of tooth reduction and to conform to the existing occlusion. Alternatively, an overall increase in the occlusal vertical dimension may be considered, although this may result in highly complex restorative care, as discussed further in Chapter 9.7.

A further approach is to place the material in supra-occlusion, hence the idea of relative axial movement, perhaps more commonly referred to as the Dahl concept.³–⁵ This refers to the axial tooth movements that occur when a localised appliance or localised restoration(s) are placed in supra-occlusion and the occlusion re-establishes full arch contacts over a period of time. The re-establishment of occlusal contacts is thought to occur through a process of controlled intrusion and extrusion of dento-alveolar segments, with an element of mandibular repositioning involving the mandibular condyles and neuro-muscular adaptation. This will be discussed in more detail in Chapter 9.4.

There are a variety of techniques available to predictably place resin composite in a direct manner, which are also discussed further in Chapter 9.4. For relatively simple cases of isolated anterior wear, such as the palatal surfaces of the upper incisor teeth, a freehand technique may be used. This may involve a conformative approach when the intercuspal position would not be changed, or there is space available in this position, or a localised relative axial movement is being anticipated. The practical section that follows provides a description of how relatively simple palatal wear affecting the anterior maxillary dentition may be restored in a freehand manner.

The freehand application of resin composite requires the operator to have a very good working knowledge of the concepts of dental anatomy, aesthetics and occlusion, as well the skills to apply resin composite in such a manner to attain a desirable and predictable aesthetic outcome. However, this technique is cost and time effective, as further laboratory stages are not required.

Procedures

Having carried out a comprehensive examination, including an occlusal and aesthetic assessment, begin by selecting an appropriate shade(s) of resin composite. This is perhaps best done while the teeth are hydrated. The use of a trial shade may help the process.

Mark the centric stops using articulating paper. Apply an appropriate form of isolation. It is best to remove any pre-existing composite restorations. Thoroughly clean the teeth using oil-free pumice slurry or air abrasion. The process should be extended on all surfaces where resin bonding will take place.

Condition the appropriate surfaces for adhesive bonding, as described in Chapter 5.1.

Place the selected enamel shade of composite resin onto the palatal surface of the affected tooth. With an appropriate plastic instrument, adapt the resin material to form the palatal contour. A paddle-shaped instrument, burnisher or interproximal carver is useful for this purpose. Resin placement should be carried over the incisal edge onto the facial surface. It is important to maintain a minimal thickness of resin composite of 1.5–2.0 mm in all areas of loading to ensure the required mechanical integrity.

Once the desired contour is achieved, the composite resin is light cured. You may choose to place a final layer of translucent resin shade to enhance the aesthetics. The analogous process is continued for subsequent anterior maxillary teeth.

After a period of 30 minutes to permit dark polymerisation, using articulating paper, initially verify the desired occlusal scheme and adjust using a diamond bur. The aim should be to provide shared contacts between the anterior teeth during protrusive mandibular movements, as well as posterior disclusion.

Assess the proportion, size and symmetry of the restorations across the midline. Features to note are listed in Box 9.3.1.