Subir Banerji and Shamir B. Mehta
Of the direct aesthetic materials available in today’s marketplace, few clinicians would dispute the role of resin composite as the most suitable form of product for the restoration of anterior teeth. It has the ability to almost mimic lost or damaged natural tooth tissue (being available in an array of shades, textures and opacities), adequate mechanical properties, stability and predictability in the oral environment, the provision of a good marginal seal, relative ease of use and repair, time and cost efficiency.
However, in order for the clinician to provide patients with a desirable result when planning anterior restorations, there is a need to understand several key principles. These include the following:
- The macro- and micro-anatomical variations that exist in the anterior dentition, including morphological variations of the whole tooth when viewed in differing planes, as well as surface textural changes and variations in the anatomy of the incisal edge.
- The fluctuations that exist in shade and colour between different patients as well as in different regions of a tooth for the same patient.
- The effects of ageing on the properties of the enamel and dentine as well as aesthetic issues.
- A good working knowledge of the available materials as well as their respective techniques of handling and application.
- The fundamentals of adhesion and clinical occlusion.
This chapter will focus on Class IV restoration.
In order to gain predictability with form when planning and preparing anterior Class IV restorations, many clinicians choose to use a silicone key to ‘copy’ a given occlusal morphology.
The silicone key is usually fabricated in polyvinyl siloxane (PVS). It is imperative that the key is extended to the premolar occlusal surfaces and has an adequate level of thickness to ensure stability and rigidity in the oral cavity. The index should be extended to the incisal edge.
Commence with shade selection prior to the application of an etchant, ideally while the tooth is moist and under appropriate lighting conditions. You may wish to use a proprietary shade guide or apply a selection of trial shades (sometimes in a layered manner) to the patient’s tooth. It is good practice to attain a pre-operative photograph of the adjacent tooth/teeth. When the latter is reduced in contrast by a factor of three, it is possible to visualise the morphological and physiological colour variations that exist in your patient’s anterior teeth, including features detailing the appearance of the incisal edge, such as the presence (or indeed absence) of mamelons, lobes, grooves, minor fractures and surface stains that you may choose to imitate. You may consider creating a sketch noting these variations, additionally documenting any macro- and microscopic variations you wish to impart into the restoration.
Following the marking of centric stops using articulating paper as well as the recording of occlusal contacts during dynamic mandibular movements, apply your chosen form of isolation. Following cavity preparation (if required), place a bevel along the entire cavity margin, facially, interproximally and palatally. The use of a chisel may prove helpful for finalisation of this stage.