The colour of natural teeth is determined by the dentine. The enamel acts as a filter and modulates the dentine shade, thereby enhancing the aesthetics of the tooth in most cases. The colour of natural teeth is therefore developed from within the tooth. With composite restorations, however, the dentist normally uses coloured composite enamel materials. The colour effect of the tooth is determined to a very large extent by these coloured enamel materials, with the colour being developed from the outside to the inside of the tooth which is the exact opposite to how colour is developed naturally. The traditional layering technique used in composite restorations adopts this approach. The composite enamel materials may be divided into coloured, modulating and translucent material for incisal edges. The coloured enamel materials form the final layer which ultimately determines the shade of the restoration. Modulating enamel materials, which do not however change the shade, are then applied to the coloured enamel material to enhance the final depth and translucency of the restoration. In an alternative layering technique the colouring is developed outwards from within as with natural teeth. In this case, dentine composites with saturated shades can be used because they are covered and modified by an additional layer of modulating enamel material which enhances the aesthetic value of the restoration in the same way as with natural teeth. With both techniques it must be ensured that these modulating enamel materials are applied in thin layers. As a final procedure, which is mainly carried out on young patients, the translucent incisal edge materials are applied to reproduce the opalescent incisal edge.
A clinical case is described below involving class IV restorations on teeth 11 and 21 using the Amaris system (Voco). This system is based on the concept of modulating enamel materials. It comprises five dentine materials of different colour saturation and three translucent modulating enamel materials. The system is easy to use and delivers predictable results. The enamel materials TN, TL or TD serve, respectively, to maintain the shade of the selected dentine, to slightly lighten it or to slightly darken it. The procedure, which is extremely simple to carry out, entails selecting the dentine composite whose shade most closely matches the desired final result and using the neutral modulating enamel material TN. This thin enamel layer over the dentine gives the restoration more depth and ‘life’. Another possibility is to select a dentine material that is a shade darker than the tooth and then to lighten this with the enamel material TL. In the author’s view this approach more accurately reproduces the transition between enamel and dentine found in natural teeth. The Amaris system also includes two flowable effect composites: HO, which is highly opaque in order to prevent discoloured dental hard tissue from showing through and to create effects and characterisations, and HT, which is extremely translucent.
There are two prerequisites that are of fundamental importance to the clinical and aesthetic success of restorations using composites: knowledge of the optical properties of natural teeth and knowledge of the restoration system to be used. Dentists with a thorough knowledge of these factors are able to determine which composite materials are to be used in which increment thicknesses in order to reproduce in a natural way the characteristics of the tooth to be restored. The challenges in placing a restoration are not limited to reproducing the shade exactly: they also include striking the right balance between translucence and opacity. The purpose of this report is to present a step-by-step account of the restoration of two fractured upper central incisors using the Amaris system, with particular emphasis being placed on the concept of composite resin stratification and finishing and polishing to provide natural-looking restorations.
References available on request.