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ePaper created 2017-08-21, 17:22:06 | version 1.38.0
Dental Tribune Asia Pacifi c Edition | 7+8/2017 TRENDS & APPLICATIONS 13 The reproduction of natural dentition All-ceramic crowns in a complex anterior restoration 1 2 Fig. 1: The situation after the implants in regions #11 and 21 had healed.—Fig. 2: The zirconium dioxide framework. Its translucency provided a good basis for the aesthetics and shade effect of the restoration. By Yuji Tsuzuki, Japan The wide variety of materials and manufacturing techniques availa- ble provide the ideal fabrication method for every indication. In combination with dental technical skills and a good understanding of shades and colours, this leads to outstanding restorations. Imitating natural dentition is the greatest challenge in the fabri- cation of prosthetic restorations. A natural appearance is always de- termined by a number of various characteristic features, so the technique applied for the repro- duction of the teeth cannot always be the same. This is the reason that it is essential for us to ob- serve, learn and recognise fi ne de- tails and continue to develop, step by step, every day. The basis for imitating nature is an under- standing of the characteristics of healthy teeth and of ceramic ma- terials. The reproduction of light optical properties in particular is a challenge that requires an in- depth perception of colours. Prop- erties such as light refl ection, transmission and fl uorescence contribute signifi cantly to a suc- cessful result. When imitating the light op- tical properties, the basic struc- ture consists of three different layers: translucent, semi-trans- lucent and opaque. The surface colour is then applied based on a 3-D colour concept. Even though state-of-the-art materials (e.g. polychromatic zirconium diox- ide) have become very popular owing to advances in materials science, layering ceramic, built up by hand, is still indispensable for aesthetic restorations. In this article, well-proven techniques will be presented based on two case reports. The IPS e.max Ceram Selection Enamel and Effect materials were used to- gether with the IPS Ivocolor stains and glazes (both Ivoclar Vivadent). Both situations pro- ved to be a challenge in terms of the reproduction of light optical properties. However, imitating nature is possible! Inspiration during the build-up When building up all-ceramic crowns, the following steps must be carried out with great care: (1) control of the opacity, which infl u- ences the brightness; and (2) char- acterisation of the incisal edge with translucent or opaque mate- rials. Concerning the fi rst point, AD Case 1 Initial situation and treatment plan The approximately 50-year- old patient had suffered a fracture of the roots of teeth #11 and 21 as a result of an accident. The teeth could not be saved. After careful extraction, considerable resorp- tion of the soft tissue at the labial aspect was observed. After consul- tation, the patient opted for im- plant treatment. Prior to this, however, an intervention had to be carried out in the area of the la- bial soft tissue. The aim was to ad- just the gingival contours so that a perfect result could be achieved despite the high smile line. Owing to the advanced soft-tissue re- sorption, a removable implant su- perstructure made from gingi- va-coloured ceramic was pro- duced, taking aesthetic and hy- gienic aspects into account. The two maxillary central in- cisors occupy an important posi- tion from an aesthetic perspec- tive, since the prominence of these teeth expresses the patient’s individuality. Furthermore, the central incisors are the starting point for the continuity and sym- metry with the other teeth. There- fore, restoration specifi cally re- quires these teeth to be unique and crafted carefully. In this case, from a prosthetic perspective, it was important to integrate the asymmetrical anterior teeth. The mandibular anterior teeth were crowded and there was no contact with the antagonists. For functional integration, the maxillary anterior crowns had to be placed in a narrow mesiodistal area. The implants were inserted in re- gions #11 and 21, taking surgical and prosthetic requirements into consid- eration (Fig. 1). After osseointegra- tion, the implants would be restored with a splinted, screw-retained all- ceramic restoration (Fig. 2).