Dental Tribune Indian Edition

14 Dental Tribune Indian Edition - July 2013Cosmetic Author_Jost P. Prestin, Germany When meeting someone for the first time, a dental technician or den- tist automatically glances at the per- son’s mouth and teeth. Generally, the unnatural grey- or purple-coloured gingiva attracts more attention then the quality of the crowns. As detailed in the following case report, ante- rior porcelain-fused-to-metal (PFM) crowns or bridges are the main reason for this unsightly gingiva. Case report A female patient came to our office in February 2012 complaining about pain in the region of teeth 22 and 23. In addition, she was unhappy about the grey colour of her maxillary gin- giva and enquired whether it could be addressed. Teeth 13–23 had been restored with PFM single crowns 15 years before (Figs. 1–3). After a detailed discussion of the state of the art in anterior aesthetics, we decided to renew all six PFM crowns and replace them with IPS e.max crowns (Ivoclar Vivadent). For all anterior cases, IPS e.max is our first choice of material. Not even all ceramic is all ceramic. Zirconium has nearly the same light transmission as PFM— almost nothing. Of course de- velopment goes on, and the first tran- slucent zirconia products have been made available. It is first necessary to understand what causes a grey-co- loured ridge in patients provided with PFM crowns. There are two principal reasons. The first is the umbrella effect.1 This appears only with PFM and someti- mes with zirconium crowns. The opa- que copings block the light (Figs. 4a & b) so the root is not able to transmit the light and brighten up the papilla from the inside. Lithium disilicate glass-ceramic (except for the MO and HO ingots) is able to mimic the natural tooth. Owing to the mineral (crystal- line) structure of the tooth substance and the natural light transmission of the IPS e.max restoration, the light is scattered in all directions inside the tooth, lighting up the gingiva from the inside (Figs. 4c & d). The second rea- son for grey gingiva underneath PFM crowns is metal oxides diffusing into the soft tissue. The possibility of dark gingiva is increased by crowns with a higher ignoble metal content. Treatment plan After preparing all the necessary pa- perwork and discussing the treatment plan again, we began removing the old crowns and finished the supra- gingival preparation in the middle of April. The stump shade of all six teeth was the same, allowing us to press the copings all at once in the same shade (IPS e.max Press LT A2; Figs. 5 & 6). The provisional was directly prepared in the office. It is important to leave enough space for the papillae so that they are not pushed away (Figs. 7 & 8). After taking the impressions using Aquasil Ultra (DENTSPLY; Fig. 9), the model work was performed (Figs. 10 & 11) and the IPS e.max copings were prepared (Fig. 12). For the pres- sing process, we used Vario Press 300.e (Zubler). The extremely short pressing time results in a very thin reaction layer. There is therefore no need to etch the item in hy - drofluo- ric acid. The advantage is the perfect fit achieved because the thin margins of the copings are not rounded by Changing grey–white back to red–white Figure 1: Old PFM crowns in situ with surrounding grey-coloured gingiva. Figure 3: View of the grey-coloured occlusal soft tissue around the anterior PFM crowns and around the PFM molars. Figure 2: Old PFM crowns, slightly exposed tooth necks of teeth 12–22 and an open margin on the crown on tooth 22. Figure 4a–d: Schematic diagram of the incidence of light. The crosssection of a tooth with a PFM crown shows that the light passes through the ceramic and is blocked by the more opaque surface of the metal coping and scattered back into the ceramic (a & b). The cross-section of a natural tooth shows that the light passes into the tooth and the mineral tooth structure scatters it in all directions (c & d). Owing to the thin alveolar bone and the thin soft tissue, the entire area around the tooth is lit up from the inside. Figure 5: Occlusal view of the preparation with packed retraction cords. Figure 6: The preparation with the same stump shade on all stumps. Figure 7 & 8: Provisional in situ with cleared papillary areas. Figure 14 & 15: Ready for the try-in. Figure 10: Close-up image of the control model. Figure 11: Occlusal checking on the model to ensure adequate space for the crowns. Figure 12: The finished IPS e.max copings on the control model. Figure 13: Close-up image of the coping margins. Figure 9: The impression, taken with Aqua- sil Ultra. Figure 16: Close-up image of the mandibu- lar anterior teeth for the ceramic build-up. Figure 17–19: IPS e.max crowns in situ at the try-in. Figure 20: Controlling the shade, inclu- ding the lips. Figure 21–24: Controlling the approximal areas.Figure 19: IPS e.max crowns in situ at the try-in.