Please activate JavaScript!
Please install Adobe Flash Player, click here for download
ePaper created 2016-04-15, 12:06:52 | version 1.38.0
Dental TribuneAsia Pacific Edition | 11/201516 TRENDS&APPLICATIONS Forsometime,IvoclarVivadenthasbeen offering a polychromatic, that is multi- coloured,ingot for the press technique: the IPS e.max Press Multi ingot. These innovative ingots integrate a smooth shadeprogression.Nuancedshadegra- dients from the enamel to the dentine allow multicoloured restorations to be pressed in a single sequence.The poly- chromatic press technique is surpris- inglysimple,ascanbeseenbelow. The press technique is a proven method for creating monolithic all- ceramic restorations in the dental laboratory. Many technicians enjoy the efficient procedure that allows themtochoosebetweenusingtheir artistic manual skills or the digital wax probe, depending on their preference. Impressive results can be achieved, especially in conjunc- tion with lithium disilicate glass- ceramics (IPS e.max Press). Exact accuracyoffit,highstrength,homo- geneity and an efficient procedure are the advantages offered by this method. Refinements of morphol- ogy and function can be applied in a targeted fashion. For several months now, the multicoloured IPS e.maxPressMultihasbeenavailable (Fig.1). This ingot features a smooth shade progression, similar to the shade gradation of the natural tooth. Only one press sequence is required to achieve a high level of chroma in the cervical and dentine areas and the desired level of translucency in the incisal region. Restorationsthatimpresswiththeir nuanced, lively appearance are the result. The Multi ingot enhances the family of the proven IPS e.max Press lithiumdisilicatematerials.Itissup- pliedinnineA–Dshadesandableach shade. The natural shade progres- sion of the ingot allows users to create polychromatic restorations usinganefficientprocedure,whether veneers, crowns or hybrid abutment crowns. Customisation is optional and is achieved with the staining technique, very much in keeping withthespiritofmanytechnicians. Contouring Thepreliminaryworkisnotessen- tially different from the known pro- cedures used in the press technique. Before or after the teeth have been suitably prepared for the placement of a ceramic restoration, the tooth shade is determined. As the shade of the remaining tooth structure has a substantial effect on the final aes- thetic outcome, the shade of the preparation should also be deter- mined, for instance by means of the IPSNaturalDieMaterialShadeGuide. If, additionally, photographs of the preparations are taken, important information can be transferred from thepracticetothelaboratorywithvir- tually no loss of data. On the basis of this information, the shade of the in- gotisselected.Animpressionistaken and a working model fabricated— usually a model with detachable seg- ments. Generally, the spacer coating onthedieplaysanessentialroleinthe accuracyoffitofthepressedceramic restoration, as the investment mate- rial (Ivoclar Vivadent) is coordinated with precisely specified parameters. Theprocedureforapplyingthespacer is essentially no different from the procedure applied for monochro- maticrestorations. Afterthedieshavebeenprepared, we recommend checking the mini- mum thickness available for the restoration. As the Multi ingots are mainly used for monolithic restora- tions, the layer thicknesses specified for the staining technique should be observed. If a veneer is to be created, thelayerthicknessofthecentralarea should be 0.3–0.6 mm, and the in- cisalthirdshouldbebetween0.4mm and 0.7 mm. Excellent results can be attained in anterior crowns using relatively little space: a thickness of 1.5mmisrequiredinthecentralarea andaminimumthicknessof1.2mm in the incisal region. In posterior crowns, the layer thickness should notbelessthan1.5mm. Contouring is performed follow- ing the conventional guidelines on shape, morphology and function. Contouring represents another fun- damental aspect of the efficient manufacture of high-quality resto- rations. The more accurate and detailed the contouring of the re- storation, the less reworking will be required later on. Once pressed, the restoration generally only needs to be glaze fired or, optionally, it may be customised with stains. The marginal areas should not be over-contouredtoavoidtheneedfor time-consuming and risky adjust- ments. It should also be borne in mind that the restoration will be characterised with stains and/or glaze after the press procedure and may therefore slightly, but only just slightly, fall short of the stipulated thicknessintheocclusalarea. Investing The Multi ingots are clearly more chromatic in the lower area than in the upper third. This gradation fol- lows the gradation found in natural teeth. The question arises as to how the shade layers of the ingot can be transferredtotherestorationsothat they are positioned in the correct place. From this point onwards, the procedure is different from the con- ventional press technique. A special wax-uptechniqueandprocessingac- cessories have been developed for thepolychromaticpressingots. The waxed-up object is laterally sprued on the investment ring. In contrast to the conventional pro- cedure, no wax sprues are used. Instead, prefabricated precision waxparts(IPSe.maxPressMultiWax Pattern), which resemble small wax platelets, are utilised for sprueing. Dependingontherestoration,either Form A or B is employed. Form A is indicated for large wax objects, such asmaxillaryanteriorcrowns(Fig.2a), and the smaller Form B for delicate restorations(Fig.2b).Aftertheappro- priate size has been chosen, the Wax Pattern is sprued to the wax-up. The waxed-up restoration should be left on the model die while sprueing to avoiddamagingtherestorationmar- gins. A drop of wax is applied on the sideoftheWaxPatternwithoutalter- ing its geometry. The conical side of the Wax Pattern is aligned towards theincisalareaofthewax-upandthe wax-up is carefully pressed against the wax. It is recommended to align the wax-up to the centre of the Wax Pattern in the investment ring. Since the shade gradation of the Multi ingot should be transferred to the visible part of the restoration, thevestibularsurfacesofthewax-up have to be aligned accordingly. Pos- terior crowns are sprued on the mesiobuccalsurface.Finally,thegap between the Wax Pattern and the wax-up is closed with a small quan- tityofmodellingwax. The IPS Multi Investment Ring Basehasbeenespeciallydesignedfor the polychromatic press procedure. The Multi investment ring contains four openings, which are congruent with the shape of the IPS Multi wax platelets. As a result, the sprued wax-upcanbeaccuratelypositioned in the investment ring (Figs. 3 & 4). A drop of positioning wax is applied intotheopeningtobeused.TheWax Pattern is then inserted into the in- vestment ring base. The incisal edge and/or occlusal surface of the wax- up should face the investment ring base.Unusedopeningsintheinvest- ment ring base are sealed with wax. Another accessory of the IPS Multi system then comes into play: the IPS e.max Press Multi Sprue Guide. Similar to a template, the Sprue Achieving a nuanced interplay of colours in four easy steps Processing the polychromatic IPS e.max Press Multi ingot By Michael Spiegel,Liechtenstein Fig.1:IPSe.maxPressMultifeaturesasmoothshadeprogression.—Figs.2a&b:Wax-upsareinvestedusingIPSe.maxPressMultiWaxPatterns(FormAandB).—Fig.3:TheIPSMulti investment ring base contains four openings, which are congruent with the shape of the Wax Pattern.—Fig. 4: Sprued wax-up attached to the investment ring base.— Fig.5:Atemplate(IPSe.maxPressMultiSprueGuide)assistsinverifyingthepositionofthewax-upintheinvestmentring.—Fig.6:Loadedinvestmentringbase.—Figs.7a–c:Investing iscarriedout usingtheconventionalmethod.Oncetheinvestment ringhasbeenfilled,theIPSRingGaugeismountedandtheinvestment ringisallowedtoset inaquiet place. 1 2a 2b 3 4 5 6 7a 7b 7c DTAP1115_16-20_Spiegel 20.11.15 14:35 Seite 1 345 DTAP1115_16-20_Spiegel 20.11.1514:35 Seite 1