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ePaper created 2016-10-04, 09:33:57 | version 1.38.0
CAD/CAM material and systems literature review | 11 CAD/CAM 3 2016 To overcome aesthetic problems of most CAD/CAM blocks having a monochromatic restoration, a dif- ferent version was developed as a multicoloured ceramic block, which was called VITA TriLuxe (Vident) and also IPS Empress CAD Multiblock; the base of the block is a dark opaque layer, while the outer layer is more translucent; the CAD software allows the clinician to position or align the resto- ration into the block for the desired outcome of the restoration.11,12 In 2014, the Enamic (VITA) material was released as a ceramic network infiltrated with a reinforcing poly- mer network that has the benefits of a ceramic and resin in one material, but no clinical data are avail- able.14 Alumina-based ceramics Alumina blocks (Vitablocs In-Ceram Alumina, VITA) are available for milling with the CEREC system (Sirona Dental) and now compatible with other mill- ing machines as well. Due to the opacity of alumi- na-based ceramic materials, the In-Ceram Spinell (VITA) blocks were developed as an alternative for anterior aesthetic restorations; it is a mixture of alu- mina and magnesia. Its flexural strength is less than In-Ceram Alumina, but veneering with feldspathic porcelain for a more aesthetic result could follow it after the milling process.14,15 Nobel Biocare developed Procera material; for its fabrication high purity aluminum oxide is com- pacted onto an enlarged die that is fabricated from the scanned data.16 The enlarged fabricated core shrinks to the dimensions of the working die when sintered at 1,550 °C; this material offers a very high strength core for all-ceramic restorations; the crown is finished with the application of feldspathic por- celain.17 More recently, In-Coris AL (Sirona Dental) has been introduced as a high-strength aluminum oxide block with similar mechanical properties as Procera.18 Lithium disilicate Lithiumdisilicateiscomposedofquartz,lithiumdiox- ide, phosphor oxide, alumina, potassium oxide and other components. According to Saint-Jean (2014) the crystallisation of lithium disilicate is hetero- genous and can be achieved through a two or three stage process depending if the glass ceramic is in- tended to be used as a mill block (e-max CAD) or as a press ingot (e-max press). Lithium disilicate blocks (Fig. 3) are partially sintered and relatively soft; they are easier to mill and form to the desired restoration comparedtofullysinteredblocks;afterthisprocessthe material is usually heated to 850 °C for 20 to 30 min- utestoprecipitatethefinalphase.Thiscrystallization Fig. 1: Number of steps comparison between traditional methods of all-ceramic restorations and CAD/CAM restorations. Fig. 2: Vita Mark II block. Fig. 3: In-house milled crown from an E-max block. Fig. 2 Fig. 3 Fig. 1 32016