Dental Asia Sep/Oct 2018

User Report DENTAL ASIA SEPTEMBER / OCTOBER 2018 40 L ithium disilicate offers us exceptional possibilities for the fabrication of natural looking dentures. In addition to its high degree of stability, the ability of this material to transmit light is what makes it so valuable. The ceramic shoulder on conventional metal ceramic crowns is a good example of the enormous aesthetic gains that can be obtained by increasing light transmission. For example, lithium disilicate exhibits positive cosmetic results, even when applied monolithically, as is done with fully anatomical restorations, particularly in the posterior region. GC Initial LiSi veneering ceramic is optimal for re̬ning or veneering in the anterior region. The cutback technique o ̫ ers a good combination of stability and high aesthetic value for this. The crown’s fully anatomical design, pressed with MT (Medium Translucency), slight vestibular reduction, lustre pastes and minimal GC Initial LiSi veneering ceramic overlays, is highly e ̮ cient. The use of these variants allows the underlying tooth substance to remain a cosmetic part of the crown without being covered by a light-blocking framework. However, the stumps must not be strongly discoloured. Medium Opacity (MO) frameworks are generally used to compensate for dark substrates. However, this opaque compact must be covered with veneering ceramics and cannot be fully contoured. The following case study describes the procedure for an all ceramic restoration with GC Initial LiSi Press (a lithium disilicate glass ceramic) on a strongly discoloured preparation. Fig. 1: The previous Zr crown on 21 Fig. 2: The dark preparation became visible after the crown was removed. Figs. 3a-b: Red discolouration in the cervical area of natural tooth (compare with colour pattern A1). The initial situation The young patient complained about the aesthetically unpleasant appearance of her Zr crown 21. The previous restoration did not match the shape and colour, and the cervical area in particular seems too opaque. A common phenomenon with zirconia is the unnatural emission of the material into the marginal gingiva (Figs. 1-2). In this case, the degree to which the gingiva in the cervical areas of the natural teeth exhibited a reddish radiation was particularly visible. Little consideration was given to this e ̫ ect with the previous restoration (Figs. 3a-b). Fabrication of the framework The crown was removed, prepared once again and moulded. After the model was created, the wax cap was fabricated using CAD/CAM (Figs. 4a-d). The object Fig. 3a Fig. 3b