cosmetic dentistry_ beauty & science

in thickness and each bulk increment light-cured for only 20 seconds, on condition that at least 2 mm on the occlusal surface is left for regular viscosity composite resin. According to the man- ufacturer, a polymerisable modulator was chem- ically embedded into one of the monomers. The viscoelasticbehaviourofthismonomerandofthe overall composition of the flowable composite allows the material to dissipate much more en- ergy than induced during curing by polymerisa- tion of the monomers. This leads to a reduction of remaining polymerisation stress by up to 60 % compared with conventional flowable composite resins.10 The volumetric shrinkage is 3.6 % but moreimportantly,thestressgeneratedduringthe polymerisation is 1.4 MPa, whereas many other flowable composites are above 4 MPa. The mate- rial is available in only one universal shade and can be used with any dentine bonding system. Figures1to19outlineaclinicalcasereportthat illustrates the benefits and clinical application of this new innovative flowable base material for direct posterior composite resin restorations. Base materials are mainly indicated for reduc- ing the volume of filling material11 or for creating adequate geometry for the cavity preparation for inlay/onlaypreparationtechniques.12 Theshapeof thecavitypreparationwilldependontheextentof the decay or the geometry of the restoration to be replaced. The removal of decay often creates un- wanted undercuts, which are not compatible with the principles of cavity preparation design for in- lays/onlays. In order to preserve as much sound enamel/dentine as possible, the internal tapered design should be obtained by the application of a base material.12 Sherreretal.13 demonstratedthattheresistance to fracture for full ceramic crowns is significantly influencedbytheelasticityofthecorematerialand luting cement. Because of the favourable proper- ties of the SDR material, it might be the ideal ma- terialtoblockoutundercutsinordertopreservead- ditional enamel for adhesion and to improve cuspal strength during ceramic inlay cavity preparations. Figures 20 to 29 demonstrate a clinical case report to illustrate the clinical application of the SDR flowable base material to allow ideal cavity preparation design for indirect posterior inlay/ onlay restorations. _Case I: SDR as base material for posterior composite restoration Fig. 1_Pre-op view of an isolated upper right maxillary sextant. Examination of the upper right first premolar revealed a defective composite restoration. Note the poor interproximal contact between the premolar and canine, as well as the inadequate contour on the distal aspect of the existing composite restoration. I 19 clinical technique _ SDR I cosmeticdentistry 4_2011 Fig. 5Fig. 4 Fig. 7 Fig. 8Fig. 6