cosmetic dentistry_ beauty & science

14 I I special topic _ composite restorations cosmeticdentistry 1_2013 physical, mechanical and optical properties, but the disguisingfeaturebetweenthetwocompositesistheir handlingproperties. Flowables are low viscosity, offering improved wetability for better adaptation to cavity floors and walls, while the universal composites offer high vis- cosity allowing optimal sculptability and carving for creating correct anatomical morphology. Hence, the clinician is faced with a catch-22, ideally adaptability is essential, but the slumping sticky flowables are not conduciveforshaping. Conversely, the high resistance to flow of universal compositesareidealforcontouringbutmaycreatevoids withintherestorationorthecavo-surfacemarginsdue toreducedfluidity.Autopiancompositeshouldpossess the handling characteristics of a flowable for adapta- tion, as well as having high viscosity for facilitating sculpting.TheSonicFillsystemresolvesthisdichotomy. _The SonicFill system The SonicFill system consists of a handpiece that dispenses a resin-based composite filling material. The handpiece, designed by KaVo (Biberach), delivers sonic energy at varying intensities, which is adjusted ontheshankfromlowtohigh(1to5)tocontrolrateof composite extrusion. The handpiece fits onto the KaVo MULTIflexcouplingandisoperatedbytheuniversalfoot control. The specially formulated deep resin is manu- factured by Kerr (Kerr Corp., USA), which incorporates modifiers that react to sonic vibrations to alter the viscosity of the material. The Unidose capsules have smaller diameter 1.5 mm tips for accessing deep cavi- ties, compared to the conventional larger 2.5 mm pre- loadedtips(PLT).Theresindispensingtipsscrewdirectly onto the handpiece head and deliver the composite when activated by the foot control. The sonic energy reduces the viscosity of the resin by 87 % allowing adaptation in deep cavities, up to 5 mm, in a single increment (Fig.1). After the foot control is released the sonic energy ceases, and the resin returns to its high viscositystate,facilitatingsculptingandcarvingtothe desired anatomical form. Another defining feature of this unique deep resin is that it can be light cured to depthsof5mm(20secondsforLEDunitswithanout- putof800mW/cm2)inasinglelayer.Additional10sec- onds curing from both buccal and lingual sides are also recommended. The final stage is polishing the white filling, which is achieved with appropriate ro- tary instruments such as OptiDisc & Opti1Step (Kerr, Switzerland)—seecasestudyinFigs.2–11.Furthermore, theSonicFillresinhasgreaterradiopacitythanenamel, allowingeasydetectionofsecondarycaries. _The concerns As with any new product, there is a degree of scep- ticism, and inertia for adopting to a new technique and material. Some of the questions asked about the SonicFillsystemincludethefollowing: Does bulk filling increase polymerisation shrinkage andassociatedstresses? A low shrinkage composite is defined as having lessthan2%polymerisationshrinkage.8Inaddition,the stresses associated with volumetric contraction are more significant since they should be lower than the shearbondstrengthofthedentineadhesivetoprevent bond failure and formation of voids at the tooth-resin interfaces. Some of the older “condensable” composites exhib- itedexcessivestressesduringthepolymerisationphase causingdetachmentofthefillingmaterialfromthecav- ity walls, resulting in marginal discrepancies and post- Fig. 10_Finishing and polishing is accomplished by using various shapes of Opti1Step polishing tips. Fig. 11_The post-operative result shows the polished SonicFill deep resin: white filling displaying acceptable aesthetics. Fig. 12_A molar tooth showing a deep tortuous cavity, ideally suited for restoring with a bulk-fill deep resin, up to a depth of 5 mm with a single increment. Fig. 13_The erratic terrain of amorphous shaped cavities are best filled a low viscosity composite for superior adaptation, which can be achieved by temperature or applying sonic energy to a resin-based composite to improve flowability. Fig. 14_A Class I cavity with undercuts at its floor for retaining an amalgam filling. Fig. 13 Fig. 14Fig. 12 Fig. 10 Fig. 11