cosmetic dentistry_ beauty & science

16 I I special topic _ composite restorations cosmeticdentistry 1_2013 Furthermore,manyobjecttostainedfissures,which are perceived as dirty teeth. In reality, patients only de- sireclean,“white”,functioningfillingstoalleviatetheir symptoms.Fromaclinicalstandpoint,posteriorfillings should possess a hermetic marginal seal to prevent breakdown, and correct anatomical form to restore occlusion. After all, amalgam fillings, which are blatantly ob- vious and unaesthetic, have routinely been placed in posterior teeth for over a century without causing a massiverevoltfromthepopulation.Therefore,offering patients white fillings that are functional and resilient at a fraction of the cost compared to layered resto- rations is an attractive option, especially in the current economic debacle; and the SonicFill system caters for thisnicheinthemarket. _Benefits For reasons mentioned above, the dental market- place has recently been flooded with bulk-fill compos- ites for direct restorations in posterior teeth. However, not all the deep resins for white fillings are identical. ThedefiningfeaturesoftheSonicFillsystemarefluctu- ating viscosity for adaptability and sculptability, single incrementbulk-fill&bulk-cureupto5mmforexpedi- ency,highwearresistancefordurability,andareduced translucencyforacceptableaesthetics.Thesekeychar- acteristics result in fewer clinical steps, saving time, reducing cost, improving effi- ciency,predictability,andlonge- vity of direct posterior compos- iterestorations. Fluctuatingviscosity Most bulk-fill composites have a fixed, unchangeable vis- cositythatrangesfrommedium (e.g. Tetric EvoCeram Bulk Fill, Ivoclar Vidadent, Liechtenstein), to low or flowable (e.g. Surefill SDRFlow,DENTSPLYCaulk,Ger- many,VenusBulkFill,Heraeus,Germany). A major drawback of universal composites is that their consistency is thick, not conducive for spreading and achieving tight adaptation to cavity walls and floors. Methods such as applying external sonic vibra- tions and temperature improve fluidity and therefore helps manipulating the composite to “fit” the erratic terrainofcavities(Fig.13).Therearenumerousexternal handheld sonic devices for applying vibrations for modelling resins, e.g. Compothixo (Kerr, Switzerland). Whilst these are efficacious for reducing viscosity of a resin, an extra step is added to the already onerous clinical procedure. Lowering viscosity is also possible by thermal means, e.g. heating resin to around 60 °C. However, the time to transfer the composite from the heating apparatus and adapting it to the cavity may cool the material, and hence negate the potential benefit. This is because heat is rapidly dissipated when the resin is placed in a tooth that acts as a heat sink at bodytemperatureof37°C,thusrevertingthecompos- ite viscosity to its unheated state. The SonicFill system overcomes the above two difficulties by lowering the viscosity at the point of delivery by applying internal vibrations to the resin, without the need for heat or externalhandheldsonicdevices. Another advantage of fluctuation viscosity is that an initial lining, or a capping occlusal layer is obviated. The difference in viscosities of a material, off course, improvesitshandlingcharacteristics,butitalsoaffects the physical and mechanical properties of the resin. Unalterable, low viscosity bulk-fill resins (e.g. Surefil SDR Flow, Venus Bulk Fill) have lower filler content to confer flowability, which in turn makes the material weaker, requiring a capping occlusal layer with a uni- versal composite to resist occlusal forces. Conversely, withmediumviscositymaterials(TetricEvoCeramBulk Fill),aninitialflowablecompositelayerisnecessaryasa lining for better adaptation to the cavity walls. Similar to stratification with a universal composite, applying aninitiallowviscositylayermayintroduceincremental voids and therefore compromise the integrity of the restoration.Fig. 27 Fig. 29Fig. 28 Fig. 23 Fig. 25Fig. 24 Fig. 26 Fig. 23_The post-operative white fillings after shaping with OptiDisc aluminium discs and polishing with Opti1Step silicone tips. Fig. 24_A large defective amalgam restorations in the right mandibular molar requiring replacement. Fig. 25_After removing the amalgam filling, extensive decay is precariously close to the pulp, which requires monitoring before proceeding to a definitive indirect restoration. Fig. 26_A steel matrix bank is placed, and dentine bonding agent applied. Fig. 27_A coronal build-up using SonicFill resin to review and monitor theendodonticstatuspriortoproviding a definitive indirect restoration. Fig. 28_Two months later the tooth was symptomless, and the SonicFill core is trimmed back for an indirect ceramic inlay. Fig. 29_An impression is taken using a polyvinyl siloxane impression material Take1 (Kerr Corp., USA) and forwarded to the dental laboratory for fabricating a ceramic inlay.