CDE0211

I 29 industry report _ compobonds I cosmeticdentistry 2_2011 Fig. 14_The pumice removes residues of the aluminium-oxide power. Fig. 15_The rinsed tooth following cleaning with pumice. Figs. 16a & b_Etchant is dispensed into the fissures (a) and continued to the surrounding uncut, aprismatic enamel (b). Fig. 17_The classical frosty appearance of etched enamel is clearly evident (compare with Fig. 12). Fig. 18a_Vertise Flow is dispensed into the fissures. dentinetubules,therebyleadingtoincompletepoly- merisation of the adhesive, and ultimately compro- misingretention.19 However,SEagentsareinnovative productsintheirinfancy,andfurtherinvivomedium and long-term trials are necessary to investigate these concerns. The eighth and future generations of DBAs should improve on the seventh generation of SE bondingagentsbyincorporatingsubstancesforre- generatingnaturalhardtissues,ratherthanlimiting their functions to adhesion. These new so-called biomaterials should have anti-bacterial, bioactive and biofunctional properties, amongst other prop- erties. _Resin-based composites The number of resin-based composites on the marketisbothimpressiveandoverwhelming.Devel- opments in composite technology over the last few decades has resulted in many novel products, and selecting the correct material for a specific clinical scenarioisbothdauntingandperplexing.Thefollow- ing generic classification categorises contemporary resin-based composites, together with their prop- erties and uses: _1. Hybrids: Universal or general purpose; low wear resistance, long-term increase in surface rough- ness, for example posterior restorations, Class I and II. _2.Micro-filled:Moreaestheticthanhybrids,retains surfacepolish/lustreovertime,forexampleClassIII, IV and V; highly filled (loaded) variants for extreme occlusal loads, for example Class I and II. _3. Nano-filled: Similar to micro-filled, most aes- thetic; aesthetically demanding regions of the mouth, high polishability, excellent optical proper- ties (opalescence, fluorescence), for example Class III, IV and direct composite laminate veneers. _4. Micro- and nano-hybrid varieties: Universal or general purpose. _5. Flowables: Low viscosity, low MOE, low filler content. Suited for areas of low occlusal loads due topoorwearresistance,lowstrengthandincreased polymerisation shrinkage. However, polymerisa- tion stress is also lower owing to the reduced filler content. Ideal for small pits and fissures not ex- posed to occlusal loads, primary dentition restora- tions, blocking undercuts for indirect prostheses (for example, inlays and crowns) and stress-reliev- ing liners for deep Class I, II, V and large cavities, preferablyfluoride-releasingvarieties,forexample giomer. Ideally, composites should possess similar physi- cal, mechanical and optical properties to the natural hard tissues they are replacing. Therefore, for highly aestheticrestorations,whereappearanceandoptical issues are of paramount concern, the ideal choice is a micro- or nano-filled composite. However, the laterareunsuitableforhigh-stress-bearingposterior restorations owing to poor wear, and in these cir- cumstances a prudent choice is a universal compos- ite, for example a hybrid or micro- or nano-hybrid. Whilst resin-based composites have revolu- tionised restorative dentistry, they are not without their problems. The main reason for the failure of composite fillings is marginal breakdown and secondary caries.20 However, it is not a faitaccompli Fig. 15 Fig. 16aFig. 14 Fig. 17 Fig. 18aFig. 16b