cosmetic dentistry_ beauty & science International

08 I I special _ MiCD cosmeticdentistry 3_2011 and intermediary bonding agents (micromechani- cal bonding) to adhere to teeth. They can be em- ployed to restore all cavity classes (Class I to VI) and areespeciallyusefulfordirectveneersandbonding. Composite resins consist of a resin matrix (commonly bisphenol A-glycidyl methacrylate [Bis-GMA] or urethane dimethacrylate [UDMA] with triethylene glycol dimethacrylate [TEGDMA] as a diluent monomer), ceramic fillers (amorphous silica and silicate particles) with coupling agent and minor additives such as initiators, activators, colouring pigments and stabilisers. Resin poly- merisation can be activated chemically and/or by light. Composite resins have excellent aesthetics, physicalpropertiesandhandlingbutaretechnique sensitive and shrink on curing (ranges from 1 to 5 % by volume). Compomers contain the essential components of GICs. The acid component is, how- ever, dehydrated and incorporated in the resin matrix. After light curing, the acid–base reaction occurs slowly when the dehydrated acid is activat- ed through water sorption resulting in a partially ionicstructurewithintheresinmatrix.Compomers arecapableoffluoridereleasebutthetotalfluoride release and re-charge is significantly lower than that of GICs.4 The water sorption needed for the acid–basereactiontotakeplacehasbeenshownto compromise the aesthetics and physical properties of compomers.5 Giomers are the most recent category of hybrid restorative material. They are touted as a true hy- bridisation of composites and GICs because they have the fluoride release and re-charge of GICs and the aesthetics, handling and physical properties of composite resins. Giomers are based on PRG tech- nology in which pre-reacted GICs are used as fillers (Fig. 2). Currently available commercial products are based on S-PRG in which only the surface of the glass fillers are reacted with polyacid and a glass core remains. Examples of giomer restorative products include Beautifil II and Beautifil Flow Plus (SHOFU). The fluoride release and re-charge of giomers are significantly better than that of compomers but lower than GICs.4,6 A recent study has reported reduced dental plaque formation and bacterial adherence on giomers when compared with com- posite resins.7 This had been attributed to the formation of a material film layer on the surface of giomer restorations after contact with saliva. This material film layer, which consists of aluminium, silica, strontium and other ions, originates from the PRG filler and has also been observed with GICs.8 The clinical performance of giomer restorations has been evaluated in several studies involving ClassI,IIandVcavitiesuptoeightyearsofduration. After three years, Matis et al.9 found no significant difference between giomer and micro-filled com- posite restorations in all the parameters evaluated. Gordanetal.10 evaluatedtheperformanceofgiomer restorationsovereightyearsandreportnorestora- tionfailure.Significantchangesweredetectedonly for marginal adaptation at occlusal surfaces and marginal staining at proximal surfaces. Although recurrent or secondary caries is a major cause of restoration failure,11 this was not observed with giomer restorations. The latter may be accounted forbytheirbetterdemineralisationinhibitioneffect atthemarginsofrestorationswhencomparedwith compomers and composites.12 _MiCD in clinical practice The spectrum of MiCD procedures and tech- niques involving the use of direct restorative ma- terials has been extensively covered.13 The modi- fication of tooth colour, shape, size, position and defects,aswellasthereplacementofmissingteeth, can be conservatively achieved with no to minimal tooth preparation. Psychological (perception, per- sonality, desire), health (general, specific, dento- gingival),functional(occlusion,phonetics,comfort) and aesthetic (macro, mini, micro) factors must be considered when designing a smile and this has been incorporated by Koirala into a Smile Design Wheel.2 The following case presentation highlights the key principles of MiD (DCMO) as it applies to aes- thetic dis-ease and precautions related to MiCD. _Case study A43-year-oldfemalepatientwasreferredbyher general dentist for management of her aesthetic Fig. 3_Panoramic radiograph of the patient. Fig. 3