cosmetic dentistry_ beauty & science International

Minimally invasive cosmetic dentistry (MiCD) aims to correct the afore-mentioned aesthetic dis- ease and to fulfil patients’ aesthetic desires and demands by using conservative and minimally in- vasive treatment options. The least amount of den- tistry is performed and any tooth structure removal iskepttotheabsoluteminimumrequiredtoachieve the desired aesthetics. The benefits of MiCD are highlighted by Koirala2 and include reduction of dental fear, increased patient confidence, promo- tion of trust, enhancement of professional image, toothpreservationandreductionoftreatmentcost. Treatment options can be broadly classified as non-invasive or minimally invasive and are listed in Table I. To achieve optimal aesthetic results, more invasive procedures, including conventional im- plants, periodontal surgery and crown therapy, are sometimes required to complement MiCD treat- ment options. _MiCD materials Inviewofthevariedprocedures,theentirerange of materials used in MiCD is beyond the scope of this article. Emphasis is placed on direct aesthetic restorative materials that conserve the maximum amountoftoothstructurebecausetheyareutilised in the majority of MiCD procedures performed in clinicalpractice.Thecontinuumofdirectrestorative materials used in MiCD, based on their setting chemistry, is shown in Figure 1. Glass ionomer cements (GICs) consist of basic glasses (calcium or strontium fluoro-aluminosili- cate) and acidic co-polymers (polyalkenoic acids) that set through an acid–base reaction. The set ce- ment consists of the original glass particles sheath- ed by siliceous hydrogel and bonded by a poly-salt matrix. Although their aesthetics is fair, they release fluoride and can chemically bond to tooth tissue. GICs also shrink minimally on setting and have a similar coefficient of thermal expansion to dentine. Indications for the highly viscous version of these cements include the restoration of non- stress-bearing areas of anterior and posterior teeth and “open-sandwich” restorations. The latter in- volvetheuseofglassionomerasabaseundercom- posite restorations. Resin-modified GICs were de- veloped to overcome the early moisture sensitivity of conventional cements. In addition to decreasing moisture sensitivity, resin modification also im- proves setting characteristics, aesthetics, physical and handling properties. The resin is typically in- corporated by substituting acidic co-polymers with a water–HEMA (hydroxyethyl methacrylate) mix- ture or the use of acidic co-polymers with meth- acrylate side chains. Despite the addition of resin, which usually constitutes 4.5 to 6 % of the set material, resin-modified GICs retain a significant acid–base reaction as part of their overall curing process, bond chemically to teeth and are capable of fluoride release and re-charge. Their caries pre- ventive effect3 and clinical uses are similar to those of their conventional counterparts. Composites,compomers(polyacid-modifiedcom- posite) and giomers (pre-reacted glass ionomer composite) all require resin polymerisation to set Fig. 2_SEM image of a giomer restorative with the PRG filler particles. (Image courtesy of SHOFU) I 07 special _ MiCD I cosmeticdentistry 3_2011 Fig. 1_Continuum of direct restorative materials used in MiCD. Fig. 1 Fig. 2