Please activate JavaScript!
Please install Adobe Flash Player, click here for download

Clinical Master Magazine

issue 1/2015 — 43Aesthetic and Restorative Dentistry Article The Natural Layering Concept (NLC) The dentin L*a*b* color measurements of teeth from the “A”, “B” and “C” VITA shade groups, have suggested that an ideal dentin replacement material should exhibitthefol- lowing characteristics:7 8 Single hue. Single opacity. Large chroma scale (beyond the four chroma levels of the VITA system). Actually, the variations of a* and b* values between various VITA shades seem not to justify the use of distinct dentin colours, at least for a direct composite restorative system.Likewise,thevariationsofthecon- trast ratio (opacity-translucency) within a singleshadegroup,donotsupporttheuse of different dentin opacities (i.e.: translu- cent,regularoropaquedentins).However, chroma (related to a* and b* values) proved to increase from light to dark shades(A1toA4orB1toB3)andthensup- port the concept of a large chroma scale covering all variations of natural denti- tions, plus some specific conditions like sclerotic dentin (as found underneath de- cays, fillings or cervical lesions). As regard to enamel, differences in tissue lightness and translucency proved to vary largely among patients and with tooth age, andthereforeconfirmedtheclinicalconcept of three specific enamel types:9 Young enamel: white tint, natural opales- cence, less translucency. Adultenamel:neutraltint,naturalopales- cence and intermediary translucency. Elderlyenamel:yellowtint,naturalopales- cence and higher translucency. This interpretation of human dentin and enamel colorimetric data led to this clin- icalapproachnamedthe“NaturalLayering Concept” (NLC), which embraces more accurately the optical and anatomical characteristics of natural teeth.3 4 5 7 It ac- tually defines the features of an optimal restorative material aimed to replace dentin and enamel, respectively. Dentins shades should be available in one single hue (close to VITA “A” shade group) with a sufficient range of chroma (covering at least the existing VITA shade range), and presenting opacity similar to natural dentin. Enamel shades should present dif- ferent tints and opacity levels, tentatively replicating the major variations found in nature.Thelatestdevelopmentofthissys- temistheinspiro(EdelweissDR);previous generations include for instance Miris® & Miris® 2 (Coltène/Whaledent), Ceram.X® duo (DENTSPLY), ASTERIA (Tokuyama), Aura (SDI) or ENAMEL HFO/HRI (Micerium). Case 1 Anadultfemalepatientshowsesthetically defective composite veneers; she hopes for a significant improvement although she has strict financial limitations, driving the treatment plan toward the replace- ment of existing restorations by a similar freehand, but improved technique (cover pagefigures).AnewgenerationNLCcom- posite system (inspiro, Edelweiss DR) was selected,duetoitsimprovedopticalprop- erties and excellent surface characteris- tics (easy polishability and good gloss re- tention), resulting from a new filler technology (homogenous nano-hybrid composite).Thismaterialhasnoclustered nano-particles or pre-polymerized fillers, which provedto impact negativelythe es- thetic performance of conventional inho- mogeneous nano-hybrid composites. A rubber dam was applied to optimize ad- hesiveandrestorativeprocedures;indeed, such extensive treatment using a direct technique would be less predictable with- out this isolation procedure, which elimi- nates moisture from breath completely, crevicularfluid extravasation and possibly slightgingivalbleeding.Restorationswere made using a bi-laminar restorative ap- proach based on one dentin shade (Body i2 for the central and lateral incisors and Body i3 for the canines; selected masses areclosetoA2andA3VITAshades).Inad- dition,asmallamountofblueeffectshade (Azur, inspiro) was placed over the dentin mamelonstoemulatelocalizedopalescent halo (Fig. 1a). Finishingandpolishingwasperformedun- derrubberdam which protect softtissues for inadvertent aggression. The primary anatomywascorrectedwithfinishingdiscs ofdecreasingcoarseness(Optidisc,Kerr). When the appropriate proximal and tooth axialprofileswereconsideredoptimal,the incisal length and profile were finished us- ing the same instruments as well as fine finishingdiamondsburs.Onlythreeinstru- mentswereusedtocompletethesecond- aryanatomy(micro-texture),startingwith aflame,finediamond(40μm),followedby a pre-polisher rubber point (Identoflex® minipoint, Kerr) and a diamond impreg- nated rubber cup (Hi-Luster, Kerr). This simplified instrument sequence led to the good surface anatomy and quality shown on Figures 1b–g. Case 2 A young male patient presents various es- thetic deficiencies. An orthodontic cor- rection previously helped to manage space excess, following congenital lateral incisor aplasia (Figs. 2a–d). The dento-fa- cialanalysis(Fig. 3)revealsaseriousasym- metrybetweenthefaceandsmilemidline, Fig. 1a Intra-operative view of the case appearing on the cover page; direct composite veneers were made of 2 only layers (dentin & enamel), with apposition of some blue & white effect shades (inspiro, Edelweiss DR) following the Natural Layering Concept (NLC). Fig.1a lowing characteristics:78 characteristics of natural teeth.3457 It ac-

Pages Overview