Dentistry www.dentistry.co.uk56 8 May 2014

CLINICAL

Restoring posterior teeth with direct resin has become functionally and aesthetically viable over the past decade. Currently, clinicians are spoilt for choice with the rapid emergence of new composite systems that offer excellent handling characteristics, improved polishablity and enhanced aesthetics. Many patients presenting with secondary caries or defective amalgam restorations demand life-like ‘white’ fillings. In addition to the aesthetic advantages, the Minamata Convention (2013), has implemented a ‘phase down’ approach to dental amalgam in the near future. Now, more than ever, it has become a necessity for clinicians to master the direct resin layering technique. The stratification of dentine and enamel characterisations found in the natural dentition is paramount to achieve aesthetic direct composite restorations. The advantages of such a technique include:• Achievingnaturalanatomicalcontour• Minimisingpolymerizationstresses• Increasepolymerizationdepth• Obtainingoptimumaestheticresults.

Centripetal layering techniqueIn this article, a centripetal layering approach for restoring a defective distal- occlusal LR5 amalgam (Figure 1) will be discussedindetail.Afterremovingthedefectiveamalgamand secondary caries, the class II cavity is converted into a class I. This can be achieved by initially building the proximal wall with a ‘shell’ of composite, with a custom shaped sectional matrix band. This technique can predictably produce ideal proximal morphology and typically prevents over contouring.

Clinical protocolShade selection, even in the posterior region, is critical to achieving life-like composite restorations. The author suggests using a composite shade guide in order of value (high to low) to select two of the closest enamel shades. Then, two freshly placed composite balls (of the chosen shades) were placed on the cusp slopes and lightcured.Optimumlightingconditions(5,500kcolourtemperature) was achieved using Optilume Trueshade,to determine the ideal enamel body shade. In this case, VenusPearlbyHeraeusKulzerwaschosen,basedonitsexcellent handling characteristics, aesthetics and strength.

During the removal of the amalgam, the adjacent proximal ridge must be protected, to prevent unwanted enameloplasty (Figure 2). Then all sharp edges were smoothed with a coarse polishing disc (Sof-Lex). In this case, successful isolation has been achieved using a sectional matrix (V-Ring), cotton wool pledgets, Optragate(lipandcheekretractor)andasalivaryejector.The matrix band is then customised with a high-speed bur to the approximate height of the required marginal ridge (Figure 3). This is critical, as the lack of visibility through the matrix band can lead to over-contouring of the marginal ridge and subsequently the entire restoration. After achieving isolation, the cavity was

sandblasted using a chairside Microetcher II containing Cojet (30-μm silanated ceramic particles). Then the total-etch technique was used with 37% phosphoric acid on enamel and dentine for exactly 15 seconds. To ensure minimum post-operative sensitivity, a thin layer of a dentine-desensitising agent (Gluma) was applied

along the exposed dentine surface. Finally, OptibondSolo (Kerr) was applied according to the manufacture’s guidelines and light cured.

To ensure accurate internal adaption, a thin layer ofA2VenusFlow (HeraeusKulzer)was applied to thebase of the cavity (Figure 4) with a probe and light cured

Mimicking nature with composite Dev Patel presents a case to demonstrate how to restore

naturally with composite

Dr Dev Patel BDS PGCert graduated from the University of Manchester 2012 and is currently enrolled on a masters course in primary care dentistry at the University of Kent. He currently works as an associate at Parrock Street Dental Clinic (Gravesend, Kent). He has a special interest in cosmetic and restorative dentistry, in particular direct composite resin artistry and

minimally invasive all ceramic restorations.

Figure 1: Pre-operative occlusal view of the pre-existing, defective amalgam restoration

Figure 2: A metal wedge guard is placed inter-proximally to prevent damage to the adjacent proximal wall

Figure 3: The sectional matrix is customised to follow the contour of the adjacent marginal ridge

Figure 4: A thin layer of Venus Flow A2 is applied along the floor of the cavity

57Dentistry www.dentistry.co.uk 8 May 2014

(starting from the most distal edge of the proximal box). Flowable composite has a low viscosity and high modulus of elasticity, allowing it to accurately adapt at the base of theproximalbox,andabsorbstressfrompolymerizationshrinkage.

The proximal ridge shell is built up with the enamel shadecomposite(VenusPearlA2),toathicknessof2mmand adapted using a saple brush, up to the top of the matrix band (Figure 5).

Then a high-chroma dentine shade composite (Venus PearlOLC)wasapplied in2mmincrements(Figure6),ensuring to follow the correct anatomical morphology (sufficient space is left for the final enamel layer). Care

is taken during the placement of each increment to minimise wall-to-wall shrinkage (conformation factor) and minimise cuspal deflection. Each increment is light cured fully for 20 seconds before the placement of the subsequent layer. The final 2mm enamel layer (Figure 7) was then placed using (Venus Pearl A2). Occlusalfissure staining was applied sparingly (Figure 8) with an endodontic size10K-File, usingVenusColor stains‘choco brown’ and ‘corn’. Any excess stains, can beremoved using a clean micro brush, and then light cured. Afinalcurethroughanoxygeninhibitiongel(Deox)wascarried out (Figure 9) to ensure complete polymerisation of the air-inhibited layer.

The sectional matrix is removed and a narrow (2mm) fine-grit interproximal finishing strip was used to finish the apical convex areas. Then the occlusion is checked and a super-fine finishing diamond was used to remove any excess/high spots on the occlusal surface. Finally, a diamond-impregnated brush (Groovy Brush, Optident)was used to polish the occlusal surfaces and produce the final lustre (Figure 10).

Figure 5: The proximal wall was formed with Venus Pearl A2 during the centripetal buildup

Figure 6: The initial high chroma dentine increment (Venus Pearl OLC) was placed and the primary anatomy was sculpted

Figure 7: The final enamel increment (Venus Pearl A2) is placed following fossa characterisation

Figure 8: Fissure stains were applied using ‘choco brown’ and ‘corn’ (Venus Color)

Figure 9: Oxygen inhibition gel was applied prior to the final light cure. Figure 10: Post-operative occlusal view

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