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ePaper created 2018-03-14, 11:21:34 | version 1.38.0
| industry Creating natural-looking composite restorations Dr Daniel H. Ward, USA Improved materials and instruments help us to pro- duce restorations that are natural looking. Composite systems have been developed that have optical qual- ities similar to the tooth structure they are replacing.1 Composite materials with dark opacity and fluores- cence are useful to recreate dentine.2 Enamel replacing materials with added translucency and opalescence give the outer surface of the tooth a realistic appear- ance.3 Layering multiple shades with differing hue, chroma and value can give the tooth a more three- dimen sional look.4 Composites have been developed with differing ap- proaches using two, three, or more layers. Having mul- tiple systems can be beneficial. Recently, a new laser (LiteTouch, AMD LASERS) has been introduced at a sig- nificantly lower cost allowing it to be incorporated into more dental offices. Being able to quickly prepare teeth often without anaesthesia has been a significant advan- tage of using hard tissue lasers.5 Small to medium sized restorations can often be prepared without the use of lo- cal anaesthetics. Let’s examine how these new materials and technologies can be used. Layered restorations Layered restorations are helpful in the anterior area to emulate the appearance of natural teeth. Restorative materials should mimic the tooth structure they replace. The deepest part of the restoration should be dark, more opaque and very high in chroma. Unfortunately, there are few dentine shaded composites that truly match dentine. Very intense yellow/brown materials are needed.6 One system which is excellent for matching tooth structure is aura (SDI). The system originally had two materials, a dentine and an enamel replacement material, but an optional middle layer has been added. This helps to block the intense chroma of the dentine and blend the restoration colour better. It also helps to make the exact thickness of the dentine and enamel shade layers less critical. The dentine shades do not coincide with any standard shading sys- tem but differ in the intensity of the chroma, ranging from Db, C1 to C7. Literature As you build up the restoration, the material should become lighter, more translucent, opalescent and have smaller filler particles. The aura system has an optional intermedi- ate layer which is a multi-purpose composite MC2 to MC5. The final enamel layer is a microfill and it comes in three shades. It is translucent and polishes well. Case presentation A 15-year-old male presented to the office with peg lateral incisors and twisted maxillary canines (Fig. 1). His mother was interested in closing the spaces between his teeth. The sizes of the teeth were measured and it was determined that the central incisors were of normal size relative to the face. The widths available for the lateral in- cisors were deemed to be 70 % of the frontal view widths of the central incisors. The widths of the maxillary canine teeth were also deemed to be 70 % of the frontal view widths of the lateral incisors. This follows the recommendations of proportional smile design using the RED proportion which states that the frontal view width proportions of the anterior teeth should remain constant as you move distally.7 The pho- tograph with template demonstrates the ability to add to the lateral incisor and the canine and give a well-propor- tioned smile that matches the face (Fig. 2). The surface of the maxillary right canine was lightly roughened using a very fine diamond to areas to be bonded (201.3VF, Premier Dental). The entire sur- face was etched with phosphoric acid for 20 seconds, washed and dried thoroughly. A universal dentine bonding agent was brushed onto the surface for 20 sec- onds, the solvent evaporated and the area light cured (All-Bond Universal, BISCO Dental). The first increment added was the dentine layer. This layer is darker than the desired restoration but more opaque in order to block light from shining through the entire restoration and prevent a grey appearance. Dentine shade 6 was used since it mimics the shade of the natural dentine (aura, SDI; Fig. 3). 12 1 2018