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40 RESTORATIVE Dental Tribune Middle East & Africa Edition | 3/2017 Realizing efficient and predictable posterior quadrant restorations Efficiency and long-lasting stability of the result are important requirements that are placed upon direct restorative procedures with composite. In this context, a system of well-coordinated materials is the definite key to success By Michael R. Sesemann, USA It is not uncommon for middle-aged and older patients to present with multiple failing amalgam restora- tions in a single quadrant. Many such restorations can be replaced conservatively with direct compos- ite. Unfortunately, however, many of the placement and accompanying adhesive protocols required for pre- dictability can be time-consuming and technique sensitive. Therefore, it is important to understand the historical development of adhesive dentistry when considering today’s etching and adhesive protocol op- tions. In the beginning Conceptualized more than 50 years ago, Buonocore proposed bonding to enamel and dentin by first treating those surfaces with phosphoric acid before applying resins. Although he considered resin tag formation in the micro-porosities of etched enamel to be principally responsible for adhesion to enamel, bonding to dentin was less predictable due to dentin’s composition, water content and smear layer. Not surprisingly, the first dental adhesives were resins that only bonded to enamel; there was little to no dentin bonding. On- going changes in material composi- tion, adhesive mechanism, applica- tion method and overall adhesive techniques fuelled the evolution of adhesive dentistry and the introduc- tion of increasingly esthetic restora- tive materials. They also led to differ- ent adhesive etching products and protocols. “Total-etch” or “etch-and-rinse” technique In “total-etch” or “etch-and-rinse” techniques, both enamel and dentin are etched with phosphoric acid to remove the smear layer and condi- tion the preparation prior to bond- ing, with enamel being etched longer than dentin. The etchant and smear layer are then rinsed off with water and dried. Because dentin should re- main moist and slightly glossy in ap- pearance, care must be taken to not over-dry the dentin. This prevents collagen fibrils from collapsing, which would create a less permeable surface for hydrophilic monomers in the adhesive, as well as a weak in- terface, potentially leading to a poor bond and postoperative sensitivity. Although wellestablished and clini- cally proven, total-etch adhesives and their associated multi-step tech- niques are often considered to be technique sensitive. Selective-etch technique With selective etching, only the enamel edges of the preparation are etched with phosphoric acid and then rinsed with water. The dentin is conditioned afterwards with either a primer or all-in-one self-etching adhesive; the smear layer is only modified, not removed by rinsing with water after primer application. This over-etching of the dentin could result in reduced bond strength and postoperative sensitivity. Self-etch technique Intended for adhesive bonding with- out separate etching, the self-etch technique relies on adhesive materi- als containing acidic monomers that etch and prime enamel and dentin. Demonstrating a milder pH level than total-etch products, self-etch adhesives pose less risk for excessive dentin demineralization, and be- cause the technique sensitive step of precisely drying the dentin is elimi- nated, collagen-fibre collapse is pre- vented. Combined, these attributes reduce the likelihood of postopera- tive issues. Realizing predictable efficien- cy today Manufacturers have successfully increased the adhesive portfolio by introducing universal adhesives that promote high bond strength to enamel and dentin, and which can be used on both dry and moist dentin. Because they are designed to work with or without phosphoric acid, universal adhesives (e.g. Adhese® Universal) are suitable for selective- etch techniques, without fear of over-etching the dentin. Materials of choice When replacing multiple failing amalgam restorations in a single quadrant using direct composite, I prefer using the selective-etch tech- nique because it delivers the “best of both worlds”. It provides strong micro-mechanical retention at the enamel margin with less probabil- ity of postoperative sensitivity, since the dentinal tubules are not com- pletely opened. My preferred adhesive for such tech- niques is Adhese Universal, which is available in traditional bottle and unique VivaPen® delivery. For me, the ergonomic, pen-like VivaPen design and angled brush cannula enhance comfort, control and speed during direct intraoral applica- tion while reducing material waste. Containing 2 millilitres of adhesive, the VivaPen can accommodate ap- proximately 190 single-tooth appli- cations, which is almost 3 times the applications per millilitre compared to conventional bottle delivery. As a result, the Adhese Universal VivaPen cost per application is considered to be lower than that of all other lead- ing universal adhesives. Also contributing to more cost- effective and time efficient direct posterior restorations is the use of a bulk-filled composite (e.g. Tetric EvoCeram® Bulk Fill, Tetric EvoFlow® Bulk Fill). Because they can be placed in a single increment or layer of up to 4 mm, then fully cured, they help eliminate time consuming tech- niques. Case presentation A 51-year-old male patient presented with multiple failing amalgam res- torations (teeth 14 through 17) that exhibited marginal leakage and re- quired replacement (Fig. 1). Rubber dam isolation was established. The existing amalgam restorations and any decay was removed using a car- bide bur and the preparations were refined using a diamond bur. Fol- lowing this, the preparations were cleaned and disinfected with 2 % chlorhexidine gluconate antibacte- rial scrub. First, tooth 17 was restored. A seg- mented matrix set-up with two 3D- XR rings (Garrison Dental Solutions) and 5.5-mm Slick Band was placed to facilitate predictable and ideal inter- proximal contacts. The preparation enamel was selectively acid-etched with 37 % phosphoric acid for 20 seconds. After a universal adhesive (Adhese Universal) had been ap- plied and light-cured, a layer of Tetric EvoFlow Bulk Fill in shade IVW was placed, then light-cured for 10 sec- onds. The cured Tetric EvoFlow Bulk Fill layer exhibited dentin opacity (Fig. 2). The restoration for tooth 17 was com- pleted with a capping layer using Tetric EvoCeram Bulk Fill, which was smoothed with a modelling instru- ment designed for composite mate- rials and light-cured for 10 seconds. Next, the restoration was contoured using a fine diamond and polished using discs and points. The cavity of tooth 14 was also conditioned with universal adhesive (Fig. 3). Then a single increment of Tetric EvoCeram Bulk Fill composite in shade IVA was ÿPage 41 Fig. 1: Preoperative view showing multiple failing side-by-side amalgam restorations in the maxilla Fig. 2: View of the completed Tetric EvoCeram Bulk Fill direct composite restoration for tooth 17 Fig. 3: Adhese Universal adhesive was applied to the preparation for tooth 15. Due to hygienic reasons, the manufacturer recommends using the VivaPen Protective Sleeve for intraoral application. Fig. 4: A single increment of Tetric EvoCeram Bulk Fill composite was placed in the tooth 14 preparation ... Fig. 5: ... and free-hand contoured utilizing a thin, long-bladed instrument. Fig. 6: Post-cure contouring of the restoration was completed using a fine diamond. Fig. 7: Interproximal polishing was completed using a finishing strip. Fig. 8: The preparation enamel in tooth 16 was selectively acid-etched. Fig. 9: An initial layer of Tetric EvoFlow Bulk Fill was placed into the cavity. Fig. 10: Finishing of the tooth 15 restoration Fig. 11: Polishing of all restorations in the quadrant using a silicone brush and diamond paste Fig. 12: The occlusion was checked after occlusal adjustments had been made. Fig. 13: Postoperative view of the completed com- posite restorations