Minimal Intervention Class II Direct Composites
Conservative restoration with a bulk-fill flowable material
One of the goals in creating composite resin materials for bulk placement is to simplify the placement of direct tooth restoration without compromising the quality of the final result. This is especially true when dealing with Class II proximal restorative placement. The gingival wall of the proximal box and its line angles between gingival and facial and lingual walls are areas that are hard to adequately fill and are therefore where most recurrent decay occurs. Bulk-fill flowables were developed to help solve this clinical issue as well as decrease the need for layering and incremental placement, which can also lead to voids and imperfections in the marginal seal.
A Class of “Smart” Composites
As previously mentioned, marginal breakdown and recurrent decay have always been the processes by which many dental restorations ultimately fail. Aside from placement technique, another challenge for long-term clinical success of a dental restorative is to find a mechanism by which the restorative material itself can slow down or prevent these processes.
Glass ionomer materials are known for their release of fluoride ions and their ability to help remineralize demineralized tooth structure. The limitation of fluoride release has always been that because of the solubility of the material in the oral environment, there is a short, finite amount of time that this protection can be available.
Giomer products are characterized by their unique surface pre-reacted glass (S-PRG) filler. S-PRG fillers have a glass core that is pre-reacted with a poly acrylic acid solution. The glass ionomer phase in Giomer fillers is protected from water sorption and material degradation by a surface modified layer. As a result, the ion exchange from a composite material that incorporates this technology has the ability to help neutralize acids that are the result of bacterial metabolism that are the direct cause of tooth demineralization and decay for extended periods of time. One material on the market that incorporates Giomer technology is BEAUTIFIL-Bulk Flowable (Shofu Dental Corporation, www.shofu.com). Giomers can give the benefit of ion exchange similar to glass ionomers, which can be especially important in a caries-prone individual.1-4
The GV Black preparation still taught in many dental schools requires removal of a large amount of healthy tooth structure to gain access to very small areas of proximal caries so that a restoration can be placed. As Dr. Ron Jackson once stated, “The edict for today’s dentists should not be extension for prevention, but prevention of extension.”5 Minimal slot preparation can be made using micro-instrumentation, such as Fissurotomy® burs (SS White, www.sswhitedental.com), to keep removal of healthy tooth structure to a minimum. The problem with very small preparations is that they are hard to condense and fill properly with traditional armamentarium. Use of a “heavy-bodied” flowable resin, such as BEAUTIFIL-Bulk Flowable (73% filled by weight) with a greater depth of cure (at least 4 mm) may be the answer for some of these clinical situations.6,7 In areas of occlusal stress, a “capping layer” of nanomicrohybrid composite can be used if deemed necessary by the clinician; however, many small preparations can be filled with a flowable alone.
A patient presented with a small carious proximal lesion that just penetrated the dentinoenamel junction on the distal surface of tooth No. 5 (Figure 1). After slot preparation with a Fissurotomy bur, the decalcified area and decay could easily be seen. After completion of the preparation, a sectional matrix (Composi-Tight® 3D XR, Garrison Dental Solutions, www.garrisondental.com) was placed (Figure 2).
The treatment plan included the use of a bulk-fill flowable to restore this preparation. Since the preparation is was very conservative and the distal marginal ridge portion of the restoration is was not an occlusal stress bearing area, the decision was made to do the entire restoration (dentin and enamel) in BEAUTIFIL-Bulk Flowable (73% filled by weight) rather than use BEAUTIFIL Flow Plus or BEAUTIFIL II to restore the enamel layer. When using a flowable resin for a Class II restoration, it is even more important that the matrix totally seals the gingival margin of the proximal box due to the viscosity of the material being less than conventional nanomicrohybrid composites.
This patient had several other proximal lesions that needed intervention due to ineffective home care, which made a Giomer restorative material an excellent choice, due to diffusion of ions to remineralize the tooth structure, creating a localized resistance to acid attack. A self-etching bonding agent (BeautiBond®, Shofu) was brushed onto the enamel and dentin according to manufacturer’s instructions, air thinned, and light cured (Figure 3). Next, BEAUTIFIL-Bulk Flowable was dispensed into the cavity. A nice feature of a flowable composite is that a precise amount can be dispensed into the cavity preparation in one application without manipulation of the material (Figure 4). Figure 5 shows the restorative material in place after light curing. It can be seen that aside from possible minor occlusal adjustment, very little finishing and polishing will be required because of the precision of the matrix as well as the control in dispensing a precise amount of restorative material to fill the preparation. When using a sectional matrix, the ring will separate the teeth enough so that if the matrix material touches the adjacent proximal surface when placed, proximal contact, even with a flowable resin, will be assured. Figure 6 shows the completed restoration after removal of the matrix. The occlusion was non-interfering, so the restoration required no finishing or polishing.
A technique has been shown to efficiently place a conservative Class II composite resin restoration using a “smart” composite material that has been shown to have a high fluoride release and recharge that can help inhibit secondary caries formation. This Giomer technology has also been shown to neutralize acid, creating an “anti-plaque” effect, which can help patients who are not particularly good at mechanical interproximal plaque removal.
1. Nakamura N, Yamada A, Iwamoto T, et al. Two-year clinical evaluation of flowable composite resin containing pre-reacted glass-ionomer. Pediatr Dent J. 2009;19(1):89-97.
2. Tamura D, Saku S, Yamamoto K, Hotta M. Saliva protein which adsorbs to composite resin containing S-PRG filler. The Japanese Society of Conservative Dentistry. 2010; 53(2):191-206.
3. Saku S, Kotake H, Scougall-Vilchis RJ, et al. Antibacterial activity of composite resin with glass-ionomer filler particles. Dent Mater J. 2010;29(2):193-198.
4. Taizou Izono T, Seitaro Saku S, and Koji Yamamoto K. Application to the tooth coating material of the glass filler containing acid reactive fluoride. The Japanese Society of Conservative Dentistry. 2009;52(3):237-247.
5. Jackson R. Giving your patients something to smile about: the art of direct resin. Lecture presented at: American Society for Dental Aesthetics Annual Conference; October 27, 2007; Palm Springs, CA.
6. Yapp R, Powers JM. Depth of cure of several composite restorative materials. The Dental Advisor Research Report. https://www.dentaladvisor.com/publications/research-reports/depth-of-cure-of-several-composite-restorative-materials.pdf. Accessed August 21, 2014.
7. Alrahlah A, Silikas N, Watts DC. Post-cure depth of cure of bulk fill dental resin-composites. Dent Mater. 2014;30(2):149-154.
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Shofu Dental Corporation
About the Author
Robert A. Lowe, DDS, FAGD, FICD, FADI, FACD
Charlotte, North Carolina