April 1, 2014
by Jack D. Griffin Jr., DMD, MAGD, ABAD, AAACD
Efficiency: to do a procedure in a quality manner while spending as little time and effort as possible. Nowhere is this more important than when placing composite restorations in the posterior. Posterior composites are the restorative backbone of many practices today, however there are clinical issues that must be dealt with including potential sensitivity, marginal integrity, leakage, placement efficiency, depth of cure, shrinkage stress, contact formation, and longevity.1-3
Many newer materials and techniques today have been designed to address such issues.4 A popular trend today is “bulk filling” of posterior restorations while attempting to gain speed by replacing tooth structure in 4mm or more light cured layers. These materials provide a potential mechanism for reducing time and effort but the handling of these materials must be understood and the technique is meticulous.
The balance between efficient placement, aesthetics, comfort, and durability must be considered. Reducing the time or steps, such as with bulk fill materials, may result in less than an optimal restoration. Clinician concerns with bulk fill materials include gap formation of the pulpal floor, damaging shrinkage stresses at the enamel interface, and incomplete polymerization of the material.5,6
The thorough and meticulous sealing of the dentinal surface and the cavosurface margins with a regenerative material BEFORE bulk placement may minimize the potential problems associated with bulk filling techniques. This article describes the attention to detail and placement techniques that provide maximum sealing where it matters most.
BULK FILL MATERIALS
The two classes of bulk fill materials are the flowables and the packables. Flowable type materials like SureFil SDR (Dentsply), Filtek Bulk Flow (3M), and BeautiFil Bulk Flowable (Shofu) all are fairly non-viscous, self-leveling materials that have a predictable 4mm depth of cure. These materials can certainly be a time saver but they all need to be “capped” with a more wear resistant material like a microhybrid composite. This additional layering adds another material to the system and care must be taken to leave sufficient room for the final covering.
The bulk fill packables have perhaps a greater inherent efficiency because they can be filled to the cavosurface/occlusal surface and do not require a covering layer. Materials such as Tetric EvoCeram Bulk Fill (Ivoclar), SonicFill (Kerr), and BeautiFil Bulk (Shofu) provide the 4mm depth of cure and wear that is similar to most other microhybrids on the market. Therefore, these materials may have the potential for the highest clinical efficiency if used properly.
The “giomer” (Shofu, San Marcos, CA) is a unique class of restorative materials that have the distinguishing feature of a stable glass ionomer core in a protective resin matrix.7 This arrangement allows for protection of the glass core from moisture giving it long-term aesthetics and durability of conventional composites with ion release and recharge.8 This surface pre-reacted glass ionomer (S-PRG) gives these materials composite-like durability, handling, and aesthetics as well as significant release of fluoride ions re-chargeability.9,10
Included in this family are both bulk fill flowables and packable composites that feature excellent clinical characteristics with the anti-bacterial, anti-plaque, anti-sensitivity features of the entire giomer class.11 The giomer line also includes flowables, sealants, nano-hybrids, and posterior microhybrids.
With the giomer family, we have a “regenerative” type material that is bio-friendly and may provide an environment where dentin prospers which may lead to less sensitivity and longer restoration durability.12 Given the ion release and their anti-plaque nature, they are excellent choices for placement at the margins and on the dentin BEFORE the bulk restorative material is placed. This allows regenerative activity to occur where it matters most.13
WHERE IT MATTERS MOST
There are two critical areas of concern with any direct composite restoration: the margins and the dentin surface. How those areas are treated determine in large measure the degree of longevity and sensitivity with the restoration. When both of those areas are handled correctly, there is a higher chance of restoration success. Despite the efficiency that comes with bulk filling materials, the margins and dentin surface are best handled with meticulous attention to detail. Once those areas are sealed and polymerization in a bio-friendly manner, the bulk filling of the preparation is relatively simple.
By placing these biofriendly materials in thin, easily light curable layers on a well bonded dentin surface and at the cavosurface margins, we are providing an environment where bulk filling can be most successful. In other words, we are treating the places where failure most readily happens in a separate, methodical manner BEFORE bulk filling occurs.
One of the most efficient restoration in a clinical setting is the class I. However, they can be the most challenging to achieve great margins and symptom free patients because of the so-called “configuration factor” (C-factor). Also because of the lack of walls that polymerization shrinkage can be compensated from.14 The effect of polymerization stresses may be minimized using bulk fill materials and thus better marginal sealing and less formation of “white lines” in enamel associated with these stresses.15
Initial tooth preparation was done with a 330 carbide bur and decay removed with a spoon and #6 round bur (Fig. 1). A selective etch technique was done on enamel only with phosphoric acid (Etch 37 with BAC, Bisco, Schaumburg IL) for 10 seconds and rinsed thoroughly (Fig. 2). The surfaces were left moist with no puddled water and universal bonding agent (All Bond Universal, Bisco) was applied in several layers (Fig. 3). Air thinning was done to remove the bonding agent solvent, to ensure an even coating, and to minimize its thickness (Fig. 4). Light curing was done for 20 seconds.
A giomer flowable material (BeautiFil Flow Plus, Shofu, San Marcos CA) was placed in a 0.5 to 1.0 mm thick layer lining all dentin and cured for ten seconds. A 0.5 to 1.0 mm layer of the same highly adaptable flowable was placed on all cavosurface margins (Fig. 5). Light curing of this material was done for ten seconds (Fig.6). The result is a well-sealed and polymerized dentinal and marginal surfaces. By being polymerized BEFORE the bulk fill material is placed ensures that polymerization stresses are resolved before the bulk material is placed. Separation between this layer and the bulk fill for any reason would be less deleterious to the overall success (Fig. 7).
A small amount of the flowable material was placed into the preparation and forced out as the more viscous bulk fill packable material (BeautiFil Bulk, Shofu) was squeezed in from a compule. This forcing out of the non-cured flowable aids in reducing voids between restoration layers. After shaping with a #6 round high speed bur the result is a very well sealed restoration without evidence of white lines associated with stresses on the cavo surface margins (Fig. 8).
Occlusion was then checked and polishing done with a rubber cup (One Gloss, Shofu) leaving a smooth and easily maintained surface (Fig. 9). Light curing was done again after all finishing was completed. It is easy to see in the post op photo where the relatively clearish bulk fill material meets the flowable material lining the margins.
It must be noted that the bulk fill material in this case was also a giomer restorative which itself releases regenerative ions and is fluoride rechargeable. By using the giomer at the margins and on dentin the restoration has anti-microbial and fluoride releasing activity in those areas even if another type of bulk fill material was used. Likewise, pre-curing of the materials along the dentin and at the margins ensures complete polymerization that is enhanced with each subsequent layer that is placed and cured.
In this case the disto-lingual cusp was fractured leaving a decayed, cracked, and failing amalgam (Fig. 1). After alloy and decay removal a regenerative calcium silicate liner (TheraCal, Bisco) was placed in a 1m or less layer and light cured for 30 seconds (Fig. 2). This liner was placed on moist dentin in the deepest part of the preparation.16 A selective etching technique was done as described above, rinsed well, and bonding agent applied, air thinned, and cured as described above (Fig. 12).
A less than 1mm layer of giomer flowable was placed on the dentin and the TheraCal liner and cured for ten seconds. This was followed by a thin layer on all margins, including the gingival portion of the box, and light cured for 30 seconds (Fig. 13). More flowable was placed, left uncured, and the more viscous bulk fill material placed to force out the uncured flowable composite to reduce the chance of voids between layers. This was then cured 30 seconds from the facial, lingual, and occlusal surfaces (Fig. 14). Shaping and polishing was completed with a round finish bur and rubber polisher. A complete cure was done again after final shaping and polishing.
The anti-microbial nature of the giomer materials is particularly beneficial at the restoration dentinal and cavosurface interfaces helping to maintain an environment needed to promote long term restoration success. With the added benefit of ion recharge and re-release and thorough curing before bulk filling material is placed, the ability to promote restoration longevity exists.
The goal of any efficient office is to use materials and techniques that give predictable results on a daily basis. This “pre-sealing” and curing technique may reduce some of the clinical problems associated with direct composite restorations by the placement of regenerative materials with maximum polymerization where it matters most.OH
Disclaimer: Dr Griffin has no financial interest in the companies mentioned in this article. www.eurekasmile.com
Jack D. Griffin earned his DMD degree from Souther Illinois University in 1987 with clinical honors and completed a general practice residency at the University of Louisville in 1988. He is currently director for PAC, the Pacific Aesthetic Continuum, and serves the community with a large St. Louis county Missouri practice.
Oral Health welcomes this original article.
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