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Inside Dentistry
July 2015
Volume 11, Issue 7

Simplifying the Placement of Posterior Composite Restorations

Unique properties and delivery system make SonicFill an excellent option


Direct posterior composites, particularly those of the Class II type, are among the most challenging restorations routinely placed by dentists. The gingival margin of the proximal box and the line angles where the buccal and lingual vertical walls meet the gingival margin are the most common places where clinical failures are seen. In these areas, poor marginal adaptation of the restorative material can lead to microleakage, recurrent decay, and ultimate clinical failure. The majority of Class II restorations are placed by clinicians on “blind faith”—ie, the proximal box portion of the restoration often cannot be evaluated for precise placement by direct visualization unless the width of the preparation extends beyond the buccal and lingual line angles of the tooth being restored. One must depend upon x-ray examination alone, which does not allow for complete evaluation of the gingival margin and line angles of the restoration.

Many dentists still use “amalgam armamentarium,” such as Tofflemire matrix bands and wooden wedges, to place Class II composites. However, unlike amalgam, composite is not condensable, and the clinician cannot deform or put pressure on a matrix band to create contact with the adjacent proximal surface. It is like “pushing around mashed potatoes” in a cavity preparation. Tofflemire type bands also create flat proximal surfaces with composite, rather than the proper convex proximal surfaces. All of these factors lead to inconsistency in the placement of these types of restorations in many clinical situations. An anatomic sectional matrix with a ring to separate the teeth slightly is better adapted to composite; it enables dentists to create a consistent proximal contact and proper convex proximal surfaces.

Additional improvements to the efficiency and predictability of Class II restorations have come in the form of advanced materials. Bulk fill as a technique for placing these composite restorations has been studied for years. Research evaluating marginal gaps and cusp deflection has shown no significant clinical difference between restorations placed with bulk-fill techniques and those using incremental placement.1-3

SonicFill™ (Kerr Corporation,, a proprietary, highly filled nano-hybrid material, represents an important step toward easier and more predictable placement of posterior composite restorations. Its delivery system uses sonic energy to lower the viscosity of the composite material, allowing for easy and precise placement of composite in bulk quantities.

Challenges of Class II Posterior Restorations

Consistent posterior direct composite placement is still difficult at times for most dentists. Some of the clinical challenges include isolating the operative field to prevent moisture contamination during placement; completing the numerous steps to create an optimal adhesive bond to tooth structure; and layering and placing a soft, non-condensable material into areas of proximal tooth preparations that are difficult to access and visualize directly, while ideally sealing the cavosurface margins. Sonic delivery of composite material in bulk, with the uniquely designed unidose tip of SonicFill, makes this task faster and more efficient compared to traditional placement techniques that involve pushing around soft restorative materials in a “blind hole” with a plugging instrument (Figure 1 through Figure 4).

Simplifying the Adhesive and Restorative Process

In addition to sonic composite delivery with SonicFill, a sixth-generation bonding resin (OptiBond™ XTR, Kerr Corporation) also helps eliminate procedural steps in the composite restorative process without sacrificing quality of the finished result. The manufacturer states that when compared to other available self-adhesive bonding agents, OptiBond XTR shows a significant improvement in the bonding to uncut enamel, which in many cases eliminates the need for selective etching of enamel prior to placement of the self-etching adhesive material.4

The SonicFill system consists of a proprietary composite resin and a unique handpiece that fits onto the coupler of a traditional high-speed handpiece. The sonic energy generated by the handpiece causes liquefaction, or a dramatic drop in the viscosity of the composite resin. Even though SonicFill is approximately 84% filled by weight, special additives in the composite are activated by the sonic energy in the handpiece, allowing the filler particles to slide very readily over one another. This means that during placement, the composite is able to intimately adapt to the cavity preparation’s internal geometry, much like a heavy-body flowable resin. The low viscosity also means that a separate flowable composite liner is unnecessary. SonicFill can precisely and uniformly fill all the intricate line and point angles of even the most complex posterior cavity preparation.

Once placement is complete and the sonic energy is discontinued, the higher viscosity of the composite resin returns. This makes it suitable for sculpting the restoration to its most precise morphologic form, which is followed by light curing and finishing using traditional techniques. SonicFill is also unique in that it has a polymerization shrinkage of approximately 1.6%5 and can be bulk filled to a depth of 5 mm while still having up to 98% full cure at its deepest point.6 One of the biggest timesaving properties of SonicFill is that a cavity preparation can be filled in a single bulk increment without layering, condensing, or “capping” with another restorative material. This creates a solid, void-free mass of restorative material similar to those that are indirectly fabricated by a dental technician.

SonicFill 2

SonicFill 2 is a second-generation SonicFill restorative material that, while maintaining all of the features and benefits of the original formulation, shows significant changes in several clinical areas.7 SonicFill 2 demonstrates polishability improved to a level comparable to other nano-microhybrids in the marketplace. It has 35% more working time than the original formulation and is less affected by operatory light. In addition, color matching and chameleon effect are improved over the original version of SonicFill to give better esthetic results in posterior areas (Figure 5 through Figure 8).


Clinicians’ needs for a simplified, precise, and predictable protocol for posterior restorations have led to material innovations in the area of bulk-fill composites. SonicFill represents one such advance, with its “on command” viscosity change and the ability to rapidly bulk fill a cavity preparation up to a depth of 5 mm in seconds. It simplifies placement by reducing the number of steps involved and the time needed to place a quality posterior direct composite restoration, making it an excellent choice for the general practitioner’s armamentarium.


Robert A. Lowe, DDS, FAGD, FICD, FADI, FACD, FIADE, received an honorarium from Kerr Corporation.

About the author

Lecturer, Educator
Private Practice
Charlotte, North Carolina

For more information, contact:

Kerr Corporation


1. Rees JS, Jagger DC, Williams DR, et al. A reappraisal of the incremental packing technique for light cured composite resins. J Oral Rehabil. 2004;31(1):81-84.

2. Gallo JR 3rd, Bates ML, Burgess JO. Microleakage and adaption of Class II packable resin-based composites using incremental or bulk filling techniques. Am J Dent. 2000;13(4):205-208.

3. Idriss S, Habib C, Abduljabbar T, Omar R. Marginal adaptation of class II resin composite restorations using incremental and bulk placement techniques: and ESEM study. J Oral Rehabil. 2003;30(10):1000-1007.

4. Walter R, Swift EJ Jr, Boushell LW, Braswell K. Enamel and dentin bond strengths of a new self-etch adhesive system. J Esthet Restor Dent. 2011;23(6):390-396.

5. SonicFill [product brochure]. Kerr website. Accessed June 9, 2015.

6. Tiba A, Hong A, Zeller G, et al. Examining the depth of cure for bulk fill composite materials [abstract 2435]. Presented at: IADR General Session; March 22, 2013; Seattle, WA.

7. SonicFill™ 2 [product brochure]. Kerr website. Accessed June 9, 2015.

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