INTRODUCTION
Let’s face it, placing successful posterior composites is exacting, tedious and time consuming. The process includes achieving the necessary isolation, selecting and placing an appropriate matrix, precise execution of the adhesive steps, the placement of a flowable resin or resinionomer liner and finally, the incremental placement, adaptation, and light curing of at least two or more layers of composite. Add to this sculpting, adjusting the occlusion and finishing and polishing and you have a procedure which just takes too much time. This in turn can produce a profitability problem for dentists who have contracted with insurance companies. Given today’s overhead per hour, dentist’s need material and technology advancements so that posterior composites can be placed faster, easier, and profitably without taking compromising shortcuts.
In recent years, materials have been introduced in an attempt to reduce some of the time and effort needed for layering and adaptation when placing posterior composites. One such composite resin material, Quixx (Dentsply Caulk-Milford, Delaware) is advocated as a true “bulk fill” composite. Nevertheless, because of its high viscosity, it still might be prudent to place a low viscosity composite resin or low viscosity resinionomer liner to achieve intimate adaptation to the pulpal and gingival floors. Although one 4 year clinical study1 showed an acceptable annual failure rate of 2.7% (a literature review analysis of posterior composite restorations reports annual failure rates for Class II composites range from 0% to 7% with a mean of 2.2%2) a real drawback of a Quixx restoration is its translucency. The high translucency allows for a 4mm depth of cure in 10 seconds using a light with a minimum of 800mW/cm2 (manufacturer’s directions for use). Unfortunately, this necessary translucency can cause restorations to look gray in appearance. [Note: this author uses the term “bulk fill” to mean the entire cavity is filled in one single increment, up to 5mm depth. Recently, some manufacturers are using this term to describe a low viscosity composite material, which can be cured to a depth of 4mm, but is used primarily as a thick base in Class I or II cavities. An additional high viscosity composite layer is placed to serve as the occlusal contacting surface.]
More recently, a low viscosity composite, Surefill SDR (Dentsply Caulk) has been introduced. It is promoted as a flowable with a reported high depth of cure (4.1mm) allowing placement of a large incremental base. This base is then surfaced with a high viscosity restorative composite resin. With a polymerization shrinkage of 3%,3 Surefil SDR would not be classified as a low shrink (<2%). However, the manufacturer claims low shrinkage stress which is actually more significant.4 The appeal of this material is that, for the majority of cavities, a well adapted posterior composite restoration with good esthetics can be achieved in less time because only two layers of composite are placed and cured, and only the second layer needs adaptation and sculpting.
NEW MATERIAL/TECHNOLOGY
A new composite resin, SonicFill™ (Kerr – Orange, California) (Figure 1) has recently been introduced. This material/technology takes the ease and efficiency of posterior composite placement even further. In essence, SonicFill™ is capable of delivering an esthetic composite restoration in one true “bulk fill” single increment. SonicFill™ is a high viscosity restorative composite which comes in tooth colored shades (A1, A2, A3, B1) and opacity, yet has a high depth of cure (5mm). The customized composite is provided in a Unidose tip. It is inserted into the cavity using a uniquely designed sonic handpiece. The handpiece fits KaVo MULTIflex air connections as well as other brands when using a compatible adaptor, available from several manufacturers including Kerr. When the tip is placed into the cavity and the handpiece activated, liquefaction occurs, resulting in an 87% drop in viscosity. The cavity fills in seconds. When the activation is ceased, the material begins returning to a high viscosity to allow for sculpting. (Figure 2) When in the activated state, the composite material does not appear to reach what would be called a “flowable” state, however, the liquefaction achieved, along with the sonic vibration, yields optimal cavity adaptation in the same manner as a true flowable. Independent testing has shown Sonicfill to have a 5mm depth of cure with a bottom to top Knoop hardness ratio of 80% or better.5-7 The high depth of cure is not accomplished by raising the translucency of the material, so the final esthetics of a SonicFill™ restoration ranges from good to very good. In this author’s experience the majority of posterior cavities measure 5mm or less, which means most posterior composite resin restorations can be restored quickly and efficiently in a single, rapidly placed true “bulk fill” increment without the need for a liner or capping layer. Of course, for cavities greater than 5mm, the first increment is pressed to place and cured before a second increment is placed. It should be noted, that although the bottom to top depth of cure ratio is above 80% for a 10 second cure using a light with an output greater than 1000mW/cm,2 Kerr recommends additional time to account for the distance between the material and the light tip when curing (see directions for use because of variations in power output among different curing lights). Finally, SonicFill™ has been shown to have similar or better mechanical properties when compared to other restorative composite resins in the marketplace.5-7
THE TECHNIQUE
A patient presented with a leaking amalgam in a lower premolar requiring replacement. (Figure 3) The existing amalgam, liner/base and recurrent caries were removed. (Figure 4) A sectional matrix system and wedge (Triodent, KatiKati, New Zealand) was placed and the contact area burnished. (Figure 5) The cavity measured less than 5mm from the gingival floor to the marginal ridge of the adjacent tooth. (Figure 6) After etching the enamel and dentin with a 30-40% phosphoric acid, Optibond FL (Kerr) a dentin/enamel adhesive was placed according to the manufacturer’s directions and light cured. (Figure 7) The SonicFill™ tip was placed into the bottom of the proximal box (Figure 8). The 1.5mm opening diameter of the SonicFill™ cannula allows access to small cavities. (Figure 9) When the handpiece is activated, the cavity is filled in less than 4 seconds. (Figure 10 & 11) It should be noted that the handpiece is withdrawn as the cavity fills but should stay within the material. A round end condenser or a silicone tipped instrument (Comporoller – Kerr) is used to press down on the material and simultaneously wipe away excess at the margins. (Figure 12) SonicFill™ is non-sticky and does not slump allowing for quick and easy shaping and sculpting with a bladed instrument. (Figures 13 & 14) Upon completion, the SonicFill™ restoration is light cured from the occlusal for 10 seconds with a curing light providing high output. In this case, the Demi Plus LED (Kerr) was used. After removing the wedge and matrix system, the restoration is light cured again for 10 seconds from the occlusal as well as 10 seconds from the buccal and 10 seconds from the lingual aspects. (Figures 15 & 16) Any excess adhesive and composite on the buccal or lingual can be easily removed with a #12 blade in a scalpel handle. (Figure 17) The rubber dam is removed and occlusion adjusted. It is the author’s preferred technique to retain any bonded occlusal flash and merely feather it with a carbide finishing bur. (Figure 18) Final finishing and polishing is accomplished quickly with a one-step rubber instrument (Progloss – Axis Dental, Coppell, Texas) used wet. (Figure 19) When dried, SonicFill™ will be seen to have a v
ery smooth matte finish, which does not pick up stain. Whereas a retained high gloss finish is important for anterior restorations, posterior restorations are always viewed wet by patients. (Figure 20)
A second case shows SonicFill™ restorations in molars at 24 months post op. (Figures 21 & 22)
DISCUSSION
Posterior Composite restorations are mainstream and represent the majority of posterior intracoronal restorations placed today.8,9 Besides satisfying patient desires for non-metal, natural looking restorations, these restorations seal teeth and provide tooth reinforcement.10-14 However, the placement of composite resin restorations is more demanding of the operator when compared to placement of amalgam fillings. Many dentists find the multiple steps quite tedious and very time consuming. The concept of “bulk fill” to reduce the time necessary to place and adapt multiple layers of composite resin has been appealing to dentists for some time. In fact, in a “voice of consumer” survey conducted by Kerr, 73% of dentists indicated they would choose a technique for posterior restorations using a bulk fill, single shade, single opacity material yielding a possibly identifiable restoration over a technique where the composite is layered with different opacities and shades to achieve imperceptible esthetics.
The concern regarding bulk fill restorations, and the reason(s) why they haven’t become standard technique, has centered around adaptation to cavity walls, depth of cure and volumetric shrinkage. SonicFill™ has been optimized to respond to a specific sonic level so the extent of liquefaction upon activation of the handpiece assures intimate adaptation to all cavity walls. Even though SonicFill™ shows a nice blend of shade and opacity with tooth structure, it still has a 5mm depth of cure using a high energy light source. As to the common perception that a bulk fill restoration will result in higher shrinkage leading to higher shrinkage stress and poor restoration outcome, this is not universally born out by the literature. Although there are published papers which seem to confirm this concern,15 there are several studies contradicting this perception.1,4,16-24 In his paper titled “Does an Incremental Filling Technique Reduce Polymerization Shrinkage Stress”, Versluis, et.al showed that “incremental filling techniques increase deformation of the restored tooth” and concluded that “it is very difficult to prove that incrementalization needs to be retained because of the abatement of shrinkage effects”.16 In another paper by Idriss, et.al., the conclusion was the “method of placement of a given material had no significant effect on the quality of marginal adaptation”.18
The amount of polymerization shrinkage stress following light curing is the result of many factors including volumetric shrinkage of the composite itself, polymerization kinetics, modulus of elasticity and the cavity configuration factor (C-Factor) to name a few. Whereas in vitro testing can be a guide (statistical significance), controlled clinical trials have the most relevance (clinical significance). In the absence of such research, which is all too common, the astute clinician is left to rely on what literature does exist, trusted colleagues and teaching clinicians and his/her own observations. In the 24 months that this author has used SonicFill™, the esthetics has satisfied all patients and the clinical performance has also met the standard of care. (Figures 23 & 24) Indeed, the only difference noted has been a significant improvement in placement efficiency and less tedious effort when doing posterior composites.
Another area of concern for some dentists may be patient acceptability of single opacity esthetics. We are used to seeing photos by teaching clinicians in lectures and in articles where posterior composite restorations virtually defy detection. As much as we dentists are impressed by this type of beautiful esthetic posterior dentistry – most patients wonder why we have placed stains in their fillings. The fact is, the vast majority of patients have a different esthetic standard in the posterior than they do in the anterior. (Figures 25& 26) Yes, they want it tooth-colored and to blend in well but I believe having the restoration completed faster and at a reasonable fee, would be preferred by all but the most discriminating patient. For those patients who desire imperceptible restorations, the dentist can use a material with a broader shade range, layer with different opacities, use tints, take more time and charge an appropriate fee.
CONCLUSION
SonicFill™ clearly breaks from tradition because it uses a single shade (A1, 2, 3 or B1), single opacity, fast, 5mm bulk fill method of placement without using liners. Significant breakthrough changes such as this can raise skepticism in some clinicians. After all, faster and easier can sometimes be red flags to lower quality. However, in this instance, teeth restored with SonicFill™ may have better cavity wall adaptation and less potential for voids. Clinical research on SonicFill™ is underway in several centers worldwide and early data is very promising. It appears that a material and technology has finally been developed that allows dentists to place posterior composites in a time period and at an efficiency that rivals amalgam. OH
DISCLOSURE:
Dr. Ron Jackson discloses that he acted as a consultant in the development of SonicFill™ and retains a financial interest in it.
Dr. Jackson is a Fellow in the Academy of General Dentistry, an Accredited Fellow in the American Academy of Cosmetic Dentistry, a Diplomate in the American Board of Aesthetic Dentistry and is Director of the Mastering Dynamic Adhesion program at the Las Vegas Institute for Advanced Dental Studies. Dr. Jackson practices in Middleburg, Virginia emphasizing comprehensive restorative and cosmetic dentistry.
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