Modern Posterior Composite Placement: An Innovative Single-Increment Technique

INTRODUCTION
With the increasing demand for aesthetic restorations and development of adhesive techniques, composite resins have become the material of choice for many clinicians, when indicated.¹ The placement of composite resin restorations using modern adhesive techniques allows for more natural aesthetics² and also the ability to place more minimally invasive restorations that conserve more natural tooth structure as compared to other restorative choices.³ However, poly­mer­ization con­traction and associated shrinkage stress have been considered to be the major disadvantages of composite resin materials.⁴ The polymerization of composite resins gives rise to internal stresses due to contraction of the material during polymerization. Shrinkage stress occurs when the contraction is blocked and the material is already hardened enough to prevent the flow of plastic compensation in the original volume.⁵

Although composite resins are often used in replacing defective amalgam fillings,⁶ clinical challenges can also be associated with these materials. These challenges (such as recurrent caries, dental and material fracture, and postoperative sensitivity) often occur via structural failures inherent in the composites themselves, originating basically from the polymerization shrinkage.⁷ Manufacturers have focused their attention on producing materials and are, at the same time, able to minimize any associated problems.^8-11

The evolution of composite resins and adhesive techniques has significantly changed the approach to posterior teeth restorations.¹² In order to improve the performance of the composite restoration in posterior teeth and to also reduce the operative time required for placement, a new class of bulk-fill resins was recently introduced in the market. This material advancement allows the clinician to place a single layer of the composite (at 4.0 to 5.0 mm thick) and to then light-cure the material in a single step.⁸ Campos et al⁹ compared the microleakage results of different bulk-fill resins and concluded that these resins have adequate cavosurface sealing that is similar to that of conventional resins applied in the incremental technique.

Figure 1. Preoperative photo of teeth Nos. 30 and 31.	Figure 2. Rubber dam was placed for optimal isolation of the operative site.
Figure 3. Preparation and caries removal was completed in tooth No. 31, and a glass ionomer liner was placed into the preparation of tooth No. 30.	Figure 4. Enamel and dentin acid conditioning, drying, and adhesive system application on tooth No. 31.

The recent introduction of SonicFill (Kerr) continues in this direction. This system combines the attributes of low viscosity (flowable) and standard viscosity (universal) materials in the same nanoparticle resin by incorporating a high percentage of filler particles (about 83.5 wt% fillers) with specific components that react to sonic energy. When the sonic energy is applied, the viscosity of the composite decreases up to 87%, causing the resin to flow proportionately. Thus, by activating the resin with ultrasonic energy and increasing the flowability, it becomes possible to easily fill the cavity. Then, after the ultrasonic energy is stopped, the consistency of the composite changes back to a higher viscosity^13,14 to become ideal for compressing and shaping posterior Class I and II restorations, and for the reconstruction of cusps as well as a cavity base after endodontic treatment. The well-designed long handpiece allows for easy access in the molar area.¹⁵

There are many articles dealing with single-increment resins;^7,8,11,16-18 however, there are only a few studies regarding the use and clinical performance of these materials. Regarding this context, the purpose of this article is to present a clinical case that demonstrates the use of SonicFill device in the creation of 2 single-increment composite restorations in posterior teeth.

Figure 5. Adhesive light-curing (tooth No. 31) (Poly Wireless [KaVo]).	Figure 6. SonicFill (Kerr) device activation (tooth No. 31).

Figure 7. Restoration sculpture (tooth No. 31).

CASE REPORT
A 22-year-old female came into the postgraduate dental clinic at the State University of Ponta Grossa for the replacement of her old amalgam and composite fillings in teeth Nos. 30 and 31. The patient reported pain in tooth No. 31, which had a carious lesion in the mesial region and wanted the amalgam filling (in tooth No. 30) replaced for aesthetic reasons.

Figure 1 shows the initial aesthetic appearance of the teeth Nos. 30 and 31. Anesthetic was administered, the shade was selected (A2, VITA scale), and a rubber dam was placed for isolation (Figure 2).

The first tooth to be treated was No. 30. The old amalgam filling was removed using a diamond bur (FG No. 1012S [KaVo]) mounted in a high-speed handpiece (Century 105-C [KaVo]). After removal of the amalgam material, the underlying carious lesion was removed using a No. 11 ½ dentin curette (Duflex [SS White Burs]) and a spherical bur (CA No. 4 [KaVo]) mounted in a low-speed handpiece (500 Series Low Speed Contra Angle [KaVo]). Since the cavity preparation was deep, the dentin-pulpal complex was protected with calcium hydroxide cement (Hydcal [Technew]). An encapsulated resin-modified glass ionomer cement base (Riva Light Cure [SDI Industry and Commerce]) was mixed, placed, and light-cured for 20 seconds (according to the manufacturer’s instructions) using an LED device (Poly Wireless [KaVo]).

Having completed the preparation on tooth No. 30, the old resin restoration in tooth No. 31 was removed using a diamond bur (FG No. 1012S). Caries was then removed with the No. 11 ½ dentin curette (Duflex) and a round bur (CA No. 4) in the low-speed handpiece, forming a medium depth occlusive mesial cavity (Figure 3). No protective liner material was required in this tooth. Next, a metal matrix (Palodent [Dentsply Sirona]) was placed and stabilized using rubber wedges (Anatomical Wedges [TDV]).

On tooth No. 31, the ionomeric cement base liner was reduced to 2.0 mm minimum depth cavity. It is important to note that a proper depth of the preparation ensures adequate composite thickness, thus making it resistant to masticatory forces. Cavosurface angles were left in enamel, with no unsupported enamel walls.

Figure 8. Acid-etching and adhesive application (tooth No. 30).

Figure 9. Bulk-fill resin composite placed using SonicFill application, and the sculpture of the unset restoration.

Figure 10. Final appearance of the completed composite resin restorations (teeth Nos. 30 and 31) after finishing and polishing.

The following steps were followed on both teeth: etching with 37% phosphoric acid (Condac 37 [FGM]) for 30 seconds on the enamel and 15 seconds on the dentin; washing with water for 30 seconds, followed by drying the enamel with the air syringe. A small cotton ball in the prepared cavity prevented dentin dehydration. Application of a 5th generation adhesive system (Ambar [FGM]) was done in 2 layers using a microapplicator (Cavibrush [FGM]) (Figure 4). The adhesive was then light-cured for 20 seconds using an LED curing light (Poly Wireless) (Figure 5).

The composite resin (shade A2) was inserted through the activation of the SonicFill device (Figure 6), starting with the pulp cavity wall and filling the cavity in a single increment (tooth No. 30). Then, in tooth No. 31, the first wall to receive the composite was the cervical wall. Throughout the procedure, the tip applicator should always remain submerged to ensure optimal flow of the composite resin in the fluidized state. At the end of the composite filling application, after interrupting the sonic energy supply, the resin assumed a thicker consistency favoring the creation of the anatomical form. It should be noted that the authors followed the manufacturer’s instructions, attaching the handpiece (SonicFill) to the air supply by using a MULTIflex compatible coupler (Borden-MULTIflex 454 NB [KaVo Kerr]).

The occlusal sculpture of the restoration was carried out with a spatula for composite restorations (Mini 1 Goldstein Flexi-Thin [Hu-Friedy]) (Figure 7). After completion of the anatomic occlusal form, the resin was light-cured using the LED curing light (Poly Wireless) for 40 seconds. The sequence of steps for tooth No. 30 and the completed restorations can be seen in Figures 8 to 10. The patient was pleased with the restorative outcome and no postoperative sensitivity was reported.

CLOSING COMMENTS
As exemplified in this clinical case report article, the SonicFill system is an efficient technique that includes convenience of use and reliability when used for the restoration of cavities in posterior teeth. This system demonstrates improved handling characteristics with excellent material consistency, the ability to easily sculpture any restoration with favorable marginal adaptation, and the ability to provide patients with quality composite resin restorations.

Acknowledgment
The authors would like to thank KaVo for the donated equipment and resins used to complete this patient case.

References

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Dr. Schubert graduated with a dental degree in 1988 from Federal University of Santa Catarina (UFSC), with specialization in operative dentistry by Associação Brasileira de Odontologia Seção Santa Catarina-UFSC, and a master’s degree in general dentistry from UFSC (2002). A former professor of dentistry at the University of Joinville Region, he served as an assistant professor until becoming coordinator of the program in 2008, and he is currently an associate professor of operative and clinical dentistry. He can be reached at ewschubert@ig.com.br.

Dr. de Geus graduated in with a dental degree in 2011 from the State University of Ponta Grossa (UEPG) and a master’s degree in restorative dentistry in 2014 from UEPG. She is a PhD student of restorative dentistry in the graduate program at UEPG. She can be contacted via email at ju_degeus@hotmail.com.

Dr. Pupo earned a bachelor’s degree (2006), a master’s degree in dental surgery (2010), and a doctorate of dental surgery (2013) in restorative dentistry from UEPG. She is an associate professor of dentistry at Federal University of Parana and acts as a visiting professor of the integrated expertise in prosthodontics and operative dentistry at Tuiuti University of Paraná. She can be contacted via email at the following address: yasminemendes@hotmail.com.

Dr. Giovana Mongruel Gomes has a master’s degree and doctorate of dentistry in restorative dentistry from UEPG. She is an assistant professor at UEPG in the department of dentistry of biomaterials, operative dentistry, and prosthodontics as well as a permanent professor of the master’s and PhD dentistry programs. A specialist in prosthodontics, endodontics, and implantology, she worked as a dentist of the Brazilian Army (Command Squadron of the 5th Brigade Armored Cavalry, Ponta Grossa) for 4 years. She can be reached via email at giomongruel@gmail.com.

Dr. Osnara Maria Mongruel Gomes graduated with a dental degree from the UEPG (1981) and has a specialization in restorative dentistry by the Brazilian Dental Association-Regional of Ponta Grossa (1991). She also holds a master’s degree in restorative dentistry (1998) and a PhD in restorative dentistry (2003) from the Universidade Estadual Paulista Julio de Mesquita Filho (UNESP). She is an associate professor at UEPG in undergraduate and graduate sensu stricto dentistry, and she is the coordinator of their postgraduate studies program. She can be contacted at osnaramgomes@uol.com.br.

Dr. João Carlos Gomes graduated with a dental degree from the UEPG (1978) and has a master’s degree in restorative dentistry (1985) and PhD in restorative dentistry (1999) from the UNESP. He is an associate professor of UEPG’s undergraduate and graduate stricto sensu dentistry. Also, he is the former rector of UEPG and former president of the Brazilian Association of Rectors of State and Municipal Brazilian Universities. He can be reached via email at the following address: gomesjoaocarlos@uol.com.br.

Disclosure: The authors report no disclosures.

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