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Inside Dentistry

June 2006, Volume 2, Issue 5
Published by AEGIS Communications


An Improved Bonding System and Flowable Composite for Fast, Effective Class V Restorations

There are certain clinical situations (eg, Class V lesions) that demand an esthetic result, but the handling characteristics of conventional composite resins make achieving that result time consuming and may require the use of larger amounts of material for proper finishing and polishing.1 Because of their handling characteristics and ease of use, flowable composites are oftentimes the material of choice for the restoration of a Class V lesion.

FLOWABLE COMPOSITES

Flowable composites have been used for more than 10 years and a number of flowable composites are currently available. Because of the various manufacturers, each flowable composite is slightly different. A new flowable composite resin from GC America (Alsip, IL), Gradia® Direct LoFlo, has many desirable characteristics for the restoration of Class V lesions.

One of the major drawbacks of flowable composites is that, because of their lower filler content, they have a larger volume of shrinkage than conventional composites. Most flowable composites have an average volume polymerization shrinkage rate of 5%. LoFlo has a shrinkage rate of just slightly more than 3%. This can lead to less contraction stress and potential microleakage of the restoration. LoFlo contains fluoro-alumino-silicate glass particles, which is a fluoride-releasing material. Because Class V lesions are oftentimes at or near the cementum (an area that can be caries-prone), fluoride release is a benefit.

All flowable composite have differences in viscosity. Some are highly fluid, while others have much less flow. These differences in viscosity can determine which flowable composite to use in which clinical situation. Gradia LoFlo has an excellent viscosity for use on Class V lesions. When placed in the cavity preparation, it will not slump, but is easily manipulated with an instrument or a brush.

In-house data from GC America has demonstrated a wear rate similar to posterior composites and significantly less than other flowable composites. This can be important in the Class V lesion that is mechanical in nature (toothbrush abrasion). The high wear rate is attributed to the high-density radiopaque prepolymerized filler. Lastly, LoFlo comes in a variety of shades, including a cervical (CV) shade which oftentimes is the perfect shade for the Class V restorations.

Flowable composites have become very popular for Class V restorations for a number of reasons, but one of the biggest reasons is that the ease of use translates to less chairtime. Another way to increase the ease of placement and reduce chairtime is to have a simple, yet effective bonding system.

Bonding

The recent explosion of no-etch bonding systems originally gained popularity because of the noticeable decrease in postoperative sensitivity. However, one of the side benefits of eliminating phosphoric etch from these bonding systems has been the potential to speed up the bonding process. G-Bond™ (GC America) may be the fastest bonding system yet introduced. When used as instructed, the entire bonding technique requires only 30 seconds.

Speed is never the sole criteria for bonding systems. Bond strength is always an important issue. G-Bond has demonstrated bond strengths to dentin of 15 MPa to 20 MPa. And in the area of enamel, where there has historically been a concern with no-etch systems, G-Bond shows bond strengths approaching 20 MPa. The added benefit of a lack of postoperative sensitivity makes G-Bond a well-suited bonding system for the Class V restoration.

CASE STUDY

The following case study demonstrates the use of Gradia Direct LoFlo and G-Bond in a commonly occurring clinical situation. Including the time to take the clinical photographs, the entire restoration was completed in less than 15 minutes.

A 40-year-old patient presented with an abfraction lesion on the facial aspect of tooth No. 10 (Figure 1). Whether from tooth flexure2 or toothbrush abrasion, the lesion presented an esthetic problem for the patient and required a restoration.

First, the occlusion was evaluated to see if the lesion was occlusally related. During a discussion with the patient, he reported that 8 years previously he had an equilibration performed by a previous dentist. Therefore, it was difficult to determine if the cause of the lesion was functional or mechanical. However, at the time of treatment, occlusion did not appear to be a contributing factor.

A size 0 retraction cord (UltraPak®, Ultradent Products, Inc, South Jordan, UT) was placed in the sulcus to maximize the amount of tooth surface that could be visualized (Figure 2). Using a medium grit No. 1 round diamond (Axis Dental, Irving, TX) the surface of the lesion was lightly prepared (Figure 3). Preparation of the surface was performed for the purpose of creating a rougher surface to bond to and removing any sclerotic dentin and/or surface stain (Figure 4).

A seventh-generation bonding system (G-Bond) was chosen as the bonding system of choice. Its ease and speed of application, lack of postoperative sensitivity, excellent formation of a dentinal interface, and reliable bond strength to enamel and dentin made G-Bond an excellent material for this restoration. The bonding solution was placed on the tooth for 15 seconds (Figure 5), vigorously air-thinned for 5 seconds, and light-cured for 10 seconds (Figure 6).

The restorative material (Gradia Direct LoFlo) was selected for a number of reasons. Its low shrinkage properties (3%) would minimize contractural stress. In addition, LoFlo contains fluoro-alumino-silicate glass, which is a fluoride-releasing material. Any fluoride release on a restoration that approximates the root surface is a benefit. The material has excellent flow properties, and will stay where placed yet will move easily with an instrument. Lastly, the CV shade was a perfect match for this patient. Figure 7 shows the application of the flowable composite. Once manipulated to place, the composite was light-cured for 20 seconds.

Finishing and polishing was easily accomplished using a 16-fluted carbide bur (ET carbide finishing kit, Axis Dental) (Figure 8). Polishing was completed with a 1-step rubber polishing disc (PDQ, Axis Dental).

A 24-hour postoperative photograph (Figure 9) shows excellent shade match and overall improved esthetic appearance of tooth No. 10.

Conclusion

The presented clinical case is a common clinical situation. Patients will appreciate the fact that the restorative procedure can be completed quickly and predictably with a highly esthetic result. Dentists will enjoy the speed in which a high-quality restoration can be placed while improving the esthetic appearance of a patient’s smile.

Proper use of this clinically excellent flowable composite and its companion bonding system can create an esthetic and long-lasting restoration.

References

1. Nash RW, Radz GM. Clinical applications of flowable composites. Restorative Quarterly. 1998; 1(1):3-6.

2. Heymann HO, Sturdevant JR, Bayne S, et al. Examining tooth flexure effects on cervical restorations: a 2 year study. J Am Dent Assoc. 1991;122(5): 41-47.

This article was written by Gary Radz, DDS.

For More Information
GC America, Inc.
Web: www.gcamerica.com
E-mail: gca_sales@gcamerica.com
Phone: 1-800-323-7063

Figure 1 An abfraction lesion on the facial aspect of tooth No. 10. Figure 2 A size 0 retraction cord (UltraPak®, Ultradent Products, Inc, South Jordan, UT) was placed in the sulcus to maximize the amount of tooth surface that could be visualized.
Figure 3 The surface of the lesion was lightly prepared using a medium grit No. 1 round diamond (Axis Dental, Irving, TX). Figure 4 The surface preparation created a rougher surface to bond to and removed any sclerotic dentin and/or surface stain.
Figure 5 The bonding solution was placed on the tooth for 15 seconds. Figure 6 The bonding solution was light-cured for 10 seconds.
Figure 7 Application of the flowable composite. Figure 8 Finishing and polishing was easily accomplished using a 16-fluted carbide bur.
Figure 9 A 24-hour postoperative photograph shows excellent shade match and overall improved esthetic appearance.

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