Predictable Class II Restorations Using Sectional Matrices

Figure 1. Triodent V3 Sectional Matrix System (Ultradent Products).

INTRODUCTION
Achieving a positive proximal contact that is anatomically acceptable is one of the most challenging manifestations of a Class II composite restoration. The purpose of this article is to explore current clinical techniques and instrumentation in order to minimize the frustrations associated with Class II restorations.

Clinical Challenges
The challenge for the dentist has always been to create contact with the adjacent tooth despite limitations with conventional matrix systems.¹ Even though a number of improvements have been made in wear resistance, strength, and the ability to bond to dentin, composite resin can’t always be formed effectively against the traditional matrix band to create optimal contacts.² This problem begins with the composite material itself. While placing the Class II restoration, even the most packable composite resins cannot adequately and predictably move the matrix band enough to establish an ideal contact form. There is a direct correlation between the type of proximal contact and food impaction, and between pocket depth and food impaction, according to Hancock et al.³ Class II caries initiates just below the proximal contact and, just as there is a correlation between pocket depth and food impaction in the proximal area, there is also a correlation between food impaction and recurrent caries at the gingival margin of existing Class II restorations.

It is well known that the Class II posterior com­posite resin is one of the most challenging restorations to place predictably and consistently. Throughout the years, many different matrix designs have been introduced in the hope of eliminating the problem of poor proximal contacts with Class II composite resin restorations. These restorations require a matrix band for placement, and need to have the marginal ridge rebuilt, the creation of a proper proximal contact, and often a large portion of the interproximal surface.

Clinical evidence suggests that Class II com­posite resin restorations may demonstrate higher rates of recurrent decay than amalgam restorations.⁴ The higher failure rates at the gingival margins of Class II composite resins can be related to many factors, including the technique sensitivity of some dentin bonding systems and polymerization shrinkage of composite resin.⁵ There can also be challenges in techniques placing highly viscous composite resin into proximal boxes without trapping air bubbles, allowing for poor marginal adaptation. Failure may also be related to contamination of the tooth surfaces due to poor field isolation. It can also be associated with poor polymerization of the resin adhesive and composite resin due to inadequate curing light output and the distance of the light guide from the gingival margin.⁶

A Brief Review of Matrix Band Systems
For many years, matrix designs have been developed with the goal of eliminating the issue of inadequate proximal contacts with composite resin restorations. Some approaches that have been used include differing types of metal, thickness of metal, and redesign of the retainer system. Other types of instrumentation, which disperse light into the interproximal area and tighten the contact, have been introduced as well.⁷

Circumferential-type matrix systems used with Class II preparations have been the most common type of technique utilized by the profession. These systems had many drawbacks, including time in preparation of the matrix band, inconsistent resulting contacts, and instances in which rubber dam isolation with the circumferential matrix band system was not possible.

Another class of matrix system is the sectional matrix, in combination with a ring. This matrix system incorporates some very unique features. It utilizes an ultrathin dead-soft stainless steel sectional matrix in combination with a ring that, when placed, is designed to achieve additional tooth separation. The fit of this sectional matrix forms an anatomically correct contact with the adjacent tooth. The clinician can place an anatomically correct wedge that is available in 3 different sizes. Due to the design of these wedges, the interdental papilla is not impinged upon, and the matrix band is effectively pushed against the cervical portion of the box to create a better marginal seal. The rings, sectional matrices, and wedges are uniquely designed for easy handling, pickup, and control during placement and removal. These are all created with built-in holes to accommodate specially designed forceps. There are many good sectional matrix systems available, including but not limited to the Palodent Plus Sectional Matrix System (Dentsply Sirona Restorative); Composi-Tight 3D XR System (Garrison Dental); and Triodent V3 Sectional Matrix System (Ultradent Products).

A sectional matrix system (such as the Triodent V3 Sectional Matrix System in Figure 1) is an excellent choice for Class II composite restorations for many reasons. The key is the NiTi V3 Ring, which provides optimal separation force to achieve consistently tight contacts. The v-shaped tines ensure that there is no competition with the wedge in the embrasure. The tines grip both teeth equally, preventing the ring from collapsing into wide cavities. The matrix band is anatomically correct, and the unique design of the matrix allows for the proper restoration of interproximal anatomy. It is an extremely simple system to use and produces great results in a short period of time while making the procedure faster.

CASE REPORT
Diagnosis and Clinical Protocol
A patient presented with old Class II amalgams (teeth Nos. 29 and 30) that had decay on the lingual aspects of the proximal portions. The buccal of tooth No. 30 had decay and an open mesial contact that was trapping food (Figure 2).

Figure 2. Pre-op photo showing teeth Nos. 29 and 30.	Figure 3. Pre-op photo showing patient contacts.
Figure 4. Teeth prepared for restoration.	Figure 5. The sectional matrix was placed.
Figure 6. The composite was placed with proper interproximal contact restored.	Figure 7. The completed restoration.

The occlusion was marked with articulating paper (Accufilm II [Parkell]) prior to treatment. This was done in order to keep the final occlusion either on all tooth structure or on all the restorative material, but not on the margins, to improve the changes for a longer-lasting restoration (Figure 3). The operative area was isolated with a rubber dam (DermaDam [Ultradent Products]) and removal of the old restorative material and associated decay was carried out; then, preparation of the proximal cavity form was accomplished (Figure 4). Next, the sectional matrix system (Triodent V3 Sectional Matrix system) was placed to close the contacts and to rebuild the ideal contour of the teeth (Figure 5). A 15-second total-etch technique was performed using a 35% phosphoric acid-etching gel (Ultra-Etch [Ultradent Products]). The etchant was then rinsed off thoroughly with water for a minimum of 15 to 20 seconds to ensure complete removal. A universal bonding adhesive (ALL-BOND UNIVERSAL [BISCO Dental Products]) was applied (as directed) for adhesion. The first layer of composite was placed using a flowable composite (BEAUTIFIL Flow [Shofu Dental]) to a thickness of about 0.5 mm. Vit-l-escence (Ultradent Products) direct composite material was then layered over the flowable composite to restore the tooth to full contour (Figure 6). Each increment of composite resin placed was no more than 2.0 mm thick. After completion of the composite placement (before matrix removal), the restoration was light-cured using an LED curing light (Demi Ultra LED [Kerr]). The occlusion was adjusted as needed, and then Jiffy Polishers (Ultradent Products) were used to polish the adjusted areas to a smooth and shiny finish.

An occlusal view of the completed Class II restorations shows that a nice chameleon effect was achieved using the restorative materials of choice for this case. The composite restorations blended with the adjacent tooth structure beautifully (Figure 7). The patient was seen 2 weeks later for a follow-up visit and reported no sensitivity.

CLOSING COMMENTS
The techniques and materials used in this case allowed for a conservative treatment while delivering a great result for this patient. The technique and dental materials used ensured that the procedure was simple, effective, and fast. When using this sectional matrix system with the latest in composite resin technology, direct Class II tooth-colored restorations can be placed that exhibit natural anatomic proximal form and have predictable proximal contact. The concepts, materials, and techniques described herein can be used to assist the clinician with useful information to make the placement of posterior composite restorations easier, predictable, and more enjoyable.

References

1. Strassler HE, Trushkowsky RD. Predictable restoration of Class II preparations with composite resin. Dent Today. 2004;23:93-99.
2. El-Badrawy WA, Leung BW, El-Mowafy O, et al. Evaluation of proximal contacts of posterior composite restorations with 4 placement techniques. J Can Dent Assoc. 2003;69:162-167.
3. Hancock EB, Mayo CV, Schwab RR, et al. Influence of interdental contacts on periodontal status. J Periodontal. 1980;51:445-449.
4. Bernardo M, Luis H, Martin MD, et al. Survival and reasons for failure of amalgam versus composite posterior restorations placed in a randomized clinical trial. J Am Dent Assoc. 2007;138:775-783.
5. Hinoura K, Miyazaki M, Onose H. Effect of irradiation time to light-cured resin composite on dentin bond strength. Am J Dent. 1991;4:273-276.
6. Felix CA, Price RB. Effect of distance on power density from curing lights. J Dent Res. 2006;85(special issue B). Abstract 2468.
7. Shuman I. Excellence in class II direct composite restorations. Dent Today. 2007;26:102-105.

Dr. Halabo is in private practice in San Diego, Calif. A graduate of Boston University’s Goldman School of Graduate Dentistry, he completed a general practice residency at the Loma Linda Veterans’ Hospital. Currently an adjunct faculty member at the University of California at San Diego (UCSD), he served as the director of dental care at the UCSD homeless clinic in Pacific Beach, Calif. An accomplished international speaker, author, and product evaluator, he has been involved in product evaluations for both the Catapult Group and Clinical Research for many years. He lectures on a variety of topics, emphasizing (1) the improvement of patient care and (2) dentists’ enjoyment of their profession by combining technological and clinical advancements with the use of simple practice management tools. He can be reached at (619) 427-0810 or at sam@samhalabodmd.com.

Disclosure: Dr. Halabo reports no disclosures.