Creating the "Perfect" Class V Composite: Matrix Is Key - Dentistry Today (2023)

INTRODUCTION
Direct composite dentistry presents a variety of placement challenges for a myriad of reasons. Class V with subgingival margins is one of the biggest daily concerns and therefore the choice of matrix to confine the restorative material is critical to the success of the final restoration. The first successful matrix was introduced to dentistry by Dr. Luis Jack in 1871.¹In contemporary terms, a dental matrix can simply be defined as a properly shaped device or piece of material that forms the missing wall of the restoration, providing a special dimension and shape to the restoration during insertion and condensation of the restorative material. However, the importance of creating the proper matrix for a direct composite resin cannot be underestimated given the complexities the practitioner faces when using these materials to restore a tooth. One of the most critical issues for a successful composite is obtaining and maintaining isolation of the preparation throughout the cleaning process, treatment of enamel and dentin surfaces, and placement of the composite. Failure to create and maintain an isolated preparation during bonding and placement procedures, regardless of the use of a rubber dam or other adjunct isolation method, may result in negative results including microleakage, hypersensitivity, and the possibility of recurrent caries. Once the proper die is in place, the ability to use the concept of "injection molding" (placing the compound under pressure in the confined die mold) allows the operator to more efficiently place the compound into a mass. void free and more. accurately seal margins prior to curing.

For years, dentistry has used clear plastic strips for most previously placed composite resins, many made of the material Mylar, which was developed by DuPont Chemical in the early 1950s. These flat two-dimensional strips somewhat confine the material. resin and allow the energy of a curing light to initiate the photoreaction of the compound. One of the underappreciated benefits of Mylar material is the transfer of an ultra-smooth surface to any part of the compound the strip touches. Research over 4 decades has shown that the compound cured against Mylar has a highly polished surface than any available diamond or carbide finishing instrument or abrasive polishing systems.^2-12However, the operator's ability to isolate a preparation using straight or flat strips can be challenging in certain situations. This can lead to a less than desirable result for both the doctor and the patient. A specific matrix (Margin Perfect Matrix, or MPM [Margin Perfect Matrix]) combined the concept of isolating a preparation apically and interproximallymitransferring the smoothness of the Mylar surface to the final restoration. By creating a 270° enveloping seal of the tooth preparation, the matrix creates subgingival areas that are smooth, eliminating the need for operator shaping and finishing.

Figure 1.Margin Perfect Matrix (MPM), for Margin Perfect Matrix, is a 0.002 in. thick, specifically cut into a shape that becomes a universal template for all anterior and premolar restorations.

The ability to adequately isolate and seal the bonding site of a Class V preparation cannot be underestimated in its contribution to the success of a direct composite. In this article, the authors will describe a protocol using a specifically designed die-cast that the dentist can use to create a fixed impression, completely isolating the prepared portions of the tooth and, by injecting the resin under pressure with a syringe, forming a " hermetic seal” in critical gingival areas being restored. As defined by the dictionary,perfectmeans: Having all the elements, qualities or characteristics required or desirable; as good as can be. The technique discussed will use a clinical case to illustrate the attributes of having a "system" or protocol to facilitate day-to-day reproducible results. In the following case report, the authors will present:

1. A demonstration of a method of subgingival matrix placement and marginal sealing
2. How MPM is customised, positioned and fixed with a bisphenol A (Bis-GMA) light-curing resin instead of a traditional wedge system
3. The use of single-dose "injection molding" as the ideal method of placing composites.

CASE REPORT
The patient had numerous demineralized cervical lesions that would be best treated with minimally invasive direct composite resin restorations.

Clinical Protocol
The first step in this case was to prepare the MPM for use.

The MPM has unique landmarks to identify and become familiar with prior to use in the oral cavity (Figure 1). Following the manufacturer's instructions for use, the matrix is ​​transformed from a two-dimensional strip to a three-dimensional mold that can be easily placed around the Class V preparation. When packaged, the matrix is ​​a cutting system-specific flat shape that is molded pressing with fingers to form the U-shaped outline of a tooth. Additionally, by rolling the interproximal points toward each other, one point at a time, a custom-shaped matrix is ​​created that allows for a 270° tooth fit. The gingival edge of the MPM will guide the matrix under the interdental papillae, forcing the matrix into the sulcus and against the tooth. The MPM is now ready to be placed around the prepared tooth and into the subgingival space (Figures 2-5).

After local anesthesia, the labial carious lesion of tooth #21 was extracted with 330 carbide (Brasseler USA) and an enamel chamfer was placed with a 40 μm diamond (889-009-3.5F [Diatech USA]) ( Figure 6).

Figure 2.The MPM matrix, before being shaped by the rolling memory, is folded into it.	Figure 3.Demonstration of the formation of the initial matrix in the form of a U-shaped tooth.
Figure 4.Roll the interproximal points toward the long axis, which positions the MPM in the interdental space.	Figure 5.The molded MPM is ready to be placed around the prepared tooth.
Figure 6.The incipient carious lesion was removed and an enamel bevel was placed with a 40 µm diamond bur.	Figure 7.Once placed around the Class V preparation, the MPM was stabilized with an unfilled adhesive resin (Heliobond [Ivoclar Vivadent]) on the outside of the matrix and subsequently light-cured.

After checking the landmarks, the interproximal wings were passed through the contact points and the upper cervical collar was placed in the groove. The matrix should surround the tooth at the base of the groove and sit firmly against the root surface. The clinician will notice that the sulcular gingival tissue will “whiten” if the MPM is placed correctly. Holding the matrix firmly in place, a light-curing Bis-GMA resin (Heliobond [Ivoclar Vivadent]) was applied to the exterior of the matrix and the adjacent (dry) teeth and gingival tissues in a horseshoe pattern, then exposed to a light source. 1,000 mW/cm2 LEDs²for 10 seconds (SmartLite Focus [DENTSPLY Caulk]). This acted as a wedge replacement and stabilized the MPM for the remaining clinical steps (Figure 7).

Here an all-out attack technique was used (Email Preparator [Ivoclar Vivadent]). After rinsing with a water jet and air drying, the universal dentin adhesive (Prime&Bond Elect [DENTSPLY Caulk]) was applied according to the manufacturer's instructions (Figure 8). The body composite (Tetric EvoCeram, shade A2 [Ivoclar Vivadent]) was then injected into the matrix using an injection molding technique to minimize voids. This was accomplished by placing the unit dose nozzle on the cervical surface, directly over the prepared margin, lifting the nozzle so that the occlusal edge of the nozzle was held firmly against the tooth surface and the apical edge of the nozzle was open. thus forcing a composite sheet to slide into the preparation and into the gingival area of ​​the matrix (Figure 9). Preheating the body compound to 130°F with a heating device (Calset [AdDent]) greatly facilitates syringing and also minimizes the potential for voids and air bubbles. In addition, using a small increment of a flowable resin (Heliomolar Flow, Color A1 [Ivoclar Vivadent]) in the preparation (not separately cured) prior to "injection" of the heated body resin can also help create an airtight seal on the interface. dental restoration.

Before polymerizing the restoration, the composite was shaped with a No. 3 brush (Cosmedent), using it as a very fine plastic instrument. The tips of the brushes can be condensed into the matrix tooth margin and used to smooth the body composite bond at chamfered margins (Figure 10).

Figure 8.Here a total etch technique was employed and, after rinsing and air drying, a universal dentin bonding agent (Prime&Bond Elect [DENTSPLY Caulk]) was placed.	Figure 9.The body compound was inserted into the mold formed by the matrix created by the MPM. Preheating the compound to 130°F with a heating device (Calset [AdDent]) facilitates application and also reduces the possibility of voids and bubbles.
Figure 10.The composite was handled with a flat chisel brush (#3 [Cosmedent]) and ancillary instruments of choice, then light-cured using an LED light source with a minimum of 1000 mW/cm.2for 20 seconds.	Figure 11.Remove the stabilizer resin collar and the MPM.
Figure 12.Note how the smooth surface of the matrix was transferred to the composite restoration, minimizing, if not eliminating, the need for rotary instruments below the gingival margin.	Figure 13.Final finishing and polishing was done with cups and abrasive points (Astropol [Ivoclar Vivadent]).

Curing was performed with a high-power LED curing light (SmartLite Focus) with a minimum power of 1,000 mW/cm²following the manufacturer's instructions. The resin-based stabilizer collar was then removed with a sickle-shaped instrument (such as a Bates 7/8 [American Eagle Instrument] rasp). Note how the smooth surface of the matrix was transferred to the composite restoration (Figures 11 and 12). This technique minimizes, if not eliminates, the need to use rotary instruments below the gingival margin.

The final finishing and polishing was done with cups and abrasive points (Astropol [Ivoclar Vivadent]) and the final result can be seen in Figure 13.

FINAL COMMENTS
Direct composite resins have become a mainstay in today's contemporary restorative practices. One of the frequent challenges for the clinician is the isolation of a subgingival Class V. By using a matrix that creates a sealed system, free of crevicular fluids and blood, along with injection molding of today's excellent composite materials, many of the pitfalls associated with gingival margin failure in Class 1 restorations are overcome. V. Flexibility of the matrix to adapt to the The shape desired by the clinician is a key feature of the MPM. This allows the operator to successfully use this matrix not only for Class V composites, but also for Class III, IV, and full direct resin veneers.

References

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Dra. Belvederebegan "injection molding" of compounds in 1985 and has been teaching continuing education to practicing dentists for over 40 years. He is a Diplomate of the American Board of Esthetic Dentistry and an Adjunct Professor at the University of Minnesota School of Dentistry, where he is Co-Director of the Graduate Course in Contemporary and Cosmetic Dentistry at the University of Minnesota. He can be contacted by email atvelvytooth@aol.com.

Divulgation. Belvedere Physician is the creator of Margin Perfect Matrix and has a financial interest in Margin Perfect Matrix, Ltd.

doctor lambertoHe is a Diplomate of the American Board of Esthetic Dentistry and a member of the American College of Dentists, the Pierre Fauchard Academy, the Academy of Sports Dentistry, and the American Society for Esthetic Dentistry. He presents progressive composite dentistry workshops internationally and is a clinical mentor and speaker in the Contemporary Esthetics and Implant Dentistry program at the University of Minnesota School of Dentistry and the Catapult Group. He can be contacted by email atddssmile@aol.com.

Divulgation. Lambert, Ph.D., has a financial interest in Margin Perfect Matrix, Ltd.