Ask the Expert: An Interview with Matthew Miller, DDS on Sectional Matrix Systems

Performing direct interproximal Class II restorations in restorative dentistry can sometimes be challenging and frustrating, especially as it relates to the intricacy of replicating the proper anatomy and contour. Selecting a matrix system that is easy-to-use and one that provides a tight and anatomically correct contact is crucial. A system that is easy-to-use and requires minimal training helps ensure that a clinician and their team can use the system effectively and efficiently. Some matrix systems available on the market are compatible with the other dental instruments and equipment already commonly used in dental offices. This can help ensure that the clinician can integrate the system into their workflow easily. It is also important to choose a system that seals the gingival box and cavosurface margins interproximally. This allows for improved marginal adaptation, minimizes the likelihood for overhangs and excessive flash, and also decreases the risk for marginal gaps and recurrent decay.

Over time with use, adhesive and composite resin will often accumulate on the ring surface. This build up of resin is not only unsightly, it can cause issues with how well the ring will adapt to the interproximal surfaces of the teeth. If in the event resin adheres to a matrix ring while performing the restoration, it can create difficulties in removing the matrix ring from the restoration without damaging the restoration itself. This is because the composite resin can harden and bond to the matrix ring, making it challenging to separate the two. In some cases, the matrix ring may need to be cut or broken away from the restoration, which can result in damage to the restoration or the need for additional adjustments and contouring. With so many universal bonding agents containing multiple primers within their chemistry, this can cause the adhesive and resin to bond to the surface of the ring unintentionally.

One way to avoid this issue, is to use a matrix system that has a ring with a non-stick surface. The DualForce™ Rings (Clinicians Choice®) tines are coated with a non-stick plastic that prevents adhesive and resin from bonding to it, thus leaving the restoration intact and the ring free of debris accumulation. A design feature such as this can ensure a smoother and more efficient restoration process.

Dental sectional matrix rings can sometimes lose their tension over time, which can affect their performance during restorative procedures. This can be due to various factors such as material fatigue, improper handling, or frequent use. Using high-quality matrix systems such as the DualForce system, will provide consistent tension and accurate adaptation during restorative procedures. The DualForce Rings unique dual-spring technology ensures that the rings maintain their tension over time, even with frequent use. This can help reduce the need for constant adjustments and replacements, saving clinicians time and money.

When rings sit flat against a tooth, it can prevent the ring from being positioned properly. This is especially true for rings that do not offer a wide clearance for access. This can result in a restoration that has an improper contour and poor interproximal contact. It can also prohibit the clinician from treating adjacent teeth at the same time. Improper ring placement can result in many issues including but not limited to: the ring popping off from an unstable placement, poor adaptation of the matrix such that the marginal seal and contour are now compromised, inadequate interproximal contacts, and difficulty placing the material leading to voids, overhangs, and other imperfections.

Some manufactures avoid this problem by creating a large ring circumference with an open access to the teeth in the area being treated. DualForce Rings sit at a 20º angle to allow for clearance away from the teeth cusps and rubber dam clamp as well as provide additional separating force between the teeth. By positioning the rings at this angle away from teeth and rubber dam clamps, it ensures that the ring is ideally seated. Therefore, the separating force in between the teeth is not compromised, nor is the contour of the restoration.

Class II restorations can present several challenges, so when working on a pre-molar or molar with a concavity in the proximal box, the restorative process can become even more difficult. These contours and concavities are due to furcations within the tooth. If these areas are not properly sealed while performing a direct restoration, then marginal leakage and excess overhanging restorative material will result.

The DualForce system includes a “Deep Seal” Active-Wedge that is designed specifically for this clinical indication by providing a tight seal at the base of the proximal box, particularly in cases where there is a concavity close to the furcation. Furcation concavities are usually hard to seal, however the “Deep Seal” wedge makes these situations easy to treat. One side of the wedge has a bubble that applies additional pressure against the matrix to press it firmly against the tooth surface and seal it off. This prevents fluid from seeping in as well as stops restorative material from leaking out causing overhangs. By having the bubble on one side of the wedge only, the rigidity and integrity of the wedge is not compromised.