Component two: The womb
A two-die, single-wedge-and-ring cutting die system is installed. This is a key part of the process. Traditional Tofflemire matrix bands were designed to work with amalgam. While they have served dentistry well for decades, as our materials have evolved, so have our needs from a matrix system. Tofflemires are designed to tighten on the tooth. As the retainer tightens the tape, it flattens out, leaving us with a flat partition wall.
Unfortunately, the back teeth do not have straight mesial walls. With amalgam, we could contour the matrix outward as we packed our amalgam, but composite cannot be packed like amalgam, so we don’t have the opportunity to contour outward and create an anatomic wall. Incision matrix systems generally have anatomic matrices that are curved. This is critical for achieving good interfacial contacts with composite resin restorations. In this case, we used the Garrison Composi-Tight 3D Fusion system.
A matrix is applied to each tooth and then secured in place with a single wedge. Once this is stable, the intermediate ring is applied to ensure proper separation. This separation force is crucial to produce an intraproximal contact. If we do not separate the tooth far enough, we will always have an open contact the width of the matrix itself. Separation uses the PDL of the tooth to create a slight movement of the tooth away from the restoration, so that when the separation force is removed, the tooth snaps back into place with a beautiful, cleanable thread-breaking contact. While the Garrison ring produces more tooth separation than a traditional Tofflemire die, it does not produce enough force to overcome the thickness of two dies. We’ll need to phase the next recovery steps in a specific order to explain this.
Once the dies, wedge and ring are placed on the tooth and secured, we are ready for the restorative steps. These begin by etching the teeth with a 35% phosphoric acid etchant. I practice the selective etching technique and apply the phosphoric acid only to the enamel. This is left in place for about 15 seconds and then washed off.
Once we have a clean, fresh formulation, it’s time to apply our glue. I use a universal adhesive, Ivoclar’s Adhese Universal VivaPen. I enjoy the flexibility of a general purpose adhesive and the ability to use the same product for all welding processes, whether direct or indirect. The Adhese Universal VivaPen gives me fresh adhesive at the push of a button and is the best instant glue system available. Inside the PowerCure 3s system (discussed below in Item 3), it can only cure for three seconds! Once Adhese Universal has been applied, blotted, thinned with air and light-cured for three seconds, it’s time to restore the teeth with our selected restorative material.
Component 3: Composite mass filler
Now that we have a matrix on each of our contact teeth and have done all the chemistry steps of the bonding process, it’s time to actually restore. Because the spacer ring cannot exceed the thickness of both matrix strips, we must restore one tooth at a time. This means that one of our matrices will be the active matrix, while the other matrix is the “Shepherd matrix”. The shepherd matrix serves to hold the space for the second restoration, ensuring that we do not overlap the outline of the first restoration. While we technically don’t restore both teeth at the exact same time, we do so effectively by making sure we don’t encroach on the space we need for both restorations.
Choose which tooth you want to restore first. I almost always choose to restore the wider bucco-lingual preparation. In this case, it is the distal part of the maxillary first premolar. I load this preparation with my restorative of choice, which in this case is Ivoclar’s Tetric PowerFill composite.
Bulk-fill composite offers some distinct advantages over its step-fill cousins. First, a reduced polymerization shrinkage is important to minimize boundary voids and leakage. Second, it makes me more efficient during these processes, reducing chair time and increasing profitability. I chose Tetric PowerFill in this case because of its ease of handling and handling, low wear characteristics and 4mm increment depth.
When used with the Bluephase PowerCure curing light, also from Ivoclar, the curing time for a 4 mm increase is only three seconds. In 3s mode, Bluephase PowerCure produces a light intensity of 3,000 mW/cm2. This allows the exposure time to be reduced to three seconds. If using any other curing light, the curing time for that material is 10 seconds (or longer based on power output). The 3s PowerCure System (including Adhese Universal, Bluephase PowerCure light and Tetric PowerFill and PowerFlow) is an excellent choice for any posterior composite restoration.
I always build my marginal ridge and meridian wall first. Here you can see my first increase of Tetric PowerFill. Because the measurement from the gingival floor to the occlusal surface was 4 mm, this wall is formed in only one increment (figure 7).
