By Lee Ann Brady, DMD
There is only one thing that I miss about placing Class II and Class III amalgam restorations; I never worried about my matrix system. If amalgam expressed out beyond the preparation margins when I condensed it into the interproximal box, I had carving instruments that could easily take care of that, so the seal of the matrix against the tooth wasn’t critical. Amalgam was easy to condense, and I could create just enough force not to stress over the presence of a contact once the band was removed. As the popularity of posterior composites has increased, the conversations and frustrations about matrix systems have increased right alongside.
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Unlike amalgam, the difficulty of condensing composite presents us with the challenge, recreating a tight interproximal contact. Maybe more importantly, trimming composite that has been extruded beyond the preparation margin around an interproximal box is difficult, frustrating, and unpredictable. So in a quest to minimize the amount of trimming we need to do with high-speed instrumentation after the composite is cured, we search for a better matrix.
I was part of this search until a few years ago. While researching matrix systems for a presentation, I came across a list of criteria that define a successful matrix, and that powerfully shifted my perspective.
A matrix system must do the following three things:
- Recreate the natural tooth shape and interproximal contact
- Seal the proximal and gingival walls of the prep
- Overcome the thickness of the band