Until today I hadn’t given any thought to the lifespan, care and maintenance of the separation rings that I use in the office to create tight interproximal contacts when placing a posterior composite restoration. The quality of the contact, however, is something I think about each and every day. Creating a contact that is tight enough and has the appropriate shape to prevent food impaction following restoration is a critical factor in success of the procedure. This last week I struggled through a patient appointment where we completed three class 3 restorations, the frustration came from trying to manage the matrix system and create those ideal contacts. This morning I went in search of an explanation for why I had so much trouble with the separation rings, for a system I have used and really loved for years.
I was surprised when the information I found supports that it might be something as simple as replacing some of the separation rings, and initiating a more careful approach for how we work with them and maintain them moving forward. What I learned is that all of the rings fatigue over time, from use, abuse and maintenance procedures like cold sterilization and a run through the autoclave. 
As the rings fatigue the amount of force they apply to separate the teeth drops off, and they become less and less effective at overcoming the thickness of the sectional matrix and the inherent polymerization shrinkage of the composite. The net result is that over time you will find it more and more challenging with older fatigued rings to create tight interproximal contacts. I went to the websites for the different brands and they all report the same finding of fatigue, recommendations for how to readjust the rings to extend their lifespan, and maintenance procedures that are designed to lengthen the lifespan. In general there are a few key points I took away from all of the research I did.
Key Points:
- Do not place the ring in the forcep until you are ready to place in the mouth. Extended time with the ring being forced apart by the forceps speeds the fatigue and decreases the effectiveness of the ring.
- Both cold sterilization and autoclaving fatigue the rings. Therefore, do not contaminate multiple rings by placing them out on the tray table. Select the most appropriate size and leave the rest out of the operatory.
- If the rings are not applying adequate pressure, follow the manufacturers recommendations for tightening.
- Follow a process of evaluating and replacing the rings as they fatigue over time.
Hi Lee Ann –
Very good points.
I use 2 kinds of sectional matrices. The V3 (Triodent) and the Compositite 3D (Garrison Dental solutions). Before these were available I used the Paladent and the Compositite Silver.
Compositite silver was purely a metal ring with tines on it. It had no reinforcement plastic on it like the newer V3 and 3D. The V3 is almost bulletproof. I’m probably 200 restorations on each and the V3 does not weaken. The 3D’s weakest link is the rubber that forms the 3D shape. It tears after a while and you will need to replace it for that reason instead of the metal giving out.
The V3 is very good and I use it for almost everything – except one instance in particular…
Anyhow – give these Plastic reinforced metal rings a shot. You will very much like them.
Aly
Hi Aly,
I will definitely check these out, sounds like a great improvement! Can they go in both the cold sterile and the autoclave with having plastic on them?
Yes. They can be autoclaved or cold sterile. My setups are in cassette’s so they get autoclaved. They get dumped in an enzyme tube before going in the autoclave to remove the majority of the resin.
For Class III’s I sometimes use David Clark’s Bioclear matrix system. The matrices are transparent mylar which are preformed and have contour. What you use as a ring in a Class II is actually a separator that is a piece of rubber with two balls on the end (Similar to Danville’s old interproximal system…) Anyhow – they hold the transparent matrix in place and will provide the teeth a nice contour.
bioclearmatrix.com
Thank you for addressing this challenge, as it is one I have been dealing with as well. I have tried just about every system that comes on the market, and can agree that over time, each of the ring systems eventually begin to weaken. I have even gone as far as to fabricate indirect resin restorations with CEREC, a solution which ends up costing me in time and materials.
We will review your recommendations, Dr. Brady. And Aly, thank you for your suggestions as well. Glad to know that I am not the only one dealing with this issue.