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For many of us composite is the first and only choice as a direct restorative material today. Although realistically we all know that no restoration lasts forever, we strive for the greatest longevity and durability we can achieve. Clinical and research data support that the two most common reasons we replace a composite restoration are recurrent decay and marginal leakage. So why should you care about the polymerization shrinkage of your composite? Simple, there is a direct linkage between the shrinkage stress of the composite and the longevity of the restoration. We have many great researchers looking at polymerization shrinkage and shrinkage stress of composite restorative materials and it’s impact on clinical performance. The results across these studies are consistent.
Venus Diamond Composite
Higher contraction stress is associated with:
- Larger gap formation at the interface between composite and the tooth
- Increased marginal leakage
- Increased crack propagation
- Decreased bond strengths
All of these factors are working against our goals and accelerate failure of the restoration clinically. There are many factors that contribute to contraction stress, some we have no control over, like the preparation “C” factor, which is dictated by the condition of the tooth. We can manage the stress through utilization of placement techniques, resilient liners and light application. Maybe most importantly we have control over the composite we use, and at the top of the list for how we compare materials should be an understanding of its “Shrinkage Stress”. Using a material that has low shrinkage stress in combination with great technique is a sure recipe for improved clinical results.
Thanks, Lee.
Is there a good recent article/research report that describes the shrinkage amounts for different composites? I’m in the process of exploring using a different composite for anterior and posterior.
Carl
Hi Carl,
I don’t know of any one research source that compares all of the current composites. It will take looking at several different papers to put together that information. Here are some places to start:
TRAC Research Nanofiller – Low Shrink Class 2 Resin Study Statistical Report, Year 1 Analysis
Koplin C.: Calculating internal stress during curing of dental composites, IADR-CED Munich 2009, presentation 145.
C. Koplin, G. da Silva Rodrigues, R. Jaeger, Fraunhofer Institut of Mechanics of Materials, Freiburg, Germany
Lee
Thanks, Lee
I find myself getting frustrated by what seems to be a lack of longevity of composites; especially class II’s. I now own a practice where the patients are still new to me, and I see problems around composites that I didn’t do. I am perplexed that I haven’t had a patient question the longevity of composites compared to some of the amalgams that lasted 30 years.
I’ve actually done a few more amalgams lat
How does shinkage affect the resin cements that bond in ceramic or composite Cerec restorations?
Sorry…I pushed “publish” before I was done editing my last comment…
I was saying that I’ve done a few more amalgams lately for situations where teeth really didn’t need full coverage or the patient wasn’t willing to do it because of cost. So I’ve felt obligated to them to discuss the pros/cons of amalgam v. composite. Some patients accept that a large composite may not last as long as a large amalgam, but are willing to accept the compromise for whatever reason they object to amalgams. Then I have the patients (usually men 55 or older) who really don’t care what it looks like as long as it can chew and lasts at a less expensive fee.
What kind of time does it take to do Cerec composites? I suspect that the shrinkage is quite a bit less since the majority of the restoration is milled…is this a good assumption? Just wondering if it is a realistic option
Hi Carl,
As far as polymerization shrinkage and resin cements, I’m not aware of much discussion on this. I’d assume it is because the bulk of material is small enough to minimize the impact and it is trapped between two restorative surfaces. But I will look into it.
As for composites and amalgams, there is still quite a bit of debate on longevity, and in truth if you follow a very precise technique with isolation composites should do well. The key to figuring out the challenges is to look at the exact types of premature failures you are seeing, and then go through the technique step by step and try and put the two together.
As for milled composites, I am a big fan, and once you have gotten skilled with the technology I find they take less time than placing composite directly, plus have lass challenges with materials, getting interproximal contacts, and yes placing them is a different process completely.
Thanks, Lee.
I’m pretty sure that the reason I’m seeing the composite failures in my “new” practice is technique issues and maybe too much reliance on flowable composite.
Unfortunately, I am not able to see how all my composites that I did in my old practice are doing. So I’m starting over “watching” the longevity of my technique.
Back to milled composite. Do you charge a similar fee to a “regular” composite? I am intrigued by this. I’m also intrigued by Gary’s use of the milled composite to open his patient’s VD like a bonded splint.
Hi Carl,
Yes I charge a similar, maybe marginally higher fee for milled composite restorations. There is an article on the site about cerec and paradigm composite you could look at and see a few case photos.
Lee
Excellent topic. Incremental fill doesn’t alter the overall % of shrinkage, but it does control the direction of shrinkage. That means significantly less stress on teeth versus bulk fill.
I was recently at a conference with George Freedman and he spoke about thermal expansion-contraction as being a bigger factor in terms of longevity.
Joe,
Thanks, I’ll have to look into thermal expansion and contraction and understand it better.
Lee