Cracked crown

This picture illustrates a bad day for the restorative dentist. A ceramic crown crack – BUMMER. Having lived through the birth and growth of bonding, and having settled into the comfort zone that was created by the total etch three step systems (the 4th generation), I was under the impression that total etch of a preparation prior to use of a bonding system would always provide the maximum bond strengths.

True, those strengths might be matched without etching the dentin, but I never thought I was reducing the bond by etching the dentin. Turns out I was wrong. There are a number of products, Clearfil SE and Unicem 2 among them, that have lowered bond strengths to dentin if you etch the dentin with phosphoric acid. Others do best WITH a total etch, All Bond Universal, Scotchbond Universal, and Elect are the three discussed by John Burgess when I became aware of this difference.

The blessing and the curse of being in dentistry at this point in history is the rapid rate of change. A short time after I started using the self-etching materials I switched to selective etch – BUT that was a move to reduce chances of sensitivity since it seemed that the bond strengths were just as good as not total etching the dentin. It seemed a prudent move in spite of the fact that I was experiencing virtually zero sensitivity as it was. I was always careful to keep things wet. Thankfully, that rationale might have saved me some additional bad days since I haven't etched a lot of dentin in the past few months.

What this reinforces for me is the importance of reading and understanding the manufacturers' recommendations when using a new product clinically. I am NOT a directions kind of guy, it's a weakness - and it might have weakened my bond strength.


Commenter's Profile Image Grady
September 13th, 2013
What about OptiBond XTR?
Commenter's Profile Image Gary DeWood
September 13th, 2013
Checking with Kerr now.
Commenter's Profile Image Gerald Benjamin
September 14th, 2013
There are so many variables that we can attribute to porcelain fracture and adhesive systems would fall very low on that list. I have used either Kerr Optibond 3A,3B or Optibond Solo Plus for the last 21 years and I would not attribute porcelain fractures to my bonding agent. More like culprits would be: 1. Using a very powerful light at full power placed very close to the feldspathic porcelain. I have watched the porcelain crack on curing. 2. Pushing too hard on the porcelain during placement in an effort to make sure that the restoration was correctly and fully seated. 3. An undiagnosed barely apparent pre-existing fracture discovered after placement. 4. Fracture on adjusting the occlusion when patients CRUSH to porcelain in an effort to be thorough and 'helpful' when asked to close and grind. I would find it extremely challenging to think of clinical trial that could isolate the bonding agent as the source of the fracture.
Commenter's Profile Image Gary DeWood
September 15th, 2013
Agreed Gerald - thanks for putting it in perspective. This appeared at a time in which I'm learning new information regarding bonding and it's kind of a ramble about what was running through my mind - that seems to be happening to me more frequently since I started my sixth decade. Always great to hear from you!
Commenter's Profile Image Gerald Benjamin
September 16th, 2013
In the late 1990s early 2000s Frank expressed an opinion that he felt that bond strength declined after 10 years. At the time, I had no reason to doubt Frank's statement. However, at the 21 year mark of dentinal adhesive dentistry, we can all agree that adhesive dentistry is a rock solid, proven long term modality. The key to excellence in adhesive dentistry remains great isolation with a rubber dam and a meticulous attention to adhesive protocols. Running 4 rooms as the same time definitely disqualifies one from practicing fine restorative adhesive dentistry.