When I graduated from dental school in 1988 most teeth that received indirect restorations also got a buildup. The buildup, in those days usually amalgam, replaced the parts of the tooth that had been lost to decay internally. This accomplished several goals, it allowed the indirect preparation to have retention form and resistance form. It also allowed for a uniform thickness of metal in the indirect restoration, which was important during the firing cycles of veneering porcelain on PFM’s. The buildup was retained in the tooth with traditional mechanical retention, facilitated by root canal therapy and posts if inadequate tooth structure remained.
Today many of us are using monolithic all ceramic restorations in the posterior. The all ceramic material means that we no longer have to be concerned about metal thickness and the ceramic firing cycles of PFM’s. The strength of the monolithic materials eliminate the concern of veneering porcelain chipping and needing to design cores for support. Lastly, the materials can be bonded directly to the tooth in addition to the inclusion of retention features so the need for specific prep features is no longer a concern. In actuality, since most of our modern materials are bonded to the tooth, we add the complexity of multiple interfaces with a buildup.
Thinking back over my practice what failed most often was the buildup, and I’d find most of them inside of crowns that came into the office in Ziploc bags. Since I moved to monolithic ceramic restorations bonded in with dual cure resin cements and no buildups I experience fewer structural failures. So, do we need a buildup or not? I’d love to see some long-term clinical studies comparing the two, but until then its up to our clinical judgement. If you are in the camp moving away from buildups take a moment and revisit your fees for all ceramic crowns and onlays.
interesting Lee. Was it the build-up or the lack of ferrula that failed the restaurations?
Pierre, Great question and I think it is a combination of factors. Obviously without the appropriate ferrule either a cemented or bonded restoration will fail, it is simply a matter of time. I find even with ferrule, often cores have limited mechanical retention and we are bonding only to dentin, and often not good quality dentin. Then we place a restoration over the top and add strain to the bonded interface. In these instances I think we have a choice of doing a monolithic bonded ceramic restoration which is now bonded to both the dentin and the enamel margins or we have to have endo done to gain mechanical retention for the core.
Lee
Hello,
I prefer a crazy schema on abutment than a buildup in all cases that i can. I think that now we have the knowledge of good bonding. I think we can succeed to bond any kind of ceramic restoration to almost any surface. I dont think that bonding a ceramic to already bonded resin will have bigger bond strength than the direct bonding of the ceramic and tooth.
So i think bondind is not problem. Is fracture a problem? Well it depends of the material. For example the monolithic zirconia is very very hard . According to my experience it can stand forces on 1 mandibular molar with thicknes of 0,5mm . It is not so esthetic but it makes the job where other materials fail.
Best Regards
Dimitris Tsanaktsidis
Couldn’t agree more! Haven’t done a build up in a very long time , ESP since using monolithic lithium disilicate in the posterior.
Hi Lee…interesting comment. I know you are suppsed to only bond to enamel with bonded all ceramic restorations….I did an inlay prep on a second molar for a patient that had had a leaking composite restoration there……the base of the proximal box (an MO) was just subgingival most likley into the dentin or at the CEJ at least…would you take the chance of bondin an e-max inlay in there (the patient wanted something esthetic) with the base of the box so deep? Thank you !! Have a good day .Sharon
Sharon,
Whether we are placing a direct composite or an indirect restoration deep proximal boxes with margins on cementum can be an issue. They can experience greater bond degradation and breakdown more quickly over time. The key steps are isolation, so rubber dam, placing cord, even placing a matrix band during cementation. I think it is actually more predictable to place an indirect restoration and seal the margins in these situations, then doing a direct.