Question: My crown fell off. I’ve searched the internet and it seems like some people are gluing their crowns back on themselves, without having to see the dentist. Do I have to go back to the dentist or can I glue it back on myself?
Answer: The recent economic woes in the U.S. have led to an increased accounts of DIYers performing their own dentistry at home. So, perhaps it is not a surprise that the most popular technique involves Super Glue.
As amusing as it sounds, I see patients using many dangerous methods to save themselves a trip the to the dentist, from emery boards to power tools (i.e. Dremel tools). I was told by a patient the other day that Super Glue worked better than Krazy Glue. Obviously he’s had some experience in differentiating between the two in their effectiveness.
It is true that cyanocrylate, the generic name for Super Glue and Krazy Glue, which contains acrylic resins methyl-2-cyanocacrylate or 2-octal cyanoacrylate, is used by physicians for wound repair. In fact, cyancrylate bonds very well to surfaces that are moist and non-porous.
Sounds perfect for that dental crown that keeps coming out, right?
Unfortunately, that notion is wrong and here’s why: The crown is a non-porous surface and can be moistened, but the tooth, despite being very moist, is also very porous. Therefore, the adhesion between the two is negligible and will not last.
But the real danger is forcing the cyanocrylate down into the tubules of the tooth and killing the tooth. This will ultimately lead to the need for a root canal or even the loss of the tooth due to resorption.
What most people may not know is that a dental crown does not stay in place via adhesion. It remains in place for years merely by mechanical retention.
Mechanical retention is best explained like this: Imagine placing an identical glass over another identical glass. Pick up the upper glass and the one below comes with it, and the two “stick” together as you lift the top glass.
Now try that with two identical bowls stacked face down on top of each other. It’s impossible to pick the bottom bowl by lifting the one placed on top. This is an illustration of the effects (and success) of mechanical retention.
So if that crown keeps falling off, it’s not due to a lack of adhesion – it’s due to the shape of the prepared tooth lacking in retentive features. Dentists typically don’t actually use glues, we use cements to prevent saliva from seeping between the crown and tooth, which prevents tooth decay. In this light, I hope you see the futility of using a product like Super Glue in your mouth.
It’s not at all about stickiness; it’s also about the shape of the tooth and the tightness of the fit, which keeps the crown from falling off.
And because the human body has a high moisture content, cyanoacrylate adhesives will bond very effectively to the skin and other body parts. Believe it or not, I have had a patient come in with his lips glued together!
Mark Burhenne DDS