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Dear Dr, Another one has broken

Aaron Goh's picture

It broke in the weekend when I was enjoying the footie on TV with a pack of crisps.

This isn't the first time a tooth filling has broken on me, but this one has got me worried, because I called my dentist today and found out that because he is moving premises, he is not open until the middle of next week.

Which made me think why my filling broke in the first place.  Years ago, we were told not to eat immediately after getting our filling done.  Somehow technology has caught up and with new materials and better understanding of the development of stresses in the filling [e.g. 1-4], I now have fillings that look like a real tooth and without having the need to wait for hours before enjoying my solid foods again. 

So maybe it is the food.  I find that there are two types of crisps, one which is softer and empties from the mouth pretty quickly, e.g. Pringles, and the other type, which I was having when my filling broke, which is harder and gets lodged on the teeth, like eating cornflakes.  Is it the high stiffness causing high compressive stresses or the stickiness causing high tensile 'dislodging' forces? What is the difference between the two types of crisps?  Is it in the structure, e.g. the degree of porosity [5], or is it in the recipe, e.g. selection of starches that gets broken down more easily by the amylase enzyme in the mouth [6]?

Then maybe it is the way I chew.  In my early PhD years I had the opportunity to work with Dr. Wendy Brown [7] and had measured the EMG and KI patterns of my own chewing.  It was clear that I wasn't 'normal', since I was having a much higher number of chews than other subjects.  I guess it is in my physiology, my build, my jaw make-up which affects my chewing efficiency and there have been many spitting tests showing this relationship [e.g. 8-10].  Perhaps the filling materials have a finite fatigue life, and the excessive chewing just shortened their lifespan.

As I contemplate a weeklong diet on bananas, I wonder if there are any out-of-the-box adhesives that I can use to stick my filling back.  Any suggestions? 

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1. Toparli M, Aksoy T [1998] Fracture toughness determination of composite resin and dentin/composite resin adhesive interfaces by laboratory testing and finite element models. Dental Materials, 14, 287 

2. Rees JS, Jacobsen PH [1998] The effect of cuspal flexure on a buccal Class V resotration: a finite element study. Journal of Dentistry, 26, 361 

3. Meyer C, et al. [2000] Development of a static simulator of the mandible. Journal of Cranio-Maxillofacial Surgery, 28, 278 

4. Arola D et al. [2001] A comparison of the mechanical behavior of posterior teeth with amalgam and composite MOD restorations. Journal of Dentistry, 29, 63 

5. Ulbricht D et al. [1994] Assessment of the crumbliness of individual fragile particulates from that of their assemblies. Powder Technology, 81, 83

6. Ferry AL et al. [2004] Effect of amylase activity on starch paste viscosity and its implications for flavor perception. Journal of Texture Studies, 35, 511 

7. Brown WE et al. [1998] Use of combined electromyography and kinesthesiology during mastication to chart the oral breakdown of foodstuffs: relevance to measurement of food texture. Journal of Texture Studies, 29, 125 

8. van der Bilt A [2002] Human oral function: a review. Brazillian Journal of Oral Science, 1, 7

9. van der Glas HW [1992] A selection model to estimate the interaction between food particles and the post-canine teeth in human mastication. Journal of Theoretical Biology, 155, 103

10. Lillford PJ [2000] The materials science of eating and food breakdown. MRS Bulletin, 25, 38 

Comments

L. Roy Xu's picture

Dear Dr. Goh,

 You proposed a very interesting topic. I had similar experience and try to use my expertise in fatigue and fracture, and composite materials to develop better dental materials. Yes, you can use “super glue” to stick my filling back. But you should make sure this glue is not harmful to your health. Probably you have to use the glue, or cement etc from dental offices again.  

We are developing new nanocomposites to improve bonding and fracture resistance. But we need 5-10 years to use these materials in dental practice--- too long.  

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