Have you been to Ladakh in India? The aerial view of the hills from the top of the Konze La at 4900 m looks mesmerizing!
If you minutely observe, this aerial view resembles the surface of your back tooth!
Imagine if one has to dig out a well on this hill to fetch a pail of water! Every Jack and Jill will have a hard time. Right?
In this way, tooth-eating bacteria are powerful. They can eat away the hardest tissue on the human body – the tooth enamel!
Incredible! Isn’t it?
In the deep and shallow grooves on the back tooth surface, these bacteria slowly dig out enamel and penetrate beyond to reach the dentin. It is when you feel tingling sensitivity. And that calls for a dentist’s intervention to do a tooth filling!
Tooth-filling Materials and Your Gen-X Dentist
In an era of advanced active biomaterials, dentists have moved from amalgam (black) tooth fillings to white tooth fillings. Chemically, these white tooth filling materials are resins, popularly called composite resins.
The cavitated tooth restored with composite resin looks like an original tooth. So, this is good news!
Well, the sweetness or bitterness of a dentist-patient relationship depends primarily on the success or the failure of a dental procedure. It is just like a blooming love story! A chance of a blame game always exists!
An aesthetic tooth filling may fail despite the utmost care taken during the procedure. Now whom to blame? Commonly, the scenario is the patient starts blaming the dentist and vice versa.
Here is one probable solution that might help stop the blame game both ways!
A piece of good news for dentists!
A Fascinating Science That Happened In 2017
A group of scientists at the Department of Oral Biology, University of Pittsburgh School of Dental Medicine, Pittsburgh, PA, United States, performed an interesting experiment to find genetic reasons behind failed tooth fillings.
Mineralized dentin of our tooth contains special enzymes matrix metalloproteinases (MMPs). Dentin MMPs are exposed and activated while restoring a tooth with composite resin. They degrade type I collagen.
The Study Rationale And Incredible Results
The scientists selected four MMP genes – MMP2, MMP3, MMP8, and MMP9. They used a genomic approach for 92 samples to study genetic variation (20 single nucleotide polymorphisms; SNPs) in these four genes.
They found that MMP2 and one of its genetic
variants were responsible for the failure of the
composite resin tooth fillings!
The Science Behind The Scene
Matrix metalloproteinase 2 (MMP2) is also known as gelatinase A. It is a membrane-bound protein which helps in healthy tissue maintenance. It helps degrade old proteins and form new proteins (extracellular matrix turnover).
MMP2 encodes an enzyme that degrades type IV collagen. In teeth, type IV collagen is present along the dental–enamel junction (DEJ).
The integrity of DEJ-collagen type IV association is essential for the stability of teeth and preventing cracks due to mechanical forces of chewing.
Thus, the mechanism underlying the genetic influence of MMP2 in the failure of extensive composite resin restorations involves the degradation of type IV collagen.
MMP2 gelatinolytic activity probably occurs both in partially demineralized dentin at the bottom of caries lesions and on the tooth surface treated with self-etch adhesives during a white filling.
With time, this gelatinolytic activity weakens the bond between the material and the remaining dentin structure. It leads to failure of the restoration (composite resin tooth filling).
Individuals who carry a particular gene variant that causes the higher activity of the MMP2 gene are at a higher risk for a composite resin tooth-filling failure.
Thus, the results of this study support that you can blame your genes and not your dentist for a broken white filling in your back tooth!
What Is The Takeaway Here?
The overall takeaway of this fascinating study is that carrying specific MMP alleles increases the degradation of the collagen fibrils at the resin–dentin-bonded interfaces, which leads to clinical failure of composite restorations.
Food For Thought
To all enthusiasts in biomedicine, biomaterial research, genomics, genetics and clinical dental research, here are a few questions to ponder…
- Could a genomic study be extended to a population to find MMP2 gene variants related to dental filling failures?
- Can clinical dental researchers conduct more explorations for various other biomaterials and decipher the root cause of failures?
- Can a population-specific chair-side test be developed to determine the MMP2 gene variant in a patient before performing a tooth filling procedure to understand the risks of success or failure?