Cavities are part of life — nine out of ten adults will have one at some point in their life and a quarter of all adults have an untreated cavity.
Getting cavities treated can be scary — but knowing more about the process can help. Dr. David Tarnowski, DMD, a general/cosmetic dentist and owner of a Sandbay Dental, walked Insider through the process.
This is a tooth with a filling. It’s seen through a mirror. In the background is a purple surgical field used by dentists to isolate the area they’re working on.
You can see the tooth has a large filling, a slightly whiter spot going across the top of the tooth.
The filling has chipped. Below it, a cavity has developed. This is the brownish-brown spot between the two adjacent teeth.
First step is to remove the damaged filling.
To get to the cavity, Tarnowski first needs to remove the damaged filling.
He does this by using a diamond burr — the shrill drill that makes the dreaded sound — to scrape back any of the filling material.
Then, he removes the infected tissue using a rounded drill.
To treat the cavity, Tarnowski digs into the tooth, getting rid of any tissue that’s been infected using a round-tipped drill.
Cavities are caused by bacteria on your teeth, gone wild.
The bacteria are always there, and mostly not a problem. When they get hold of food like sugars and starches, they make an acid. That acid dissolves the enamel on the teeth little by little.
That happens every time you eat. But if the attacks are repeated, for instance, if you eat sweets and chips several times in a day, that can become too much for the tooth and create a hole.
The bacteria grow deeper and deeper into the tooth. The infection can get very painful, and be dangerous if untreated.
The only way to treat it is to drill into the tooth to get rid of the infected material.
After stripping off the infected tissue, what’s left is clean tissue from inside the tooth, called dentin.
But it can’t be left exposed like this without any enamel to protect it.
If the dentin is exposed, the teeth will become more sensitive to hot and cold and be more vulnerable to infection.
To help prevent any further damage, Tarnowski needs to fix the tooth with resin.
Once the tooth is clean, it’s time to fill in the gap.
Fixing a tooth is a little like doing construction work: you first need to do some prep to make sure your material will stick to your surface.
The first step is to cover the surface in etchant — that’s the blue liquid above.
An etchant is a mild acid that dissolves the surface of the tooth slightly. This makes the surface a little more porous to help it attach to resin, the material used to fix the tooth.
Then, a bonding agent is added to create a base to build the filling from.
Tarnowski then applies a bonding agent to the tooth using a small brush.
Bonding agents are made of hard resin that seeps into the pores created by the etchant. As the resin hardens, it creates a base from which the filling can be built.
Resin doesn’t like sticking to the surface of the tooth, that’s why you have to treat it with etchant before you bond it. But resin loves sticking to resin, so having this base layer is crucial for the filling to stick.
Now that the bonding agent has hardened, Tarnowski can start repairing the tooth.
Dental resins contain materials that make them go harder if they are exposed to certain types of light.
That’s why your dentist will often reach for a blue light when repairing your teeth. When applied to the resin, it triggers it to harden. Dentists apply the resin layer after layer, hardening it at each stage to rebuild the tooth.