Why Do I Need a Filling?

A filling is one of the most basic procedures that a dentist will perform on a patient. Most people have had one or two in their lives, myself included, but why does one need them? Let’s look.

To understand the need for a filling, we need to understand a little bit about how the tooth is put together. Without getting too technical or going into too much detail, the tooth is comprised of three layers, and amazingly enough, so is a peanut M&M. Both have a hard outer shell, a softer middle layer, and house the most important part in the center. If we understand these layers, then we can better understand when fillings are needed and why.

Layer 1 – The Hard Candy Shell

The candy shell on the peanut M&M does an important job to keep the candy from melting in your mouth and not in your hand. The outer layer of the tooth is called Enamel, it is the hardest material in the human body, and does much of the same task, it protects the more delicate structures that lie below it.

Layer 2 – Chocolate

The chocolate in the M&M makes up the bulk of the candy and is softer than the candy shell. The second layer of the tooth follows the same pattern, it is called Dentin and is much softer than Enamel and it too makes up the majority of the tooth.

Layer 3 – Peanut

The peanut lays at the heart of the M&M and is the coveted prize possession. One could argue the most important part of the candy (if not you would just buy regular M&Ms). At the core of the tooth lies the Pulp Chamber, a collection of nerves and blood vessels, the heart of the tooth, and the source of the tooth’s vitality.

So how does this tie into cavities? When sugars are consumed a process called Demineralization begins. It’s a complex procedure, but in essence if enough sugars are consumed and or/not removed the tooth begins to become soft and a cavity begins to form.

Using the M&M layers as an example, if the outer shell begins to soften, the process can still be reversed. You may have heard a dentist say that they want to “watch” a tooth, or “keep and eye” on it. As long as this process doesn’t go beyond the hard outer shell, then often the process can be reversed.

Once the outer shell is broken though, and the chocolate is compromised, now we have a cavity. At this point the dentist will need to go in and remove the softened tooth replace it. That replacement is a filling, and that softened tooth is a cavity. Remember, the chocolate, or Dentin, makes up the majority of the tooth, so cavities and fillings can vary greatly in size.

Now, if the cavity passes through all the chocolate, and reaches the peanut, at this point a filling will not cut it. Once the cavity is through Dentin and into the Pulp Chamber, or sometimes just close to the Pulp Chamber, a Root Canal is needed, or worse, the tooth needs to be extracted and an implant placed.

So the next time you are snacking on a handful of Peanut M&Ms, pause and think about the layers of that M&M and of your teeth, and why we need fillings. And then go and brush to avoid the process yourself.

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