Woman undergo dental scaling treatment

The Real Reasons You Might Need a Root Canal After a Filling

Fillings are supposed to fix cavities. So why is your dentist recommending a root canal?

There are many reasons why cavities can form under the fillings, but a few of them are more common than others.

Reason #1: Your old filling was deep and the cavity made it deeper

Before dentistry got to where it is today, dentists relied on a method of filling teeth called “extension for prevention.” This means that when they treated a small cavity, they were taught to make the filling even wider to prevent other areas from being affected. They also had to make the filling deep enough to withstand the materials they used then, specifically the silver amalgams.

Now your dentist knows better. They only treat the area that needs treatment using materials that are strong, even when they’re thin.

Reason #2: Your old filling actually damaged your tooth

The old silver fillings (also known as amalgam, metal, or mercury fillings) expand and contract when you eat and drink hot and cold things. This happens inside the tight space the filling is crammed into, creating microscopic cracks that can’t be seen with a set of eyes or even an x-ray. Over time, those cranks get bigger and the filling no longer fits against the tooth properly. This allows food and plaque to get inside and infect your tooth. In most cases, your dentist can remove all of the bacteria from inside the tooth when they replace the filling, but they can’t see it all, and it can kill the nerve of the tooth.

Reason #3: Good old-fashioned wear and tear

Like any other part of your body, teeth are susceptible to wear and tear.

If you’ve made it to your 30s or 40s without having any cavities, the chances of you losing your teeth (other than from an accident or lack of care) are slim. But on the other hand, if you’ve had the same tooth treated more than once, there is a risk that the treatment will be more than the nerve of the tooth can take, and it will eventually die. This is especially common in the back teeth where the chewing pressure is the heaviest, which further damages the nerves in your teeth.

Reason #4: You grind your teeth

Your teeth touch each other between 2,000-3,000 times per day when doing simple things like eating and swallowing. If you grind your teeth, that number goes up significantly. If you clench your teeth, not only are they touching more, they’re touching at a force that is killing the nerves of your teeth.

There is a common misconception that you only clench or grind your teeth while you’re sleeping, but studies show that patients who clench or grind do it all day long. This means that the night guard your dentist made for you to wear while you sleep doesn’t actually solve the problem.

So what is the problem and how can you solve it?

If your teeth don’t touch evenly everywhere when you close your mouth, your muscles will work your jaw to “rub out” the spot or spots that are affecting your bite. The problem with that is that once one area is worn away, a different area is uneven, so you grind more. The cycle repeats itself until the teeth are flat and nothing is in the way.

Sounds like an ideal solution, right?

Not so fast. Before the teeth become flat, a lot of pressure is placed on the teeth. Those with larger fillings, especially in the back, become so injured that the nerve of the tooth dies.

There are a number of ways to correct an uneven bite, including orthodontic treatment (braces) or placing crowns on some or all of the teeth to build biting surfaces that meet each other properly and to add back all of the “tooth” that was ground away to begin with. This can be a pretty extensive procedure, but the goal is to strengthen teeth that have suffered years of damage and prevent any further damage caused by uneven wear and tear.

If your dentist has told you that you need a root canal even though you’ve already had a filling, they’re not doing it because they want to. They’re doing it to be proactive when it comes to managing your oral health.

If you think it’s been a while since you’ve treated your teeth to some TLC, reach out to Dr. Andrea Stevens.

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