How are cavities filled?

What is a cavity? 

A cavity is a hole in the tooth caused by tooth decay, which is caused by acid secreted from mouth bacteria that dissolves the outer layers of the tooth, enamel, and dentin, resulting in a hole. Unless treated, mouth bacteria will continue to destroy healthy tooth structures, and the cavity will continue to grow until the decay is removed and the tooth is restored with a filling.

What to expect when getting a cavity filled

Usually, you have already had an exam, and your dentist will have taken and reviewed x-rays, discussed the treatment plan with you, and explained your filling material options. Never be afraid to ask questions. 

Your dentist will set aside the appropriate amount of time to comfortably finish the procedure. Its duration will be based on how many teeth are being filled, the size of the cavity, the type of filling material being used, and if there are any special considerations, such as the need for sedation. If you have a single tooth restored, and your cavity is not overly large or complicated, then your appointment will typically last between 30 minutes to one hour.

How are cavities filled?

The dentist will numb the area with a local anesthetic and ensure it takes effect before beginning the procedure. This should keep you comfortable and pain-free. The decay is removed using a dental drill or laser, and then the edges of the cavity are prepared so a healthy tooth structure surrounds the hole. The filling material is then placed and shaped to restore the tooth to good health and function.

What are cavities filled with?

Cavities can be filled with different types of materials. The primary materials used are: 


This is the most common type of material used for dental fillings. Composite is made of resin filled with quartz or ceramic particles that make a tooth-colored, hard, durable, long-lasting filling. Composites bond directly to the tooth and are best for small to medium-sized fillings.


Amalgam, a metallic filling made by mixing silver, mercury, and other trace metals into an extremely hard, durable filling, was the standard filling material for more than 100 years. It is more durable than composite. While amalgam was once the most common material used due to its ease of placement, affordability, and durability, it is no longer as popular due to its silver/gray appearance and concern over the use of mercury.


When the decay is more extensive, and significant tooth structure has been lost, composite and amalgam fillings are not durable enough to withstand long-term stress. In these cases, your dentist will usually recommend a crown. Crowns require multiple appointments, are fabricated in a dental laboratory, and are more expensive than direct-placed fillings.

How long does numbness occur after a dental filling?

After the procedure, you may remain numb for some time. The length of time depends on the person and the scope of the procedure. Your dentist will typically give you instructions after the procedure as to how long to be careful with chewing and when the numbness will go away.

What are the potential complications with cavity fillings?


A dental filling can sometimes chip or pull away from the tooth, causing a small opening where bacteria can enter, re-infect the tooth, and grow. If your filled tooth suddenly feels rough, you experience cold sensitivity or pain, or your dental floss tears when you floss over a filling between your teeth, then your tooth may be reinfected with decay, and you should contact your dentist. This usually doesn’t occur until years after a filling has been placed. This may occur sooner if the filling is damaged. If you receive regular dental check-ups, then these problems can usually be caught early.


Your teeth and fillings experience stress in a normal life of chewing, grinding, and temperature extremes from food and beverages. You may also just bite down on something hard or get hit in the mouth while playing sports. Consequently, a filling can break, fall out, or crack. If you notice damage to your filling(s), immediately contact your dentist.

How long will fillings last?

Fillings don’t last forever, but a well-placed composite or amalgam filling can last 10 years or longer. There is a wide range of risk factors that determine filling longevity. The size and location of the filling and the type of filling material are important, but patient factors play a major role as well, including chewing habits, daily oral hygiene, and regular dental checkups. The dentist’s determination of when the filling has failed and should be replaced may also affect the longevity of fillings.  


1.  What Is the Procedure for Filling a Cavity? (2020, July 27) from 

2. Cavity Fillings: What to Expect, Types & Potential Problems. (n.d.) from  

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