3 Reasons for Bad Smell Coming From Crowns and Bridges

Do you notice that sometimes even if you brush and floss every day, there is an awkward bad smell coming from your mouth (sometimes even smells like poop or rotten food), and you have no idea where or how it happens? Actually, it can be caused by different reasons, but believe it or not, the crown or bridge inside your mouth could be one of the possible reasons too!

A dental crown, also known as a dental cap, is a prosthesis used to cover a tooth. The purpose of the crown is to protect a weakened tooth that is prone to fracture. For example, a tooth with a large cavity or a tooth which has undergone root canal treatment may need to be protected by a crown.

A dental bridge is a prosthesis used to replace the missing tooth (teeth). It fills the gap with an artificial tooth and is joined to the adjacent crowned natural teeth, which are known as the abutment teeth.

Crowns and bridges stick to the natural teeth with the help of dental cement or glue and these make them ‘fixed’ to the teeth.

How do these crowns and bridges cause bad smell to your mouth? Let us look at the 3 general reasons for it.

Three reasons for having bad smell from crown and bridge

The main cause of having a bad smell from the crown or bridge is due to the bacterial growth and ongoing infection surrounding or under the prosthesis.

So, how does the bacteria or infection arise inside or surround the tooth that is sealed with crown and bridge? Basically, there are 3 ways:

Gum-related/ hygienic problem

Proper oral hygiene is equally important for the tooth-covered with crown or bridge. Inadequate or improper cleaning causes the dental plaque to accumulate around the covered tooth or the surrounding gum, leading to tooth decay ^[1] or gum inflammation (gingivitis). Both of these may cause you to have bad breath.

Tooth-related problem

Yes, tooth decay can happen under a crown or bridge, even if the tooth is root canal treated. In fact, the tooth decay under a crown or bridge is not uncommon.It usually occurs at the margin between the tooth and the crown.^[2] It is also caused by the deposits of bacteria and that’s why it can turn your fresh breath into bad breath.

Inadequate cleaning or improper prosthesis design could be the underlying causes of the tooth decay. Early detection is especially important here to prevent failure of the crown or bridge together with the underlying tooth.

This condition is very similar to the tooth decay that happens under a filling. Click here to know more the signs of cavity under the filling or dental prosthesis.

Prosthesis problem: 

Sometimes, the dental prostheses like crown and bridge may have some defects which can impede proper cleaning of the underlying tooth. The dental plaque may start accumulating around the tooth, causes gum disease and tooth decay, which in turn result in bad breath. ^[3]

These prosthesis-related problems include but are not limited to ^[1]:

• Faulty design
• A long-span bridge
• Loose prosthesis ^[4]
• Surface defects 
• Gap between tooth structure and the prosthesis ^[2]
• Fractured/ cracked prosthesis

Solutions/ Treatments for bad smell from crown or bridge

Bad breath can be caused by many reasons. Finding out the real reason is important because the smell is giving you the sign that something has gone wrong.

To get rid of it, you have to know the reason. Covering it with a minty mouthwash or mouth spray will just leave the problem to reappear more seriously in the future.

Below are the two main things you can do to solve the problem:

1. Visit your dentist immediately

Visit your dentist to find out the exact cause of the bad breath. A prompt appointment is the key to understand the real reason, and in the case of bad smell originating from the prosthesis, to preserve the tooth structure and the crown or bridge for as long as possible.  The dentist will check your mouth and the prosthesis visually and may also need to take an x-ray.

The treatment delivered depends on the root cause:

a. Gum inflammation (gingivitis or periodontitis): 

There is a range of treatment options to treat gum inflammation based on the severity. It can start from the most important method which is oral self-care, professional cleaning, to the more complicated treatments such as deep cleaning and surgical treatment. 

b. Tooth decay:

Tooth decay can be solved by simple filling or root canal treatment (if the center of the tooth called pulp is infected). Depending on the damage from the decay, the existing crown or bridge may or may not need to be replaced with a new one.

However, if the damage is too severe to be repaired, the tooth has to be removed. In this case, a new bridge or other type of dental prosthesis is necessary to replace the old crown or bridge.

c. Prosthesis-related problem: 

Generally, the ‘irreversible’ errors such as faulty design, long-span bridge, or severely broken prosthesis may require the dentist to remove the existing old prosthesis. A newly designed crown or bridge would be made. 

On the other hand, if the problem is because of ‘reversible’ errors like rough surface, loose prosthesis and minor gap between tooth structure and prosthesis^[4], it is possible to keep the existing prosthesis with necessary dental adjustments.

Bear in mind that the dentist will judge the severity of the defects and whether they can be solved without having to make a new prothesis based on the condition.

2. Oral self-care practices

You can prevent the crowned teeth from decay by taking good care of the hygiene. In fact, the level of oral hygiene is the main factor affecting the condition and the lifespan of a bridge or crown. Here are some ways to take care of your prosthesis at home:

a. Correct tooth brushing at least twice a day.
b. Proper flossing between the crown, bridge and natural teeth by using an interdental floss or interdental brush.

c. Using Superfloss or floss threader to clean the dental plaque or food particles that stuck under the artificial tooth (also known as pontic) of a dental bridge.
d. Visiting dentist regularly every 3-6 months according to the advice given by your dentist. 

What can happen if you delay treatment?

A bad smell coming from the prothesis could already mean a sign of delayed treatment. If it is left for a longer time, it could cause further damage to the gum, the teeth, or the prosthesis, depending on the cause of the problem. The following are some possible consequences of delayed treatment:

1. Gum infection destroying the bone and tissues supporting the teeth. Teeth may become loose and eventually need to be removed if left untreated.
2. Pain due to tooth infection or gum infection.
3. Extensive decay leading to tooth breakdown that requires removal of the prosthesis and the tooth.
4. Shorter lifespan of the prosthesis.

Reference

1. Naz, A., Musharraf, H., Jawad, A., Zia, K., Kumar, B. and Lone, M., 2020. Assessment of Failure of Prosthesis in Fixed Prosthodontics Among Patients Reporting To A Teaching Dental Hospital of Karachi. Journal of the Pakistan Dental Association, 29(03), pp.105-109.
2. Halawani, S. and Al-Harbi, S., 2017. Marginal adaptation of fixed prosthodontics. International Journal of Medicine in Developing Countries, pp.78-84.
3. Zigurs G, Vidzis A, Brinkmane A. Halitosis manifestation and prevention means for patients with fixed teeth dentures. Stomatologija. 2005;7(1):3-6. PMID: 16254469.
4. Le T, Le T. Symptoms of a Loose Dental Bridge & Steps to Fix it [Internet]. Bunker Hill Dentistry. 2021 [cited 26 April 2021]. Link.
5. Miller DB. A new protocol and standard of care for managing open crown margins. Gen Dent. 2019 Mar-Apr;67(2):19-22. PMID: 30875302.