Why It Smells Bad When You Floss (and What to Do About It)

If you notice a bad smell while flossing your teeth, it is usually a sign that something is off beneath the surface. The odor often comes from bacteria, trapped food, or early tooth decay being disturbed during the flossing process.

In this blog, we will explain the most common reasons for the bad smell, what it could mean for your oral health, and what you can do to fix it. At Power Road Dental Care in Mesa, AZ, we help patients treat the root of the problem with professional cleanings and personalized care.

The Main Causes of Bad Smell When Flossing

A bad smell from flossing almost always points to trapped food particles, odor-causing bacteria, or active decay.

1. Food Debris Stuck Between Teeth

Food particles, especially proteins and carbohydrates, break down between the teeth when left too long.

• Smell comes from bacterial decomposition: When anaerobic bacteria digest trapped food, they release sulfur compounds that produce a foul smell or unpleasant odor.
• Common with tight or misaligned teeth: These areas trap leftover food particles and allow accumulation of bacteria in hard-to-reach areas.

2. Plaque Buildup and Poor Oral Hygiene

If you don’t floss regularly, plaque buildup hardens into tartar, trapping odor-causing bacteria under the gums.

• Plaque is easy to overlook but harmful: It builds up along the gumline and between teeth, trapping bacteria that release sulfur compounds linked to bad breath and odor when flossing.
• Skipping daily flossing allows bacteria to build up: A bad smell during flossing is often a sign of trapped plaque and poor oral hygiene habits.

3. Gum Disease or Early Gingivitis

Gums that bleed or feel tender during flossing may already be inflamed due to gingivitis or early periodontal disease.

• Bacteria accumulate in gum pockets: These emit volatile sulfur compounds, contributing to a bad taste and unpleasant smell in the oral cavity.
• Foul smell is an early sign: If untreated, it can advance into full gum disease and lead to gum recession and tooth loss.

4. Tooth Decay Between Teeth

Cavities between teeth are harder to detect until they become severe.

• Floss can disturb areas of hidden decay: An unpleasant odor or bad taste after flossing may be caused by bacterial activity in decayed tooth structure between teeth.
• Lingering bad taste is a warning sign: A metallic or foul taste may indicate hidden decay, infection, or another underlying dental issue.

5. Old Dental Work or Faulty Restorations

Worn or leaking fillings and crowns can trap bacteria, food particles, and plaque in hard-to-clean areas.

• Decay can form beneath the surface: Flossing may disturb these areas, releasing a strong, unpleasant odor caused by bacterial buildup.
• Tight spaces or poor margins make it worse: If floss cannot glide smoothly, bacteria and debris may collect around the restoration, contributing to the bad smell.

How to Maintain a Cleaner, Healthier Mouth

If flossing causes a foul odor, it is a sign that bacteria or buildup needs to be removed. The steps below can help you improve your oral hygiene and eliminate the smell.

1. Floss Daily and Use Proper Technique

Gently guide floss below the gumline and wrap around each tooth in a C-shape. Do not snap the floss!

• Use a fresh section of floss for each tooth.
• Focus on both sides of each gap, not just one.
• Switch to a water flosser if traditional floss is difficult.

2. Brush Thoroughly

Use a soft-bristled toothbrush and angle it toward the gumline.

• Brush for two minutes, twice daily. Focus on each quadrant of the mouth (30 seconds in each quadrant). 
• Consider purchasing an electric toothbrush for a more thorough clean. 

3. Clean Your Tongue

Bacteria on the tongue contribute heavily to bad breath.

• Use a tongue scraper every time you brush.
• Scrap the tongue before brushing and make sure to rinse well after scraping. Go back as far as you can on the tongue (bacteria like to hide way at the back!) Smooth edge tongue scrapers are more effective than serrated edge tongue scrapers. And your toothbrush is not effective at scraping anything off your tongue.

4. Use an Antibacterial Mouthwash

Many people reach for mouthwash when they have bad breath, but this can actually contribute to bad breath! Mouthwash isn’t recommended for everyone, so make sure you ask your dentist if it is right for you. 

5. Schedule a Professional Dental Cleaning

Tartar and plaque buildup cannot be removed with brushing or flossing alone. While a good oral hygiene routine helps prevent buildup, professional cleanings are still essential.

During your visit, your dental team will remove hardened deposits, polish your teeth, and check for early signs of gum disease, cavities, or other issues that may not be visible at home.

Schedule a Professional Cleaning in Mesa, AZ

If it has been awhile since your last cleaning and exam, or if you are searching for a dentist in the East Valley accepting new patients, you’re in the right place! 

If you are in the Phoenix East Valley, book an appointment at our dental office in Mesa, AZ, call (480) 664-1438 or visit us at 2500 South Power Road, Suite 102, Mesa, AZ.

In the meantime, check out Our Services and our Blog for advice on maintaining a healthy smile between visits and preventing common dental concerns.

FAQs