What is a cavity in a tooth?
A cavity in a tooth is the visible result of tooth decay (dental caries): bacteria break down the outer and then the inner layers of the tooth. At first, decay may look like a white or brown spot on the surface; as it progresses, a hole forms that the dentist can detect. This page is about that hole and how it is repaired; the disease itself, its causes and its prevention are covered on the tooth decay page.
How a cavity is treated depends on how deep it is, from a filling to a root canal and a crown: see the table of stages and the treatment section below.
What does a cavity look like, and what are the symptoms?
What a cavity looks like depends on its stage. Early on, a white or brown spot may appear with no visible hole. As decay advances, a small pit or hole appears; at an advanced stage the hole can be large, dark and clearly visible, and you may feel it with your tongue.
Symptoms of a hole in a tooth include sensitivity to hot, cold or sweet foods, pain when chewing, spontaneous pain with no trigger, and lasting discomfort around the affected tooth.
A cavity is not always painful, especially at first. That is why regular dental visits are the most effective way to find cavities early.
| Stage | What it looks like | What you feel | Treatment |
|---|---|---|---|
| Early decay in the enamel | White or brown spot, no hole | Usually no symptoms | Fluoride and good hygiene can stop the process |
| Hole in the enamel | Small pit or hole | Usually no pain | Composite filling |
| Decay in the dentin | Larger, darker hole you may feel with your tongue | Sensitivity to sweet, hot or cold | Filling, inlay or onlay; pulp capping for a deep hole |
| Decay in the pulp | Large dark hole, sometimes a broken tooth | Spontaneous pain or pain when chewing, sometimes swelling | Root canal and crown, sometimes extraction |
At the clinic, cavities are found through a careful visual exam, a fine dental explorer that checks the texture of the tooth, and X-rays when needed. The images also help show you where the hole is and how much damage it has done.
Where cavities form: types of holes in teeth
Cavities are classified by where they develop, as the table shows. Root cavities are more common in older adults with gum recession: roots are covered by cementum, a relatively thin layer that resists acid less well than enamel, so they decay more easily. A cracked tooth is not a cavity, but bacteria can enter the crack and cause decay there.
| Type of cavity | Where it forms | What leads to it |
|---|---|---|
| Pit and fissure | Chewing surfaces of molars and premolars | Bacteria and food trapped in natural grooves |
| Between teeth | Where two teeth touch | Areas a regular toothbrush does not reach |
| Cervical | Along the gumline | Gum recession or poor oral hygiene |
| Root | Exposed roots | Gum recession |
| Secondary | Next to or under existing fillings | Microscopic leakage |
Treatment is adapted to the type of cavity, its position, its depth and its cause. Small to medium cavities are usually restored with composite; more advanced ones may need metal-free zirconia or E-MAX restorations.
How a cavity deepens, layer by layer
1. The enamel
A cavity develops through a gradual loss of minerals caused by acids that mouth bacteria produce from sugars and starches. Over time, this creates tiny gaps in the enamel that widen and deepen toward the inner layers of the tooth.
2. The dentin
Once through the enamel, decay reaches the dentin, a softer tissue that resists acid less well, so the cavity grows faster. Dentin contains microscopic tubules leading to the nerve, so a cavity at this depth often causes pain and sensitivity to hot, cold, sweet or sour foods.
3. The pulp
When the cavity reaches the pulp, it causes infection and inflammation. Severe pain, extreme sensitivity, swelling and other signs of pulpitis can appear. At this stage a root canal is usually needed, or in severe cases an extraction, which is why a hole should be treated before it gets this deep. When decay has destroyed a large part of the tooth, see rotten teeth.
How does the dentist find cavities?
The clinical exam uses a dental mirror and instruments to check every surface, with special attention to grooves, chewing surfaces and the spaces between teeth. A gentle explorer helps assess how hard the enamel is and find soft areas that indicate demineralization or active decay.
X-rays are essential for cavities that cannot be seen. Bitewing X-rays are particularly effective for decay between teeth. X-rays are taken only when the information is expected to affect treatment, at the lowest possible dose (the ALARA principle).
Complementary technologies such as laser fluorescence can help spot early demineralization, but they do not replace the clinical exam and X-rays; the clinic does not use lasers.
Cavity treatment: how to fix a hole in a tooth
Treatment depends on the size, position and depth of the cavity.
Composite filling
For small to medium cavities, a tooth-colored composite filling is usually the treatment of choice. The composite is matched to the shade of the tooth, so the filling is barely visible, and preparing the cavity removes very little healthy tooth.
Inlay or onlay
When a larger restoration is needed, especially in molars, an inlay or onlay is a suitable option. Made in the clinic's lab from ceramic or zirconia, often the same day, it fits the cavity precisely and supports the tooth. An inlay fills the grooves of the chewing surface; an onlay also covers one or more cusps.
Pulp capping
When a deep cavity comes close to the pulp, pulp capping can protect the vitality of the tooth and may avoid a root canal. A bioactive material placed over the area encourages a new protective layer of dentin; the tooth is then restored with a filling or another restoration.
When a cavity has destroyed the tooth to the point that it had to be extracted, the missing tooth can be replaced with a dental implant or a bridge, depending on the bone and the neighboring teeth.
Examination, treatment plan and price quote
detailed and personalized
During the consultation, Dr Haim Aseriel examines your teeth, explains all the options and gives you a transparent price quote, with no obligation. The clinic is at 12 HaTnufa Street, Jerusalem.
Are cavities common, and who gets them?
Cavities are among the most common oral health problems worldwide. In the United States, about 90% of adults aged 20 to 64 have had decay in their permanent teeth, and about one in five has untreated decay (Dye B et al., 2015; CDC, 2024). Most cavities can nevertheless be prevented with good oral hygiene and healthy habits.
Anyone can get cavities, but children and teenagers are a high-risk group because of frequent sweets and sweetened drinks combined with imperfect hygiene (see cavities in kids). Other risk factors include a diet rich in simple carbohydrates, too little fluoride, reduced saliva and some chronic conditions.
1 in 5
US adults aged 20-64 has untreated decay (CDC)
Adults with gum recession are prone to cavities on exposed roots, and old fillings or poorly fitting crowns can leave gaps where secondary decay starts.
Some medicines cause dry mouth, which raises the risk, because saliva rinses away food and neutralizes acids. Frequent snacking, especially on simple carbohydrates, gives bacteria more opportunities to attack enamel.
How to avoid new holes in your teeth
Brushing twice a day with fluoride toothpaste and cleaning between your teeth daily are the first line of defense. Fluoride strengthens enamel against the acids produced by bacteria. Detailed prevention advice is on the tooth decay page.
Limit sugar, especially between meals
Cutting down on sugary foods and drinks, particularly sticky ones or those that stay in the mouth, reduces the risk. Drinking water after meals helps rinse away food and lower acidity.
Sealants and professional fluoride
Regular check-ups and professional cleaning catch problems early. Sealants protect deep grooves on back teeth, and professional fluoride treatments strengthen enamel.
At the clinic, at 12 HaTnufa Street in Talpiot, south Jerusalem, the dentist assesses the depth and position of the cavity and explains the options in English, with a written quote. Opening hours: Sun 8:00–19:00 · Mon 9:00–19:00 · Tue–Wed 9:00–21:00 · Thu 8:30–21:00 · Fri 8:00–14:00.
Hole in a tooth: frequently asked questions
No. Once a hole has formed in the enamel or dentin, it does not close by itself and the dentist needs to restore it. Only at the earliest stage, when there is a white or brown spot without a visible hole, can decay sometimes be stopped with remineralizing treatment such as fluoride applied by the dentist, together with brushing with fluoride toothpaste and cutting down on sugar.
No. In its early stages a cavity usually causes no pain, which is why regular check-ups are the main way to find it early. Pain usually appears once decay reaches the dentin, as sensitivity to sweet, hot or cold foods, and later, as it approaches the pulp, as spontaneous pain or pain when chewing.
An untreated cavity keeps getting deeper: decay goes through the dentin and reaches the pulp, where it can cause inflammation, infection and an abscess. More complex treatment is then needed, such as a root canal and a crown, and sometimes an extraction. Fever, swelling spreading to the eye or neck, or difficulty swallowing or breathing require going to the emergency room immediately.
Sources
- Dye B et al., NCHS Data Brief, 2015 – View the study
- Centers for Disease Control and Prevention, 2024 Oral Health Surveillance Report – View the page
- American Dental Association / U.S. Food and Drug Administration, The Selection of Patients for Dental Radiographic Examinations – View the page
- National Institute of Dental and Craniofacial Research, Tooth Decay, 2025 – View source
