Cavities (dental caries) can show up in many ways — from small dark spots to large areas of breakdown. This article describes common visual signs, why some decay is hidden and how dentists confirm a diagnosis.
This information is for general education and not a diagnosis. If you suspect a cavity or have dental pain, arrange a professional assessment so your dentist can recommend appropriate tests and treatment options.
How cavities develop and what causes visible changes
Cavities form when tooth enamel and dentine are weakened by acids produced by bacteria feeding on sugars and starches. Over time this process can create surface roughness, discolouration or actual holes in the tooth.
Visible changes depend on where decay starts, how fast it progresses and whether the tooth has previous restorations. Early decay may be subtle; advanced decay can cause clear structural loss.
- Initial demineralization — chalky white areas where enamel has begun to break down
- Enamel breakdown — brown or black spots as decay penetrates the tooth surface
- Cavity formation — visible holes or soft areas in enamel or dentine
Common visual signs of a cavity
Some cavities are obvious on the surface, while others start between teeth or under restorations. Visual clues a dentist looks for include changes in colour, texture and tooth structure.
Because appearance alone can be misleading, dentists combine the visual exam with other tests to confirm whether an area is active decay or staining.
- Dark brown or black spots on chewing surfaces or between teeth
- White, chalky patches that may indicate early enamel demineralization
- Visible pits, holes or crumbling edges on a tooth
- Sensitivity or pain when biting or with sweet, hot or cold foods (may accompany visible changes)
When a cavity isn't obvious: diagnostic tools your dentist uses
Not all decay is visible. Decay can develop between teeth or under existing fillings and veneers. Dentists use several diagnostic tools to detect hidden problems before they cause major damage.
Belman Dental Centre uses digital X-rays and the iTero Element 3D scanner to aid diagnosis; these tools can reveal decay that isn’t apparent on visual inspection alone.
- Clinical visual and tactile exam — the dentist inspects and may use a dental explorer carefully
- Bitewing and periapical digital X-rays to show decay between teeth and under restorations
- 3D scanning (iTero Element) to review tooth surfaces and restoration fit
- Other adjuncts such as transillumination or photographic documentation when appropriate
What to do if you think you have a cavity
If you notice discolouration, a pit, sensitivity or a broken filling, book a dental assessment. Treatment options — from fluoride and sealants to fillings, crowns or root canal therapy — depend on the extent of decay and will be decided after an exam and any necessary imaging.
If you have severe pain, swelling, trouble breathing, uncontrolled bleeding or serious facial trauma, seek immediate emergency care (call 911 or go to an emergency department). For non-life‑threatening concerns, contact your dentist to arrange an assessment.
- Avoid self-diagnosing based on photos or brief checks — only a clinical exam can confirm active decay
- Care recommendations, timelines and fees depend on an individual clinical assessment
- Manage short-term sensitivity with over‑the‑counter analgesics per label instructions and avoid very hot or cold foods until seen
Good to Know
Questions About This Topic
Can I tell if I have a cavity just by looking?
Not reliably. While some cavities are visible as dark spots or holes, others begin between teeth or under restorations and won’t be apparent without a clinical exam and imaging such as digital X-rays.
Do cavities always cause pain?
No. Early decay often causes no symptoms. Pain tends to appear as decay reaches the dentine or approaches the nerve. Lack of pain does not mean there is no decay — an exam can detect problems early.
How are cavities treated at the dental office?
Treatment depends on the size and location of the decay and may include preventive measures (fluoride, sealants), composite or amalgam fillings, onlays or crowns, or root canal therapy for deeper infection. Your dentist will recommend appropriate options after assessment.
Recognizing visual signs of cavities helps you seek care earlier, but photos and self-checks can’t replace a professional exam. If you suspect decay, a dentist can use clinical tests and imaging to confirm the diagnosis and discuss personalised treatment.
If you need an assessment in Toronto, contact Belman Dental Centre at 1881 Yonge St., Suite 403, Toronto, Ontario M4S 3C4 or call 1-416-486-1136 to arrange an appointment. Dr. Noah Belman graduated from the University of Toronto Faculty of Dentistry and completed postgraduate training with the Misch Implant Institute, The Pankey Institute and Spear Education.
Educational note: This article provides general information and is not a diagnosis or a substitute for care from a dental professional who has examined you.