The 5 Stages of Tooth Decay

• June 19, 2025
• Dr. Catherine-Anne Walsh

Tooth decay doesn’t happen overnight—it develops in stages, often starting without any pain or visible signs. By understanding the stages of tooth decay, you can take action early and prevent minor dental issues from turning into major problems.

At The Dentist at 70 Pitt Street, we believe in early detection, prevention, and minimally invasive treatment. In this blog, we’ll explain what tooth decay is, walk you through each stage, and show you how to stop tooth decay before it leads to permanent damage.

What Is Tooth Decay?

Tooth decay is the breakdown of your tooth’s structure caused by bacteria that feed on sugars and starches in your diet. As these bacteria digest food particles, they produce acid that erodes the tooth enamel—the outer protective layer. Over time, this can lead to cavities, pain, and infection if not treated.

There are several types of tooth decay, including:

• Enamel decay (surface-level damage)
• Root decay (affecting the exposed root)
• Recurrent decay (around existing fillings or restorations)

The good news? Catching early signs of tooth decay allows for preventive care and often avoids the need for more complex treatments.

The 5 Stages of Tooth Decay

Tooth decay is a progressive condition that develops in distinct phases. Identifying the stages of tooth decay early is key to preserving your natural teeth and avoiding invasive treatments. Here’s what each stage involves and how it affects your oral health.

Stage 1: Demineralisation

This is the earliest stage of tooth decay and often the easiest to miss. After you eat or drink—especially sugary or starchy foods—bacteria in your mouth produce acid that starts attacking the tooth enamel, stripping away essential minerals.

Signs of Stage 1:

• White or chalky spots on the tooth surface
• No pain or sensitivity yet
• Plaque build-up, especially along the gum line

At this stage, tooth decay is reversible. With daily brushing, a fluoride-rich toothpaste, professional fluoride treatments, and dietary changes, you can stop the decay and remineralise your enamel.

Regular check-ups at The Dentist at 70 Pitt Street are crucial for spotting these subtle early signs before they progress.

Stage 2: Enamel Decay

If demineralisation is left unchecked, the enamel begins to physically break down. Small holes—commonly known as cavities—start to form. These cavities are permanent and cannot be reversed without professional treatment.

Signs of Stage 2:

• Mild to moderate sensitivity to hot, cold, or sweet foods
• Visible discoloration (yellow, brown, or black spots)
• Pits or small holes on the tooth surface

This stage of tooth decay requires a dental filling to restore the tooth structure and stop the decay from progressing further. We use gentle, minimally invasive techniques at The Dentist at 70 Pitt Street to treat enamel damage effectively and preserve as much of the natural tooth as possible.

Dentin decay is when the cavity spreads beyond the enamel and reaches the dentin.

Stage 3: Dentin Decay

When the cavity spreads beyond the enamel, it reaches the dentin, the softer layer beneath. Dentin contains microscopic tubules that connect to the inner nerve of the tooth, so decay in this layer often causes noticeable discomfort.

Signs of Stage 3:

• Increased sensitivity to temperature and sweet foods
• Sharp pain when chewing or biting
• A deeper visible cavity

Dentin decay progresses more rapidly than enamel decay due to its softer structure. At this point, delaying treatment increases the risk of nerve involvement and infection. Your dentist may recommend a larger filling, inlay/onlay, or a crown to restore the tooth.

Stage 4: Pulp Damage

Once decay reaches the pulp, the innermost part of the tooth, it can cause severe inflammation and infection. The pulp contains blood vessels and nerves, so damage here can result in intense pain and swelling.

Signs of Stage 4:

• Constant, throbbing pain that may radiate to the jaw or ear
• Swelling or tenderness in the gums
• Sensitivity that lingers after eating or drinking

This stage often requires root canal therapy to remove the infected tissue and save the tooth. If left untreated, the infection can spread to surrounding tissues and even into the bloodstream. The team at The Dentist at 70 Pitt Street offers root canal treatments using the latest techniques to help preserve your tooth and alleviate discomfort.

Stage 5: Abscess Formation

An untreated infection in the pulp can result in a dental abscess—a pocket of pus caused by bacterial infection. This is the most serious stage of tooth decay and can have widespread effects on your oral and general health.

Signs of Stage 5:

• Severe, constant pain
• Swelling in the gums, jaw, or face
• Fever or swollen lymph nodes
• A bad taste in the mouth or pus discharge

This is a dental emergency. Without prompt care, the infection can lead to tooth loss, bone damage, and systemic illness. Depending on the severity, treatment may involve drainage of the abscess, root canal therapy, or extraction. We prioritise urgent care at The Dentist at 70 Pitt Street to manage advanced decay safely and promptly.

To stop tooth decay, there are a few things you’d need to do such as flossing daily and brushing your teeth twice a day.

How to Stop Tooth Decay

Tooth decay is preventable, especially in the early stages. Here’s how to stop it before it progresses:

• Brush twice a day with fluoride toothpaste.
• Floss daily to remove plaque between teeth.
• Avoid sugary snacks and acidic drinks.
• Drink water after meals.
• Schedule regular check-ups and cleans at The Dentist at 70 Pitt Street—our preventive care services are designed to stop tooth decay before it starts.

How to contact us at our Sydney CBD clinic

• Day Time +61292333399
• After Hours 0406986909
• Email Us: info@thedentist.net.au

1/70 Pitt St, Sydney NSW 2000, Australia
Mon & Thu: 8am – 7pm
Tue, Wed & Fri: 8am – 5pm
Saturday: 8am – 1pm
Sunday: closed

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FAQs

What does tooth decay look like?

Early signs of tooth decay may appear as white or brown spots on the enamel. As decay progresses, you might see small pits, holes, or dark spots. Advanced stages can include visible cavities or even tooth fractures.

Is tooth decay reversible?

Yes, tooth decay is reversible—but only in the earliest stage (demineralisation). With proper oral hygiene and fluoride, enamel can remineralise. Once a cavity forms, however, professional treatment is required.

How long does it take for tooth decay to develop?

The timeline varies depending on your oral hygiene, diet, and risk factors. In some cases, decay can progress over months; in others, it may take years. Catching it early is key to minimising damage.

What’s the difference between the types of tooth decay?

Enamel decay affects the outer layer. Dentin decay spreads deeper, causing more sensitivity. Root decay affects exposed roots, common in people with receding gums. Recurrent decay occurs around existing fillings. Your dentist can identify the specific type and recommend the right treatment.

General Information Disclaimer: The content provided here is for informational purposes only and is not intended as medical advice, diagnosis, or treatment. Always seek the advice of your health professional with any questions you may have regarding a medical condition. The information on this site is general in nature and may not reflect current medical developments or research. Your reliance on any information provided by this site is solely at your own risk.