Why Are My Teeth Suddenly Sensitive? Causes and What You Can Do

Sensitive teeth happen when the protective enamel on your teeth wears down or your gums pull back, exposing the softer dentin layer underneath. This allows hot, cold, sweet, or acidic triggers to reach the nerve endings inside the tooth and cause pain. About 1 in 4 Australian adults experience dentin hypersensitivity at some point, and it's one of the most common complaints I hear at Bradbury Dental Surgery.

I've been treating sensitive teeth in Campbelltown and the Macarthur region for over 30 years, and the causes range from something as simple as brushing too hard to something that needs attention quickly, like a cracked tooth or advancing gum disease. The good news? Most sensitivity is treatable once you know what's behind it.

This guide covers every common cause, what your specific sensitivity pattern is telling you, home remedies that actually work, and when it's time to come in.

What Causes Sensitive Teeth? The Science in Plain English

Tooth sensitivity (the clinical term is dentin hypersensitivity) comes down to one thing: exposed dentin.

Your teeth have three layers:

• Enamel: the hard, white outer shell that protects the crown of your tooth. It's the hardest substance in the human body, but it can't repair itself once it's gone.

• Dentin: the layer underneath enamel. It's softer, yellowish, and full of thousands of tiny channels called dentinal tubules. Each tubule runs from the outer surface of the dentin straight to the nerve inside the tooth.

• Pulp: the innermost layer containing blood vessels and nerves. Pain signals start here.

  
  

Below the gum line, a thin layer called cementum protects the root surface instead of enamel. It's much thinner and wears away more easily.

When enamel erodes, gums recede, or cementum is lost, those dentinal tubules become exposed. Cold water, hot coffee, a bite of chocolate, even a blast of cold air can travel through the tubules and trigger the nerve. That's the sharp, sudden zing you feel.

Understanding this mechanism matters because the cause of your sensitivity determines the right fix. And different triggers point to different problems.

The Most Common Causes of Tooth Sensitivity

These are the causes I see most often in practice, roughly in order of how frequently they walk through our door:

1. Enamel erosion (acid wear, aggressive brushing)

2. Gum recession

3. Teeth grinding and clenching (bruxism)

4. Cavities and tooth decay

5. Cracked or chipped teeth

6. Sensitivity after dental work (fillings, crowns, cleaning)

7. Teeth whitening

8. Medications and dry mouth

9. Acid reflux (GORD)
   

Enamel Erosion (Acid Wear and Aggressive Brushing)

Enamel erosion is the most common reason teeth become sensitive over time. Once enamel thins or wears away, the dentin underneath is exposed and every temperature change registers as pain.

The main causes of enamel erosion:

• Acidic food and drinks: citrus fruits, soft drinks (including sugar-free ones), sports drinks, wine, fruit juice, vinegar-based dressings. The acid softens enamel, and over time it wears away.
  

• Brushing too hard or using a hard-bristled toothbrush: I see this constantly. Patients who scrub aggressively thinking it means cleaner teeth are actually stripping enamel from the outer surfaces, particularly along the gum line where enamel is thinnest.
  

• Frequent vomiting: conditions like bulimia or severe morning sickness expose teeth to stomach acid repeatedly. The erosion pattern is distinctive and usually affects the inside surfaces of the upper front teeth.
  

• Acid reflux (GORD): this deserves its own section, and I'll cover it below.
  

A 2019 meta-analysis published in the Journal of Dentistry estimated that about 1 in 3 dental patients have some degree of dentin hypersensitivity, with peak prevalence in adults aged 25 to 40. Women are affected slightly more than men.

If you drink a lot of citrus, soda, or sports drinks, try rinsing with plain water afterwards and waiting at least 30 minutes before brushing. Brushing immediately after acid exposure actually accelerates the damage because the enamel is temporarily softened.

Gum Recession

When your gums pull back from the tooth, they expose the root surface. And root surfaces aren't covered by enamel. They're covered by cementum, which is much thinner and wears away faster.

Gum recession is a major cause of sensitivity, especially in patients over 40. The most common reasons gums recede:

• Gum disease (gingivitis progressing to periodontitis)

• Brushing too hard over many years

• Genetics (some people have naturally thinner gum tissue)

• Tobacco use

• Grinding or clenching putting lateral force on teeth
  

The sensitivity from gum recession tends to be worst at the gum line and is usually triggered by cold drinks, cold air, or touching the exposed area while brushing.

If your gums are receding, treating the cause matters more than masking the sensitivity. Our gum disease treatment page covers what's involved, and our post on reversing early gum disease explains what you can do at home alongside professional care.

Teeth Grinding and Clenching (Bruxism)

Grinding wears down enamel from the biting surfaces of your teeth. Clenching puts enormous compressive force on the tooth structure. Both expose dentin over time and make teeth progressively more sensitive.

I see bruxism-related sensitivity a lot in patients who don't realise they grind. The clues: sensitivity across multiple teeth (not just one), worn or flattened biting edges, jaw soreness in the morning, and headaches near the temples.

Our post on how to manage teeth grinding naturally covers the home management side, and a custom occlusal splint can protect your teeth from further damage while you sleep.

Cavities and Tooth Decay

A cavity is a hole in the enamel. Once it breaks through to the dentin, sensitivity spikes. This is often the first sign of a cavity that a patient notices: a tooth that suddenly reacts to sweet food or cold drinks when it didn't before.

Key clue: if one tooth suddenly becomes sensitive and it wasn't before, a cavity or early decay is one of the first things to rule out. Sensitivity to sweets is particularly suggestive of decay because sugar draws fluid through the dentinal tubules, triggering the nerve.

If caught early, a dental filling can seal the dentin and stop the sensitivity. Left too long, the decay reaches the pulp and you're looking at root canal treatment or extraction.

Cracked or Chipped Teeth

A crack in a tooth can be invisible to the naked eye but still let temperature changes and pressure reach the dentin or pulp. Cracked tooth sensitivity has a distinctive pattern: sharp pain when you bite down in a specific way, or when you release the bite. It's often inconsistent, which makes it frustrating for patients.

I see cracked teeth most often in patients who grind, patients with large old fillings (the filling weakens the remaining tooth structure over time), and patients who've bitten into something unexpectedly hard.

Sensitivity After Dental Work (Fillings, Crowns, Cleaning)

This is one of the most common questions I get: "Why are my teeth more sensitive after I just had them cleaned?" Or "My filling was fine before, now it hurts." Here's what's happening with each:

After a scale and clean: When tartar builds up along the gum line, it actually insulates the root surface. When we remove that tartar during a scale and clean, the root surface that was hidden underneath is suddenly exposed to the world. It's like removing a blanket. The sensitivity is temporary and usually settles within 1 to 2 weeks as the tooth surface adjusts.

After a filling: Placing a filling involves removing decay and working close to the nerve. Some post-operative sensitivity is normal, especially to cold, and typically resolves within 2 to 6 weeks. If it's getting worse rather than better after that window, come back in.

After a crown: Similar to fillings. The tooth was prepared (shaped down), and the nerve was disturbed. Sensitivity to hot and cold for a few weeks is common. If it persists past 6 to 8 weeks, the nerve may need further assessment.

Teeth Whitening

Both professional and over-the-counter whitening products use peroxide-based agents that penetrate enamel to break down stain molecules. In the process, they can temporarily irritate the dentinal tubules and increase sensitivity.

Whitening-related sensitivity is usually temporary and resolves within a few days to a week after stopping treatment. Using a desensitising toothpaste for 2 weeks before whitening can reduce the effect.

If you have existing sensitivity or thin enamel, talk to us before whitening. Our teeth whitening service includes assessment to make sure whitening is appropriate for your teeth.

Medications and Dry Mouth

This is a cause that rarely gets mentioned, but I ask about medications whenever sensitivity doesn't have an obvious explanation.

Certain medications cause dry mouth (xerostomia) as a side effect, and saliva is one of your mouth's main defences against acid erosion. Without enough saliva, enamel breaks down faster. Medications that commonly cause dry mouth include:

• Antihistamines (hay fever, allergy medications)

• Antidepressants (SSRIs, tricyclics)

• Blood pressure medications (diuretics, ACE inhibitors, beta-blockers)

• Asthma inhalers (salbutamol/Ventolin is acidic and can erode enamel, particularly on the back of the upper front teeth)
  

If you're on long-term medication and you've noticed your mouth feels dry or your teeth are becoming more sensitive, mention it at your next dental visit. We can recommend strategies to protect your enamel, including prescription-strength fluoride products.

Acid Reflux (GORD)

Gastro-oesophageal reflux disease (GORD) is a hidden cause of tooth sensitivity that I look for in patients whose erosion pattern doesn't match their diet. GORD affects roughly 1 in 7 adults globally, and a 2022 meta-analysis found that patients with GORD have a significantly higher risk of dental erosion.

What happens: stomach acid travels up the oesophagus and into the mouth, usually at night or when lying down. It's strong enough to dissolve enamel over time. The erosion typically shows up on the inside (palatal) surfaces of the upper front teeth first, which is a pattern I can spot during an exam even if the patient doesn't know they have reflux.

If I see this erosion pattern and the patient hasn't been drinking excessive amounts of acidic drinks, I'll ask about heartburn, regurgitation, and sleep quality. Sometimes I'm the first practitioner to raise the possibility of GORD. A referral to their GP for assessment can address both the reflux and the ongoing dental damage.

What Your Sensitivity Trigger Tells You

Different triggers point to different problems. This is something I use clinically every day to narrow down the cause, and it's useful for you to understand before you come in.

What Triggers Your Sensitivity	Most Likely Cause	How Urgent
Cold drinks, cold air, ice cream	Exposed dentin from enamel erosion, gum recession, or a recent dental procedure	Low to moderate. Start with desensitising toothpaste. See a dentist if it persists beyond 2 weeks.
Hot drinks and hot food	Possible pulp inflammation (pulpitis). The nerve may be irritated or infected.	Moderate to high. See a dentist soon. Heat sensitivity often indicates a deeper problem than cold sensitivity.
Sweet food (chocolate, lollies, soft drinks)	Likely a cavity, exposed root surface, or failing filling. Sugar draws fluid through exposed dentinal tubules.	Moderate. Book an appointment. Sweetness sensitivity often points to active decay.
Biting down or pressure	Cracked tooth, high filling, or fracture line. Pain on release of bite is a strong indicator of a crack.	Moderate to high. Don't delay. Cracks can progress quickly.
Cold air or breathing through your mouth	Widespread enamel erosion or multiple areas of gum recession.	Low to moderate. Often manageable with desensitising toothpaste and a soft brush.
Sensitivity that lingers for minutes after the trigger is removed	Possible irreversible pulpitis (nerve damage). The nerve may not recover.	High. See a dentist promptly. Lingering pain is different from a quick zing.

The key distinction: a brief, sharp zing that fades quickly is usually dentin hypersensitivity. Sensitive teeth to cold fall into this category most of the time. But pain that lingers for 30 seconds or more after the trigger is removed suggests the nerve itself is inflamed, and that typically needs professional treatment.

Why Are My Teeth Sensitive on One Side?

Sensitivity that's concentrated on one side of your mouth usually points to a localised cause rather than a generalised condition like enamel erosion.

Most likely reasons for one-sided sensitivity:

• A cavity or crack in a specific tooth on that side

• Gum recession worse on one side (often from brushing harder on your dominant-hand side: right-handed people tend to brush the left side harder, and vice versa)

• A failing or fractured filling on one side

• An impacted or partially erupted wisdom tooth irritating the gum and nearby teeth

• One-sided grinding pattern putting more force on that side
  

If sensitivity is isolated to one tooth or one quadrant, that's a strong signal to get it checked rather than waiting to see if it settles.

Home Remedies for Sensitive Teeth

If your sensitivity is mild and you want to try managing it at home first, these strategies have clinical evidence behind them.

Desensitising toothpaste (the most effective home remedy). 

Toothpastes containing potassium nitrate (like Sensodyne or Colgate Sensitive) work by blocking the transmission of pain signals through the dentinal tubules. They need at least 2 weeks of twice-daily use before you'll notice a real difference. Don't rinse with water after brushing. Spit out the excess but leave the residue on your teeth so the active ingredients have time to work.

Switch to a soft-bristled toothbrush. 

If you're using a medium or hard brush, switch immediately. And ease up on pressure. Brushing harder doesn't clean better. It strips enamel.

Fluoride mouth rinse. 

An over-the-counter fluoride rinse used once daily can help strengthen weakened enamel and reduce sensitivity over time. We also offer professional fluoride treatments in-clinic for more stubborn cases.

Cut back on acidic food and drinks. 

If you're drinking soft drinks, citrus juice, or sports drinks daily, that's likely a contributing factor. Swap to water where you can. If you do have something acidic, rinse with plain water afterwards and don't brush for at least 30 minutes.

Don't brush immediately after eating. 

Wait 30 minutes. Your enamel is softer right after eating (especially after acidic food) and brushing too soon accelerates the erosion.

Stay hydrated. 

Dry mouth accelerates enamel breakdown. If you're on medications that cause dry mouth, sip water throughout the day and consider a saliva substitute product.

For a deeper guide on immediate pain relief strategies, our post on how to stop sensitive teeth pain covers the treatment side in detail.

When to See a Dentist About Sensitive Teeth

Mild, occasional sensitivity to cold that comes and goes is common and usually manageable at home. But certain patterns mean you should book an appointment rather than waiting.

See a dentist if:

• Sensitivity is getting worse, not better

• One tooth has become suddenly sensitive when it wasn't before

• You have sensitivity to hot food or drinks (not just cold)

• Pain lingers for 30 seconds or more after the trigger is removed

• You can see a visible hole, dark spot, or chip in the tooth

• Your gums are bleeding, swollen, or pulling back from the teeth

• Sensitivity started after an injury to the face or mouth

• Over-the-counter desensitising toothpaste hasn't helped after 4 weeks
  

One thing I've noticed over the years treating patients across Campbelltown and the Macarthur region: some families out here are on tank water rather than mains supply. NSW mains water is fluoridated, which gives your enamel continuous low-level protection against erosion. If you're on tank water or primarily drink bottled water, your teeth miss out on that. Bring it up with your dentist so we can factor it into your preventive care, including whether professional fluoride application would benefit you.

Ready to Get Your Sensitivity Sorted?

If your teeth have been sensitive for more than a couple of weeks, or if the sensitivity is sudden and you're not sure why, it's worth getting it assessed. Most of the time I can identify the cause in a single appointment with a thorough examination and x-rays.

We treat sensitive teeth regularly at Bradbury Dental Surgery, and the solution is often simpler than patients expect. Whether it's a fluoride treatment, a filling, gum disease management, or just a change in brushing technique, we'll explain what's going on and walk you through your options.

Patients from Camden, Narellan, Mount Annan, and across the Macarthur region visit us for exactly this type of care.

Call Bradbury Dental Surgery on (02) 4628 2151 or book online.

Frequently Asked Questions About Sensitive Teeth

Can sensitive teeth go away on their own?

Sometimes. If the sensitivity is caused by a temporary irritant, like a recent dental cleaning, whitening treatment, or a short bout of acidic food, it can settle on its own within 1 to 2 weeks. But if the sensitivity is caused by enamel erosion, gum recession, a cavity, or a crack, it won't resolve without treatment. The underlying cause needs to be addressed.

Is tooth sensitivity a sign of a cavity?

It can be. Sudden sensitivity in one tooth, especially to sweet food or cold, is one of the earliest symptoms of a cavity. But sensitivity can also come from enamel erosion, gum recession, a cracked filling, or grinding. The only way to know for sure is a dental examination with x-rays.

Why are my teeth sensitive to cold but not hot?

Cold sensitivity alone is usually a sign of exposed dentin from enamel wear or gum recession. The dentinal tubules react to the rapid temperature change, sending a quick, sharp signal to the nerve. This is the most common and least concerning type of sensitivity. It typically responds well to desensitising toothpaste and fluoride treatment. Hot sensitivity, on the other hand, can indicate pulp inflammation, which is a more serious concern.

How long does sensitivity last after a filling?

Post-filling sensitivity to cold is normal and usually resolves within 2 to 6 weeks. The deeper the cavity was, the closer the filling sits to the nerve, and the longer sensitivity may take to settle. If sensitivity is still present or worsening after 6 weeks, the filling may need to be adjusted or the nerve may need further assessment.

Can pregnancy cause sensitive teeth?

Yes. Hormonal changes during pregnancy (particularly increased progesterone) can make gums more prone to inflammation and swelling, which can lead to gum recession and exposed root surfaces. Morning sickness also exposes teeth to stomach acid, eroding enamel over time. Pregnancy-related sensitivity is common and usually manageable with a soft brush, desensitising toothpaste, and fluoride rinse. Let your dentist know if you're pregnant so we can adjust your preventive care.

Does sensitive teeth toothpaste actually work?

Yes, for the right type of sensitivity. Desensitising toothpastes containing potassium nitrate work by calming the nerve inside the tooth, reducing its ability to transmit pain signals through the dentinal tubules. They take about 2 weeks of consistent use to build up their effect. They work well for generalised dentin hypersensitivity from enamel erosion or gum recession. They won't fix a cavity, a crack, or an inflamed nerve. If desensitising toothpaste hasn't helped after 4 weeks, see your dentist.