Sensitive Teeth Or Receding Gums? How To Tell The Difference

📖 11 min read  ·  Updated 04/07/2026

Sensitivity Is A Symptom, NOT A Diagnosis

Almost everyone who searches for sensitive teeth is looking for a product. That is the wrong first move. Sensitivity is not a condition in itself — it is the nerve reporting that dentine, the living layer beneath your enamel, has been exposed to the outside world. What exposed it is the actual diagnosis. And at least eight different problems can do it.

Recession, acid erosion, a cracked tooth, decay, a failing filling, gum inflammation, whitening, grinding. Each one produces a recognisably different pain. Each one needs a different response. Two of them will resolve on their own. Three of them get materially worse if you ignore them and just buy a tube of toothpaste. Reaching for a desensitising toothpaste before you know which one you have is not treatment — it is muting a smoke alarm.

The Mechanism: Why Exposed Dentine Hurts At All

Enamel has no nerves. Dentine does — indirectly, and in a way that explains everything about how sensitivity behaves.

Dentine is not solid. It is riddled with microscopic channels called dentinal tubules, running from the outer surface of the dentine inward to the pulp, where the nerve lives. Those tubules are filled with fluid. When dentine is exposed — by gum recession at the root, or by enamel loss at the crown — the open ends of those tubules meet the outside world.

Cold, heat, sweet, acid, air and touch all cause that tubular fluid to move. The rapid fluid shift deforms the nerve endings at the pulpal end of the tubule, and the nerve interprets that mechanical deformation as sharp pain. This is the hydrodynamic theory, first proposed by Martin Brännström in the 1960s, and it remains the accepted explanation for dentine hypersensitivity.

Two consequences follow directly, and both are diagnostically useful. First, the pain is fast — fluid movement is instantaneous, so the pain is instantaneous. Second, the pain is brief — once the fluid settles, the nerve stops firing. That is why real dentine hypersensitivity is over in seconds. Anything slower or longer is a different mechanism entirely.

The One Test That Sorts Almost Everything: How Long Does It Last?

Before you look at gums, enamel or anything else, time the pain. This single observation separates the problems a toothpaste can help from the problems that need a drill.

Everything below assumes you have passed the first test — that your pain is genuinely sharp and short. If it is not, stop reading and book an appointment. That is the most useful sentence in this article.

Cause 1 — Receding Gums And Exposed Roots

The root of a tooth has NO enamel. It never did. It is covered by a thin, soft layer called cementum, which is designed to sit safely below the gum line, and which wears away quickly once it does not. When the gum margin migrates towards the root, that surface is exposed — and its tubules open.

How Recession-Driven Sensitivity Presents

It is rarely a single tooth. Recession is a pattern, not an accident, so it tends to affect several teeth at once — most often the canines and premolars, most often on the outer, cheek-facing side, and most often worst on the side you brush hardest. Right-handed people commonly recede more on the left. Run a fingernail up the tooth: where you feel a distinct step or ledge, enamel has ended and root has begun.

The usual drivers are heavy horizontal brushing with a hard brush, a history of gum disease, thin gum tissue, and orthodontic movement. The recession itself does not hurt. The exposed root does.

Recession does not reverse on its own — the gum does not grow back. What you can do is stop it advancing and calm the surface it has exposed. Full detail here: Receding Gums: What Can Actually Be Reversed.

Cause 2 — Acid Erosion Stripping Enamel From The Crown

The second route to exposed dentine comes from the opposite direction. Instead of the gum retreating to reveal the root, the enamel dissolves off the crown.

Enamel is mineral. Acid dissolves mineral. Below roughly pH 5.5, enamel begins to demineralise — and a startling amount of what Australians consume sits well below that: soft drink, sports drinks, energy drinks, citrus and citrus water, wine, cider, kombucha, vinegar dressings, and flavoured sparkling water. Add the internal sources — reflux, and repeated vomiting from any cause — and the acid arrives from behind the teeth as well.

How Erosion-Driven Sensitivity Presents

Broad rather than pinpoint. Frequently the front teeth. The teeth may look thin, glassy or slightly translucent at the biting edges, and the surfaces can lose their crisp contours and take on a rounded, polished appearance. Old fillings may start to stand slightly proud of the tooth around them — not because the filling grew, but because the enamel around it dissolved.

Cause 3 — A Cracked Tooth

A cracked tooth is the imposter that most often gets mistaken for sensitivity, and it is the one that punishes the delay hardest.

The signature is unmistakable once you know it: sharp pain when you BITE down on something — and, tellingly, another jolt when you RELEASE. That release pain happens because the two segments of the tooth flex apart under load and snap back together as the load comes off, moving fluid through the dentinal tubules underneath. It is usually one tooth. It is usually a molar. It is very often a molar with a large old filling in it, because a heavily filled tooth has less intact structure holding it together.

Cold sensitivity often rides along with it, which is exactly why people misfile it as ordinary sensitivity and buy a toothpaste. A crack is a mechanical failure of the tooth. It does NOT heal, it does NOT respond to toothpaste, and it propagates. Caught early it is usually a crown. Left long enough it becomes a root canal, or an extraction.

Cause 4 — Decay And Failing Fillings

Decay reaches dentine and produces sensitivity for exactly the same hydrodynamic reason — the tubules are open, just from a cavity rather than from wear.

The tells are localisation and sweetness. Decay-related sensitivity is usually ONE tooth, usually in one specific spot you can point to, and it is often disproportionately triggered by sweet things. As the lesion deepens, the character of the pain changes — the short sharp jab starts to linger. That transition from short to lingering is the pulp becoming inflamed, and it is your last comfortable off-ramp before a root canal.

A failing filling behaves the same way. Old restorations develop marginal gaps and micro-leakage; fluid and bacteria track underneath; the dentine beneath is exposed. If sensitivity is concentrated on a tooth that already has a filling in it, assume the filling is the suspect until a dentist says otherwise.

Cause 5 — Grinding And Clenching (Bruxism)

Bruxism produces sensitivity by three separate routes at once, which is why it is so often missed.

The supporting evidence is usually somewhere other than the teeth: waking with a tight or aching jaw, morning headaches at the temples, a partner who reports the noise, and a scalloped edge to the tongue. Bruxism needs a diagnosis and, in most cases, an occlusal splint. A desensitising toothpaste can soften the symptom. It cannot stop the force. Treat the force.

Cause 6 — Post-Whitening Sensitivity

Peroxide-based whitening — in-chair or take-home — commonly causes transient sensitivity. Peroxide penetrates enamel and dentine to reach the stain molecules, and in doing so it can produce a temporary, reversible irritation of the pulp.

The defining feature is that it is temporary. Whitening sensitivity typically settles within a few days of stopping treatment and does not leave lasting damage to the tooth. If your sensitivity started with a whitening course and is fading week by week, it is behaving normally. If it started with whitening and is NOT fading — or it has localised to one tooth — whitening is no longer the explanation. Something else was there first.

Cause 7 — Gum Inflammation Itself

Sore gums are not sensitive teeth. People conflate them constantly, and the two feel genuinely different once you pay attention.

Gingival pain is dull, tender and diffuse — an ache in the tissue, not a jolt in the tooth. The gums look red or puffy rather than pale pink and firm. They bleed when brushed or flossed. There is no cold trigger and no sharp shooting quality. That is inflammation, not dentine exposure.

The complication is that the two travel together, because untreated gum inflammation causes the recession that then exposes root and causes real sensitivity. Sort the inflammation and you remove the engine driving the future recession. See What Causes Bleeding Gums: Every Cause Explained and 7 Warning Signs Of Gum Disease You Should Never Ignore.

The Differential Table: Work Out Which One You Have

Read across the row that matches your symptoms. The trigger, the duration, and the number of teeth involved will identify your cause in almost every case.

What Actually Helps — Honestly

Here is the part most product pages leave out. Desensitising toothpaste works on ONE of the nine rows in that table — genuine dentine hypersensitivity from exposed dentine. It does nothing for a crack, a cavity, a leaking filling or a grinding habit. Match the tool to the problem.

If It Really Is Dentine Hypersensitivity

On fluoride specifically, if you have been told to avoid it, read Is Fluoride In Toothpaste Safe? What The Evidence Says before you make that call — removing fluoride from an already-eroding mouth is the wrong direction.

When To Stop Self-Treating And Book A Dentist

The Australian Dental Association's public guidance is unambiguous: persistent tooth pain warrants professional assessment. Sensitivity that responds to a desensitising toothpaste within a few weeks is reasonable to manage at home while you address the cause. Everything on this list is NOT.

Note the AIHW's ongoing reporting on oral health in Australia: a large share of adults delay or avoid dental care on cost grounds, and problems that were cheap to fix become expensive ones. A cracked tooth caught at the crack is a crown. The same tooth six months later is a root canal, and sometimes an extraction. The delay is the expensive part.

Where LACALUT Fits

LACALUT has been making clinical oral care in Germany since 1925. Two products are relevant to everything above, and each is aimed at a different row of the table.

Neither is a substitute for a dental examination, and neither can address a crack, a cavity or a grinding habit. Use them for what they are formulated for. Get the rest diagnosed.

Medical disclaimer: This article is for general information only and does not constitute dental or medical advice. Tooth sensitivity has multiple possible causes, several of which require professional diagnosis and treatment. Consult a registered dental practitioner for assessment of any persistent tooth pain.

Frequently Asked Questions — Sensitive Teeth And Receding Gums