Does drilling a tooth hurt, and when do you need an anaesthetic?

Key points in brief

• With a shallow cavity, drilling a tooth usually does not hurt: you mainly notice vibration, drill noise and cold water, sometimes a brief twinge. Deep cavities may hurt without anaesthetic.
• Besides the depth of the cavity, what matters is how sensitive you are to pain and whether the tooth already hurts or reacts to cold for a long time.
• After examination, the dentist usually suggests anaesthetic for a deep cavity, but you can request it for a shallow one. Agree a hand signal to stop immediately, especially without anaesthetic.
• After an anaesthetic, your lip, tongue or cheek usually stays numb for a few hours. Do not eat until feeling returns, because a numb lip is easy to bite.
• Over time a cavity usually gets deeper, and the deeper it goes, the more often drilling needs an anaesthetic.

What affects whether drilling a tooth hurts

Pain during drilling depends above all on how deep the cavity goes. Enamel, the hard outer layer of the tooth, does not itself hurt. Decay usually causes no symptoms until it reaches the dentine, the layer that lies under the enamel and surrounds the pulp. The pulp is the tissue with nerves and blood vessels inside the tooth.

Dentine is crossed by microscopic tubules filled with fluid. Nerve endings reach into them from the pulp side. The drill, the cold water and the stream of air probably move the fluid in the tubules, and this movement stimulates the nerves. That is why work in the dentine can cause a brief, sharp twinge. The less dentine is left over the pulp, the more strongly the pulp reacts to treatment. Dentists call a cavity deep when it reaches the last quarter of the dentine before the pulp.

Where the cavity sits also matters. Near the gum - where enamel no longer covers the tooth - the dentine is sometimes exposed and reacts to cold, air or the touch of an instrument. A cavity in that area can therefore be felt even though it is not deep.

The condition of the pulp itself matters too. With deep decay, bacteria cause inflammation in the pulp, which increases as the cavity grows. A tooth with an inflamed pulp may hurt on its own or react to cold for a long time. A tooth that has had root canal treatment no longer has a pulp, so during drilling you usually feel only pressure and vibration. People also differ in how sensitive they are to pain, so similar drilling feels milder to one person and more noticeable to another.

Drilling a tooth means that the dentist removes the decay with a drill and prepares the cavity for a filling. Early decay confined to the enamel is often treated without drilling. At a check-up, the dentist assesses when decay can be stopped without a drill and when a cavity already needs filling. Cavities are treated within restorative dentistry, the branch of dentistry focused on keeping your own teeth.

Questions to ask your dentist before drilling

At the start of the visit, you can ask your dentist:

• How deep is the cavity, and does it reach close to the pulp?
• Will this cavity need an anaesthetic?
• How should I let you know that I can feel something or need a break?
• • How long will the visit take, and can everything be done in one visit?

What you feel at each stage of the visit

A visit at which the dentist removes decay and fills the cavity usually has five stages.

1. Assessing the cavity

Assessing the cavity usually does not hurt. You may feel something, mainly during a cold test. The dentist examines the tooth, compares it with an X-ray and asks whether the tooth reacts to cold or sweet things. Sometimes they check this themselves by touching the tooth with a small piece of cold cotton wool, because a cold test helps to assess the condition of the pulp.

What matters is how long the pain lasts after something cold, because pain that lingers more often points to inflammation of the pulp. Based on your answers, how the tooth looks and the X-ray, the dentist suggests either an anaesthetic or treatment without one. Also tell the dentist about pain that comes on by itself or wakes you at night, because this changes the plan for the anaesthetic, and sometimes for the treatment as well.

2. Anaesthetic or treatment without it

When the dentist numbs the tooth, you feel the needle prick, and then pressure or a stretching sensation for a moment. Numbness usually sets in after a few minutes. For upper teeth, it is most often the area around the treated tooth that goes numb. For lower back teeth, half of the lip and tongue often go numb, because the injection there numbs a larger nerve. The anaesthetic switches off pain, but usually not the sense of pressure, so you still feel the instruments pressing and the vibration.

If you are afraid of the needle prick itself, say so before the injection, because the dentist can first numb the gum with a gel. With a shallow cavity, the dentist can work without an anaesthetic if you both agree, and give one as soon as you feel pain.

3. Removing the decay

While the tooth is being drilled, the drill vibrates and makes a high-pitched sound. Water runs onto the tooth the whole time, and a thin suction tube removes it from your mouth. The noise alone can increase anxiety, even when nothing hurts. Without an anaesthetic, a shallow cavity usually gives only vibration and a feeling of cold. Every so often the dentist dries the tooth with a stream of air, which can cause a brief twinge where dentine is exposed. Close to the pulp, dentine transmits stimuli more strongly, and the twinge can be more noticeable. If something hurts, raise your hand. The dentist will stop, and an anaesthetic can be given or topped up.

4. The filling

Placing the filling usually does not hurt. With a cavity between two teeth, you feel pressure or a stretching sensation, because the dentist fits a thin metal band and a small wedge. Then they dry the tooth, prepare its surface and place the filling in layers. Each layer is hardened with light from a curing lamp. Finally, the dentist asks you to bite on articulating paper - a thin coloured paper - and smooths the filling where it meets the teeth of the opposite jaw. If, even with the anaesthetic, you feel that the filling clearly gets in the way when you bite together, say so straight away.

The dentist chooses the material before the procedure. How best to restore a large cavity depends mainly on how much healthy tooth is left.

5. Leaving the practice

After a visit with a local anaesthetic, you leave with a numb lip, tongue or cheek on the side of the treated tooth. While the numbness lasts, your speech may be less clear, and your bite is hard to judge because your teeth cannot feel exactly how they meet. The numbness usually wears off after a few hours. Until then, do not eat, do not have hot drinks, and take care not to bite your lip or cheek.

With or without an anaesthetic: how the decision is made

The dentist usually suggests an anaesthetic when the cavity reaches deep into the dentine, when the tooth already hurts or reacts to cold for a long time, and when a large filling is being replaced. In these situations, drilling a tooth without an anaesthetic can be painful. A shallow cavity can be treated without an anaesthetic if you cope well with the procedure and would rather avoid numbness after the visit. In that case, agree with the dentist that they will stop at your first signal, not only once they have finished a stage.

Treatment without an anaesthetic has its advantages: there is no injection, and you do not leave with a numb lip. It also has a drawback: if pain starts halfway through, you have to wait a few minutes for the anaesthetic to take effect. So when it is hard to judge before drilling how deep the cavity is, some patients prefer to have an anaesthetic from the start.

You can always ask for an anaesthetic, including for a shallow cavity and when the dentist has not suggested one. Treatment without an anaesthetic is not for everyone. People who tolerate pain less well are more often afraid of dental visits. For them, asking for an anaesthetic is a sensible choice.

With an anaesthetic, drilling usually does not hurt. However, an anaesthetic does not work equally well for everyone, and the hardest tooth to numb is one with severe inflammation of the pulp, especially a lower molar. If an anaesthetic has ever worked poorly or worn off too soon for you, mention it before the procedure.

What affects how long a filling takes

A filling usually takes longer the larger the cavity is and the harder it is to reach. With back teeth, especially the last ones, access is more difficult and the tooth is harder to keep dry, so treatment takes longer. These things make the visit longer:

• waiting for the anaesthetic to take effect,
• a cavity between two teeth, where a band and a wedge need to be fitted,
• a deep cavity, where the dentist removes decay carefully close to the pulp,
• replacing an old filling before placing a new one,
• a large cavity that is filled in many layers.

With a very deep cavity, the dentist sometimes removes the decay over two visits to reduce the risk that the pulp becomes exposed. Once the dentist has seen the cavity and the X-ray, they can tell you how much time to set aside. This cannot always be predicted precisely, because an X-ray shows only roughly how deep the cavity is. The full depth becomes clear only once the decay has been removed.

How to make the visit easier

At the start of the visit, tell the dentist if you are afraid or if having a tooth drilled was painful last time. This makes it easier to plan the anaesthetic and the pace of treatment. Fear of the dentist is common, and people who are afraid come for visits less often. If you are afraid too, it is worth starting with ways to manage fear of the dentist, even before you book the filling.

Agree on a simple signal, such as raising your hand, that means “break” or “it hurts”. You can ask the dentist to tell you before each next step - for example, the moment they are about to start drilling or fit the band. During a longer visit, ask for short breaks to close your mouth and relax your jaw.

What to do if fear of pain makes you put off treatment

First let the dentist look at the cavity, because only then is it clear whether drilling the tooth will be felt and whether an anaesthetic is needed. Over time a cavity usually gets deeper, and the closer it comes to the pulp, the more often the procedure needs an anaesthetic. If the tooth starts to hurt on its own or wakes you at night, do not put off treatment any longer. You can ask for an anaesthetic however deep the cavity is.

Frequently asked questions

Can drilling a tooth damage the pulp?

With a shallow cavity the risk is small, because a thick layer of dentine remains over the pulp. In a deep cavity, the pulp may become exposed or inflamed. The dentist may therefore deliberately leave a thin layer of softened dentine over it, which usually stops decaying under a tightly sealed filling. If the pulp does become exposed, it can be protected straight away, and further treatment depends on its condition.

Does a filling hurt more when an old one is being replaced?

It does not always hurt more, because what you feel depends mainly on how deep the old filling went and whether decay has developed underneath it. Removing the old material causes noticeable vibration, and with a deep filling the dentist works close to the pulp, so they usually suggest an anaesthetic. When replacing an old amalgam filling, the silver-coloured kind, the dentist usually also places a rubber shield over the tooth.

Is decay removed only with a drill?

No. The drill is the main instrument, but the dentist can remove softened dentine with a hand instrument shaped like a small spoon. There are also methods that use agents to soften the decay, a laser or a stream of air with powder, but they usually take longer and are used alongside the drill. Early stages of tooth decay can often be stopped without drilling.

Is it better to treat several cavities in one visit or over several?

Cavities on the same side can often be treated in one visit, sometimes with a single anaesthetic. Their depth also matters, as does how long you cope well with treatment. Several deep cavities, or treatment on both sides of the mouth, are sometimes spread over several visits so that no single visit is too tiring. Tell the dentist what suits you better.

Does sensitivity to cold before the visit mean drilling will be felt more?

It may, if the sensitive spot is the same one the dentist is going to treat: the stream of water and air acts on exposed dentine much as a cold drink does. Pain that lingers after something cold more often points to inflammation of the pulp, and such a tooth can be harder to numb. Before the procedure, describe to the dentist how long the pain lasts.

Can you eat as soon as you leave the practice after a filling?

If the tooth was numbed, wait to eat until full feeling has returned to your lip, tongue and cheek. You cannot feel a numb lip, so it is easy to bite it until it bleeds or to burn it with a hot drink. If you had no anaesthetic, ask the dentist before you leave when you can eat and whether to be careful about anything.

How long does the numbness last after the visit, and what should you watch out for?

Numbness usually lasts a few hours and wears off gradually. Until then, do not eat, do not have hot drinks, and do not test the feeling by biting your lip. If the feeling has not come back by the next day, call the practice. The tooth may be slightly sensitive for a few days. Tell your dentist about pain that gets worse or comes on by itself.

Read more:

• Aesthetic and Restorative Dentistry in Warsaw
• Tooth decay stages: when can it be stopped without drilling
• Composite filling, ceramic inlay or crown: what decides is how much tooth is left
• Tooth sensitivity - why cold hurts and what actually helps
• Secondary caries: when an old filling really needs replacing, and when it can be left alone

Content and liability disclaimer

This article is informational and educational in nature and does not constitute medical advice, a diagnosis or a therapeutic recommendation — it does not replace a consultation with a specialist. If you are experiencing symptoms, have doubts or are facing a decision about treatment, consult a dentist. The methods described and the data cited are general in nature. The results of scientific studies relate to populations, not to an individual patient. The course and outcome of therapy depend on the individual clinical situation and may vary between patients. No information contained in this article constitutes a guarantee of result. The content has been prepared with due care, based on publicly available medical knowledge and the scientific publications indicated in the Sources section. We do not advise taking or refraining from any health-related action solely on the basis of the content of this article, without prior consultation with a doctor.

Sources

Source 1

Links https://doi.org/10.1111/iej.70132 │ https://pubmed.ncbi.nlm.nih.gov/42017497/

Description Schwendicke F, Kosan E, Banerjee A, Baysan A, Bjørndal L, Ceballos L, et al. „Deep Caries Management: EFCD-ESE-ORCA S3-Level Clinical Practice Guideline.” International Endodontic Journal. 2026;59(7):1298-1315.

Source 2

Links https://doi.org/10.1111/iej.70192 │ https://pubmed.ncbi.nlm.nih.gov/42246072/

Description Caviedes-Bucheli J, Ulate E, Munoz HR, Ríos-Osorio N. „The Role of Neuropeptide Y in Dental Pulp: Balancing Neurogenic Inflammation and Pain Modulation.” International Endodontic Journal. 2026;59(10):2028-2045.

Source 3

Links https://doi.org/10.1186/s12903-020-01199-z │ https://pubmed.ncbi.nlm.nih.gov/32762733/

Description Liu XX, Tenenbaum HC, Wilder RS, Quock R, Hewlett ER, Ren YF. „Pathogenesis, diagnosis and management of dentin hypersensitivity: an evidence-based overview for dental practitioners.” BMC Oral Health. 2020;20(1):220.

Source 4

Links https://doi.org/10.1016/j.identj.2026.109727 │ https://pubmed.ncbi.nlm.nih.gov/42407140/

Description Wang J, Zhao Y, Han R, Tang W, Zhang C, Zhang H, et al. „Guiding Caries Removal Through Biological Principles: A Narrative Review on Selective Caries Tissue Preservation.” International Dental Journal. 2026;76(5):109727.

Source 5

Links https://doi.org/10.1111/iej.70007 │ https://pubmed.ncbi.nlm.nih.gov/40734367/

Description Rujirawan T, Osiri S, Chotvorrarak K. „Efficacy of Combined Versus Supplementary Injection Techniques With Inferior Alveolar Nerve Block for Mandibular Molars With Symptomatic Irreversible Pulpitis: A Systematic Review and Network Meta-Analysis.” International Endodontic Journal. 2025;58(11):1681-1710.

Source 6

Links https://doi.org/10.1186/s12903-025-07123-7 │ https://pubmed.ncbi.nlm.nih.gov/41188798/

Description Panya S, Chongarnon S, Chintaroj S, Prommanee S, Thaweesapphithak S, Fakhruddin KS, et al. „Comparative evaluation of 2% mepivacaine and 2% lidocaine for inferior alveolar nerve block: a double-blind randomized clinical trial.” BMC Oral Health. 2025;25(1):1735.

Source 7

Links https://doi.org/10.1111/adj.12926 │ https://pubmed.ncbi.nlm.nih.gov/35735746/

Description Hoffmann B, Erwood K, Ncomanzi S, Fischer V, O’Brien D, Lee A. „Management strategies for adult patients with dental anxiety in the dental clinic: a systematic review.” Australian Dental Journal. 2022;67(Suppl 1):S3-S13.

Source 8

Links https://doi.org/10.1111/idj.12613 │ https://pubmed.ncbi.nlm.nih.gov/32929752/

Description Sukumaran I, Taylor S, Thomson WM. „The prevalence and impact of dental anxiety among adult New Zealanders.” International Dental Journal. 2021;71(2):122-126.

Source 9

Links https://doi.org/10.1186/s12903-025-06441-0 │ https://pubmed.ncbi.nlm.nih.gov/40615860/

Description Nermo H, Petrenya N, Steingrímsdóttir ÓA, Stubhaug A, Nielsen CS, Hadler-Olsen E. „Experimental pain tolerance is associated with dental anxiety – the Tromsø study 2015–2016.” BMC Oral Health. 2025;25(1):1096.