A patient bites into a seed hidden in a piece of bread and feels a brief, sharp twinge — not at the moment of pressure, but as the bite is released. The pain passes within a second. It returns a week later, with a sip of cold water. The radiograph shows nothing concerning, the tooth is not mobile, the gum is healthy.
This is a common scenario in which a cracked tooth presents at the surgery. The answer to the question “can it be saved” is: in most cases yes — what decides the matter is the extent of the crack, which is not visible to the naked eye. A crack that stops within the crown of the tooth can usually be managed with a restoration covering the cusps (the raised points of the chewing surface that transmit forces during biting). A crack that extends below bone level and divides the root usually means the tooth has to be removed.
What to do before you get to the surgery
If a fragment of the tooth has broken off, it is worth keeping it in a moist environment (milk, saline, saliva) and bringing it to the appointment — sometimes it can be bonded back into place. A sharp edge can be covered with orthodontic wax. Until the appointment, it is best to chew on the opposite side and to avoid hard and cold foods.
What should not be done is gluing tooth fragments back yourself with shop-bought adhesives, or filling the crack with anything on your own initiative — this makes later treatment more difficult and may seal infection inside the tooth.
Signs that call for an urgent appointment: facial or gingival swelling, spontaneous pain that worsens at night, fever, tooth mobility, bleeding from the area of the crack, pain radiating to the ear or temple. Swelling that increases rapidly and makes opening the mouth or swallowing difficult requires contact with a clinician the same day — the infection may then be spreading beyond the tooth itself.
If, on the other hand, the cracked tooth merely gives a sharp twinge on biting and none of the above symptoms is present, the situation is not an emergency — but nor is it something to postpone for months.
Why a cracked tooth can be difficult to diagnose
A cracked tooth is a tooth in which a crack has formed that begins in the enamel and — apart from the most superficial forms — reaches the dentine, while the fragments of the tooth still lie against one another and separate only under the pressure of chewing. This definition also explains why the diagnosis can be difficult.
A crack is not a cavity — there is no space in it for an instrument and it casts no shadow on a radiograph. For the crack to become visible, the X-ray beam would have to run exactly in its plane. A typical crack in a molar, however, runs from front to back, while the beam comes from the buccal side — so it crosses the crack transversely. On a radiograph a cracked tooth looks healthy.
The second difficulty is the character of the pain. Patients describe it as “shooting” and brief, and the most characteristic symptom is pain on release of pressure, not on biting itself: the fragments of the tooth separate for a moment and return to place, irritating the pulp (the living tissue inside the tooth). In the clinical literature this constellation of symptoms is known as cracked tooth syndrome.
In our day-to-day clinical practice at Modern Dental & Orthodontics (Klinika MDO) we see patients who have been unable to point to the aching tooth for months — and that in itself is a clue. Diffuse pain on biting in the posterior region should raise the suspicion of a crack.
Where cracks in teeth come from
Cracks rarely have a single cause — usually several factors that weaken the tooth combine with several that load it. The most common background is an extensive restoration, particularly an old one, leaving the thin walls of the cusps unprotected. Under load such a tooth behaves differently from a solid tooth: the cusps flex sideways instead of transmitting forces down the long axis of the tooth.
The second factor is occlusal overload, that is excessive loading of the tooth during biting — bruxism, meaning the habitual grinding and clenching of teeth, and isolated traumatic contacts in which a single cusp takes the forces intended for the whole arch. In an almost eight-year follow-up published in Dental Materials bruxism was one of the factors that markedly increased the risk of restoration failure.
The third group comprises one-off events: biting on a stone, a bone or an ice cube — not so much a cause as the moment at which a weakness building up over years becomes apparent. A separate and common group is teeth after root canal treatment.
Five types of crack — from a craze line in enamel to a vertical root fracture
Not every “crack” means the same thing. We distinguish five situations whose prognoses differ so widely that using one word for all of them is misleading.
Craze lines in enamel
Fine, superficial lines within the enamel. They are painless, do not progress and require no treatment — at most they are an aesthetic concern in the anterior region.
Fractured cusp
A fragment of the tooth wall breaks off, most often alongside a large restoration that has weakened it. The fracture line usually bypasses the pulp, so the symptoms are mild. The tooth is restored with a filling or an onlay — a restoration covering the chewing surface together with the cusps, less invasive than a crown.
Cracked tooth proper
The crack runs from the chewing surface towards the root and may reach the pulp, but the tooth remains in one piece. This is the situation in which the method of restoration materially changes the prognosis.
Split tooth
An advanced stage of the previous type: the crack has divided the crown into two mobile fragments. Preserving the tooth intact is usually not possible.
Vertical root fracture
The crack begins in the root and runs towards the crown; it most often affects teeth after root canal treatment. The symptoms can be misleading and the prognosis is poor.
Table: type of crack, prognosis and management
| Type of crack | What happens in the tooth | What you feel | Prognosis | Typical management |
| Craze lines in enamel | fine lines in the outer layer, with no deeper extension | nothing; sometimes noticed by chance | very good | observation; aesthetic correction if desired |
| Fractured cusp | a fragment of the tooth wall breaks off, away from the nerve | a sharp edge cuts the tongue, brief pain on biting | good | filling or an onlay covering the cusps |
| Cracked tooth proper | the crack extends deeper and may reach the nerve; the tooth is still in one piece | “shooting” pain on release of pressure, sensitivity to cold | moderate to good, depending on the restoration | a restoration covering the cusps (onlay or crown); root canal treatment if the nerve is irreversibly inflamed |
| Split tooth | the tooth is divided into two mobile fragments | the tooth is divided into two mobile fragments | poor | extraction; in mandibular molars sometimes hemisection, in maxillary molars — amputation of the affected root |
| Vertical root fracture | a crack in the root, often below bone level | recurrent swelling, a “pimple” on the gum, dull discomfort | very poor | extraction or removal of the affected root |
Why a crown or an onlay improves the prognosis so markedly
This is the best documented piece of the puzzle. A 2024 systematic review published in Journal of Dentistry included 27 clinical studies, 26 of which entered the meta-analysis. It analysed the fate of cracked teeth according to the method of restoration.
Let us begin with observation alone. In asymptomatic cracks it proved effective in eight out of ten patients over three years — which justifies restraint towards painless cracks discovered by chance. The situation changes once symptoms appear.
In teeth with a preserved vital pulp, survival reached 92.8–97.8% over follow-up periods of one to six years. The key comparison, however, is between two restorative strategies. When a cracked tooth was restored with an ordinary filling, without covering the cusps, the risk of pulpal complications was more than three times higher than after a crown had been placed, and the risk of tooth loss around eight times higher — although for this second figure the researchers caution that the estimate is imprecise and the true difference may be either small or very large. The direction, however, is unambiguous.
The picture is stronger still in teeth after root canal treatment: those without a crown were extracted more than eleven times more often. The authors’ conclusion is unequivocal — for a symptomatic cracked tooth, and for teeth after root canal treatment, they clearly recommend a full crown. One caveat: the meta-analysis compared fillings without cusp coverage only with full crowns, so it does not settle how far an onlay covering the cusps matches a crown.
The mechanism is easy to picture. A filling restores the cavity but does not bind the fragments of the tooth together — with every bite the cusps still separate sideways and the crack slowly deepens. A restoration covering the cusps acts like a band: it transfers chewing forces onto the whole structure instead of onto the edges of the crack. Laboratory research points in the same direction: in a study in Clinical Oral Investigations, carried out on extracted premolars after root canal treatment, restorations covering the cusps performed better under cyclic loading than those leaving the walls unprotected — the result also depended on the way the core was built up.
How long will such a restoration last
The material matters less than the fact of covering the cusps, but it is not irrelevant. In an almost eight-year follow-up published in Dental Materials ceramic and composite onlays performed almost identically for the first six years — more than 98% of them survived; only later did ceramic prove more durable. A review of monolithic CAD/CAM zirconia crowns published in Journal of Prosthodontic Research showed survival of 91–100%, but over a short follow-up — on average slightly more than a year. That is too little for conclusions about durability over many years, and the authors are duly cautious here.
A well-made restoration requires the same as your own tooth: meticulous hygiene around the margin and control of the occlusion. The most common reasons for failure are caries at the margin of the restoration and overloading. We write more about the choice between an onlay and a full crown in the article overlay and onlay — onlay or crown.
How we diagnose a cracked tooth and what treatment involves
The first appointment is primarily about diagnosis, because no single method gives certainty. The basis is the bite test — the patient bites on a flexible wedge placed in turn on each cusp; pain on release of pressure indicates the side of the crack. Transillumination, that is shining a strong light through the tooth, reveals the crack as a dark line. Staining the crack and examining the tooth under magnification with a microscope also help. Cone-beam computed tomography (CBCT) is useful mainly where a vertical root fracture is suspected; a very narrow crack often does not show up on it.
Very often it is only after the old restoration has been removed that the extent of the crack becomes apparent — which is why the final treatment plan is sometimes settled during the procedure rather than before it. It is worth knowing this, so that it is not taken as a change of mind.
With a healthy pulp, the typical course involves two appointments: at the first the tooth is prepared and protected with a temporary restoration, at the second — after several days to a fortnight or so — the finished restoration covering the cusps is fitted. The procedures are carried out under local anaesthesia and in most patients they are painless; where the pulp is severely inflamed, anaesthesia can be harder to achieve and needs to be supplemented during the procedure. Where root canal treatment is required, one or two further appointments are usually added, and the restoration is made once it has been completed.
For the first few days after the procedure the tooth may be tender on biting; pain that increases rather than subsides calls for contact with the practice. We carry out the diagnosis and restoration of cracked teeth within restorative and aesthetic dentistry.
When root canal treatment is needed
A crack in itself is not an indication for root canal treatment — what decides the matter is the condition of the pulp. If the pain is brief, provoked by a stimulus and quickly subsides, the pulp is usually reversibly irritated; the priority then becomes prompt protection of the tooth with a restoration covering the cusps, sometimes preceded by a temporary orthodontic band holding the fragments together for the duration of the diagnostic work- up.
If, however, the pain arises spontaneously, wakes the patient at night or persists long after a thermal stimulus, root canal treatment is necessary, followed — without exception — by a restoration covering the cusps. A review published in International Endodontic Journal lists the presence of cracks among the factors credited with influencing tooth survival after root canal treatment — alongside the amount of remaining tissue, the position of the tooth and the timing of the definitive restoration.
One limitation is worth knowing: a crack does not “knit together” after root canal treatment. Endodontics resolves the infection, but it is the restoration that determines whether the crack stops deepening.
When a cracked tooth cannot be saved
Three situations mean a poor prognosis for a cracked tooth:
- The crack extends below bone level. It is then impossible to make a well-sealed restoration or to maintain a healthy gingival attachment.
- The tooth is divided into two mobile fragments. They work independently and no restoration will stop this.
- A vertical root fracture has been diagnosed. The crack is a permanent pathway for bacteria, and the accompanying bone loss progresses.
From the perspective of the clinical team at Modern Dental & Orthodontics (Klinika MDO), what matters is that prolonging attempts to save such a tooth worsens the conditions for any future replacement — progressive bone loss makes later implant treatment more difficult. A separate issue that has to be differentiated from a crack is tooth resorption — the symptoms can be similar, and the management entirely different.
What next, if the tooth cannot be saved
Losing a posterior tooth is not a situation without a solution, but it does require a plan. Over time the gap causes the adjacent teeth to tilt and the opposing tooth to over-erupt, which makes later replacement more difficult. This is why the decision on what will replace the extracted tooth is best taken alongside the extraction, and not years later.
Three routes are worth considering: an implant with a crown, a bridge supported on the adjacent teeth, and a removable prosthesis. The choice depends on the condition of the bone, the adjacent teeth and the occlusal conditions, and always requires individual diagnosis.
How to reduce the risk of another tooth cracking
A cracked tooth is rarely an isolated event: the factors that led to it usually act on the remaining teeth as well.
A handful of measures achieve the most: replacing very extensive, old fillings with restorations covering the cusps before the tooth cracks; protecting the teeth from the effects of bruxism — most often with an occlusal splint worn at night; the splint does not eliminate the grinding habit itself, but it distributes the forces across the whole arch and removes overload from individual teeth; correcting overloaded occlusal contacts at check- ups; avoiding biting hard objects — ice cubes, stones, pens. In people who have had root canal treatment on a posterior tooth, the key point is not to delay the restoration covering the cusps.
Frequently asked questions
Does a cracked tooth always have to be removed? No. Removal is required above all for teeth split into two mobile fragments and for those with a vertical root fracture. Cracks that stop within the crown can usually be managed with a restoration covering the cusps. The decision turns on the extent of the crack and on whether it extends below bone level.
Is a crack in a tooth visible on a radiograph? Usually not. For the crack to be visible, the X-ray beam would have to run exactly in its plane, whereas a typical crack runs across the beam. The radiograph mainly serves to assess the bone. Diagnosis rests on the bite test, transillumination, staining of the crack and examination of the tooth under magnification with a microscope.
How much does treatment of a cracked tooth cost? The cost depends on the extent of treatment — protecting the tooth with an onlay alone is one thing, root canal treatment completed with a prosthetic crown quite another. A reliable estimate is possible only after examination, diagnostic tests and establishing the extent of the crack. We provide detailed pricing information during the consultation, once a specific course of action has been planned for the tooth in question.
Does a cracked tooth hurt? Not always. Craze lines in enamel are entirely asymptomatic and are sometimes detected by chance. A crack reaching the dentine usually produces brief, sharp pain on release of pressure and sensitivity to cold. Spontaneous pain, persisting long after a thermal stimulus or waking the patient at night, suggests pulpal involvement and requires more urgent intervention.
How long can treatment of a cracked tooth be delayed? The longer the tooth functions without protection, the deeper the crack extends — and it is its extent that determines the prognosis. Research shows that cracked teeth without a restoration covering the cusps are extracted many times more often than those protected with a crown. A consultation within a few days of symptoms appearing is sensible.
Why do teeth after root canal treatment crack more often? Several factors contribute: the loss of tissue during preparation of the cavity and the canals, the absence of pulpal sensation which in a healthy tooth limits the force of biting, and the frequent coexistence of extensive restorations. This is why such teeth, molars in particular, in most cases require a restoration covering the entire chewing surface.
Does a cracked tooth need treatment if it does not hurt at all? Not always straight away. In entirely asymptomatic cracks, observation alone proved effective in eight out of ten cases over three years. The condition, however, is regular monitoring and a prompt response if pain on biting or sensitivity appears — a sign that the crack is deepening.
Will the pain disappear immediately once a crown is fitted? It usually subsides quickly, because the restoration prevents the fragments of the tooth from separating during biting. For the first few days the tooth may still be tender on biting, and this is typical after the procedure. Pain that increases, or that appears spontaneously after several weeks, calls for renewed assessment of the pulp.
Summary
A cracked tooth is a diagnosis in which the prognosis is determined not by the severity of the pain but by the extent of the crack and the method of restoration. Craze lines in enamel require no treatment; a fractured cusp and a crack stopping within the crown usually carry a good prognosis; a split tooth and a vertical root fracture usually mean loss of the tooth. The data are consistent: a restoration covering the cusps reduces the risk of tooth loss many times over compared with an ordinary filling, and in teeth after root canal treatment the difference is greatest. The final decision depends on the individual clinical situation and requires an examination, which no description of symptoms can replace.
Read more:
- Restorative and aesthetic dentistry — scope of treatment
- Overlay and onlay — onlay or crown
- Tooth resorption — what is worth knowing
- Why root canal treatment is sometimes challenging
- Root canal treatment - before and after. What happens to the tooth
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
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Source 2 Links https://doi.org/10.1007/s00784-021-04319-3 │ https://pubmed.ncbi.nlm.nih.gov/34846558/ Description Fráter M, et al. „Fatigue performance of endodontically treated premolars restored with direct and indirect cuspal coverage restorations utilizing fiber-reinforced cores.” Clinical Oral Investigations. 2022;26(4):3501-3513.
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Source 5 Links https://doi.org/10.1016/j.dental.2023.10.017 │ https://pubmed.ncbi.nlm.nih.gov/37821330/ Description Lempel E, et al. „Clinical evaluation of lithium disilicate versus indirect resin composite partial posterior restorations – A 7.8-year retrospective study.” Dental Materials. 2023;39(12):1095-1104.