What clenching changes in an expensive restoration
- Bruxism no longer closes the door to implants, but it does move the patient into a higher-risk group. Pooling 27 studies, the odds of losing an implant were roughly twice as high in people with probable bruxism. That is a comparison between two groups. It says nothing about the fate of any single implant.
- With crowns on a patient’s own teeth the picture is milder. In a group of 1037 crowns followed for eleven years on average, grinding raised the risk of losing the restoration by roughly half, while the type of material did not change the outcome at all.
- Ceramic veneers last a decade in more than 19 cases out of 20. The studies cited here do not show by how much clenching lowers that figure. What is known is that in one study the risk of fracture was twice as high in people with bruxism.
- With crowns on a patient’s own teeth the most common failure is not a fractured ceramic. It is loss of retention: the restoration coming away from a worn, low tooth.
- A night guard is the protective element whose benefit has been quantified, and even so most of that knowledge comes from laboratory models rather than from observation of patients.
The line “you don’t do veneers on someone with bruxism” is sometimes heard at dental practices. It sounds reasonable: if someone grinds their teeth, ceramic stands no chance. Studies from recent years do not, however, confirm that prohibition.
Why does bruxism shorten the life of a prosthetic restoration?
Not by one mechanism but by three. The first two look the way patients imagine them. The third is the one that fails most often, and it is mentioned more rarely.
The first is overload. Occlusion is the way the upper teeth meet the lower ones, and in clenching the pressure acts for longer and more often than in eating; ceramic tolerates repeated loading worse than a single load, so chipping and a cracked crown usually appear not after one mouthful but after years.
The second is wear. Wear of prosthetic restorations usually goes together with wear of the opposing teeth: both are worn down. Complications related to wear of the material were reported most often with full-arch restorations made of acrylic on a metal framework. That is how a review of ten studies of implant-supported restorations came out; bruxism and the absence of a night guard recurred in it as accompanying factors regardless of the material. Wear was measured quantitatively in that review only for some of the materials. Much less is known today about the fate of the teeth working against a restoration than about the fate of the restoration itself.
The third mechanism is the most underrated. It is loss of retention: the restoration debonding or decementing. A worn tooth is lower, it has less surface to hold a crown, and lateral forces act on that surface unfavourably. Loss of retention turned out to be the most common cause of losing a crown in a large Swedish cohort, more common than fracture of the tooth and many times more common than chipping of the ceramic.
A restoration that has “come off” is usually not destroyed, provided the tooth underneath has not suffered.
Can you have veneers if you have bruxism?
You can, though on stricter terms than someone who does not clench their teeth: enough enamel has to be left at the incisal edges, and the force has to be brought under control before any preparation.
A separate article covers how long porcelain and composite veneers last; bruxism is one risk factor there, and the whole subject here.
A point of reference: survival of ceramic veneers came to about 96 per cent after 10.4 years on average. That is what pooling nine studies covering 1688 veneers gave. The studies in that review usually excluded people with parafunctions, that is, among others, clenching and grinding of the teeth. Where they were not excluded, patients most often received a night guard. Material did not differentiate that result markedly: feldspathic porcelain, leucite-reinforced ceramic and lithium disilicate came out similarly, although the last of these had noticeably fewer technical complications after a decade.
Now the part that concerns clenching. In the pairing of bruxism and veneers, more in the available data depends on the night guard than on the type of ceramic, although this rests on a single study. The risk of a veneer fracturing was twice as high in people with bruxism as in the rest. Within the bruxism group itself, the night guard was what counted. In those who did not wear one the risk was seven times as high as in those who did. A risk twice as high does not, at the same time, mean that fracture is the rule. Both figures come from one study included in the review rather than from pooling them all, and that is how they have to be read.
There is one more condition, rarely talked about, that decides most where clenching is involved: a veneer bonded to enamel holds better than a veneer bonded to dentine - and in someone who has been wearing their teeth down for years, enamel at the incisal edges simply runs short. What exactly is removed during preparation and how much tissue is left is covered by a separate article: do veneers damage teeth.
There is also a limit. When there is no enamel left at the incisal edges, when wear has reached the dentine over a large area, or when the occlusal vertical dimension across the whole arch needs rebuilding, a veneer is not the first choice - even if that is what the patient came for.
Crowns and bridges: which material withstands overload better?
The answer is this: in the available data the type of material differentiates the outcome more weakly than is usually assumed.
A crown on a patient’s own tooth holds in roughly nine cases out of ten at five years and in eight out of ten at ten years. This was calculated on 1037 crowns followed for eleven years on average at a Swedish university clinic, where four in five of the restorations were made by students. Higher results have been reported in other centres, although within that study itself the operator did not differentiate survival. Bruxism raised the risk of losing a crown in this group by roughly half. The difference was marked enough that it is hard to put down to chance. A figure like that does not, however, settle the fate of any single crown. The type of material did not affect survival at all. The outcome depended on whether the crown stood at the front, whether the tooth was vital, and whether the patient clenched.
There is also a result pointing the other way. In none of the four groups compared did a single technical complication occur over three years. Survival of molar crowns made of lithium disilicate and of zirconia ran from 95.2 to 100 per cent. When complications on the tooth under the crown were counted as well, the bruxism groups came out worse. Restorations free of any complication came to 81.5 and 85.7 per cent, against 95.2 and 95.8 in the groups without bruxism. That difference was small enough to have arisen by chance. The study covered 93 patients with random allocation of material. Sleep bruxism was diagnosed in it by questionnaire, clinical examination and a portable recording of muscle activity during sleep. Night guards were deliberately not used.
A monolithic crown is made throughout of a single material. A veneered crown has a hard core, that is a framework, covered by a thinner layer of ceramic - and it is that layer which chips.
Three years is too short and 93 people too few to detect a difference of moderate size. This result does not overturn the observations from long cohorts. What it does show is that in this short follow-up a single monolithic crown on a molar was not the element that failed first.
About multi-unit restorations on a patient’s own teeth the studies cited say nothing: the Swedish cohort covered single crowns only, and bridges were excluded from it. With an extensive restoration, on the other hand, the price of one complication rises, because a repair concerns the whole construction.
| Solution | What fails first | What the clinical data show |
|---|---|---|
| Feldspathic porcelain veneer | chipping of the edge, fracture | a decade with no loss of the restoration in more than 19 cases out of 20; the most technical complications of the three ceramics |
| Lithium disilicate veneer | marginal leakage, fracture | survival as above, markedly fewer technical complications after a decade |
| Zirconia veneer | no data | only 40 restorations followed for 2.6 years on average; there is nothing here to draw a conclusion from |
| Monolithic crown (zirconia, lithium disilicate) | wear of the surface, decementation | not a single failure of the crown itself over three years, including in people with confirmed sleep bruxism and with no night guard; short follow-up, 93 patients |
| Ceramic-veneered crown on a framework | chipping of the veneering layer | chipping is the typical complication of layered restorations |
| Full-arch implant-supported restoration, acrylic on metal | wear of the material, screw loosening | wear complications reported most often among the solutions assessed |
The table sets out modes of failure and is not a ranking. The choice between all-ceramic and zirconia crowns depends on the tooth and on its place in the arch. Bruxism and implants looks quite different in the data.
Bruxism and implants: what disappears along with the periodontal ligament
Here the difference follows from anatomy and it is qualitative.
A natural tooth hangs in its socket on the periodontal ligament - a thin layer of fibres that cushions pressure and carries sensation; an implant is fused directly to bone, so force goes straight into the bone and into the prosthetic components, with no cushioning and no feedback signal telling you to ease off.
Bruxism does not rule implants out. For years it was treated as a contraindication, and today’s literature does not sustain that position. It does raise the risk, and that can be seen in the figures. The odds of losing an implant were roughly twice as high in people with probable bruxism as in the rest. This was calculated on 2105 implants in the first group and 10 264 in the second, pooling 27 studies; the length of follow-up did not change the result. That figure compares the two groups with each other and no more. On its own it does not say how often implants are lost. So odds twice as high do not mean that one person in two with bruxism will lose the implant.
That figure has two limitations. “Probable bruxism” meant in these studies at least this much: the patient reported clenching or grinding and a dentist confirmed it on examination. Instrumental measurement was not required. Bone loss around the implants the authors were unable to count separately: the studies reported it as a whole, without breaking it down into people who grind and the rest. The association of bruxism with marginal bone loss therefore remains unresolved, while the mechanical complications are well documented: screw loosening and screw fracture, abutment fracture, fracture of the framework.
Bruxism and implants is therefore not a question of whether the implant will integrate. It is a question of servicing the construction over the years that follow. In everyday clinical practice at Modern Dental & Orthodontics (Klinika MDO) we meet the situation that a patient remembers an appointment when something hurts, and a loosened screw does not hurt at all.
A protocol for protecting prosthetic work
Protection is spread over three stages, and none of them replaces the others.
Before treatment. Diagnosing bruxism and its form. In 2025 an international expert panel updated the definitions of bruxism and the grading of diagnostic certainty: a history is weighted one way, a clinical examination another, and instrumental measurement another again. Bringing the force under control means something different in each form. In the sleep form the night guard does the work: it protects the restoration, but it does not remove the habit. In the awake form the work is on the habit itself. How long this stage should last has not been established, and evidence from studies in people with implant-supported restorations is scarce.
The foundation is assessed separately: whether the margins of the restoration will rest on enamel or already on dentine, because the bond to enamel is more durable. Nobody has established a threshold below which a restoration is not made - the assessment is clinical, tooth by tooth.
During treatment. The safer design is one that can be serviced. The method of retention counts here: a screw-retained restoration can be removed, checked and screwed back, a cemented one usually cannot. Studies comparing the two forms of retention in bruxism are lacking, so the literature cited recommends neither of them. Beyond that, crowns on adjacent implants are splinted together.
The occlusion is set so that contacts are distributed evenly and so that it is not the new restoration that guides the mandible in lateral movements. Studies settling which occlusal scheme is the most favourable for implant-supported restorations do not yet exist.
After the restoration is fitted. A night guard and check-ups. Stress here means the force acting inside the material. Under a night guard, stresses in the implant fell by one third at low loading and by almost three quarters at high loading. The greater the force, the more marked that fall. This was measured on laboratory models, however, so the figures describe the behaviour of the material under study conditions. They do not measure the course of treatment in a patient. How the type of guard is selected is covered by the article on night guard types.
A check-up after the restoration is fitted has a different purpose in bruxism from an ordinary examination for caries, and the literature cited does not set the interval between visits - it is set individually. What is checked at that appointment is:
- the tightness of the screws in implant-supported restorations;
- the contact points, and whether the occlusion has shifted;
- the condition of the restoration’s surface and of the opposing teeth;
- the condition of the guard itself, because it too wears down and stops fitting.
What to do before prosthetic treatment begins
First the night guard and bringing the force under control, only then the fixed restoration. The order is sometimes reversed, and that is a planning error.
An approach the reverse of the customary one has been described: the guard is made before restorative treatment, the cause of the wear is brought under control on it, and only then does the work move on to a fixed restoration. Where several teeth are being restored at once, this order decides the whole plan, because changing the occlusal vertical dimension after the restorations have been cemented usually means making them again.
It is also worth establishing in advance what will happen if something fractures. A debonded restoration can often be reattached in a single appointment; a ceramic chip is sometimes polished or made good with composite in the mouth, but a fracture through the full thickness usually means making the restoration again. With implant-supported restorations this answer weighs more than the choice of ceramic, and it depends on the method of retention.
Frequently asked questions
Will veneers hold at all in someone with bruxism?
Usually yes, though on worse terms than in someone who does not clench their teeth. Most depends on how much enamel is left under the veneer, because ceramic holds better to enamel than to dentine. In one study the risk of a veneer fracturing was twice as high in people with bruxism, and among them seven times as high without a night guard as with one.
Can an implant fracture from grinding?
It can, though the literature cited does not give the frequency of such fractures. Bruxism and implants is above all the risk of damage to the intermediate components: screw loosening and screw fracture, abutment fracture, fracture of a framework supported on several implants. An implant fused to bone has none of the cushioning that the periodontal ligament gives at a natural tooth, so the load goes straight into the mechanical joints.
I have crowns or implants and the clenching was detected later. Do they have to be replaced?
Usually not. Replacement is not the default step: a guard is made over the existing restoration, the tightness of the screws and the contact points are checked, and what is replaced is whatever has actually fractured or worn. Bruxism and implants then comes down to a question of servicing, not of rebuilding. A suspicion of clenching is worth reporting to your dentist on its own, even if nothing hurts.
Is zirconia more resistant than glass ceramic?
In laboratory tests zirconia withstands higher loads. The translation into an outcome in a patient is nevertheless weaker than is assumed. In a study with random allocation, zirconia and lithium disilicate crowns produced not a single technical complication over three years, including in people with confirmed sleep bruxism. Complications on the tooth under the crown were more frequent, although that difference could have arisen by chance.
Does a night guard have to be worn permanently after prosthetic treatment?
Bruxism is not a condition that passes once the restoration is fitted, so protection is usually long-term. A night guard does not treat the cause of clenching: it takes the load onto itself and wears down instead of the restoration. For that reason it needs its fit checked periodically, and replacing from time to time.
Does the warranty cover a restoration fracturing from grinding?
What most often counts is whether the patient wore the recommended night guard and attended check-ups, rather than the type of ceramic. The details are set down by the practice in its warranty terms, however, and those differ between clinics. It is worth asking for those terms in writing before treatment begins and reading which situations are excluded from them.
What should you do when a crown has already fractured?
Keep the broken fragment and go to the practice, even when nothing hurts. A sharp edge cuts the tongue and the cheek, and an exposed tooth decays faster. Until the appointment nothing should be glued back on by yourself. The dentist will assess whether a repair will do, or whether the restoration needs making again.
Read more:
- Dental crowns Warsaw
- Night guard types — hard, soft or repositioning splint. How the type is selected
- How long do veneers last? Durability of porcelain and composite in the light of studies
- How Long Does All-on-4 Last? Durability, Reviews and Other Important Information
- Zirconia, all-ceramic or metal-based crown? A comparison of modern prosthetic solutions
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.
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