Inlays and Onlays

A filling made in the mouth may be enough

Many cavities, including fairly large ones, can be filled directly in the mouth with tooth-coloured composite. Two reviews, from 2023 and 2024, compared direct composite fillings with laboratory-made composite inlays and onlays in large back-tooth cavities, and reached different conclusions³. One found no significant difference; the other reported fewer failures with direct fillings⁴. Both rated the certainty of their evidence as very low, and neither covers ceramic onlays. No cavity size has been identified at which a filling stops being enough; the choice depends on how much of the walls and cusps remains.

An inlay or an onlay may suit

• Inlay: there is a large cavity or an old filling that needs replacing, but the remaining walls of the tooth are sound.
• Onlay: one or more cusps are weakened, cracked or broken and need covering, while the rest of the tooth is sound.

A crown may suit better

A crown may be recommended for a tooth that is badly damaged or broken, weakened by a large filling, root-filled, worn down or cracked⁵. The tooth is shaped all round to make room for a crown. Where the tooth allows, an inlay or an onlay removes less of the tooth. See our page on dental crowns for details.

Back teeth after root canal treatment

A root-filled back tooth can be restored with a filling, an onlay that covers the cusps, or a crown. A Cochrane review updated in 2015 found only one small study comparing a crown with a filling. It did not find any study⁶ comparing an inlay or onlay with a crown. So the evidence does not favour one option for every tooth; the decision rests on how much sound tooth is left. For root canal treatment, see our page on root canal treatment.

When extra care is needed

• Clenching or grinding. A review of ceramic onlays found that they appear to fail more often⁷ in people with this habit. The same review also found failure more often on root-filled teeth and on teeth further back in the mouth. Tell your dentist if you clench your teeth.
• A high risk of decay. One analysis looked at 2,816 composite fillings in back teeth followed for at least 5 years. Failure was more common⁸ in people at high risk of decay and in fillings that covered more surfaces of the tooth. That study was about fillings made in the mouth; even so, preventing decay matters for every restoration.

Assessment: can the tooth be restored this way?

The right option is decided at an examination, with X-rays where needed. The dentist looks at how much sound tooth is left and whether the walls and cusps are weakened or cracked. The dentist also checks whether the nerve of the tooth is healthy. Your bite, and any clenching or grinding, are taken into account as well. Your medical history, the medicines you take and whether you smoke are reviewed too.

Whichever restoration is chosen, decay in the tooth and any gum disease around it are treated first. For gum disease, see our page on gum disease treatment. If tests show that the nerve of the tooth has died or cannot recover, root canal treatment comes before the restoration.

• Leaving it alone. If the tooth has no decay, crack or pain that needs treatment, leaving it alone is also an option. An old filling that is still sound, for example, does not need replacing just because it is old. If there is decay or a fracture, waiting will not solve it; ask your dentist how long you can wait.
• Repairing the old filling. Studies comparing the repair of defective direct fillings with their replacement found no significant difference⁹ in the risk of failure. Only 3 studies were included in that review; the risk of bias was high and the certainty of the evidence very low.
• A filling made in the mouth. Tooth-coloured composite is shaped directly in the tooth and hardened with light. No laboratory is needed.
• Inlay. A piece made outside the mouth to fit the tooth is bonded into the space between the cusps.
• Onlay or overlay. The weak cusps are covered as well. The aim is to protect the biting surface of the tooth without reducing it as much as a crown does.
• Crown. It covers the whole visible part of the tooth. It is considered when little sound tooth is left.

All of these options are also available from dentists in the UK, and a UK opinion and written plan give you something to compare. You can say no, or ask to stop, at any stage. Once a tooth has been prepared, that step cannot be undone.

Materials and design choices

The design depends on how much of the biting surface needs covering. An inlay stays between the cusps, an onlay covers one or more cusps and an overlay covers all of them. The thickness of the restoration and the shape of the prepared tooth also matter; see the section on how inlays and onlays are made.

The materials used are:

• Ceramic. Tooth-coloured glass ceramics and porcelain. One of these is lithium disilicate, which you may see called e.max. That name comes from a manufacturer's product family, IPS e.max, which includes more than one ceramic.
• Resin-matrix ceramic and composite. Resin-based materials reinforced with ceramic particles.
• Gold. Gold inlays and onlays, like porcelain ones, are made in a dental laboratory to fit the tooth¹⁰. Gold is sometimes used on molars.

The material depends on the state of the tooth, your bite and your habits. Our sources do not rank one material above another.

Laboratory-made inlays and onlays are made to fit the tooth and usually need two appointments¹⁰. Your dentist plans the time between the appointments. Whether a local anaesthetic is needed is decided by your dentist according to the extent of the work. How the appointments fit a trip is covered in "Treatment in Antalya when you live in the UK".

How much of the tooth is removed depends on the decay, the old filling and any cracks. According to a review of ceramic onlays, at least 2 mm of ceramic on the biting surface⁷ has been linked with longer survival. So has a tooth shape that helps hold the onlay in place. This does not mean the same amount is removed from every tooth.

Risks and complications

• Fracture and chipping. The most common reason ceramic inlays and onlays fail is fracture or chipping of the restoration¹¹. Less often, the restoration comes loose or decay starts at its edge. Even when the cusps are covered, a crack in the tooth can progress.
• The nerve of the tooth. The figures here are from published studies, not our own records. A review pooled 37 studies. The teeth in these studies were alive at the start and were treated with indirect restorations such as crowns, partial restorations or bridge supports. In about 5 in every 100 of these teeth¹² the nerve lost its vitality. Studies that followed teeth for more than ten years found about 7 in 100. The certainty of this evidence is low. If that happens, the tooth needs root canal treatment to save it. The review does not show that this risk is lower for an onlay than for a crown.
• Decay. An inlay, an onlay or a crown does not protect the tooth from decay. New decay can start at the edge where the restoration meets the tooth.
• Sensitivity. After the treatment the tooth may be sensitive to hot and cold for a while.

Benefits and limitations

• In a laboratory study on plastic model teeth, full crown preparations removed about two thirds to three quarters¹ of the visible part of the tooth. For inlays and small bonded preparations the figure was about 5 to 27 per cent. A 2025 review, citing the same laboratory study, gives about 36 to 47 per cent¹³ for partial coverage restorations. These are laboratory values and give only a sense of scale. The studies do not show that leaving more tooth makes the tooth itself last longer.
• The restoration is made in a laboratory to fit the tooth, and ceramic ones are tooth-coloured.
• On a tooth that does not need a crown, the cusps can be covered without reducing the whole visible part of the tooth.

The limitations:

• It cannot be undone. Tooth is removed for an inlay or an onlay; the enamel and dentine removed do not grow back. From then on, the tooth needs a restoration to protect it.
• A laboratory stage. A laboratory-made inlay or onlay usually needs two appointments, and the tooth has a temporary filling in between.
• The long term is uncertain. Studies comparing onlays with crowns are short; which lasts longer over decades is not known.

After an inlay or onlay is bonded, you can usually return to your normal day the same day. The tooth may be sensitive for a while. If you had a local anaesthetic, do not eat until it has worn off. If your bite feels high in the first few days, tell your dentist; it can be adjusted.

Daily care

• Brush your teeth twice a day with fluoride toothpaste, and clean between your teeth every day with floss or an interdental brush.
• Do not bite hard objects such as ice, pens or nutshells.
• If you clench or grind your teeth, tell your dentist; they may suggest a night guard.
• Keep up regular check-ups. Once you are back in the UK, these are usually with a dentist in the UK.

If you are thinking about whitening, discuss it beforehand. Whitening does not lighten ceramic and composite restorations¹⁴ the way it lightens natural teeth; next to whitened teeth, the restoration can look darker.

In short: no single number of years can be given. The figures below come from published studies, not from the clinic's own results. They come from different patient groups and follow-up periods, and they are not enough to rank the options against each other. Staying in the mouth does not mean there were no problems or no repairs during that time. No filling lasts forever¹⁰; over time it can break, wear or change colour.

Ceramic inlays and onlays. A meta-analysis pooled studies with more than five years of follow-up. Of every 100 glass-ceramic and porcelain inlays, onlays and overlays, about 92 to 95 were still in the mouth after five years¹¹. After ten years the figure was about 91. Another review of ceramic onlays found large differences⁷ between the results of individual studies.

Partial coverage in randomised trials. A meta-analysis of randomised trials looked at ceramic onlays and partial crowns on back teeth. It estimated three-year survival at about 94 in every 100 restorations in lithium disilicate and 89 in resin-matrix ceramic¹³. None of the trials gave a formal definition of survival. The difference was not significant and the certainty of the evidence was low. According to the authors, the long-term performance of these restorations is uncertain.

Onlay or crown? Studies comparing onlays or partial crowns with full crowns on back teeth found no significant difference² in survival at one and three years. Most of these studies were not randomised, the group sizes were very unbalanced and follow-up was short. Another review rests on only 3 studies and focuses on back teeth with MOD cavities, which involve three surfaces (front, biting and back). It writes that an onlay may be an advantageous alternative to a crown, but that the evidence is not enough to draw meaningful conclusions¹⁵.

Crowns. A 2026 review looked at single crowns on natural teeth. The four material groups reported here are monolithic lithium disilicate, porcelain-veneered zirconia, porcelain fused to metal and monolithic zirconia. Of every 100 crowns in these groups, about 97 to 99¹⁶ were still in the mouth after five years.

Root-filled teeth. In a review of bonded onlays and overlays on root-filled teeth, with no comparison group, 121 of 1,254 restorations failed¹⁷. Failure was about 4 in 100 restorations in studies lasting 2 to 4 years. It was about 11 to 21 in 100 in studies lasting 7 years or more. According to the authors, in most failures the tooth appeared restorable; however, some of the failures involved loss of the tooth¹⁷.

The outcome depends on the tooth, the bite, the material, the fit of the restoration and how it is cared for.

See a dentist if any of the following happens after the restoration. While you are in Antalya, that is the clinic; once you are home, it is usually your own dentist in the UK.

• Sensitivity that does not settle, or keeps getting worse
• Pain brought on by something hot that lingers afterwards
• Toothache that lasts more than 2 days¹⁸, or that does not go away when you take painkillers
• Pain when you bite, or a bite that feels high
• A crack, chip, looseness or the restoration coming out (keep the piece and do not glue it back yourself)
• Food catching at the edge of the restoration, bleeding gums or a dark line at the edge
• The temporary filling falling out
• Pain that starts on its own or wakes you at night

Throbbing pain, swelling in your face or a high temperature are not expected after an inlay or onlay. See a dentist where you are without delay, and do not wait for the clinic's reply. If you think you have a dental abscess, do not wait. An abscess does not go away on its own and needs urgent treatment by a dentist¹⁹. In England, if you do not have a dentist or cannot get an emergency appointment, the NHS says to call 111 or use 111 online¹⁹. Elsewhere in the UK, check the urgent dental care route where you live.

Emergencies. The NHS lists the following as needing urgent medical help¹⁹. Do not wait for a dental appointment or for the clinic's reply. In the UK, call 999 or go to A&E. In Turkey, the emergency number is 112.

• Difficulty breathing, speaking or swallowing
• A lot of swelling inside your mouth
• Swelling around your eye or in your neck¹⁸
• Pain in the eye, or sudden problems with your sight
• Difficulty opening your mouth

Before you fly home

Make sure the inlay or onlay has been bonded, your bite checked and the surface polished. Make sure too that you have written care instructions, a written record of the treatment and a way to reach the clinic.

Once you are back in the UK

If a problem comes up that is not urgent, write to the clinic and send photographs, and see your own dentist in the UK. If you do not have a dentist, use the urgent dental care route described above for urgent problems (in England, NHS 111). In the emergencies above, do not wait for a reply.

Your treatment is provided by our clinic in Antalya, Turkey, and carried out there by the clinic's dentists. The inlay or onlay itself is usually made in a dental laboratory; ask which laboratory makes it, and where.

In Turkey, as in the UK, a dentist does not have to be a specialist to make inlays and onlays. Turkish law authorises every dentist²⁰ to diagnose and treat the teeth, the gums and the tissues of the mouth and jaw. It ties the specialist title to a specialist certificate²⁰, issued and registered by the Ministry of Health²¹. Two of the nine dental specialties the law sets²⁰ are prosthodontics (in Turkish, protetik diş tedavisi) and restorative dentistry (restoratif diş tedavisi). The prosthodontics training curriculum includes onlays and crowns²². In the UK, dentists do not have to join a specialist list²³ to practise a specialty. They may use the title "specialist" only if they are on the GDC's list.

Ask who will examine you, prepare the tooth and bond the inlay or onlay. Ask what their title is, where they qualified, and whether they hold a Ministry-registered specialist certificate, and in which specialty. Ask for the answers in writing.

A laboratory-made inlay or onlay usually needs two appointments¹⁰. At the first, the tooth is prepared and an impression or scan is taken; at the second, the restoration is bonded. In between, the restoration is made in the laboratory and the tooth has a temporary filling. How many days you need in Antalya depends on how many teeth are treated and on the laboratory stage. It also depends on whether decay or gum disease needs treating first, or the tooth needs root canal treatment. Other treatment planned in the same trip matters too. If you are thinking about whitening, raise it before the plan is made, because the shade of the restoration is chosen to match your teeth.

Before you book, ask for a written preliminary plan based on the photographs and any X-rays you send. It should set out the appointments and how many days they need. Tell the clinic about any medical conditions and the medicines you take. The preliminary plan is not a diagnosis or a final treatment plan. The General Dental Council says you should always be assessed by a qualified dentist before being given a treatment plan and cost estimate²⁴. For an inlay or onlay, that assessment is the examination in Antalya. It confirms or changes the preliminary plan, and with it the days and the cost. If it changes, ask for the revised plan in writing before treatment starts.

The final choice between a filling, an inlay, an onlay and a crown is made at the examination. How much of the tooth is removed depends on the decay, the old filling and any cracks. So ask for the plan to state what would change for your trip if the examination points to a different restoration. You can say no, or ask to stop, at any stage. Once a tooth has been prepared, that step cannot be undone. Ask before you book what you would pay if an inlay or onlay turns out not to suit the tooth. Ask too what you would pay if you decide not to go ahead.

Plan the trip so that the inlay or onlay is bonded before you leave. A temporary filling is not the finished treatment. If your trip may end before the restoration is bonded, agree in writing who will finish the treatment, where and when. If your dentist suggests a night guard, ask whether it will be made before you leave or by your dentist in the UK.

Inlays and onlays are also made by dentists in the UK, and a UK opinion and written plan give you something to compare.

Flying. A 2023 review of flying after dental treatment suggests waiting at least 24 hours after restorative treatment²⁵, and longer after surgical procedures. These times assume there is no pain, swelling or bleeding where you were treated. The authors note that the research is limited and comes mainly from military aviation. Treat it as a starting point for your dentist's advice, not as a rule.

Your own dentist

The UK General Dental Council suggests talking to your own dentist²⁴ before you go. They need to know the plan in case problems come up later. If you do not have a dentist in the UK, it helps to find one before you travel.

An inlay or onlay needs check-ups for as long as it is on the tooth, and over time it may need repair or replacement. These visits are usually with a dentist in the UK, so plan them before you travel. National guidance in England (NICE) says the interval between check-ups should be set for each person according to their risk²⁶ and discussed with them.

Your records

Ask for a written record of the treatment to take back to your dentist. It should show which teeth were restored, whether each has an inlay or an onlay, and the material used. Ask for copies of your X-rays too. The NHS lists exchanging medical records and arranging aftercare back home²⁷ among the things to consider before treatment abroad. In Turkey, the health tourism regulation entitles international patients to an itemised bill. On request, they also get free copies of the records of the materials used, the tests and the imaging²⁸.

If a problem appears after you are home

Problems that appear after you return are usually first seen by your own dentist in the UK. For a problem that is not urgent, you can also write to the clinic and send photographs. Before you start, ask for the clinic's written terms. Check what they say about an inlay or onlay that breaks, chips or comes out after you are home. Ask whether a repair would be done in the UK or on another trip, and who pays for the repair and the travel.

What the NHS does and does not do

If you later need NHS dental care in England or Wales, having been treated abroad does not by itself shut you out of it. An NHS dental practice that accepts you for a course of treatment, not only an urgent appointment, provides clinically necessary treatment, with your consent²⁹. This means the treatment that every NHS dental contract must offer, and it may not be a new inlay or onlay. However, the free repair or replacement²⁹ an NHS practice can give for its own work does not apply to work done by another provider. The NHS also states that it is not liable for negligence or failure of treatment²⁷ when you have treatment abroad. On the NHS England routes that fund planned treatment abroad, you cannot get reimbursement for dental treatment³⁰. Ask any dentist about the cost before they repair or replace an inlay or onlay.

The NHS guidance quoted here is for England, and for England and Wales where stated. Scotland and Northern Ireland have their own NHS rules, which this page does not cover; if you live there, check the arrangements.

Travel insurance

The NHS says that most travel insurance policies will not cover you for planned treatment abroad²⁷, so you may need specialist cover. Tell your insurer about your plans.

The General Dental Council lists questions to ask before treatment abroad²⁴. Below are its questions, some of them combined, with what this page can answer today and what to ask for in writing. Question 10 is one of our own.

1. Who will carry out my treatment, and what are their qualifications? The treatment is provided by our clinic in Antalya, Turkey, and carried out there by the clinic's dentists. Ask for the name of the dentist who will prepare the tooth and bond the inlay or onlay. Ask where they qualified and what their title is (see who carries out the treatment, above).
2. Will the dentist speak English, or will there be a translator? Ask before you book who will explain the plan, the consent form and the aftercare instructions to you, and in which language.
3. Are you regulated by a professional body and registered with it? The GDC notes that it cannot guarantee that other countries have an equivalent regulator²⁴. In Turkey, a health facility needs an authorisation certificate²⁸ from the Ministry of Health to treat international patients. Authorised facilities appear in a register the Ministry publishes³¹, so you can check it yourself. The authorisation belongs to the facility, not to the dentist, and it says nothing about the result of your treatment. Ask for the treating dentist's own registration details as well. See health tourism authorisation.
4. How many times have you carried out this treatment, what are your rates of success and complications, and can you give references? The figures on this page come from published studies, not from the clinic's own results. We publish no figures of our own yet, and this page carries no patient reviews. Ask for the clinic's figures in writing, and how they were collected.
5. Is the work guaranteed, are the terms in writing, and for how long do they apply? This page makes no guarantee. Ask for the clinic's written terms for an inlay or onlay that breaks, chips or comes out, and for handling complications. Read them before you commit. Check how long they apply, what they exclude, and whether they cover a repair after you are back in the UK.
6. What aftercare do you provide, and who can I contact after the treatment? For a problem that is not urgent, you write to the clinic and send photographs. Check-ups, and problems that need someone to look in your mouth, are with a dentist in the UK, usually your own. Ask which channel to use, in which language, and how quickly you can expect a reply.
7. If there are complications, or I am unhappy with the result, who pays for further treatment, extra flights and the hotel? Is further treatment included in the cost? Ask for the answer in writing before you commit.
8. Do you have insurance to cover this treatment? In Turkey a facility treating international patients must take out complication insurance for surgical and interventional procedures carried out in an operating theatre²⁸. That does not by itself tell you whether your treatment is covered, so ask which procedures in your plan, if any, fall under it. Ask too, in writing, whether the clinic or the treating dentist holds insurance for complications or errors, what it covers and whom it protects.
9. Do you have a complaints system, and can I see a copy? Ask for it before treatment. The GDC says it cannot resolve complaints or help with refunds³²; its investigations concern the dentists on its own register. Turkey's health tourism regulation makes the facility responsible for complications and medical malpractice arising after the health service it provided²⁸.
10. What happens if the examination shows that an inlay or onlay is not right for my tooth? A filling or a crown may suit the tooth better, and the plan, the days and the cost change with it. You can say no, or ask to stop, at any stage; once a tooth has been prepared, that step cannot be undone. Ask before you book what you would pay in that case.

The NHS names warning signs to think about before booking any treatment abroad. They are a hard sell, a lack of information, pressure to make a quick decision, no discussion of possible complications, and no mention of aftercare³⁰. Apply them to this clinic too.

This page does not give prices. A treatment plan is prepared for you after an examination. The main factors are:

• Which of a filling, an inlay, an onlay or a crown suits the tooth
• The chosen material
• Any treatment needed first: decay, gum treatment or root canal treatment
• A night guard, if needed
• Repair or replacement that may be needed over time
• The number of trips the appointments need

Ask for your plan in writing, including what it covers and what will be done, and where, if the restoration breaks or comes out. Ask too who pays for further treatment and extra travel if there is a complication.

Ask whether the examination and any X-rays are included. If you are comparing with a quote from a UK practice, compare what each one includes, item by item. Check too whether both propose the same restoration for each tooth.