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 recent reviews 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. A crown is fixed in place and you cannot take it out yourself, and the tooth is shaped all round to make room for it. 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 2015 Cochrane update searched for studies up to 2015. It found only one small study comparing a crown with a filling, and did not find any study⁶ comparing an inlay or onlay with a crown. So no option can be said to be always the best; 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 and the medicines you take 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.

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, lithium disilicate, is best known under the brand name e.max.
• 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 "If you are coming from abroad".

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. 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 figures here are from published studies, not from our own records. 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, such as onlays and partial crowns. 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 always depends on a restoration.
• 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 to your regular check-ups.

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. See our page on teeth whitening for details.

In short: no single number of years can be given. The rates below come from published studies, not from our own records. 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 had defined survival formally. 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? A 2022 review looked at studies comparing onlays or partial crowns with full crowns on back teeth. It 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:

• Sensitivity that lasts longer than a week or keeps getting worse, or pain that starts with heat and lingers
• 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

Emergencies. Throbbing pain, swelling in the face or a fever mean you should see a dentist where you are without delay. Do not wait for the clinic's reply. If a swelling makes it hard to breathe or swallow, or spreads quickly across your face or neck, do not wait for a dental appointment. Go to an emergency department wherever you are. In an emergency, call the emergency number of the country you are in; in Turkey it is 112.

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 and a way to reach the clinic. Take the written record of your treatment with you for your dentist at home.

Once you are home

If a problem comes up that is not urgent, write to the clinic and send photographs. Photographs do not replace an examination, so see your dentist at home as well. In the emergencies above, do not wait for a reply.

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, you receive a written preliminary plan with the appointments and how many days they need. It is based on your photographs and any X-rays you send. Tell the clinic about any medical conditions and the medicines you take. The examination confirms or changes the plan, and with it the days and the cost. If it changes, you receive the revised plan in writing before treatment starts. You can say no, or ask to stop, at any stage. Once a tooth has been prepared, that step cannot be undone. 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.

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 at home.

Flying. A 2023 review of flying after dental treatment suggests waiting at least 24 hours after restorative treatment¹⁸, 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 dentist at home. Talk to your own dentist before you go. They need to know the plan in case problems come up later. If you do not have a dentist where you live, 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 likely to be with a dentist where you live. Ask for a written record of the treatment to take back to them. It should show which teeth were restored, whether each has an inlay or an onlay, the material used, and copies of your X-rays. 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 imaging¹⁹. UK guidance (NICE) says the interval between check-ups should be set for each person according to their risk²⁰; agree it with your dentist at home. Before you travel, check the rules of the health service or your insurer in the country where you live about care after treatment abroad.

Questions to ask before you commit. Before you agree to treatment abroad, ask:

1. Who will carry out my treatment, and what are their qualifications?
2. Are you regulated by a professional body and registered with it?
3. Is the work guaranteed, are the terms in writing, and for how long do they apply?
4. What aftercare do you provide, and who can I contact after the treatment?
5. If there are complications, who pays for further treatment, extra flights and the hotel?
6. Do you have a complaints system, and can I see a copy?

A longer list, with our answer to each question, is on our page about dental treatment abroad.

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.