An inlay or onlay is a custom-made restoration, usually of ceramic, composite resin or gold, that is made outside the mouth and then bonded or cemented into a back tooth. It repairs damage that is too large for an ordinary filling but not severe enough to need a full crown, so more of your natural tooth is kept.
What are inlays and onlays?
Inlays and onlays are indirect restorations: instead of being shaped directly in your mouth like a normal filling, they are made to measure, usually in a dental laboratory, from an impression of the prepared tooth, and then fixed in place.
The difference is how much of the tooth they cover:
- An inlay sits inside the tooth, between the raised points of the chewing surface, which are called cusps.
- An onlay extends over one or more cusps to protect them. When it covers most of the chewing surface, it is sometimes called an overlay.
Both are used mainly on premolars and molars, the back teeth that do most of the chewing.
The middle ground between a filling and a crown
A direct filling is quick and keeps the most natural tooth, but a very large filling must resist chewing forces on its own and can leave thin, fragile walls. Our article on how composite white fillings are done and how long they last explains where fillings work well.
A crown covers the whole tooth down to the gum line, so the tooth has to be reduced on every side; our guide to types of dental crowns and their differences explains the options. Inlays and onlays sit between the two: they reinforce the tooth where it is weak and leave healthy enamel untouched elsewhere.
| Option | How it is made | Tooth removed | Typical use |
|---|---|---|---|
| Filling | Shaped in the mouth | Least | Small to moderate cavities |
| Inlay | Made to measure | Little | Larger cavities, strong cusps |
| Onlay | Made to measure | Moderate | Weak or broken cusps |
| Crown | Made to measure | Most | Badly damaged or cracked teeth |
When is an inlay or onlay a good option?
Typical situations include:
- An old, large filling that is breaking down or leaking.
- A cavity too wide for a filling to be expected to last, while the outer walls of the tooth are still sound.
- A chipped or broken cusp on a back tooth.
- A back tooth after root canal treatment that still has enough healthy structure; read why a crown is often recommended after root canal treatment to see why covering the cusps matters.
An inlay or onlay is usually not suitable when very little tooth remains, when there is a deep crack or when biting forces are very heavy. A full crown, such as a zirconia crown made step by step, is then often more predictable. Active decay or gum disease is treated first.
Materials: ceramic, composite and gold
Ceramic
Ceramic inlays and onlays are tooth-coloured, resist staining and can be matched closely to your enamel. They are bonded with an adhesive, which helps support the remaining tooth walls. Ceramic is hard but can chip if it is very thin or if you grind heavily.
Composite resin
Composite is the tooth-coloured resin of white fillings, here hardened outside the mouth for extra strength. It is gentle on the opposing teeth and easy to repair, but over the years it may wear and stain more than ceramic.
Gold
Gold alloys have the longest track record. They are very durable, need little thickness and are kind to the opposing teeth, but their colour means they are mostly chosen for back teeth that are not visible.
The choice is made after an examination, based on the position of the tooth, the size of the restoration, your bite, any grinding habit and your preferences.
The treatment step by step
In most cases an inlay or onlay is completed in two visits, roughly one to two weeks apart, depending on the laboratory. Each visit usually takes about an hour.
- Examination: the tooth, nerve and gum are checked, usually with an X-ray.
- Preparation: under local anaesthesia, the old filling and any decay are removed and the cavity is shaped so the restoration can slide into place.
- Impression and shade: an accurate impression is taken and, for tooth-coloured materials, the shade is chosen.
- Temporary filling: the tooth is closed while the restoration is being made.
- Fitting: at the second visit the fit, contacts and bite are checked, then the inlay or onlay is bonded or cemented and polished.
Does it hurt?
Thanks to local anaesthesia, most people feel pressure and vibration rather than pain. Mild sensitivity to cold or biting for a few days afterwards is common and usually settles on its own. If you feel anxious, say so: each step can be explained and paused.
Aftercare, lifespan and possible problems
Until the final restoration is fitted, avoid sticky and very hard foods on that side.
- Brush twice a day with fluoride toothpaste and clean between your teeth daily, because the edge of the restoration can still decay.
- Avoid biting ice, nutshells or packaging, and ask about a night guard if you grind your teeth.
- Keep regular check-ups and scaling.
With good care, well-made inlays and onlays often last ten years or more. Possible problems include temporary sensitivity, loosening, chipped ceramic, decay at the edge and, occasionally, inflammation of the nerve in a tooth that was already deeply decayed, which may then need root canal treatment.
What determines the cost
There is no fixed price for an inlay or onlay. The cost depends on the material, the size of the restoration, the laboratory work, the number of teeth and whether other care, such as root canal treatment, is needed first. A consultation allows the dentist to give you a clear, personalised plan.
Inlays and onlays at Ajam Dental Clinic in Tripoli
Ajam Dental Clinic offers inlays and onlays as part of its prosthodontic and restorative treatments, alongside composite fillings and crowns. Prosthodontic work is the focus of Dr. Abdel Rahman Ajam, who holds a DDS and an MSc in Aesthetic and Prosthetic Dentistry. When a tooth needs root canal treatment first, this is carried out at the clinic by a visiting specialist endodontist.
Patients come to our clinic on Fouad Chehab Boulevard from across Tripoli — Abu Samra, Al-Qobbeh, El Mina, Al-Haddadine and the old souks — as well as from Akkar and the rest of North Lebanon. If an old filling is breaking or a back tooth feels weak, contact us on WhatsApp to book a consultation.
Frequently asked questions
Is an onlay as strong as a crown?
In many situations an onlay protects a back tooth very well, because it covers and holds together the weak cusps much as a crown does. The difference is that it leaves the healthy sides of the tooth untouched. A full crown remains the stronger choice when little tooth is left, when there is a deep crack or when the tooth has lost most of its walls. Your dentist weighs these points during the examination and on the X-ray, and recommends the most conservative option that can be expected to last in your mouth.
Can my old silver filling be replaced with an inlay or onlay?
Yes, this is one of the most common reasons for an inlay or onlay. Old amalgam, or silver, fillings that are cracked, leaking or surrounded by new decay are often large, and replacing them with an even bigger filling can leave the tooth weak. After the old filling is removed, the dentist assesses how much sound tooth remains and then suggests a filling, an inlay, an onlay or a crown. An amalgam filling that is intact and causing no problems usually does not need to be replaced; the decision is based on the condition of the tooth.
Can an inlay or onlay be done in one visit?
Usually not. Because the restoration is made to measure after the tooth has been prepared, most inlays and onlays need two appointments, with a temporary filling in between. Some systems allow a ceramic restoration to be milled by computer and fitted on the same day, but the usual approach is a laboratory-made piece fitted at a second visit. What matters most is an accurate fit and careful bonding. Your dentist will tell you in advance how many appointments your treatment involves and how long the temporary filling needs to stay in place.
Will people be able to see my inlay or onlay?
Ceramic and composite inlays and onlays are tooth-coloured and the shade is matched to your own teeth, so in most cases they are hard to tell apart from natural enamel, especially on back teeth. Gold restorations are visible when you laugh or open wide, which is why they are mainly chosen for teeth at the very back of the mouth. If appearance is important to you, mention it at the consultation so that it is taken into account when the material is chosen.
What should I do if my temporary filling falls out or breaks?
Contact the clinic soon so the tooth can be closed again. A prepared tooth without its temporary filling can be sensitive, food and bacteria can enter the cavity, and the tooth or its neighbours can shift slightly, which may affect how well the final restoration fits. Until your appointment, keep the area clean with gentle brushing, avoid chewing on that side and avoid very hot, cold or sweet foods. Do not try to fix it with household glue or other improvised materials.
Are inlays and onlays used on front teeth or for children?
Rarely. Front teeth are thin and do not have cusps, so they are usually restored with composite bonding, veneers or crowns instead. In children, decayed baby teeth are generally treated with fillings or other approaches suited to teeth that will later fall out. At our clinic, all dental care for babies, children and teenagers is handled by Dr. Soumaya Ajam, who holds a University Diploma in Paediatric Dentistry, and she explains which restoration suits a young patient's tooth.
Have a question about your teeth?
Send a WhatsApp message to Dr. Abdel Rahman Ajam or Dr. Soumaya Ajam, or call the clinic to book a consultation.
This article provides general information for patients. It does not replace an examination by a dentist, who can advise you on your own situation.
