Crowns, onlays and inlays: the right restoration for each tooth

Crowns, onlays and inlays are laboratory-made restorations that rebuild a tooth when a filling would be too large to last. At Dental & Wellness London in Islington, Dr Vishal Patel plans them on one principle: use the smallest restoration that will give a stable, long-term result. That often means an onlay or inlay rather than a full crown, because it keeps more of your own tooth.

This page explains how each restoration works, how to tell which one a tooth needs, the onlay vs crown and inlay vs onlay decisions, what the process involves, how long they last, the risks and what they cost. If you live or work nearby, our dental crowns in Islington page covers local appointments and getting to the clinic in more detail.

What are crowns, onlays and inlays?

All three are made outside the mouth, usually in ceramic, from a precise digital scan, and then bonded or cemented to the prepared tooth. The difference is how much of the tooth they cover.

• An inlay sits inside the tooth, filling a cavity between the cusps (the raised points on a back tooth). It is the most conservative of the three.
• An onlay fills the cavity and also covers one or more cusps. It protects weakened walls of the tooth without removing the healthy structure that a crown would require.
• A crown covers the whole visible tooth, down to the gum line. It gives complete protection where a tooth has lost a lot of structure, has cracked, or has had root canal treatment.

Because ceramic inlays and onlays are made in a laboratory and bonded, they are stronger and better sealed than a very large direct filling, and they can be shade-matched to sit quietly within your smile. Where the cavity is small or medium, a white filling placed directly in one visit remains the more conservative choice.

How we decide which restoration a tooth needs

The decision is clinical rather than cosmetic. We look at how much healthy tooth remains, the thickness of the walls around the cavity, whether there are cracks, where the tooth sits in your bite, and whether it has been root-filled. Our working order is simple: composite where the tooth can support it, an inlay or onlay where a filling would be too large, and a crown only where the tooth genuinely needs full coverage.

Onlay vs crown

An onlay replaces and protects the weakened parts of a tooth while leaving its healthy walls in place. A crown requires the tooth to be reduced on every side. Where both would work, an onlay is usually the better long-term choice because it removes less tooth and keeps the margin above the gum, where it is easier to clean and monitor. A crown is the right answer when too little sound tooth remains for an onlay to hold, or after root canal treatment on a back tooth, which is more prone to fracture.

Inlay vs onlay

The question is whether the cusps are strong enough. If the cavity sits between sound cusps, an inlay is enough. If one or more cusps is thin, cracked or undermined, covering it with an onlay prevents the tooth splitting under biting load. We assess this with magnification, photographs and the bite, and we explain what we see before recommending anything. Our guide to chipped and cracked teeth explains how small fractures develop and why early protection matters.

Who crowns, onlays and inlays suit

These restorations are typically recommended for:

• large or failing old fillings, including old amalgam fillings that have cracked the tooth around them;
• cracked or fractured back teeth, particularly where biting is painful;
• teeth weakened by decay where too little structure remains for a direct filling;
• back teeth after root canal treatment, which usually need cuspal protection;
• worn teeth, where restoring height and shape protects the bite.

They are not the answer for every problem. A tooth with active gum disease or unresolved infection has to be treated first. A missing tooth needs a different solution, such as a dental implant or a bridge. And where the concern is the appearance of front teeth rather than their strength, porcelain veneers or bonding may be more conservative. If you grind or clench, we address that alongside the restoration, because grinding is a common cause of cracked teeth and failed restorations (see teeth grinding and bruxism).

Materials compared

• Ceramic inlays and onlays are bonded to the tooth, which strengthens what remains and seals the margins well. They are tooth-coloured and resist staining.
• Porcelain-bonded crowns have a metal substructure under the porcelain. They are strong and suit back teeth under heavy load, though a thin dark line can sometimes show at the gum over time.
• Full-ceramic (Emax) crowns contain no metal, transmit light like natural enamel and suit teeth where appearance matters, as well as many back teeth. They are our usual choice where the bite allows.

We recommend the material that suits the position of the tooth, your bite and how visible it is, and we explain the reasoning in your written plan.

The process, step by step

1. Assessment. A dental examination (£65, 30 minutes) or, if you are in pain, a dental problem assessment (£75). We take X-rays where needed, check for cracks and assess the bite and gums.
2. Written plan. You receive the options, the recommended restoration and its cost in writing before any treatment.
3. Preparation. Under local anaesthetic, decay and old filling material are removed and the tooth is shaped. A digital scan is sent to the laboratory and a temporary restoration is fitted.
4. Laboratory work. The ceramic is made over roughly two weeks.
5. Fitting. We check the fit, contact points, colour and bite, then bond or cement the restoration permanently.
6. Review. We check the bite and gum response at your next visit, and keep an eye on the restoration at routine examinations.

Results, longevity and aftercare

Well-made ceramic restorations are durable, and many last 10 to 15 years or longer with good care, although results vary. The most common reasons they fail are new decay at the edges, grinding and gum disease, all of which are largely preventable. Brush twice a day, clean between the teeth daily, keep up with 30-minute hygienist appointments and regular examinations, and wear a night guard if we advise one. Avoid biting on ice, pen lids or very hard foods with restored teeth.

Some sensitivity to temperature in the first days after fitting is normal. If a restoration feels high, sharp or loose, or sensitivity persists beyond a couple of weeks, contact us so we can check it.

Risks, and how we reduce them

• Loss of tooth structure. Any preparation is irreversible. We choose the most conservative restoration that will last and avoid crowning teeth that an onlay could protect.
• Nerve irritation. Deep decay or extensive preparation can inflame the nerve, and occasionally a tooth later needs root canal treatment. We assess the nerve before treatment and protect it during preparation.
• Fracture or debonding. More likely with heavy grinding. We check the bite carefully and advise on protection.
• Decay at the margins. Placing margins where they can be cleaned, and regular hygiene, reduces this risk.
• Sensitivity. Usually short-lived; see sensitive teeth for what is normal and when to call.

Crown, onlay and inlay cost in Islington and London

Our fees are set per restoration and confirmed in writing before treatment:

• Ceramic inlay: £750
• Ceramic onlay: £850
• Porcelain-bonded crown: £950
• Full-ceramic (Emax) crown: up to £1,200

The dental examination is £65 and the dental problem assessment £75. Root canal treatment, where needed first, is £550 to £950; our article on root canal cost in the UK explains what affects that range. 0% APR finance over 12 months via Tabeo is available, subject to status. When comparing dental crown cost across London, check whether temporaries, laboratory fees and the review are included; ours are.

Why choose Dental & Wellness London

Restorations are planned by Dr Vishal Patel, BDS (Liverpool), MSc Aesthetic & Restorative Dentistry (Manchester), GDC 103127, a member of the American Academy of Cosmetic Dentistry with around 20 years in dentistry and over 15,000 cases. His postgraduate training is in restorative dentistry, which is the discipline behind deciding when a tooth needs an onlay and when it needs a crown. We do not replace sound restorations without a clinical reason, and where a tooth can be left alone, we say so. You can read more about how we approach broader restorative and cosmetic work on our cosmetic dentistry page.

Common questions about crowns, onlays and inlays

Is an onlay better than a crown?

Often, when the tooth allows it. An onlay protects the weakened parts of a tooth while keeping its healthy walls, so less tooth is removed and the edge usually sits above the gum where it is easy to clean. A crown is better when too little healthy tooth remains, or after root canal treatment on a heavily restored back tooth.

How much does a dental crown cost in London?

At our Islington clinic, a porcelain-bonded crown is £950 and a full-ceramic Emax crown up to £1,200. A ceramic onlay is £850 and an inlay £750. Your written plan confirms the exact restoration and fee after a £65 examination, and 0% APR finance over 12 months via Tabeo is available, subject to status.

How long do crowns and onlays last?

With good care, many ceramic crowns and onlays last 10 to 15 years or longer, although results vary. The main causes of failure are new decay at the edges, grinding and gum disease. Daily cleaning between the teeth, regular hygiene appointments and a night guard where advised all help a restoration last.

Does getting a crown or onlay hurt?

Preparation is done under local anaesthetic, so most people feel pressure and vibration rather than pain. Some tenderness of the gum and sensitivity to cold is common for a few days. If the bite feels high or sensitivity persists beyond two weeks, we see you to check and adjust it.

Do I need a crown after root canal treatment?

For back teeth, usually yes, or at least an onlay covering the cusps. Root-filled back teeth are more prone to fracture under biting forces, and cuspal protection reduces that risk. Front teeth that have lost little structure can sometimes be restored with a filling instead. We assess each tooth individually.

If you are still weighing up your options, our overview of emergency dentist in Islington brings them together in one place.

Getting here

Dental & Wellness London is at 222 Essex Road, Islington, London N1 3AP, on the ground floor and wheelchair accessible. Essex Road station (Great Northern line) is two minutes' walk away, and Highbury & Islington is one stop north. Buses 38, 56, 73, 341 and 476 stop on Essex Road close to the door. From Angel it is a 15 to 20 minute walk up Essex Road.

Many patients cycle or use Lime and Forest e-bikes; from Dalston it is about ten minutes by bike. We are open Monday to Friday, 8am to 7pm, by appointment only, with no walk-ins and no weekend sessions, so every appointment has the time it needs.

If you are coming from the north, our Highbury page has more detail on the route.