What Are Inlays and Onlays?
An inlay is an indirect filling, fabricated in ceramic or gold, that sits within a posterior tooth.
An onlay is a custom-made protective covering for a tooth, also made in ceramic or gold, which overlaps the cusps of the tooth to protect it from flexure.
This article describes inlays and onlays in London and their benefits compared with the other options available.
Inlays and Onlays Versus Fillings and Crowns
Compared with traditional fillings and crowns, inlays and onlays have a level of conservatism that is unmatched by conventional materials and methods.
Inlays and onlays are custom made, which means they are not placed directly in the mouth while you sit in the chair. This is the key difference from a filling. The material is also entirely vitrified, a single monolithic piece, whereas composite and amalgam fillings are built up in multiple layers and are affected by compression and polymerisation reactions. This allows inlays and onlays to last comparatively much longer.
A crown goes all the way around the tooth and protects it circumferentially. An inlay or onlay does not. It preserves more of the natural tooth structure, thereby limiting the amount of reshaping the tooth needs.
Materials Used
The materials typically used are:
- Lithium disilicate ceramics
- Leucite-reinforced ceramics
- Zirconium dioxide
- Composite resin
- Gold alloys
- Metal alloys
The difference between them comes down to how much aesthetic accuracy you would like. Gold and metal options will not look as aesthetic, as they do not blend into the natural teeth, but gold has excellent bacteriostatic properties and tends to last 20 to 30 years.
Ceramic options such as lithium disilicate tend to be the treatment of choice because they are highly bondable. They have a glass-ceramic component and can be chemically bonded to the tooth itself. Zirconia is the least likely to be used, purely because it cannot be bonded and requires a mechanical lock onto the tooth, which brings it closer to a crown.
Our team at Marylebone Smile Clinic is expertly trained in managing inlays and onlays, and especially in replacing white and silver fillings. Very large white and silver fillings can undermine a tooth, making it more liable to break. Inlays and onlays specifically protect against this without committing to a full crown. Contact our team now to get started.
The Treatment Process, Step by Step
Step 1: Examination and consultation
We start with an examination and consultation, looking in detail at your teeth, their biomechanical limits and constraints, and the condition of your existing dental work and fillings. Inlays and onlays are typically designed for a tooth that has already had some dentistry done, rather than an unrestored tooth.
Step 2: Preparation
This is a longer session under local anaesthetic, in which the old filling is removed and the tooth is assessed for its cusp height to width ratio and the relative isthmus width. This tells us how much coverage is needed around the cusps, if any.
If no cusp needs coverage, an inlay will suffice, which sits in the fissures and contact points of the tooth. An onlay provides more cuspal protection, and is typically used for a root canal treated tooth or one that has had a much larger filling.
A temporary inlay or onlay is provided for about 2 weeks while the final one is being made. During this time, it is recommended to bite gently onto it and to be careful in general.
Step 3: Fitting the final restoration and bite adjustment
The final ceramic is chemically bonded to the tooth. If it is a gold inlay or onlay, it is also bonded to the tooth using a metal primer. This is a critical step because it dictates the long-term success of the restoration. Cleanability is important, because excess cement must be removed so that the margins are clear and smooth.
The bite is then corrected and adjusted. Small bite adjustments are typically common in this case, and expertise in occlusion is important to avoid causing an interference. An interference means that forces are redirected to another part of the mouth, which can cause chips elsewhere. How often have you seen a dental crown fitted and then another tooth break next to it? This is due to interferences.
Our team at Marylebone Smile Clinic are experts in occlusion and are published in peer-reviewed journals on the subject.
Cost and Finance of Inlays and Onlays in London
Inlays and onlays can range from an NHS Band 3 treatment of about £250, all the way up to £1,495 per tooth in central London. The variation depends on the complexity of your situation, the specific skills and materials used by the operator and clinical team, and the clinical effectiveness of the treatment you can expect.
In our hands at the clinic, our team, led by Dr. Sahil Patel, is likely to give you a 15 to 20 year lifespan on onlays and a 10 to 15 year lifespan on inlays.
Frequently Asked Questions
How long do dental inlays and onlays last?
Typically 10 to 20 years. Where you sit within this range depends on the existing condition of the tooth, how the tooth sits within your bite, and how you maintain it long term.
What is the difference between an inlay, an onlay and a crown?
An inlay sits within the fissures of the tooth. It does not overlap the cusps, so it sits right in the middle, where the contact points are. An onlay overlaps the cusps but does not cover the tooth circumferentially. A crown covers all the visible aspects of the tooth and extends circumferentially from gum line to gum line.
How much do dental inlays and onlays cost in London?
Typically anything from £995 up to £1,495 per tooth.
Is the procedure painful?
Typically no, because you will be under local anaesthetic. If the tooth has severe decay, you may experience some mild sensitivity afterwards, but this will resolve once the tooth has been sealed.
Dentist at Marylebone Smile Clinic and an Accredited member of the British Academy of Cosmetic Dentistry.
GDC number: 258353. Last reviewed: 9 November 2026