Quick answer: A full crown covers the prepared tooth, while an onlay rebuilds part of it and covers weakened biting surfaces. An onlay may preserve more untouched tooth in a suitable case, but it is not automatically the better option. The decision should follow an examination, not a preference for the smallest restoration or the lowest price.
If a large filling has broken or your dentist has suggested a crown, ask whether a partial restoration is also an option. This guide explains the terms, the questions worth asking and Abi Dental Care’s published fees in Maida Vale.
Crown, inlay and onlay: the differences at a glance
| Restoration | What it covers | Question to ask |
|---|---|---|
| Inlay | A custom-made restoration replacing a missing area within the tooth. | Could a direct filling meet the same need? |
| Onlay | Part of the tooth, including weakened biting surfaces. | Which parts need coverage and which can be kept? |
| Full crown | The prepared tooth, with coverage around it. | Why is full coverage recommended for this tooth? |
The NHSBSA explanation of inlays and onlays describes onlays as restorations that extend over weakened parts of a tooth. The terminology is useful, but the design recommended for your tooth matters more than its label.
Does an onlay always save more natural tooth?
Partial coverage can leave some surfaces untouched. However, both options may require tooth preparation. Keeping tissue is valuable only when the remaining tooth and proposed restoration can function together appropriately. A full crown should not be the automatic answer to every large filling, and an onlay should not be promised before assessment.
Leeds Teaching Hospitals’ patient guidance on crowns notes that crowns involve removal of tooth structure and that alternatives may sometimes be suitable. Ask your dentist to show you the damaged area and explain the reason for the proposed coverage.
What should the dentist assess before recommending treatment?
The discussion should consider the remaining tooth, existing restorations, the bite and the health of the surrounding gums. Depending on the findings, the dentist may need X-rays or tests of the tooth’s pulp. Active dental disease may need attention before the final restoration is planned.
Useful questions include: Is there decay beneath the old filling? What can be assessed now, and what may only become clear after it is removed? If the findings change, will you explain a revised plan and estimate before proceeding?
Are ceramic crowns and onlays the same material?
The words crown and onlay describe the restoration’s design, not one particular material. Options can include ceramics, metal alloys and, for some restorations, resin-based materials. Appearance, the forces on the tooth, available space and the method of attachment all influence selection.
The American Dental Association’s overview of indirect restorative materials explains that materials have different properties and clinical uses. Ask which material is proposed and why it suits your tooth; a brand name alone does not explain the treatment plan.
What happens during treatment?
Custom restorations are made from a record of the prepared tooth. A conventional impression or digital scan may be used, depending on the planned treatment. Laboratory-made restorations generally involve preparation and a later fitting appointment; a temporary restoration may be needed between visits. Confirm the sequence with the practice rather than assuming same-day treatment.
Our crowns, inlays and onlays service page explains treatment at Abi Dental Care. Ask how to look after any temporary restoration and whom to contact if it becomes loose.
How much do crowns and onlays cost in Maida Vale?
Abi Dental Care’s published fee guide lists crown, inlay and onlay treatment at £800–£1,400. This combined range was checked on 21 September 2026. It is not a separate fixed price for each design, and it does not establish that an onlay will always cost less than a crown.
Request an itemised estimate stating the restoration, material, appointments and any separate examination or other treatment charges. Compare the proposed work as well as the total. If root canal treatment is also recommended, our root canal cost guide explains the separate published fees.
Longevity and looking after the restored tooth
No crown or onlay has a guaranteed lifetime. Discuss the maintenance expected for your particular restoration. Leeds Teaching Hospitals recommends fluoride toothpaste twice daily, cleaning between the teeth, limiting how often sugar is consumed and regular dental reviews for crowned teeth.
Ask what changes should prompt a review and whether grinding or clenching needs attention in your plan. The aim is to maintain the tooth and restoration, not to treat fitting day as the end of care.
Questions to take to your appointment
- Can you explain why a filling, onlay or crown is appropriate for this tooth?
- How much healthy tooth would each suitable option leave?
- What are the main risks and alternatives in my case?
- What is included in the written estimate?
- What happens if the tooth needs additional treatment?
- What follow-up and maintenance should I plan for?
Discuss your options at Abi Dental Care
Dr Hamid Kiani, principal dentist and owner of Abi Dental Care (GDC 248584), has clinical interests in minimally invasive dentistry, crowns, inlays and onlays. Learn more about the practice or request an assessment in Maida Vale to discuss a personalised treatment plan.
This is general patient information, not a diagnosis or a recommendation for an individual tooth. Sources checked 21 September 2026. The NHS and professional sources linked above provide clinical background; Abi Dental Care is a private practice and the fees shown are its own.
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