Inlay vs Onlay vs Crown: Which Is Right for Your Tooth?

Inlays, onlays and crowns all rebuild a damaged tooth, but they differ in how much healthy tooth they remove and how much of the tooth they protect. A crown removes about 67.5 to 75.6% of the tooth structure during preparation, while an onlay or partial crown removes about 35.5 to 46.7%, yet a systematic review found no significant difference in survival between onlays and full crowns at 1 and 3 years. Ceramic inlays and onlays reach 91% survival at 10 years, so the conservative option is not the weaker one when it is correctly indicated. This guide compares inlays vs onlays vs crowns on tooth preservation, lifespan and indications, then explains how the choice is made for your tooth.

The information in this article is for educational purposes only and does not constitute medical advice. Consult a qualified dental professional before making any treatment decisions.

What is the difference between an inlay, an onlay and a crown?

The difference is how much of the tooth each restoration covers. An inlay fills the centre of the biting surface between the cusps, an onlay extends over one or more cusps, and a crown caps the whole visible tooth above the gum. Inlays and onlays are partial restorations that keep the natural walls of the tooth, whereas dental crowns replace the outer shell entirely. All three are made in a laboratory and bonded or cemented in place. The table below sets the three options side by side.

Feature	Inlay	Onlay	Crown
Coverage	Centre of the biting surface	One or more cusps	Whole visible tooth
Tooth removed	Least	About 35.5 to 46.7%	About 67.5 to 75.6%
Typical use	Moderate decay inside the cusps	Larger decay or a broken cusp	Root-filled, cracked or heavily broken teeth
Materials at MDC	Composite or E-max ceramic	Composite or E-max ceramic	E-max, zirconia or full porcelain
Visits	Usually 2	Usually 2	Usually 2
Relative cost	Lower in the UK, US and Germany	Lower in the UK, US and Germany	Higher abroad; close to onlay fees in Turkey

Current fees for each option are listed on the clinic’s price list.

In this video, our dentist compares inlays, onlays and crowns and explains which restoration suits which kind of tooth damage.

The most important row for long-term tooth health is how much structure each option removes.

Is an onlay better than a crown?

An onlay is better than a crown when the tooth has enough sound structure to support it, because it preserves far more natural tooth while performing as well in the short to medium term. A systematic review and meta-analysis found no statistically significant difference in survival between onlays or partial crowns and full crowns after 1 and 3 years, and no difference in fracture rates (Wang and colleagues, 2022). The same review reported that full crown preparation removes roughly twice as much tooth as an onlay. A crown remains the better choice when the tooth is root-filled, cracked through or has lost most of its walls. Inlays raise a slightly different comparison.

Is an inlay better than a crown?

An inlay is better than a crown for moderate decay that sits inside the cusps, because it rebuilds the tooth without cutting away healthy walls. It is not a substitute for a crown when the cusps are weak, cracked, or missing, since an inlay does not protect them from splitting under biting forces. In practice, an inlay is closer to a large laboratory-made filling, and a crown is a protective cap. When the choice is between an inlay and an onlay, the deciding factor is the cusps.

Inlay vs onlay: which do you need?

You need an inlay when the damage is inside the cusps and an onlay when one or more cusps are affected. Covering a weakened cusp with an onlay reduces the risk of it breaking off later, while an inlay keeps preparation to a minimum when the cusps are sound. Where the whole biting surface needs protection but the sides of the tooth are healthy, an overlay covers all the cusps without the deeper preparation of a crown. Lifespan data helps put these options in context.

How long do inlays, onlays and crowns last?

Ceramic inlays, onlays and overlays show 92 to 95% survival at 5 years and 91% at 10 years (Morimoto and colleagues, 2016), and indirect composite versions about 91% at 5 years (Fan and colleagues, 2021). Crowns also perform well over similar periods, and short-term evidence shows no significant survival difference between onlays and crowns. Fracture and root canal complications are the most common reasons partial restorations fail, which is why teeth with a living nerve and sound walls suit them best. The factors below decide which option fits your tooth.

How do you choose between an inlay, an onlay and a crown?

The choice depends on how much healthy tooth remains, whether the nerve is alive, and the forces the tooth takes. The dentist examines the tooth and X-rays and considers:

• Remaining structure: thick, sound walls favour an inlay or onlay; thin or cracked walls favour a crown.
• Nerve status: root-filled teeth are more brittle and are usually crowned.
• Tooth position: molars take higher chewing forces than premolars.
• Grinding: bruxism may call for stronger materials, cusp coverage or a night guard.
• Material: composite costs less and repairs easily; E-max ceramic resists wear and staining.

At MDC the restoration is planned from a digital scan and made in the in-house laboratory, so the dentist can choose the most conservative design that still protects the tooth. Once fitted, all three restorations need the same care.

How do you care for inlays, onlays and crowns?

You care for inlays, onlays and crowns by brushing twice a day with a soft brush, cleaning between the teeth daily and avoiding very hard foods. The margin where the restoration meets the tooth is where decay starts, so interdental cleaning matters more than any special product. If you grind or clench, a custom night guard protects both the restoration and the natural teeth. Regular check-ups let the dentist inspect the margins before small problems grow. The questions below cover the details patients ask about most.

Are inlays and onlays better than fillings?

Inlays and onlays are better than fillings for large cavities, because a laboratory-made restoration fits more accurately and rebuilds lost contact points and cusps more predictably. For small cavities, a direct filling is quicker, cheaper and removes less tooth. Our guide to composite inlays and onlays explains what inlays and onlays are and how they are made. The dentist usually recommends a filling first and moves to an inlay or onlay when the cavity is too wide.

Which material is best for an onlay?

E-max ceramic suits onlays that need maximum wear and stain resistance, while composite suits a lower budget or easier repair. Both are bonded to the tooth and both show high survival in review data. Details of the ceramic option are on the porcelain inlays and onlays service page. Gold is also durable but is rarely chosen today because it is not tooth-coloured.

When is a crown the only option?

A crown is usually the only option when the tooth is root-filled, cracked through or has lost most of its walls, because a partial restoration cannot protect it from splitting. Heavily worn teeth and teeth that need a change of shape or colour are also crowned. Zirconia suits back teeth that take high forces, and our page on zirconium crowns explains the material. The choice of crown material then follows the same logic of strength and appearance.

Is an onlay cheaper than a crown?

In the UK, the US, and Germany, an onlay usually costs less than a crown, but in Turkey the difference is small. In Istanbul, a ceramic onlay costs about €250 to €350 per tooth, close to the fee for a zirconia crown, so price rarely decides between them. That makes the condition of the tooth the deciding factor: an onlay keeps more healthy structure when the walls are sound, and a crown protects a tooth that is root-filled or cracked. Treatment in Istanbul saves patients up to 75% against private fees at home, whichever restoration is chosen.

Sources

Wang, B., Fan, J., Wang, L., Xu, B., Wang, L., & Chai, L. (2022). Onlays/partial crowns versus full crowns in restoring posterior teeth: a systematic review and meta-analysis. Head & Face Medicine, 18(1), 36. https://doi.org/10.1186/s13005-022-00337-y (verified 2026-09-21)
Morimoto, S., Rebello de Sampaio, F.B.W., Braga, M.M., Sesma, N., & Özcan, M. (2016). Survival Rate of Resin and Ceramic Inlays, Onlays, and Overlays: A Systematic Review and Meta-analysis. Journal of Dental Research, 95(9), 985–994. https://doi.org/10.1177/0022034516652848 (verified 2026-09-21)
Fan, J., Xu, Y., Si, L., Li, X., Fu, B., & Hannig, M. (2021). Long-term Clinical Performance of Composite Resin or Ceramic Inlays, Onlays, and Overlays: A Systematic Review and Meta-analysis. Operative Dentistry, 46(1), 25–44. https://doi.org/10.2341/19-107-LIT (verified 2026-09-21)