Inlays and Onlays — Custom Restorations Between Fillings and Crowns

Inlays and onlays sit in the middle ground of restorative dentistry. They are stronger and longer-wearing than a standard filling, but more conservative than a full crown. At Sandgate Family Dental we use inlays and onlays when a back tooth has more damage than a filling can comfortably support, yet still has enough healthy structure to avoid full-coverage treatment.

If your dentist has mentioned an inlay or onlay, or you would like to understand your options for a heavily filled back tooth, book an appointment online for a calm, unhurried discussion. We see patients from Sandgate, Brighton, Shorncliffe, Bracken Ridge, and the wider northern Brisbane area.

What inlays and onlays are

Inlays and onlays are custom-made restorations bonded into a prepared back tooth. They are sometimes called indirect restorations because they are made outside the mouth — either in a dental laboratory or, in some cases, with in-chair digital milling — and then bonded into place at a follow-up visit.

The difference between the two comes down to coverage:

An inlay sits within the cusps (the raised points) of a back tooth, replacing the inner part of the chewing surface.
An onlay extends over one or more cusps, replacing both the inner surface and a portion of the outer wall.

Both are precisely contoured to your existing tooth, then bonded to give a strong, sealed restoration that feels and functions like part of the tooth.

When an inlay or onlay may be suggested

Your dentist will usually consider an inlay or onlay when:

A back tooth has decay or an old filling too large for a direct filling to support reliably.
One or more cusps have fractured or are at risk of fracturing.
You want a more durable, longer-wearing restoration than amalgam or composite for a heavily loaded molar.
The tooth still has enough healthy structure to avoid the more extensive preparation needed for a full crown.
An older filling is failing — see our page on replacing old fillings.

Front teeth are usually restored with composite bonding or veneers rather than inlays. Inlays and onlays are most commonly used on premolars and molars where chewing forces are highest.

Inlays, onlays, fillings, and crowns — the spectrum

It helps to think of restorations as a spectrum from least to most invasive:

Composite or amalgam filling — placed directly in the tooth in one visit, ideal for small to moderate cavities.
Inlay — laboratory-made, fits inside the cusps, suited to moderate to larger cavities where a direct filling may not seal or wear well.
Onlay — laboratory-made, covers one or more cusps, used when a tooth needs cusp protection but a full crown is not yet necessary.
Crown — covers the whole tooth, used when the remaining structure is significantly weakened or after root canal treatment.

The aim is to match the restoration to the amount and pattern of damage — restoring strength without removing more tooth than is needed.

Materials we use

Inlays and onlays can be made from several materials. Your dentist will recommend one based on the location of the tooth, the bite forces involved, and your priorities for appearance.

Ceramic and porcelain

Tooth-coloured, strong, and resistant to wear. A common choice for premolars and visible molars because they blend with the surrounding tooth.

Composite resin

Tooth-coloured and easier to repair if damaged later. Often a more economical option, but generally not as wear-resistant as ceramic for heavily loaded back teeth.

Gold

Very long-wearing and gentle on opposing teeth. Less commonly chosen today because it is not tooth-coloured, but still considered an excellent option for back molars where appearance is not a concern.

The benefits of an inlay or onlay

An inlay or onlay can:

Preserve more healthy tooth than a crown.
Restore chewing strength to a heavily filled tooth.
Seal the tooth precisely and reduce the risk of further decay around the margins.
Provide a tooth-coloured, well-contoured result on visible back teeth.
Be longer-wearing than a large direct filling in many situations.

No restoration lasts forever. Longevity depends on bite forces, hygiene, grinding habits, and the underlying tooth — your dentist will discuss realistic expectations for your tooth at the assessment.

What to expect at the appointment

Treatment usually takes two visits.

1. Assessment and planning

We talk through what you have noticed, take a small digital X-ray, and assess how much healthy tooth remains. Where appropriate we will discuss whether a filling, inlay, onlay, or crown is the most suitable option for your specific tooth.

2. Preparation and impression

The tooth is gently numbed, the decay or old filling is removed, and the area is shaped to receive the inlay or onlay. We take a digital scan or impression and fit a temporary cover so you can eat comfortably while the restoration is made.

3. Bonding the restoration

At the second visit the temporary is removed and the custom inlay or onlay is checked for fit and bite, then bonded in place. We polish the margins, review your bite, and explain how to look after the tooth.

For patients who prefer fewer visits, some indirect restorations can be made on the same day using in-chair digital milling — we will tell you whether this is suitable for your tooth.

Looking after an inlay or onlay

Care is similar to caring for a natural tooth — gentle brushing twice a day, daily flossing, and regular check-ups and cleans. If you grind or clench at night, a custom nightguard can help protect the restoration and the surrounding teeth.

Who inlays and onlays may suit

Patients with a moderate-to-large cavity or fractured cusp on a back tooth.
Those replacing an old, failing filling where a direct filling may not be ideal.
Patients who want a tooth-coloured restoration on a visible premolar or molar.
Anyone wanting a more conservative option than a crown when enough healthy tooth remains.

If the tooth is significantly weakened, or if the nerve is involved, a crown or root canal may be more appropriate. Your dentist will explain the reasoning either way.

Health funds and payment

We are a HICAPS provider, so where you have eligible dental cover we can process your health fund claim at the practice and you only need to pay any gap. The rebate you receive depends on your individual policy, your level of cover, and your annual limits — your fund can confirm what is covered before treatment. Information on major dental cover may also be useful when planning a larger restoration.

We can provide an itemised treatment plan with item numbers so you can check your entitlements ahead of time. Payment plan options are available for larger treatment.

Inlay and onlay FAQs

How is an inlay different from a filling?

A filling is shaped directly inside the tooth in one visit. An inlay is custom-made outside the mouth and then bonded in. Inlays usually involve two visits and are chosen when a filling would be too large to seal and wear well.

How is an onlay different from a crown?

An onlay covers one or more cusps but leaves more of the underlying tooth intact than a crown. A crown covers the whole tooth and is preferred when significantly more of the tooth has been lost or weakened.

How long do inlays and onlays last?

Many last a long time when looked after, but longevity varies with material, bite forces, hygiene, and habits like grinding. Your dentist will give you a realistic picture for your tooth at the planning visit.

Will I need to take time off work?

No — both visits are normal dental appointments. Some patients have mild soreness for a day or two after the bonding visit, especially if the tooth was already sensitive.

Are inlays and onlays covered by health funds?

They are usually claimable under major dental cover, but rebates depend on your policy and annual limits. We will provide item numbers so your fund can confirm what is covered for you.

Can an old filling be replaced with an inlay?

Often yes — particularly when the existing filling is large and the surrounding tooth is starting to flex or crack. Your dentist will assess whether replacement with an inlay, onlay, or crown is appropriate.

Are inlays and onlays suitable for front teeth?

They are mostly used on premolars and molars. For front teeth, options such as dental bonding or veneers are usually more appropriate.

Related information

Speak to our team

If you have a heavily filled or fractured back tooth and you would like to understand whether an inlay or onlay is right for you, the team at Sandgate Family Dental is happy to talk through your options without pressure. Book an appointment online or phone the practice during opening hours.