If your dentist has just told you that a cavity is "too big for a filling but doesn't need a full crown," you've landed in the exact spot this article is written for. The answer, in most cases, is an inlay or an onlay a custom-made restoration that sits in the middle ground between the two. It's a less-talked-about option, but for the right tooth it can save you structure, money and a second visit down the track.
This guide walks through what inlays and onlays actually are, when they beat a large filling or a crown, how porcelain, composite and gold compare, how long each tends to last, and what you can expect to pay in Perth in 2026.
What Is a Dental Inlay or Onlay?
An inlay or onlay is a custom-fabricated restoration, made from porcelain, composite resin or gold, that is bonded or cemented into a tooth after decay or an old filling has been removed. Unlike a filling, which is soft and moulded directly into the tooth at the chair, an inlay or onlay is shaped outside the mouth (either by a lab or an in-chair milling machine) and then fitted precisely into place.
The difference between the two comes down to how much of the tooth they cover:
Inlay — fits within the grooves (cusps) on the biting surface of the tooth, similar in footprint to a large filling.
Onlay — extends over one or more of the cusps to cover part of the chewing surface, offering more coverage and protection than an inlay while a dental crown covers the whole tooth, an onlay only covers the top (or cusps) of the tooth.
Think of it as a scale: filling → inlay → onlay → crown, with each step covering progressively more of the tooth.
Inlay vs Filling: When Is an Inlay the Better Choice?
A standard composite filling is still the right call for small to moderate cavities, and it's usually cheaper and faster see our white fillings guide for how tooth-coloured fillings compare with older amalgam. But a direct filling has limits. Once a cavity is wide, deep, or involves the space between teeth, packing in soft composite at the chair becomes harder to shape accurately and more prone to shrinking, leaking at the edges, or fracturing under bite force.
An inlay is generally a better choice than a large filling when:
The decayed area is too wide for composite to be reliably shaped and bonded in one sitting
A previous large filling has failed or is leaking at the margins
You want a stronger, more precisely fitted restoration without removing healthy tooth structure for a crown
The tooth is still structurally sound enough that it doesn't need full-coverage protection
If the cavity is small and the remaining tooth walls are strong, a direct filling remains the simpler, lower-cost option. Our dental fillings page covers what a standard filling involves.
Onlay vs Crown: When Is an Onlay the Better Choice?
This is where most of the "is there something in between?" questions come from. A full crown involves shaving down the entire tooth to make room for a cap that covers it completely it's the right call when a tooth is heavily broken down, cracked, or has had root canal treatment and needs maximum protection. See our crown cost guide for a full breakdown of crown pricing and materials.
An onlay is generally the better choice than a crown when:
The tooth has lost one or two cusps but the rest of the tooth structure is healthy
Your dentist wants to preserve as much of the natural tooth as possible
The damage is confined to the biting surface rather than wrapping around the sides of the tooth
You want a strong, long-lasting restoration without the more extensive tooth reduction a crown requires
A crown is still the better option when the tooth is extensively cracked, has very little remaining structure, has had a root canal (see our guide on root canal treatment and costs in Perth), or needs full-coverage protection against further fracture. Your dentist will usually make this call after looking at how much sound tooth structure is left once old fillings or decay are removed not before.
Porcelain vs Composite vs Gold: Comparing the Materials
Each material has a different balance of appearance, strength and cost.
Porcelain / ceramic
The most popular choice for visible back teeth because it closely matches natural tooth colour. Porcelain onlays and inlays are strong, tooth-coloured, and blend in beautifully with your natural smile, though that aesthetic comes at a price. It bonds well to tooth structure and resists staining over time.
Composite resin
The most affordable option and tooth-coloured, but it's often the most affordable option, looks natural but isn't quite as durable as porcelain or gold, and might need to be replaced sooner, especially for people who grind their teeth. A reasonable choice for smaller restorations or as a budget-conscious option.
Gold
Not tooth-coloured, but extremely durable. Gold may not match your tooth colour but it's incredibly durable, and many dentists still recommend it for back molars where strength matters most. Some patients choose gold for molars that don't show when they smile and where longevity matters more than appearance.
How Long Do Inlays and Onlays Last?
Lifespan depends heavily on material, bite force, grinding habits and how well the margins are maintained with regular check-ups:
Composite resin — typically the shortest-lived of the three, more prone to wear and more likely to need replacement sooner for people who grind their teeth
Porcelain/ceramic — generally holds up well for a decade or more with good home care and regular reviews
Gold — often considered the most durable material for inlays and onlays, frequently lasting the longest of the three
As with crowns and fillings, longevity also comes down to how well the restoration's margins are sealed and maintained — this is why your six-monthly check-up matters as much as the material you choose.
What Do Inlays and Onlays Cost in Perth (2026)?
Pricing varies by tooth, lab fees, complexity and whether the restoration is milled in-chair (CEREC-style) or made in an external lab. As an indicative guide for Perth in 2026:
| Type & Material | Indicative Perth Price Range (per tooth) | |---|---| | Composite resin inlay | $500 – $900 | | Composite resin onlay | $600 – $1,000 | | Porcelain/ceramic inlay | $800 – $1,400 | | Porcelain/ceramic onlay | $900 – $1,800 | | Gold inlay/onlay | $800 – $1,600 |
The cost of an inlay varies depending on size and complexity, and inlays and onlays can range from roughly $800 to $1,600 for ceramic and gold options at Perth clinics, with composite sitting below that range. For context, Perth is among the most expensive Australian cities for dental treatment, running about 10-12% above the national average, which is worth keeping in mind if you're comparing quotes from interstate price guides.
By comparison, our crown cost guide and a straightforward composite filling via our fillings page sit either side of this range — which is exactly the gap an inlay or onlay is designed to fill.
What pushes the price up:
Onlays typically cost more than inlays because they cover more of the tooth
Porcelain/ceramic involves more lab or milling time than composite
Multiple cusps needing coverage, or a tooth needing a build-up first, add to the fee
Whether the restoration is made same-day in-chair or sent to an external lab (requiring a second visit)
Will My Health Fund Cover an Inlay or Onlay?
Inlays and onlays are typically classified under general or major restorative dental on most Australian extras policies, similar to crowns and large fillings. How much comes back depends on your specific level of cover, your fund's classification of the item, and whether you've hit your annual limit — so it's worth checking your policy details or asking your clinic to run a quote through HICAPS before you commit. Some funds treat ceramic/porcelain restorations differently to gold or composite, so it's worth clarifying the item number with your dentist's reception team.
Getting an Inlay or Onlay in Perth: North Beach Dental
If you've been told a tooth might need something more than a filling, North Beach Dental is a good option to start with. The clinic offers inlays and onlays alongside a broader range of restorative and cosmetic services including cosmetic dentistry, veneers, dental implants, All-on-4 full-arch solutions, root canal treatment and dentures so if your assessment reveals a tooth needs more extensive work, you won't need to be referred elsewhere.
FAQs
What is a dental onlay?
An onlay is a custom-made restoration that covers one or more cusps of a tooth's biting surface, offering more coverage than a filling or inlay without the full-coverage approach of a crown.
Is an inlay better than a filling?
For small cavities, a standard filling is usually sufficient and more cost-effective. An inlay becomes the better option once the cavity is too large or awkwardly shaped for a direct filling to be reliably placed.
Is an onlay better than a crown?
An onlay preserves more natural tooth structure than a crown and is often appropriate when only the biting surface is damaged. A crown is still necessary when the tooth has extensive damage, cracks, or has undergone root canal treatment.
How much does a porcelain onlay cost in Perth?
Indicative 2026 pricing for a porcelain/ceramic onlay in Perth sits roughly between $900 and $1,800 per tooth, depending on complexity and lab fees.
What is a ceramic inlay cost in Australia generally?
Across Australia, porcelain inlays and onlays generally range from $800 to $1,200 per tooth, with Perth often sitting at or above the upper end of that range given the city's overall dental cost premium.
How long do onlays last?
Porcelain and gold onlays commonly last a decade or more with good care, while composite resin onlays tend to need replacement sooner, particularly for patients who grind their teeth.
Will my health fund give an onlay rebate?
Most extras policies that cover major or general dental will provide some rebate toward an inlay or onlay, but the exact amount depends on your policy level and annual limits check with your fund or ask your clinic to confirm the item number before treatment.
Next Steps
If you've got a tooth that's too big for a filling but you're not sure it needs a full crown, start with an examination. Explore our inlays and onlays treatment page for an overview, compare it against our crowns and bridges page and fillings page, or go straight ahead and book an appointment with North Beach Dental to get a proper assessment and a firm quote for your specific tooth.
Tags
