Both white composite fillings and porcelain inlays restore damaged teeth, but they’re quite different treatments and the right choice depends on the specific situation.
If you’ve been advised that you need a dental restoration at our Dreghorn practice and you’re trying to understand your options, this comparison sets out what each treatment involves, where each performs best, and how the costs compare.
What Is a Porcelain Inlay?
A porcelain inlay is an indirect restoration: it’s made outside the mouth in a dental laboratory (or increasingly by a CAD/CAM milling machine), and then cemented into the prepared tooth at a second appointment. It’s essentially a pre-fabricated filling made from porcelain or ceramic material, custom-fabricated to fit the exact shape of the prepared cavity.
Inlays are typically used for larger cavities in back teeth where the decay has involved the chewing surface but hasn’t extended to the cusps. When the restoration needs to extend over one or more cusps, it becomes an onlay. Both are “indirect” restorations as opposed to the “direct” composite filling placed chair-side in a single visit.
Key Differences Between Composite and Porcelain Inlay
| Feature | White Composite Filling | Porcelain Inlay |
|---|---|---|
| Number of appointments | One | Usually two (preparation, then cementation) |
| Made in | Chair-side, during appointment | Dental laboratory or CAD/CAM machine |
| Material | Composite resin | Porcelain, ceramic, or composite block |
| Durability | Good; 7 to 12 years typically | Excellent; 15 to 25 years or more |
| Stain resistance | Moderate | Very high |
| Strength under load | Good for small to medium cavities | Superior; better for large posterior cavities |
| Cost | Lower: typically £80 to £200 | Higher: typically £400 to £900+ |
| NHS availability | Back teeth on NHS use amalgam; composite is private | Typically private |
When a Composite Filling Is the Better Choice
For small to medium-sized cavities, a direct composite filling is usually the more appropriate option. It’s placed in a single appointment, requires no laboratory stage, costs considerably less, and in the right clinical situation performs very well. For cavities involving one or two surfaces of a back tooth, composite is the standard recommendation at most practices.
Composite is also more easily repaired if a small area chips or wears. New composite can be added incrementally. An inlay that chips may need to be replaced entirely.
In our experience, many patients who ask about inlays are doing so because they’ve read something online about their superiority, without understanding that for the size of cavity they have, composite would perform just as well and at a fraction of the cost.
When a Porcelain Inlay Is Worth Considering
For larger cavities, particularly those occupying a significant portion of the occlusal (chewing) surface of a molar, a porcelain inlay offers genuine advantages. The material is fabricated under controlled conditions in a laboratory, which allows for more precise fit and a harder, more wear-resistant surface than chair-side composite can reliably achieve.
Porcelain is also more colour-stable over time. It doesn’t absorb pigments from food and drink the way composite does, which means the appearance is more likely to remain consistent over a decade or more.
Actually, there’s a third scenario worth mentioning. Some patients specifically want porcelain inlays to replace old, large amalgam restorations, particularly where the amalgam has caused cusp cracking or where the tooth has significant structural weakness. In these cases, the superior strength and fit of an inlay can genuinely protect the tooth better than composite would.
The Decision in Practice
Look, most back-tooth cavities of routine size are best treated with a direct composite filling. It’s quicker, cheaper, and clinically sufficient. The step up to an inlay makes sense when the cavity is large, when long-term durability is a priority, when aesthetics matter particularly (the stain resistance and precise fit are noticeable over time), or when the patient is replacing a large old amalgam and wants the best long-term outcome.
For NHS treatment in Scotland, inlays are generally classified as a private procedure. Adults over 26 pay 80% of NHS treatment costs capped at £384 per course, and amalgam remains the NHS-funded option for posterior teeth. For details on NHS dental charges in Scotland, NHS Inform’s receiving dental treatment page sets everything out clearly.
If you’re facing a decision between a composite filling and an inlay, our team at StormDental in Dreghorn can give you an honest assessment of what’s appropriate for your specific tooth and situation. Call us on 01294 218733 and we’ll give you a clear recommendation before you decide.
