Three restorations, three indications
When a posterior tooth is substantially weakened by deep caries, an old large filling or a fracture, three main options are available: the inlay, the onlay and the crown. All three are lab or chairside fabricated restorations made of ceramic, composite or gold that bridge the damaged area of the tooth.
The choice is not arbitrary but medically indicated. A crown that replaces an inlay unnecessarily sacrifices tooth substance. An inlay that actually needs a crown does not hold and leads to fracture. This article explains the distinction and when what makes sense.
What an inlay is
An inlay is a custom-made insert that is bonded into a prepared cavity in the tooth. The tooth largely retains its original shape. Cusp tips and edges of the occlusal surface are preserved from own tooth substance.
Indication: medium-sized defects in the center of the occlusal surface without involvement of the cusps. Classically after medium-sized caries or as replacement of an old large composite filling when the cusps are still intact.
Materials: full ceramic (lithium disilicate or zirconia), composite (lab-processed) or gold. Full ceramic is standard today, gold is chosen more rarely but lasts very long.
What an onlay is
An onlay is an extension of the inlay concept. It additionally replaces one or more cusps of the tooth. The contour and function of the cusp is restored by the onlay material.
Indication: larger defects where a cusp is weakened or already fractured but the remaining substance is still sufficient to anchor the onlay. Also for root-treated posterior teeth where the crown is not yet medically mandatory.
Materials as inlay: full ceramic, composite or gold.
What a crown is
A crown covers the tooth completely above the gum. It is cemented or bonded onto a prepared tooth stump. Cusps, occlusal surfaces and side surfaces are formed by the crown material.
Indication: severe substance weakening, multiply restored teeth, all root-treated posterior teeth with greater substance loss, fractured teeth with unstable remaining substance.
Materials: full ceramic (zirconia or lithium disilicate), metal-ceramic, in rare cases full metal (gold).
Comparison by criteria
Substance preservation
Inlay sacrifices the least tooth substance, crown the most. With the crown the entire tooth is ground around by about one to two millimeters. With onlay and inlay the tooth largely remains in its form.
The rule of thumb: the less healthy tooth substance sacrificed, the better for long-term tooth preservation. Inlay is the most substance-saving option as long as the indication fits.
Lifespan
With correct indication and proper use all three restorations last comparably long. Studies show survival rates of:
- Inlay made of full ceramic: above 90 percent after ten years
- Onlay made of full ceramic: above 85 percent after ten years
- Full ceramic crown: above 90 percent after ten years
- Metal-ceramic crown: above 95 percent after ten years
- Gold inlay or crown: above 95 percent after twenty years
The lifespan depends more strongly on oral hygiene, caries susceptibility and bite loading than on restoration type.
Costs
Inlay and onlay are usually cheaper than the crown because less material and lab effort is needed. Concrete amounts depend on material and effort. We do not name fixed prices on the website because the Swiss dental tariff is standardized and treatments vary strongly per patient. Range across Switzerland:
- Inlay: typically CHF 800 to 1,500
- Onlay: typically CHF 1,000 to 1,700
- Full ceramic crown: typically CHF 1,500 to 2,200
- Metal-ceramic crown: typically CHF 1,200 to 1,700
More on the cost structure generally in the article on health insurance at the dentist.
Treatment duration
Classically two sessions with two to three weeks pause. First session: preparation, impression or digital scan, provisional restoration. Second session: definitive incorporation.
With practices with CEREC system the treatment is possible in one session (chairside): preparation, intraoral scan, fabrication of the restoration in the practice, immediate incorporation. The session lasts two to three hours.
Aesthetics
Full ceramic restorations are color-adapted to the natural teeth and practically indistinguishable from own teeth in the front area. In the posterior area the material is usually not visible, which is why gold or metal-ceramic remain acceptable options there.
Decision matrix by constellation
Medium-sized caries in the center of the occlusal surface, cusps intact
Recommendation: inlay. Substance-saving, long lifespan, aesthetically inconspicuous.
Larger defect with weakened cusp
Recommendation: onlay. Cusp is supported and rebuilt by the onlay material without having to grind the whole tooth.
Very severe substance loss with unstable cusps
Recommendation: crown. When the remaining substance is insufficient for inlay or onlay, the crown is the statically safe option.
Root canal with moderate substance loss
Recommendation: onlay or crown. Root-treated posterior teeth need substantial stabilization. With moderate substance loss the onlay can suffice, with severe weakening the crown is indicated. More on root canal treatment in the article Root canal or implant.
Multiply restored tooth with old large fillings
Recommendation: crown. The multiply damaged tooth substance is unstable. The crown holds it together and protects against further fractures.
Fractured tooth after trauma
Recommendation: crown. When the tooth is longitudinally or obliquely endangered, the crown holds the fracture sites together.
Front tooth defect
Recommendation: veneer or direct composite restoration, in rare cases crown. Front teeth have different loading patterns than posterior teeth. Inlay and onlay are rarely indicated there. With discolorations or mild defects the direct composite restoration is often sufficient, with stronger defect a veneer (bonded to the front of the tooth) or a crown.
What insurance pays
Swiss basic insurance does not generally cover inlay, onlay and crown. There are rare exceptions with accident consequences or severe systemic diseases. Supplementary insurance with dental care module can cover part. More in the article on health insurance at the dentist.
How we proceed at Resident
In the initial consultation and after findings (clinical examination, X-ray, possibly intraoral scan), we assess the defect extent and the remaining substance. On this basis we recommend the restoration that is long-term sensible for your constellation.
We do not recommend an inlay if the remaining substance is insufficient. We conversely do not recommend a crown if an inlay is the statically and biologically sufficient solution.
You receive a written cost estimate with detailed listing. When two options are sensible (such as onlay versus crown), we prepare two separate cost estimates for comparison on request. More in the article on the written cost estimate.
Arrange an appointment at your location for the assessment and consultation.