Filling vs Inlay vs Onlay vs Crown: Cost, When to Choose, and Decision Guide
Not every cavity is a filling. When too much tooth structure is damaged, your dentist may recommend an inlay, onlay, or crown instead. Understanding the full restoration spectrum helps you evaluate your dentist's recommendation and plan for costs.
The Restoration Spectrum
Up to 30% loss
Filling
$50-$300
Lifespan: 5-15 yrs
Coverage: 80% (basic)
20-40% loss
Inlay
$500-$1,200
Lifespan: 10-20 yrs
Coverage: 50% (major)
30-60% loss
Onlay
$600-$1,500
Lifespan: 10-20 yrs
Coverage: 50% (major)
50%+ loss
Crown
$800-$3,000
Lifespan: 10-25 yrs
Coverage: 50% (major)
| Restoration | Cost | Lifespan | Visits | Coverage | Best For |
|---|---|---|---|---|---|
| Filling | $50-$300 | 5-15 yrs | 1 | 80% (basic) | Direct restoration placed into a prepared cavity. Suitable for small to medium cavities. |
| Inlay | $500-$1,200 | 10-20 yrs | 1-2 | 50% (major) | Indirect restoration that fits within the cusps of the tooth. Lab-made or CEREC. |
| Onlay | $600-$1,500 | 10-20 yrs | 1-2 | 50% (major) | Like an inlay but extends over one or more cusps. Sometimes called a partial crown. |
| Crown | $800-$3,000 | 10-25 yrs | 2 | 50% (major) | Covers the entire visible tooth. Required when too much structure is gone for other options. |
The 50-60% Rule
If more than 50 to 60% of your tooth structure is damaged or missing, a filling will not hold. The remaining tooth walls are too thin to support a direct restoration, and the filling is likely to fracture or the tooth is likely to crack under chewing forces.
Between 30 to 60% damage, inlays and onlays are the middle ground. They provide more structural support than fillings while preserving more tooth than crowns. Below 30%, a standard filling is almost always sufficient.
Under 30% Damage
Standard Filling
Small to medium cavity. Any material works. Cost: $50-$300.
30-60% Damage
Inlay or Onlay
Large cavity or cusp involvement. More structural support. Cost: $500-$1,500.
Over 60% Damage
Crown
Extensive damage or post-root-canal. Full coverage required. Cost: $800-$3,000.
When Your Dentist Says "Crown" but You Want a Filling
When a Second Opinion Makes Sense
- The cavity is medium-sized and you feel the tooth is still structurally sound
- No cusps are broken or cracked
- The tooth has not had a root canal
- You are primarily concerned about cost and willing to accept a shorter lifespan
- The dentist recommends a crown on a tooth that has never been filled before
When a Crown Is the Right Call
- A cusp has broken or cracked (a filling cannot replace a missing cusp)
- The tooth has had a root canal (weakened structure needs full coverage)
- More than half the tooth is already filling material
- The tooth has been filled and refilled multiple times
- The crack extends below the gum line
Insurance Classification Differences
The type of restoration directly affects how much insurance pays. This creates a financial incentive that can influence your decision.
80%
Fillings
Basic restorative. Your out-of-pocket: $30-$90 for a $200 filling.
50%
Inlays & Onlays
Major restorative. Your out-of-pocket: $250-$750 for a $1,000 inlay.
50%
Crowns
Major restorative. Your out-of-pocket: $400-$1,500 for a $1,500 crown.
The jump from 80% to 50% coverage means your out-of-pocket cost increases dramatically when you move from filling to inlay/onlay/crown territory. This is worth discussing with your dentist when the treatment is borderline.
CEREC Same-Day Ceramics
CEREC (Chairside Economical Restoration of Esthetic Ceramics) uses a 3D scanner and in-office milling machine to create ceramic inlays, onlays, and crowns in a single visit. This eliminates the temporary restoration and second appointment required by traditional lab-made restorations.
CEREC restorations typically cost $500 to $1,000 for inlays/onlays, which falls between a large composite filling and a traditional lab-made ceramic. Not all dental offices have CEREC equipment, but availability is growing.
CEREC blurs the line between a filling and an inlay. If your dentist recommends a CEREC inlay for a borderline cavity, it may be a reasonable middle ground: more durable than a large composite filling, less expensive and invasive than a crown, and completed in one visit.