If you’ve ever been told you “need a filling” (or an inlay, or a crown) and you nodded along while quietly thinking, “Wait… what are we actually talking about here?”, you’re not alone. Dental treatment names can sound like they’re describing the same thing: fixing a tooth. And yes, they’re all ways to repair damage—but they’re not interchangeable.
Think of a tooth like a small, high-performance tool. It has a hard outer shell (enamel), a supporting layer (dentin), and a living center (pulp). When damage happens—from cavities, cracks, wear, or old dental work breaking down—the right repair depends on how much tooth structure is missing and where that damage sits. That’s where fillings, inlays/onlays, and crowns come in.
This guide breaks down the differences in plain language: what each option is, when it’s used, what it feels like to get it done, how long it lasts, and how to decide between them without needing a dental dictionary. Along the way, we’ll also touch on cosmetic alternatives and related treatments so you can see the full picture of modern tooth repair.
Start with the basics: what problem are we solving?
Most restorative dental work is trying to solve one (or more) of these issues: decay (a cavity), a fracture or crack, worn-down tooth structure, or a failing old restoration. The key question isn’t just “Is the tooth damaged?” but “How much of the tooth is compromised, and can it still handle biting forces?”
Small damage can often be patched with a filling. Moderate damage might call for a more engineered piece like an inlay or onlay. Bigger structural loss—especially if the tooth is cracked, heavily decayed, or has had a root canal—often needs the full-coverage protection of a crown.
Another factor is location. Back teeth (molars) take serious chewing pressure, so restorations need to be strong and stable. Front teeth can be about strength too, but aesthetics often play a bigger role. That’s why the “best” option is usually the one that fits your tooth’s needs, your bite, and your goals—not just what’s cheapest or fastest.
Fillings: the quick repair for small-to-medium cavities
What a filling actually is
A filling is the most common dental restoration. After removing decay (or cleaning up a small fracture), the dentist places a material into the missing space to rebuild the tooth’s shape. The goal is to seal the tooth, stop further decay, and restore normal function.
Today, most fillings are tooth-colored composite resin. It bonds to the tooth and can look very natural. Silver-colored amalgam fillings still exist too, though they’re less common than they used to be, especially on visible teeth.
Fillings are a great solution when the tooth still has plenty of strong enamel and dentin around the damaged area. In other words: the tooth is mostly intact, and you just need to patch a localized spot.
When fillings make the most sense
Fillings are usually recommended for small to moderate cavities, minor chips, and areas of wear that don’t involve a big portion of the chewing surface. They’re also commonly used to replace older fillings that have worn down or developed leakage at the edges.
They’re popular because they’re typically done in one visit, require less removal of healthy tooth structure than bigger restorations, and are cost-effective. If the damage is limited, a filling can be an excellent long-term solution.
That said, fillings have limits. If a cavity is wide or deep, a filling may not have enough tooth structure to bond to securely, or it may flex under pressure and crack over time. That’s where inlays, onlays, or crowns may be the better call.
Pros, trade-offs, and what can go wrong
On the plus side, composite fillings look natural and bond well, and they can often be repaired if a small edge chips. For many people, they’re the simplest way to get back to eating comfortably without a big procedure.
The trade-off is durability in larger restorations. Composite can wear down over time, especially in people who grind their teeth or have a heavy bite. Fillings can also stain at the margins, and if there’s not enough tooth left supporting them, they can crack or fall out.
If you’ve ever had a filling replaced with a bigger filling, and then a bigger one again… that’s a common “restoration cycle.” The more tooth structure you lose, the more you may need a restoration that reinforces the tooth rather than simply patching it.
Inlays and onlays: the “custom-fit” middle ground
What are inlays and onlays?
Inlays and onlays are indirect restorations, meaning they’re made outside your mouth (in a lab or with in-office milling) and then bonded onto your tooth. They’re often made from porcelain/ceramic, composite, or gold.
An inlay fits inside the cusps (the pointed parts) of a tooth—kind of like a precise puzzle piece that fills the center. An onlay goes a step further and covers one or more cusps, wrapping over part of the chewing surface for extra strength.
People sometimes call these “partial crowns,” but it’s better to think of them as a strong, custom-built upgrade from a large filling. They’re designed to restore shape and strength without covering the entire tooth like a crown does.
When an inlay/onlay is usually the best option
Inlays and onlays are often recommended when a cavity or old filling is too large for a standard filling, but the tooth still has enough healthy structure that a full crown would be overkill.
They’re especially useful on molars and premolars where chewing forces are high. If the tooth has a fractured cusp or a large area of decay on the biting surface, an onlay can protect the tooth from splitting while preserving more natural tooth than a crown would.
They can also be a smart choice if you want something longer-lasting and more stain-resistant than a large composite filling, particularly if you’ve had repeated issues with fillings breaking in the same tooth.
Why they’re often stronger than large fillings
Large fillings can behave a bit like a patch on a cracked sidewalk: they fill the hole, but they don’t always reinforce the surrounding structure. Inlays and onlays, on the other hand, are made as a single solid piece and bonded to the tooth, which can help distribute biting forces more evenly.
Because they’re fabricated outside the mouth, they can be shaped with very precise contacts and contours. That can mean better fit, better bite alignment, and less chance of the “high spot” feeling that sometimes happens with direct fillings.
And since many inlays/onlays are ceramic, they can look extremely natural—especially in areas where you don’t want any dark metal showing when you laugh or yawn.
Crowns: full coverage when a tooth needs serious backup
What a crown is (and what it isn’t)
A crown is a cap that covers the entire visible portion of a tooth above the gumline. It restores the tooth’s shape, strength, and function by essentially giving it a new outer shell.
Crowns can be made from porcelain, ceramic, zirconia, metal, or a combination. Modern materials—especially zirconia and high-strength ceramics—can be both durable and good-looking.
A crown isn’t just a “bigger filling.” It’s more like a protective helmet for a tooth that’s at risk of cracking, breaking, or losing more structure. It’s often recommended when the tooth needs reinforcement, not just repair.
Common reasons dentists recommend crowns
Crowns are often used when a tooth has a very large cavity, a major fracture, or a lot of missing structure from repeated dental work. They’re also common after root canal treatment, because root-canaled teeth can become more brittle and prone to cracking.
Another reason is when a tooth is badly worn down from grinding (bruxism) or acid erosion. If the tooth is too short or fragile to hold a filling or onlay reliably, a crown can rebuild it to a stable, functional shape.
If you want a deeper look into how crowns are used as part of a broader tooth restoration plan—especially when teeth are weakened or missing—this is a helpful reference point. (And no, a crown doesn’t automatically mean your tooth was “beyond saving”; it often means you’re saving it in the most protective way.)
What getting a crown is like
Traditionally, crowns take two appointments: one to prepare the tooth and take impressions, and another to cement the final crown. In between, you wear a temporary crown. Some clinics also offer same-day crowns with digital scanning and milling, depending on the case.
During preparation, the dentist removes decay and shapes the tooth so the crown can fit over it. This does involve removing more tooth structure than a filling or inlay/onlay, which is why crowns aren’t the first choice for small damage.
Once placed, a well-fitted crown should feel like a natural tooth. You should be able to chew normally, floss around it, and forget it’s there—other than appreciating that you can finally eat on that side again without worry.
Comparing them side by side: how to tell what you need
How much tooth structure is missing?
This is the big one. If the tooth is mostly intact and the cavity is small, a filling is usually enough. If the cavity is wide or the tooth has a weakened cusp, an inlay or onlay can provide more strength and stability.
If the tooth has extensive damage—like a large fracture, a huge old filling, or very little natural tooth left—a crown is often the safest long-term option. It’s designed to hold the tooth together under pressure.
One way to think about it: fillings replace missing tooth structure; inlays/onlays replace and reinforce; crowns replace and protect the entire outer surface.
Where is the damage located?
Damage on the chewing surface of a molar is different from a small cavity on the side of a premolar. Molars take heavier forces, and restorations there need to withstand years of grinding, chewing, and temperature changes.
Front teeth are a different story. They don’t take the same crushing forces, but they’re more visible and often more prone to chipping. A tiny chip might be managed with bonding, while more extensive damage could require a veneer or crown depending on the situation.
Location also affects aesthetics. Tooth-colored materials are often preferred for visible areas, which can influence whether you choose composite, ceramic, or another option.
How long do these restorations last?
Longevity depends on your bite, oral hygiene, diet, and whether you grind your teeth. But in general: fillings can last many years (often 5–10+), inlays/onlays commonly last longer (often 10–15+), and crowns can also last 10–15+ or more with good care.
The more complex the restoration, the more technique-sensitive it can be. Fit and bonding matter a lot. Two people can get the “same” crown and have very different experiences depending on bite forces, gum health, and how well the margins are maintained.
If you grind at night, a night guard can dramatically extend the life of any restoration—especially ceramics—because it reduces the stress that leads to cracks and chips.
Materials matter more than most people realize
Composite vs ceramic vs metal: a quick reality check
Composite (tooth-colored resin) is commonly used for fillings and sometimes for inlays/onlays. It bonds well and looks natural, but it can wear and stain more than ceramic over time.
Ceramic and porcelain materials are popular for inlays/onlays and crowns because they’re stain-resistant and can mimic natural enamel translucency. Some ceramics are very strong, but they can still chip if you have a heavy bite or clench a lot—especially on thin edges.
Metal (including gold) is incredibly durable and gentle on opposing teeth, which is why it has such a strong track record in back molars. The drawback is obvious: it’s visible. Many people prefer tooth-colored options unless the tooth is far back and aesthetics aren’t a concern.
How dentists choose a material for your specific tooth
Material choice isn’t just “white vs not white.” It’s about thickness requirements, bite forces, how much tooth is left, and whether the margins are near the gumline (where moisture control can be trickier).
For example, a zirconia crown might be chosen for a molar with heavy chewing forces, while a more aesthetic ceramic might be selected for a front tooth where appearance is the priority. Inlays/onlays often use ceramic for a balance of beauty and strength.
Budget can play a role too, but it’s worth asking what you’re trading off. Sometimes paying a bit more for a material that fits your bite and habits can save you from repeated repairs later.
What about chips, cracks, and cosmetic fixes?
Small chips: when bonding can be enough
Not every chip needs a crown. If a front tooth has a small chip and the tooth is otherwise healthy, composite bonding can often restore the shape quickly and naturally.
Bonding is especially handy when the damage is cosmetic or limited to enamel. It can usually be done in one visit and doesn’t require removing much tooth structure. It’s also repairable if it chips again.
If you’re curious about how dentists approach bonding chipped teeth, it’s a great example of a conservative option that can make a big difference—particularly for front teeth, small fractures, and minor shape fixes.
When a crack changes the plan
Cracks are tricky because they’re not all the same. A tiny craze line in enamel might be harmless, while a crack that runs into dentin can spread under chewing pressure. If a tooth is cracked, the goal often shifts from “fill the hole” to “stop the tooth from splitting.”
That’s why cracked molars frequently end up with onlays or crowns. A filling might seal the area, but it won’t necessarily protect the cusps from flexing and pulling apart over time.
If you’ve ever had pain when biting down that disappears when you release, that can be a classic symptom of a crack. It doesn’t automatically mean you need a crown—but it does mean the tooth needs a careful evaluation.
Veneers vs crowns: similar look, different purpose
Veneers are thin shells placed on the front surface of a tooth, mainly for aesthetics—color, shape, minor alignment, or small chips. Crowns cover the whole tooth and are usually about strength and protection as much as appearance.
Sometimes people ask for a crown when what they really want is a cosmetic upgrade, and sometimes they ask for a veneer when the tooth actually needs structural reinforcement. The right choice depends on how much tooth is damaged and how your bite hits that tooth.
For patients exploring smile changes beyond basic repairs, custom veneers can be a helpful topic to read up on—especially if your teeth are healthy but you’re unhappy with their shape or shade. It’s not the same category as a filling or crown, but it often comes up in the same conversations.
The decision-making process: questions worth asking at your appointment
“How big is the cavity or fracture, really?”
It’s completely fair to ask your dentist to show you what they’re seeing—whether that’s on an X-ray, an intraoral photo, or a mirror. Understanding the size and location of the damage helps the recommendation make sense.
If the dentist is recommending an inlay/onlay or crown, ask what would happen if you chose a filling instead. Sometimes a filling is possible but not ideal; other times it’s likely to fail quickly. Knowing the “why” makes the trade-off clearer.
You can also ask whether the tooth has cracks, how close the decay is to the nerve, and whether there are signs of leakage around an old restoration.
“What are the risks if I wait?”
Not every issue is an emergency, but some problems get more expensive the longer you ignore them. A small cavity can often be filled. A larger cavity may need an inlay/onlay. If it progresses and the tooth weakens or the nerve gets irritated, you might be looking at a crown—or even a root canal plus crown.
Waiting can also increase the chance of a tooth cracking, especially if there’s already a large old filling or a weakened cusp. That’s one reason dentists sometimes recommend a crown “before it breaks.” It’s not always upselling; it can be prevention.
If cost is a concern, ask about timing and priorities. Sometimes you can stage treatment, but it’s best done with a clear plan rather than hoping the tooth stays quiet indefinitely.
“How will this feel in my bite?”
Comfort matters. A restoration that’s slightly too high can cause soreness, sensitivity, or even jaw tension. Fillings can usually be adjusted quickly. Inlays/onlays and crowns can also be adjusted, though it depends on the material and how much adjustment is needed.
Ask how your bite will be checked, and what to do if something feels off after the appointment. Most dentists expect a small number of bite adjustments—it’s normal and fixable.
If you clench or grind, bring it up. It can influence material choice and whether you should consider a night guard to protect your new restoration.
Aftercare: how to make your restoration last
Daily habits that matter more than people think
Even the best dental work can fail early if plaque builds up at the edges. Brush twice a day, floss daily, and pay extra attention around restored teeth—especially near the gumline where margins can collect plaque.
Diet plays a role too. Frequent sugary snacks and acidic drinks increase the risk of decay around restorations. It’s not that you can never have them; it’s the constant exposure that causes trouble.
If you’re prone to sensitivity after a filling or crown, avoid extremely cold foods for a few days and give the tooth time to settle. If sensitivity lingers or gets worse, that’s worth a follow-up.
Chewing, clenching, and the “don’t use your teeth as tools” rule
Hard foods (ice, hard candy, popcorn kernels) can chip both natural teeth and restorations. Ceramic inlays/onlays and crowns are strong, but they’re not indestructible—especially at thin edges.
Clenching and grinding are major drivers of cracks and restoration failure. If you wake up with sore jaw muscles or notice flattened teeth, ask about a night guard. It’s one of the simplest ways to protect your investment.
Also: don’t open packages with your teeth. It sounds obvious, but it’s a surprisingly common cause of chips and fractures—especially on front teeth.
Real-world examples: what treatment often looks like
Scenario 1: a small cavity caught early
You go in for a routine checkup, and the dentist finds a small cavity between two teeth. The tooth is otherwise strong, and the decay hasn’t undermined the cusps.
In many cases, a conservative composite filling is perfect here. It seals the area, restores the surface, and you’re done in one appointment.
This is the best-case scenario—and it’s why regular exams and cleanings matter. Early detection keeps treatment smaller.
Scenario 2: an old large filling that keeps breaking
You’ve had a big filling in a molar for years. Recently, you’ve noticed it feels rough, or a corner broke off. The tooth has less natural structure left, and the cusps are more vulnerable.
This is where an onlay can shine. Instead of patching the patch again, an onlay can cover and protect the weakened cusp while preserving more tooth than a crown would.
Depending on the crack risk and remaining tooth structure, a crown might also be the safer long-term option. The deciding factor is often how much of the tooth is compromised and whether cracks are present.
Scenario 3: a tooth with a root canal
After a root canal, the tooth is no longer living tissue in the same way, and it can be more prone to fracture—especially if it’s a molar that takes heavy chewing forces.
Many root-canaled teeth are restored with a crown to protect them from splitting. Sometimes a build-up (core) is placed first to replace missing internal structure, and then the crown goes on top.
There are exceptions, but the general idea is: once a tooth has been significantly weakened, full coverage is often the best insurance policy.
Quick myth-busting that helps the whole topic make sense
“A crown means my tooth is doomed”
Not true. A crown is often a way to save a tooth that would otherwise crack or keep losing structure. It’s protective, not punitive.
In fact, many crowned teeth last for decades with good care. The crown doesn’t make the tooth “worse”—it’s usually placed because the tooth needs reinforcement.
The real risk is ignoring a tooth that needs coverage until it fractures below the gumline, which can make it much harder (or impossible) to restore.
“Inlays/onlays are just fancy fillings”
They do replace missing tooth structure like fillings, but the method and performance can be very different. Because they’re made as a single solid piece and bonded, they can be more durable and precise for larger restorations.
They’re not always necessary, and they’re not always the best option—but they fill an important gap between “simple filling” and “full crown.”
If your dentist suggests an onlay instead of a large filling, it’s often because they’re trying to reduce the chance you’ll be back in a year with a broken cusp.
“If it doesn’t hurt, I don’t need to treat it”
Unfortunately, cavities and cracks can be painless until they’re big. Pain often shows up when the problem is close to the nerve or when a crack starts moving under pressure.
That’s why X-rays and exams matter: they find issues before they become emergencies. Treating early is usually simpler, faster, and less expensive.
If you’re on the fence, ask for clarity on what the dentist sees now and what the likely progression looks like over time.
Fillings, inlays/onlays, and crowns all do the same general job—repairing teeth—but they do it at different levels of strength and coverage. The “right” choice depends on how much tooth is damaged, where the damage is, and how much protection the tooth needs to keep functioning comfortably for years.