Index / Cosmetic
Crowns & onlays
Keep as much tooth
as the tooth
will let you keep.
A cracked or heavily filled back tooth needs covering. Whether that means a full crown or a partial onlay depends on how much sound tooth is left — and the answer should always be the smaller of the two that will work.
Why people come here
- He teaches occlusion and full-mouth rehabilitation to other dentists
- Fellowships in three academies — FAGD, FACE and FICOI
- The complex cases other practices refer out
- A written, itemized plan before anything is scheduled
Onlay or crown
The difference is how
much gets cut away.
A crown covers the whole tooth, which means reducing it on every surface. An onlay covers only the parts that need covering — the weakened cusps and the biting surface — and leaves the rest of the tooth and its enamel intact. Bonded ceramic made this possible; before adhesive dentistry, the full crown was often the only option.
An onlay is the better choice whenever enough sound tooth remains to support one. A crown becomes the right answer when the tooth is already so broken down, or so heavily filled, that there is not enough left to bond a partial restoration to reliably.
Both are made from the same ceramics. The decision is about how much tooth has to be removed to deliver the result, and it is made with the tooth in front of you, not from a radiograph alone.
Why crowns fail
The porcelain is rarely the culprit.
Patients who have had three crowns break on the same tooth usually assume the material is at fault. Occasionally it is. Far more often the restoration is being asked to absorb a force the bite is concentrating on it, and the next one will break in the same place for the same reason.
That is why the bite is checked and measured before and after a crown is fitted here, and why a tooth that keeps breaking triggers a conversation about occlusion rather than another identical crown. Dr. Nosti published Six Guidelines to Minimize Porcelain Fractures in Dentaltown in March 2011; most of them are about load, not ceramic.
What is actually checked when a restoration keeps failing
- Whether that tooth is taking the first and heaviest contact when you close
- Whether it is being loaded sideways when you move your jaw, which ceramic tolerates far worse
- Whether a clenching habit is multiplying every one of those forces overnight
- Whether the opposing tooth is in a position that makes the problem unavoidable
- Whether the margin is sound, or whether decay underneath is the real story
Questions
Crowns and onlays, answered.
Do I need a crown or can I just have a filling?
A filling restores a tooth; it does not reinforce it. Once a cavity or a crack has taken out enough of the tooth that the remaining walls flex under load, a filling becomes a wedge and the tooth eventually splits. The rough threshold is when the filling is wide enough that the cusps are no longer supported, and that is a judgment made by looking.
Will it need a root canal?
Not usually. Preparing a tooth for a crown or onlay does irritate the nerve and a small percentage of teeth — typically cited in the low single digits for conservative preparations — eventually need root treatment afterward. Teeth that were already heavily filled or already sensitive carry a higher risk, and you will be told if yours is one of them.
How many visits?
Two in most cases: preparation with a provisional, then fitting. Some cases suit a single visit with a digitally designed and milled restoration. Which applies depends on the material the tooth needs and whether the bite requires a provisional stage to test.
Metal, porcelain-fused-to-metal, or all-ceramic?
All-ceramic for almost everything now. Lithium disilicate where appearance matters, zirconia where strength matters most, and gold still has a place on a back tooth in a heavy clencher with limited space — it is kinder to the opposing tooth than any ceramic and lasts a very long time. Porcelain fused to metal is largely a thing of the past.
Keep reading
Next step
Start with an examination and a straight answer.
A consultation includes an examination, the records the case needs and a written, itemized plan. If what you are asking for is not the right treatment, Dr. Nosti will say so and tell you what is.