What is the difference between porcelain with metal crown and Onlay? Which of these have a stronger?

Question

substance and last longest?

Answer 1

Hi! I've been in dentistry for over 25 years years. I'll try to explain this so you understand. I'm assuming this is a a molar tooth.
A porcelain crown fused to metal covers the WHOLE tooth and should last many years. If you have great oral hygiene, it can last 20-25 years. I've seen more.
An Onlay can be gold or porcelain and it fits only the part of the missing tooth. So if you cracked a cusp off, the onlay will cover that plus any other part of the tooth that is decayed or missing.
I personally don't do onlays anymore. The reason is they can decay around the edges when the bonding wears down because people DO grind and clench and the onlay can break. Most peole will NOT wear a night guard every night and you should with an onlay to protect if from grinding in your sleep.
While MOST people don't think the clench or grind they do. But they do. Just go for a drive and see how many times you do. Also the onlay can come lose like a crown, but the fraacture rate is higher. For the cost I would do the crown, it will wear better and and protect the remaining area of tooth and root structure and less chance for a root canal later. IMO

Answer 2

It depends on how much of the tooth is involve.
They're both good restorations however you want to consider preserving as much tooth as possible.
The PFM or porcelain fused to metal is more invasive b/c the dentist will need to shave alot more tooth structure inorder to put the crown over that tooth.
An onlay is less invasive b/c it only restore the part of the tooth that is decay,fracture or missing.
If PFM begins to decay you may not be able to detect it clincally or on x-rays since the crown covers the entire tooth. They can sometimes detect decay by checking the margins (edges of crown next to gum)
On the otherhand, the edges of an onlay may show signs that it is leaking (decay) since it doesn't cover the entire tooth.
Hope this helps