My question is can a type 4 gold inlay/onlay be converted into a type 4 gold crown ?

If you were a patient in my office, I'm sure my lab would not mind making the switch.  The full crown would likely cost you more because in would contain a lot more gold.  I am amazed that you decided to go with a gold inlay/onlay, because most cosmetic dentists place bruxzir (full zircoium) crowns on back teeth for the strongest and most cosmetic solution.  Zirconium crowns are extremely strong and long lasting.  They are the same material that makes up man-made diamonds, known as cubic zirconias, which have about 80% of the strength of natural diamonds.  Good luck and I hope this helps. Follow me if you have more questions.Sarah Thompson, DMD

Good thing the endodontist discovered the crack, as this is one of the huge reasons teeth fail and need to be extracted.  The full crown will cover more of the tooth and give you much more protection.Unfortunately, your dentist will have to change the way he prepared your tooth, take a new impression, and the lab will have to make a completely new crown.  The lab can most likely use the gold from the inlay/onlay, but will undoubtedly need more gold for the full crown.  But honestly, the cost of the crown and the dentist's costs from the lab have little to do with the actual amount of gold used.  The majority of the costs have to do with the time and labor, both from the dentist and the lab.You appear to have your facts backward, gold does not flex better than composite, it flexes less!  Gold is also stronger than composite.That being said, unless it is your very back tooth, most dentists would recommend some kind of porcelain restoration rather than gold.  Porcelain-fused-to-metal is the most common type of restoration.  Newer all-porcelain materials like Emax porcelain, are for many dentist rapidly becoming their material of choice.  It has no metal in it, but extremely strong, well fitting and natural looking.  And, it can be bonded to the tooth for a better seal, something that can't be done with gold crowns.  In my mouth, I would want Emax rather than gold, unless it was the very back molar.

I am glad to see your dentist is an advocate of gold.  I am too.  I have gold crowns on all four of my second molars.  I expect to die with them.  Yes, your dentist can modify the inlay preparation to include coverage of the pointy (cusp) areas of your tooth.  Then your inlay moves into an onlay/crown design.  This is a good treatment for second molars.  On first molars, there is a chance that the gold will flash at the edge of your smile or as you talk.  And if you have a tooth colored provisional in there now, you will not know this until the gold restoration is cemented.  I very rarely put gold crowns on first molars.  If your tooth in question is a first molar or a tooth closer to the front of your mouth, I advise you to inquire about an eMax crown.  As we are both in CT, If you would like to talk more, or would like more information, please follow me or contact us through my website. Good luck!