In general, most dentist do not guarantee crowns for more than a few months, so I would not expect your dentist to cover crowns that are 4 years old. However, at my office, we guaranty our crowns will not crack, chip or full off for at least 10 years, but we expect our crowns to last 20-30...
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...
Based on the photo that you've provided, it appears that your husband may very well need a crown. Not having dental insurance should not be a huge barrier, because dental insurance usually doesn't pay more than 50% of the cost of crowns anyway and no more than $1,000 to $2,000 per year....