implant crown failure

In March I had a second implant and crown placed next to an existing implant and crown, both molars on the lower left side.  When the dentist placed the crown in March, it felt tight, but I got used to it.  Last week, the crown next to the new crown came apart while eating a piece of bread.  I'm wondering if the friction between the two crowns caused by the fit being too tight caused the crown to fracture over time.

Many thanks,
Cristi

[scottma]

If the crown is porcelain fused to metal, it is unlikely that the crown breaks into pieces. I would assume porcelain chips off  and the metal substructure is intact. The reason for  porcelain fracture is too much occlusal forces imposing on the crown. Going back to your restorative dentist is advised.

[pchendry]

thanks for the reply. I wasn't sure from your reply - do you think that the tight fit between the two crowns caused one of them to fracture?   Yes, the post is still there and intact.  Only the crown fractured and fell apart.   I've been back to the dentist who is fitting the crown - he is consulting with the endodontist and thinks the top of the post needs to be replaced.  But I think the issue is with the fit between the crowns.  

[scottma]

Tight contact is probably not the cause of porcelain fracture.