Implant crowns don’t fit well: What can I do?

I had four dental implants put in around 12-18 months ago. Two of them I have no problems with, but the two other ones on my lower right jaw, canine and premolar regions 43 and 44, have just looked and felt wrong since the implant crowns were put in. They don’t fit right, and one is also much shorter than the teeth it is next to. The bulge on the inside of my mouth where the implants crowns are is now too thick and causes my tongue to either get bitten or I have to tuck it behind and under the implant crowns. There is also some gum trauma from the ill fitting crowns. My dentist says that he can’t make them any thinner because this would seriously jeopardize the strength and stability of the implants and crowns. Also, he claims the dentist who placed the implants didn’t put them in deep enough, and that’s why the crowns don’t fit. Either way something needs to be done. I’m wondering what you think may be wrong and how might I fix the problems with the crowns?

![]implant crowns that don't fit](http://choosedentalimplants.com/wp/wp-content/uploads/gravity_forms/2-bc85009ec8be9291457147b316f87deb/2013/02/image.jpg)