Dental implants when your mouth is too small?

I recently had tooth #30 removed and a bone graft done on that site. The oral surgeon is suggesting a dental implant (this is the last molar I have on that side). My dentist however says that my mouth isn't large enough to allow room to correctly place the implant in the correct position (risking failure due to the position and the weight distribution). Is this something I should be willing to risk? The other option the dentist gave was for a partial on the bottom.