All-on Four Titanium Embedded in Acrylic prosthesis not tacking down?


I would gratefully appreciate some direction on this situation. I don’t do a lot of these, so I do not know for sure if this can be remedied easily. Upon delivery of a Nobel Biocare implant case, I was able to seat one or two of the retention screws. However, the other two did not seem to bite and I was not able to torque them. The screws continued to turn without tightening. I had tried a try-in of the bar only and I was able to torque all the screws. I don’t understand what happened.

I have had occasion to remove the prosthesis for some minor soft tissue grafting on the posterior abutments. I found a lot of plaque/food debris around the abutments. Am I correct in thinking that if the cylinders were fitting properly, this would not be found?

I suppose my bar is not completely accurate and what I am wondering, is if it is reasonable to section the prosthesis into 4 segments, screw them into the implants and lute them together with acrylic for welding at the lab. Has any one else performed this procedure and is it feasible?

Thank you ever so much for anyone’s advice in advance. If more information is needed I will respond. And thank you for this forum.