Tips for fixed removables

Whether working with a milled bar or a cast bar knowing what will be built around it comes from experience. Different technicians and labs follow different protocols for working on these cases, but there are definite factors that must be taken into account when creating a denture that will be attached to a number of implants.

Amos Harting, CDT, owner of Harting Dental Arts Lab in St. Louis said he likes to design a bar to attach the implants and then scan the bar design to allow digital production. The actual denture design will come from the patient’s anatomy and the implant placement. It will need to provide the function and esthetics based on any limitations created by those factors.

“You build the foundation first and then put the house on top of it,” Harting said. “If you don’t design the foundation right, the top of the house is never going to be right, or the hybrid denture or crown and bridge case is never going to be right.”

Another factor that must be considered is the bite forces involved with a restoration that is mounted to implants. Because they are screwed into bone without a periodontic ligament beneath it, implant supported prosthetics need to be able to withstand extreme bite forces, said Preat Corp. founder and CEO Tom Bormes. Still with the problem of retention solved by the implants, the design of these restorations can focus on how to esthetically replace the patient’s natural function.

But even with that variable removed, Jim Collis, CDT, owner of Collis Prosthodontic Laboratory in Rolling Meadows, Ill., said the designs for these restorations require a lot of thought. The placement of the implants can determine how the occlusion should be set and what materials to choose. The fact that there will be a rigid bar behind the teeth and implants behind the bar means the denture teeth chosen for the restoration must be very strong, because if one breaks off, it will be difficult to retrieve the fixed dentures to replace the tooth.

“You have to make sure you use the proper tooth,” Collis said. “You want to use a tooth that is consistent in its material make up.”

Chuck Genco, CDT, General Manager of Van Hook Dental Studio in Tempe, Ariz., agreed saying the choice of teeth is important, and he likes to use Ivoclar Vivadent’s SR Phonares or Hereaus’ Premium teeth. There is a wide range of systems Genco feels comfortable working with, and he said the material options in terms of teeth and acrylics make it possible to find a solution to fit almost every case.