Zirconia is a durable and aesthetically pleasing material that can be used to provide patients with a well-fitting prosthesis. It is also a particularly desirable choice for edentulous patients wishing to replace a complete arch of teeth. Outlined below is an overview of the fabrication process, although the exact procedure can vary.
After the preliminary impression is taken with impression copings, the dental lab will create an initial working model, complete with soft tissue. Next, a bite block is created with screw-retained temporary cylinders and a wax rim. These non-engaging temporary cylinders help ensure the bite block will not move while being used to record the jaw relationship. Once the bite block has been smoothed and finished, notches or retention grooves are created in the posterior surfaces. These grooves help improve the accuracy of the bite recording through retaining impression material from the opposing bite.
Bite registration can be taken in a conventional way, using the cylinder screws to keep the bite rim firmly in place. The shade and mold of denture teeth are selected during this appointment. Once bite registration has been completed by the clinician and returned to the dental lab, the working model is mounted on an articulator and evaluated to ensure the implant trajectories are correct or are adjusted as needed. Approximately 10mm of clearance is needed for a full zirconia implant-retained prosthesis. The next stage is to set up the prosthesis as a wax try-in for the patient. The wax try-in can be evaluated in the same way as an ordinary denture try-in. If adjustments are needed, a new bite registration should be taken.
At this stage, the dental lab will also provide a verification jig and a special custom tray. The verification jig helps ensure a passive fit and is supplied fully sectioned and numbered so each section can be seated on the appropriate implant. Once correctly in place, the sections can be bonded together with a suitable material. The final impression is taken using the special custom tray fitted over the verification jig. The entire case is then returned to the dental lab.
If the wax try-in was approved, the provisional prosthesis can be made and fitted and which serves as a temporary. This temporary prosthesis is designed and fabricated using CAD/CAM technology and patients can wear the temporary for up to four weeks to evaluate its function and design. The final appointment is to fit the permanent prosthesis which can then be screwed in place. It is best to cover the screws with cotton or another material before sealing up the access holes with light cured composite or acrylic. The access holes should be covered to prevent bacterial build-up.
Patients generally need a follow-up visit a week later in order to check that the occlusion is perfect. After this time, they should follow a regular maintenance schedule that includes six month hygiene appointments where prophylaxis is performed underneath the prosthesis. The prosthesis should be removed annually for a more thorough cleaning allowing for the condition of the screws to be assessed. Any showing signs of wear can be replaced at this time.
From start to finish, a full zirconia implant retained prosthesis will need a minimum of five dental appointments. If modifications are required at the try-in stage, this number will increase. Although the procedure is complex, the final restoration should be aesthetically pleasing and will be resistant to fractures, chips, and stains.
Please be reminded that should you wish to discuss an implant case in more detail, our experienced technical team is here to assist you.