[Computer aided design and manufacturing of the framework of PFM fixed bridge]

We have carried out a research on the method for Computer Aided Design and Manufacturing (CAD/ CAM) of the framework of porcelain-fused-to-metal(PFM) fixed bridge. Taking the missing of the mandibular first molar as an example, firstly, we used ATOS II 3D scanner to collect the 3D data of the abutment teeth and used the acquried data to design the coping crowns. Secondly, the relevant standard bridge was selected from the standard bridges database and was deformed inaccordance to the characteristic of the patient. Then it was set to the correct position between the coping crowns automatically based on the restricting lines and faces. Finally, the connector was designed to connect the coping crowns and the bridge based on the touching area. The final product was manufactured by 3-axis NC milling machine. The results of examination showed that the framework of PFM fixed bridge fitted the abutment teeth very well, and the hardness of the connector and the precision of the whole model were feasible and reasonable. The method of designing and manufacturing the framework of PFM fixed bridge from CAD/CAM is practicable, efficient and accurate. It is also an important part of homemade dental CAD/CAM system.