Purpose To analyze the accuracy of transferring casts in maximal intercuspal position to a virtual articulator by using transfer plates in the laboratory scanner before and after occlusal optimization. Material and methods Five sets of standard dental casts were mounted on a mechanical articulator in maximal intercuspal position. The number and position of occlusal contacts were determined with 12‐μm articulating foil. After a calibration process according to the manufacturer's instructions, the mountings were transferred to a virtual articulator using the transfer plates in a laboratory scanner. The occlusion of the digital casts was determined before and after the occlusal optimization process. Then, the sensitivity and positive predictive value were determined by comparing the occlusal contact points in the virtual articulator with those in the mechanical articulator. To evaluate trueness, the occlusal surface of the maxillary teeth in the mechanical articulator was recorded by polyvinyl siloxane occlusal record in maximal intercuspal position and retained on the mandibular arch. The trueness was calculated as the deviation between the occlusal surface of the maxillary teeth in the mechanical articulator and the virtual articulator. To evaluate precision, one set of the casts was scanned 10 times. And the deviation of the interarch position of the maxillary arches when superimposing the mandibular arches of every 2 different scans was calculated. Results The sensitivity before occlusal optimization (0.14 ± 0.15) was significantly lower than that after occlusal optimization (0.82 ± 0.10) (p = 0.003). However, there was no significant difference between the positive predictive value before (0.80 ± 0.45) and after (0.81 ± 0.09) occlusal optimization (p = 0.952). The trueness before (91.0 ± 10.7 µm) and after (75.4 ± 25.2 µm) occlusal optimization had no significant difference (p = 0.249). The precision before occlusal optimization (11.6 ± 3.8 µm) was significantly superior to that after occlusal optimization (75.6 ± 39.2 µm ) (p < 0.001). Conclusions The accuracy of transferring casts in maximal intercuspal position to a virtual articulator using transfer plates in the laboratory scanner could be improved after occlusal optimization and can meet the clinical needs for occlusal design and analysis of prostheses.

Background Precise occlusal design of implant-supported fixed prostheses is difficult to achieve by the conventional wax-up method, often requiring chairside adjustments. The computer-aided design (CAD) method is promising. This study aims to compare the occlusal contacts and clearance of posterior implant-supported single crowns designed by the CAD and conventional methods. Methods Sample size calculation indicated fourteen samples per group. Two sets of type-IV plaster casts with a single implant analog inserted in the posterior teeth region were mounted as master casts in a mechanical articulator in maximal intercuspal position (MIP). Seven working cast sets were obtained from each master cast by a closed tray technique, and mounted in MIP. Two implant-supported single crowns were designed with an occlusal clearance to achieve light occlusal contact in each working cast set by CAD and conventional method, separately. For the CAD group, the crown was designed in digital models obtained by scanning the working casts. For the conventional group, wax-up of the crown was prepared on the working casts and scanned to generate a STL file. In the working and master casts, mean and minimum occlusal clearances in the designed occlusal contact area of the both finished prostheses were calculated using the occlusal clearance (OC) and occlusal record (OR) method. The prostheses’ occlusion was evaluated in master casts. Results For the evaluation in the working casts, both design methods had similar mean occlusal clearances by the OC method (195.4 ± 43.8 vs. 179.8 ± 41.8 μm; P = 0.300), while CAD group resulted in a significantly larger minimum occlusal clearance in the designed occlusal contact area (139.5 ± 52.3 vs. 99.8 ± 43.8 μm; P = 0.043). Both design methods had similar mean and minimum occlusal clearances by the OR method (P > 0.05). For the evaluation in the master casts, both design techniques had similar mean and minimum occlusal clearances, number and distribution of occlusal contacts, and lateral interference ratios (P > 0.05). Conclusion Occlusal contact and clearance of posterior implant-supported single crowns designed by the CAD method can be at least as good as those designed by the conventional wax-up method.

Objectives: To investigate the effect of a novel interocclusal recording method on the occlusal accuracy of implant-supported fixed prostheses for partially dentate patients with distal extension. Materials and Methods:Twenty patients with two or more adjacent teeth missing in the distal extension and scheduled to receive implant-supported fixed prostheses were enrolled. Two interocclusal recording methods were used: placing polyvinyl siloxane (PVS) on the interocclusal recording caps (test), and placing PVS on healing abutments (control). The intraoral occlusal contacts in maximal intercuspal position (MIP) were compared with those in the mounted casts to calculate sensitivity and positive predictive value (PPV). Then, patients were randomly allocated into two groups to determine which interocclusal record would be used. The implant prostheses' evaluations mainly included occlusal adjustment height, volume, and time, occlusal contact score based on articulating paper examination. Paired-samples t-test, Mann-Whitney U test, and least squares regression analyzed the statistic differences. Results:The test method had higher sensitivity to detect intraoral occlusal contacts than the control method (p = .002), but similar PPV (p = .10). During the prostheses' evaluations, the occlusal adjustment height in the test group was significantly lower than that in the control group [99.4 (53.2, 134.2) vs. 159.0 (82.3, 247.8) μm, p = .03],while the occlusal contact score before adjustment was higher (p = .006). The groups had similar occlusal adjustment volume and time. Conclusions:The novel interocclusal recording method for implant-supported fixed prostheses was more accurate and could reduce the occlusal adjustment.