Fit of 3Y-TZP complete-arch implant-supported fixed dental prostheses before and after porcelain veneering

Abstract

Statement of problemTo minimize technical complications, implant-supported fixed dental prostheses must fit well. The fit of complete-arch veneered zirconia frameworks has not been fully evaluated. PurposeThe purpose of this in vitro study was to evaluate the fit of screw-retained zirconia implant-supported complete-arch maxillary frameworks for fixed dental prostheses before and after porcelain veneering. Material and methodsTen stone casts simulating an edentulous maxilla and provided with 6 abutment analogs were produced. For each stone cast, 1 zirconia framework was fabricated by computer-aided design and computer-aided manufacturing. The fit was analyzed by using a coordinate measuring machine in 3 dimensions (x, y, and z axes) using best fit by virtual matching of center point coordinates before and after porcelain veneering. Also, the horizontal distances between implant position pairs P1–P6, P2–P5, and P3–P4 were measured. Furthermore, an optical microscope was used to evaluate vertical fit at the terminal abutments after porcelain veneering. ResultsBefore the porcelain veneering procedure, the frameworks had a mean horizontal misfit of 27.7 μm in the x-axis and 12.0 μm in the y-axis. In the vertical dimension (z-axis), the mean misfit was 2.4 μm and the mean 3D misfit value was 32.3 μm before veneering. Porcelain veneering increased the mean misfit by 0.2 μm in the horizontal plane (x and y axes), 0.4 μm in the vertical plane, and 0.4 μm in 3D; the difference before and after veneering was not statistically significant (P>.05). The mean ±standard deviation vertical misfit at the terminal abutments was 9.2 ±2.9 μm, optically recorded after porcelain veneering. The measured horizontal distances between implant position pairs P1–P6, P2–P5, and P3–P4 increased to 0.9 μm, 2.0 μm, and 1.9 μm, respectively, after porcelain veneering. The difference for the implant position pair P2–P5 was statistically significant (P<.05). ConclusionsScrew-retained zirconia implant-supported complete-arch maxillary frameworks for fixed dental prostheses have a fit well within the range of 30 μm in the horizontal plane and 10 μm in the vertical plane. The porcelain veneering procedure did not affect the fit of the frameworks.