CAD/CAM fabrication accuracy of long‐ vs. short‐span implant‐supported FDPs

Abstract

Abstract Objective To compare the precision of fit of long‐span vs. short‐span implant‐supported screw‐retained fixed dental prostheses ( FDP s) made from computer‐aided‐design/computer‐aided‐manufactured ( CAD / CAM ) titanium and veneered with ceramic. The null hypothesis was that there is no difference in the vertical microgap between long‐span and short‐span FDP s. Materials and methods CAD / CAM titanium frameworks for an implant‐supported maxillary FDP on implants with a flat platform were fabricated on one single master cast. Group A consisted of six 10‐unit FDP s connected to six implants ( FDI positions 15, 13, 11, 21, 23, 25) and group B of six 5‐unit FDP s (three implants, FDI positions 21, 23, 25). The CAD / CAM system from Biodenta Swiss AG (Berneck, Switzerland) was used for digitizing (laser scanner) the master cast and anatomical CAD of each framework separately. The frameworks were milled ( CAM ) from a titanium grade V monobloc and veneered with porcelain. Median vertical distance between implant and FDP platforms from the non‐tightened implants (one‐screw test on implant 25) was calculated from mesial, buccal, and distal scanning electron microscope measurements. Results All measurements showed values <40 μm. Total median vertical microgaps were 23 μm (range 2–38 μm) for group A and 7 μm (4–24 μm) for group B. The difference between the groups was statistically significant at implant 21 ( P = 0.002; 97.5% CI −27.3 to −4.9) and insignificant at implant 23 ( P = 0.093; −3.9 to 1.0). Conclusions CAD / CAM fabrication including laboratory scanning and porcelain firing was highly precise and reproducible for all long‐ and short‐span FDP s. While all FDP s showed clinically acceptable values, the short‐span FDP s were statistically more precise at the 5‐unit span distance.