Purpose: To compare the precision of adaptation of cobalt-chromium (Co-Cr) three-unit fixed dental prostheses (FDPs) fabricated using different techniques.
Materials and Methods: A master model was prepared to receive a three-unit FDP. This model was duplicated 60 times from a silicone mold. The dies (N = 60) were scanned and divided into three groups (n = 20 each) to receive FDPs made of presintered Co-Cr (CS), laser-sintered Co-Cr (LS), or cast Co-Cr (Gi). Frameworks were layered with ceramic, and each framework was seated on its specific model. The replica technique was used to measure the marginal and internal discrepancies in the mesiodistal and buccolingual planes. Prepared silicone samples were examined with scanning electron microscopy. Obtained data were analyzed using Levene test, t test, and analysis of variance (α = .05).
Results: When overall mean discrepancy values were compared in the mesiodistal plane, LS showed better adaptation than Gi (P = .025). Similar adaptation was found for CS and Gi, and for CS and LS (P = .169 and P = 1.000, respectively). In the buccolingual plane, the difference in fit was not significant among the three tested groups (P > .05). In a pairwise comparison between materials, a net increase in discrepancy values was noted between measurement points 1 and 5 (P = .57). Differences in discrepancy values within points were significant. This was confirmed at the abutment level on some measurement points. Within each material, differences were significant at several measurement locations at the abutment level in both the mesiodistal and buccolingual planes.
Conclusion: Within the limitations of this study, three-unit Co- Cr FDPs showed similar marginal and internal discrepancy values. Presintered and laser-sintered Co-Cr alloys can be considered for three-unit FDP fabrication.
