Marginal-internal adaptation and fracture resistance of CAD/CAM crown restorations

Abstract

This study evaluated the marginal adaptation and fracture resistance of CAD/CAM-fabricated zirconia crowns luted using different luting agents. Twenty crown restorations were produced using IPS ZirCAD zirconium oxide blocks (IZC), and another 20 using Lava zirconium oxide blocks (L). Ten teeth were used as control. Luting agents used were an etch-and-rinse adhesive (Variolink II) and a self-etch adhesive (Multilink Automix). Internal and marginal adaptation was evaluated using silicone replica technique. Fracture resistance was evaluated using a compression test. Marginal discrepancy was 89.26 μm for L crowns and 88.84 μm for IZC crowns, and difference was statistically insignificant. However, L crowns showed significantly larger axial and occlusal gaps than IZC crowns (p<0.05). Fracture resistance of IZC-Multilink was higher than the other groups, although the difference was not significant. Results showed that CAD/CAM-fabricated crowns showed acceptable in vitro marginal discrepancies and fracture strengths.

Comparative fracture behavior of monolithic and veneered zirconia posterior fixed dental prostheses

“…Lava Zirconia is the most studied zirconia system. The results of the study are similar to previous studies in crowns 21,22) , but higher than the most studies in FDPs, with values below of 2,000 N 23,24) . Nevertheless, it is important to consider that fracture load presented by the groups tested, higher than 1,000 N, was higher than maximum chewing forces reported in the literature, which is expected to be around 700 N for healthy young adults 21,25) .…”

“…In the study 3-point flexure test until fracture was used as previously reported 4,18) . The veneering ceramic fractured before than the core in 100% of the Lava zirconia FDPs, similar to previous study in crowns 21) , but different to other findings 22) . Chipping of porcelain veneer could be due to a higher mechanical properties of zirconia core 28) .…”

In vitro evaluation of marginal and internal adaptation of three-unit fixed dental prostheses produced by stereolithography

“…As with some specimens, however, the marginal gap figures were even beyond 120 µm which was considered a clinically acceptable value of marginal gap for McLean and von Fraunhofer 19) . The silicone replica technique, which was used as a gap measure in this study, has been widely used in previous studies 10,[15][16][17][18] . Harris and Wickens 17) reported that the advantage of this method is its nondestructiveness, in that the FDP models or tooth preparations are protected.…”

“…These 12 points were classified as one of margin (points 1, 6, 7, and 12), axial wall (points 2, 5, 8, and 11),and occlusal (points 3, 4, 9, and 10). The gap was defined as the vertical distance between the model and the FDP 14) , the silicone replica technique being used in accordance with prior studies 10,[15][16][17][18] . For measurement, the FDPs were filled with a light body silicone, and approximately 50 N of finger pressure was then applied to the epoxy model along the long-axis of the abutment.…”

Fabrication of crown restoration retrofitting to existing clasps using CAD/CAM: Fitness accuracy and retentive force

“…Regarding the crown alloys in this study, the CAD/CAM crowns were milled from titanium alloy, but an Ag-Pd-Au alloy was chosen for the conventional method since the accuracy of cast titanium could not be enough due to the low castability of the thin area [22][23][24]. Many measurement methods have been reported for evaluating the accuracy of the clasp fitness [25][26][27][28][29][30]. In the present study, fitness accuracy was evaluated by measuring the film thickness using high viscosity white silicone impression material in accordance with the methods of Osada [27] and Shimpo [28].…”