Fracture resistance of single-unit implant - supportedcrowns: effects of prosthetic design and restorative material

Fracture Resistance Of Single-Unit Implant-Supported Crowns: Effects Of Prosthetic Design And Restorative Material Fracture Resistance Of Single-Unit Implant-Supported Crowns: Effects Of Prosthetic Design And Restorative Material Fracture Resistance; İmplant; PEEK; Screw-Cement Crown. Fracture Resistance; İmplant; PEEK; Screw-Cement Crown. Purpose: To evaluate the fracture resistance and fracture patterns of single implant-supported crowns with different prosthetic designs and materials.Materials and Methods: One hundred and forty-four identical crowns were fab-ricated from zirconia-reinforced lithium silicate (ZLS), leucite-based (LGC), andlithium disilicate (LDS) glass-ceramics, reinforced composite (RC), translucent zir-conia (ZR), and ceramic-reinforced polyetheretherketone (P). These crowns weredivided into 3 subgroups according to restoration design: cementable crowns on aprefabricated titanium abutment, cement-retained crown on a zirconia-titanium baseabutment, and screw-cement crown (n = 8). After adhesive cementation, restorationswere subjected to thermal-cycling and loaded until fracture. The fracture patternswere evaluated under a stereomicroscope. Statistical analysis was performed by us-ing 2-way ANOVA/Bonferroni multiple comparison post hoc test (α = 0.05).Results: For each prosthetic design, ZR presented the highest fracture resistance(p ≤ 0.005). Other than the differences with ZLS and RC for screw-cement crowns(p > 0.05) and RC for crowns on zirconia-titanium base abutments (p > 0.05), LGCshowed the lowest fracture resistance. P endured higher loads than LDS (p < 0.001),except for the crowns on zirconia-titanium base abutments (p > 0.05). Cementablecrowns presented the highest fracture resistance (p < 0.001), other than LGC andLDS. The differences between LGC crowns (p > 0.05) or LDS crowns on prefab-ricated titanium and zirconia-titanium abutments were nonsignificant (p = 0.133).Fragmented crown fracture was predominant in most of the restorations. Screw andabutment fractures were observed in ZR screw-cement crowns, and all P crowns wereseparated from the abutments.Conclusions: Restorative material and restoration design affect the fracture resis-tance and fracture pattern of implant-supported single-unit restorations. Cliniciansmay restore single-unit implants in premolar sites with the materials and prostheticdesigns tested in the present study.