Mechanical Behavior and Fracture Loads of Screw‐Retained and Cement‐Retained Lithium Disilicate Implant‐Supported Crowns

• Published in: Journal of prosthodontics 2021-10, Vol.30 (8), p.690-697
• Main Authors: Camatta, Hercules Pessin, Ferreira, Rodrigo Melim, Ferrairo, Brunna Mota, Strelhow, Samira Sandy, Rubo, José Henrique, Mori, Aline Akemi, Ferruzzi, Fernanda
• Format: Article
• Language: English
• Subjects: Cement; cement‐retained prosthesis; ceramics; Dental prosthetics; Dentistry; Implant supported prosthesis; Lithium; Load; Mechanical loading; Mechanical properties; screw‐retained prosthesis; Titanium; titanium inserts; Ti‐base; Transplants & implants
• ISSN: 1059-941X; 1532-849X
• DOI: 10.1111/jopr.13298

Purpose To evaluate the fatigue survival, fracture loads and failure modes of monolithic lithium disilicate screw‐retained crowns, attached to titanium insert, and cement‐retained crowns. Materials and Methods Internal tapered connection implants, embedded in acrylic resin at 30° inclination, were restored with lithium disilicate restorations, simulating a maxillary premolar (n = 20), with different designs: screw‐retained titanium base abutment‐crowns, and cement‐retained crowns. The specimens were submitted to cyclic mechanical loading (1.2 × 106 cycles with a load of 0‐250 N at 2 Hz). Surviving specimens were subjected to single load to fracture in a universal testing machine and failure modes were determined with the aid of an optical microscope. Maximum load values were analyzed statistically using the t‐test and differences in failure modes were analyzed using the chi‐squared test (α = 0.05). Results All specimens survived the cyclic mechanical loading. Fracture load was significantly higher for screw‐retained crowns (821.69 ±196.71 N) than the cement‐retained crowns (577.03 ± 137.75 N) (p = 0.005). Ceramic failure was the predominant mode, with no statistical difference between groups. Conclusions Screw‐retained and cement‐retained lithium disilicate crowns survived the cyclic mechanical loading. The use of titanium inserts to support a monolithic restoration enhances the fracture strength of the crown/abutment system.